If you do not need this report after it has served your purpose, please return it to 

the Geological Survey, using the official mailing label at the end

UNITED STATES DEPARTMENT OF THE INTERIOR 

Harold L. Ickes, Secretary

GEOLOGICAL SURVEY 

W. C. Mendenhall, Director

Professional Paper 188

A GEOGRAPHIC AND GEOLOGIC RECONNAISSANCE 

OF SOUTHEASTERN UTAH

BY

HERBERT E. GREGORY 

WITH CONTRIBUTIONS BY MALCOLM R. THORPE

UNITED STATES

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1938

For sale by the Superintendent of Documents, Washington, D. C. - - -- -- ----- Price 60 cents

CONTENTS

A bstract. ___...--_-..---..--_..---_.._.---..

Introduction. _ _________________________

Scope and purpose_________________

Previous exploration________________

Related investigations.__..__-_____..

Acknowledgments, __-_-____-___-__.

Suggestions to travelers_____________

Chapter 1. Geography._________________

Location, extent, and accessibility-... 

Note on the map.__________________

Topographic outline_______-_-_-__.

Geographic districts.________________

Basis of subdivision.____..___._.

Sage Plain_____________________

Abajo Mountains._______________

San Juan Valley_-__--__-_-_-__. 

Elk Ridge-_-__--_------.___-..

Alien Canyon country ___________

Grand Gulch Plateau___________

Lime Creek Valley__-___-__..-._. 

Dark Canyon Plateau.__________

White Canyon.________________

Red Rock Plateau__--_______._.

Wilson Mesa_ _--______-______-

Glen Canyon___________________

Beef Basin.____________________

Climate. ___-___^______--__________

General relations.______________

Precipitation. __________________

Records.__________________

Geographic distribution. 

Variation from year to year_ _ 

Seasonal distribution ________

Temperature. ___-___-_-_____-__

Wind.-___---_--_--_---.-.--.. 

Soil.______-_-_--.---___-__________

Vegetation.________________________

Animal life_________________________

Mineral wealth.____________________

Inhabitants. _______________________

Basket Makers and Cliff Dwellers. 

Piutes, Utes, and Navajos _______

White settlements ______________

History..._ ____ ____________

Population. _ _______________

Industries. _-__--___.___-__ 

Farming.______________

Stock raising.__________

Chapter 2. Sedimentary rocks________---_

General stratigraphic relations__ __. _

Carboniferous formations____________

History and correlation__________

Pennsylvanian formation. _______

Hermosa formation _________

Permian formations______________

Rico formation.____________

Cutler formation____________

Terminology.

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Chapter 2. Sedimentary rocks Continued. 

Carboniferous formations Continued. 

Permian formations Continued. 

Cutler formation Continued.

Halgaito member. __________________

Contact of Halgaito and Cedar Mesa 

members. _______________________

Cedar Mesa sandstone member. ______

Contact of Cedar Mesa and Organ 

Rock members. ___--_-_-_--______

Organ Rock member. _-_-_-_________

De Chelly sandstone and Hoskinnini 

members. ____-__--- ----_-_____

Permian-Triassic erosion interval _______.._.__

Triassic formations. ____________._____._________'

Regional relations. _________________________

Moenkopi formation (Lower Triassic) _________

Moenkopi-Shinarump erosion interval- ________

Shinarump conglomerate. _____-___-._--___-_

Chinle formation. _ _________________________

Chinle-Wingate contact. ____________________

Jurassic formations. __________-__-___..-__-____-_

General features. _ ____-___-__---__--_--.-_-_

Major divisions of the Jurassic _____-___-__-__

Glen Canyon group (Jurassic?) _-_-___---_____

Wingate sandstone... ___________________

Kayenta formation. _ ___________________

Navajo sandstone____ ___________________

San Raf ael group (Upper Jurassic) ____________

Distribution __ _ _______________________

Carmel (?) formation _ _________________

Entrada sandstone. _____________________

Summerville (?) formation. ______________

Morrison formation (Upper Jurassic) j_ ____._._

General features. _______________________

Bluff sandstone member. ________________

Recapture shale member___-_--_.-_____-_

Westwater Canyon sandstone member _ _. 

Brushy Basin shale member______________

Morrison-Dakota (?) contact. __ ______________

Cretaceous formations.. _ ________________________

Distribution and topographic expression _______

Dakota (?) sandstone- ________--__-__--__-__

Lithologic features.. ______-_____-------__

Stratigraphy and correlation _____________

Mancos shale __ ___________________________

Tertiary formations. ____________________________

Quaternary formations. ___--__-___--___-________

Stratigraphic sections.. __________________________

Chapters. Igneous rocks. --________.._----___________

Regional relations. _ _ _-__--__--___-____ _^_ ______

Bell Butte dike....... _ ___________ ________

Petrography of the Abajo Mountains, by Malcolm R.

Thorpe-_--__--__-_.-_---_---'_-___-__.___

Typical rock___________._____-______. ______

Hornblende andesite from Twin Peaks __ _____

Dacite from North Peak____. ________________

m

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SO 

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CONTENTS

	Page 

Chapter 3. Igneous rocks Continued.

Petrography of the Abajo Mountains Continued.

Dacite from Abajo Peak_-.____-__________.__ 81

Dacite from Horsehead Peak_________________ 81

Andesite from Mount Linnaeus.______________ 81

Dacite from Johnson Creek Basin.._________ 81

Andesite from South Peak.__________________ 81

Contact rock from North Creek ______________ 82

Ehy olite from Horsehead Peak _______________ 82

Volcanic breccia at Gold Queen mine__________ 82

Andesite (?) from dike in North Canyon_____ 82

Trachyte from dike in North Cany on _ ________ 82

Rhyolite from dike in North Canyon._________ 83

Hornstone in North Canyon.________________ 83

Dacite dike on Abajo Peak_________________ 83

Andesite dike on Abajo Peak_________________ 83

Gold ore from Recapture Creek_____________ 83

Andesite from Innis mine___-__-_--__________ 84

Metamorphic rock from Duckett mine_______ 84

Greenstone from Dream mine ________________ 84

Low-grade ore from Dream mine_____________ 84

Chapter 4. Structure___---------_--__---_____--_____ 85

Regional relations------------------------._______ 85

Sage Plain downwarp___________________________ 85

Monument upwarp. ____________________________ 85

Comb monocline__________________________ 86

Raplee anticline.___________________________ 86

Mexican Hat syncline________-______________ 86

Mitten Butte anticline._____________________ 86

Oljeto syncline--__--_--_---------_------__- 88

Organ Rock anticline.... __-____-__..---______ 88

Balanced Rock anticline.____________________ 88

Other folds.... .. 88

Faults.----.---.-------_ ._-__--________ __.- 89

Structure of the Abajo Mountains, by Malcolm R.

Thorpe.______________________ ' 89

General features____._______________________ 89

Local features_-----_____---____--_______-__ 90

Chapter 5. Physiography.__-_-__._-_______.---____-- 92

Regional relations_---______-_--______-___----__- 92

Age of the topographic features __________________ 94

Factors that*influence erosion____________________ 94

Climate and run-off.________________________ 94

	Page 

Chapter 5. Physiography Continued.

Factors that influence erosion Continued.

Stream gradients. __________________________ 95

Vegetation__ _ ______________________________ 95

Ground water_ _____________________________ 96

Relation of topography to geology ________________ 96

Relation of streams to structure __________________ 96

Form of valleys __ ____.-_-_----______-________ 97

Rate of denudation. _____-___-----_-----_-----__ 98

Physiographic features. _ ________________________ 99

General relations. __________________________ 99

Erosion surfaces. _ __________________________ 100

Gravel-floored terraces _-___ ______________.__ 100

Canyon fiU...._. .___._________.._._.___ _ _ 101

Alluvial terraces. ___________________________ 101

Landslides.------------------ ______________ 102

White Canyon bridges.------------------- _ 103

Arches and windows- _____--_-______--______ 105

Rock shelters_______--_----___-_______-____ 105

Sand dunes-____---_--_---_---__-_--------- 106

Chapter 6. Economic geology. _______________________ 107

Copper _._ _______________-___---_---__ ___---_-_- 107

Distribution and origin ______________________ 107

Copper Queen mine_ ____________-__-__-_--_- 107

Dolly Varden and Blue Dike mines ___________ -107

Gold_____-_-_---_----------------_- ----------- 108

River placers _ ____________________________ 108

Gold in the Abajo Mountains _______---_-____ 108

Coal. ___------__--__--_-------------------_--- 110

Oil___________ -----_--_----------_------------. 111

Distribution..--. . ___________________________ Ill

San Juan oil field, by H. D. Miser. ____-_-_-._ 111

Oil seeps. _ ______-_--_________-_--____ 111

Development---_______-_____-----_-_-_- 112

Difficulties of exploration. __. ____________ 113

Geologic occurrence of oil.____-_-_---___. 113

Surface water. _____ 

Water for stock

Ground water

Wells.

Index

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ILLUSTRATIONS

PLATE 1. Reconnaissance geologic map and generalized 

sections of the San Juan country, southeastern Utah.-_-_-_-___-___-____.-________

2. A, Abajo Mountains from western edge of Sage 

Plain; B, Lake on flank of Abajo Mountains 

between Johnson and Recapture Creeks; C, 

San Juan River 1 mile below mouth of McElmo Creek____________________________ *

3. A, San Juan Canyon above Honaker trail; B,

San Juan Canyon 6 miles below Spencer 

Camp; C, View looking south across San 

Juan River at Bluff ____-_--__-___-______

4. A, Bears Ears, on south edge of Elk Plateau; 

B, Mexican Hat; C, Lime Creek Valley showing erosion surface and vegetation ________

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PLATE 5. A, Cataract Canyon; B, View looking northwest from head of Armstrong Canyon______

6. A, White Canyon between Rock Springs and 

Soldiers Crossing; B, Clay Hills; C, Entrance 

to Moki Canyon at Red Cone Spring; D, 

Castle Butte on divide between White 

Canyon and Red Canyon._______________

7. Glen Canyon: A, View looking upstream at 

junction of Colorado and San Juan Rivers; 

B, View looking southwest across the canyon 

at Hite; C, View looking downstream at 

mouth of Moki Canyon______-___________

8. A, Ruins of cliff house, Hovenweep National 

Monument; B, Ruins of Cliff Dwellers' house, 

Butler Wash; C, Cliff house in White Canyon ___________________________________

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CONTENTS

Page

PLATE 9. A, Navajo summer house near mouth of Butler 

Wash; B, Red House Cliffs, 4 miles north of 

San Juan River; C, Wall of Johns Canyon 

near its head; D, Sandstone and shale in 

Armstrong Canyon____--_-__----_-_--___ 42

10. Columnar sections: A, Kaiparowits region; 

B, San Juan country; C, Southwestern Colorado__._________-__--___--__-_-______ 42

11. A, View in Johns Canyon near its junction with 

San Juan Canyon; B, Wall of Road Canyon; 

C, Wall of Arch Canyon near its head- _____ 58

12. A, Cliff near Star Springs, White Canyon; B, 

East entrance to Clay Hills Pass; C, View on 

Rasp trail; D, Variegated marls at Clay 

Hills. _________________________________ 58

13. A, Divide between White Canyon and Red 

Canyon; B, Wall of Castle Wash; C, Dry 

Creek, Alien Canyon country; D, West face 

of Black Mesa-___-__--------__---_--__- 58

14. A, View near mouth of Cottonwood Wash; B,

Goblet of Venus; C, Brushy Basin___.___- 58

15. Correlation chart showing relations of the 

Jurassic formations of the San Juan country 

to those in adjoining regions._____________ 58

16. A, View on Recapture Creek; B, Comb Wash 

at mouth of Arch Canyon; C, Eastern flank 

of Monument upwarp on Blanding-Kigalia 

road; D, West flank of Raplee anticline at 

Mexican Hat.._______--_._..---__-__-__ 90

17. Geologic and topographic map and sections of

the Abajo area, San Juan County, Utah____ 90

18. A, Valley of Butler Creek; B, Talus slope on 

igneous rock in Abajo Mountains; C, Balanced Rock anticline.---.---__--__--___- 90

PLATE 19. A, Comb Wash; B, Owachomo Natural Bridge 

in wall of Armstrong Canyon. _ ___________

20. A, Valley fill of sand and clay exposed by recent 

erosion in Comb Wash; B, Sipapu Natural 

Bridge, White Canyon _ ________________

21. Kachina Natural Bridge, White Canyon. ____

22. Diagrams showing formation of natural 

bridges: A, Sipapu Natural Bridge; B, 

Kachina Natural Bridge. __-___-_---_-___

23. A, Fishmouth Cave; B, View across White 

Canyon at Sipapu Natural Bridge; C, Cathedral Arch, Arch Canyon....... ________

24. Natural arches in Arch Canyon: A, Cathedral 

Arch; B, Keystone Arch____-_._______l__

25. Rock shelters: A, B, C, In Cedar Mesa strata 

in White Canyon; D, In Bluff sandstone 

member of the Morrison on the north side/ 

of San Juan River near Bluff.^ __________

26. Rock shelters: A, At contact of Bluff sandstone and San Rafael strata on the south 

side of San Juan River near Bluff; B, In 

Cedar Mesa sandstone, Fable Valley. _____ 

FIGURE 1. Diagram showing seasonal and annual distribution of rainfall __ _ ___________________

2. Structure map of Elk Ridge. ____________!__

3. Erosion surfaces on tilted beds: A, Near inouth 

of Comb Wash; B, Along the Causeway between Elk Ridge and the Abajo Mountains.

4. Rock shelters: A, At contact of Dakota (?) 

and Morrison in Cottonwood Canyon; B, In 

thin-bedded Cedar Mesa strata at Cigarette

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THE SAN JUAN COUNTRY

A GEOGRAPHIC AND GEOLOGIC RECONNAISSANCE OF SOUTHEASTERN UTAH

By HERBERT E. GREGORY

ABSTRACT

The San Juan country includes an area of about 3,800 square 

miles east of the Colorado River in San Juan County, southeastern 

Utah. This paper is based on reconnaissance geographic and 

geologic surveys made in 1910, 1915, 1925, and 1927-29. The 

region described comprises 12 districts characterized by differences in topography, soil, vegetation, water supply, and other 

factors that affect human activities. It is a semiarid country in 

which the small population is grouped about the base of the Abajo 

Mountains and on the San Juan River, where water is available 

for irrigation. Stock ranching is the chief industry. Exploitation of the mineral resources has proved unprofitable. Of the 

sedimentary rock formations the oldest exposed is the Hermosa, 

of Pennsylvanian age. Above it lie the Rico and Cutler formations, 

of Permian age; the Moenkopi, Shinarump, and Chinle formations, of Triassic agej'the Wingate sandstone, Kayenta formation, 

and Navajo sandstone, tentatively assigned to the Jurassic; the 

Carmel (?) formation, Entrada sandstone, and Summerville (?) 

formation, of Jurassic age; the Morrison formation, of Upper Jurassic age; and the Dakota (?) sandstone and Mancos shale, of 

Upper Cretaceous age.

The igneous rocks include granites and granite gneiss, found 

at the bottoms of deep wells; augite minette, in a single dike; 

and hornblende latite, exposed in the laccolithic Abajo Mountains.

The sedimentary beds have been folded into low anticlines and 

shallow synclines that have a general north-south trend and 

plunge steeply eastward. The anticlines and synclines affect all 

the rocks exposed and probably date from a pre-Tertiary period. 

In the Abajo Mountains the beds are steeply upturned as the 

result of intrusion that took place probably in early Tertiary 

time. Here and there the beds are broken by faults of small 

length and displacement.

The physiographic history is in general that of the Colorado 

Plateaus, of which the San Juan country is a part. Two cycles 

of erosion are outlined, the later one divided into epicycles. 

Conspicuous erosion features are the natural bridges in White 

Canyon, the dissected Comb anticline, and the deep, verticalwalled canyons within which enormous accumulations of gravel 

are in process of vigorous removal.

INTRODUCTION

SCOPE AND PURPOSE

The surveys of Sitgreaves (1851-52), Whipple 

(1853-54), and Ives (1857-58) in north-central and 

western Arizona, of McComb (1859) and Hayden 

(1874-76) in southwestern Colorado and extreme 

eastern Utah, of Fremont (1842-44), Gunnison (1853), 

and King (1868-79) in central Utah, and of Powell 

(1872-75) and Wheeler (1869-79) in southern Utah 

and northern Arizona resulted in the delineation of the 

salient features of the Colorado Plateau province.

The reports of these explorers faithfully outline the 

geography and geology of Arizona west of Echo Cliffs 

and of Utah west of the Paria River, north and west 

of the Kaiparowits Plateau in the immediate vicinity 

of Glen and Cataract Canyons, and along the UtahColorado boundary. The desire for information regarding the unmapped part of the plateau province, 

in particular the regions north, south, and east of 

Glen Canyon, led to the formulation of plans for 

reconnaissance surveys of northeastern Arizona and 

southeastern Utah. The purpose in view was twofold (1) to describe the topography, climate, soil, 

vegetation, and water supply as a guide in the development of vast areas of unallotted lands bordering 

Glen Canyon; (2) to map and interpret the geologic 

formations in at least sufficient detail to serve as a 

basis for comparative regional studies in stratigraphy, 

physiography, and structure.

In carrying out these plans studies were made of 

the Navajo country during the field seasons 1909-11 

and 1913 and of the Kaiparowits region in 1915, 1918, 

1922, and 1924. The present report gives the results 

of a continuation of these studies, made with the same 

scope and purpose. It is based on field work done in 

1909-10 and 1915, in connection with previous studies, 

and in 1925, 1927, 1928, and 1929, with specific reference to the San Juan country. In 1915 a 2 weeks' 

preliminary survey was made of White Canyon and 

Elk Ridge in association with Dr. Malcolm R. Thorpe, 

who remained in the field to map in detail the geology 

of the Abajo Mountains. Field work of 1925 included 

studies of the canyons heading in Elk Ridge, of upper 

Red Canyon, and of Castle Wash west of the Clay 

Hill Divide. In 1927 the region including Butler 

Wash, Comb Wash, and middle Grand Gulch was 

studied, and the traverses made in 1925 were extended 

from Castle Wash to the junction of the San Juan 

and Colorado Rivers, along Moki Canyon, Cedar 

Canyon, lower Red Canyon, and Glen Canyon, to 

connect with the traverse of White Canyon made in 

1915. Routes of travel were chosen with a view to 

gaining information regarding the large area between 

Comb Wash and Glen Canyon that had not been 

visited by scientific parties, thus providing material 

for a comparison of the structural and stratigraphic 

features of the Kaiparowits region and upper Glen
THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

Canyon with those along the San Juan River examrined in 1909. During short field seasons in 1928 and 

1929 the geologic features of the San Juan Valley and 

of the canyons northwest of Elk Ridge received chief 

attention.

The field work was necessarily a reconnaissance, 

supplemented here and there with more complete 

geographic and stratigraphic studies. Within the 

time available detailed investigation was impossible, 

because of the large size of the area, the diversity of 

the topographic features, the scarcity of water and 

forage, and the necessary search for feasible routes of 

travel. Moreover, except for the borders of the area 

and the top of Elk Ridge, the existing maps are as 

misleading as helpful, and the information available 

from "old timers" relates chiefly to the region east of 

Comb Wash and the strips of country bordering wellmarked trails from Elk Ridge down White Canyon 

and Castle Wash. In a scientific sense most of the 

field traverses of 1915, 1925, and 1927 were pioneer 

undertakings.

PREVIOUS EXPLORATION

On his memorable journey from Santa Fe through 

Colorado, Utah, Nevada, and California in 1776, 

Escalante followed an Indian trail that before his time 

had been traversed in part by Fray Alonzo de Posada 

and by Don Juan Maria de Rivera, who reached the 

Colorado near Moab in 1761. From descriptions in 

Escalante's diary, the route may be traced with considerable accuracy. At his crossing of the Green 

River near Jensen, the cottonwood trees that sheltered 

his party still stand. Among his guides was Muniz, a 

member of Rivera's expedition, who may have passed 

on from Rivera the names used in the diary La Plata 

Mountains, Sierra Abajo, Datil Mountains (Monument Valley?), La Sal Mountains, and San Xavier 

(Grand, Colorado) River.

In 1859 an expedition in charge of Capt. J. N. Macomb, Topographic Engineers, U. S..A., crossed Sage 

Plain, passed the east base of the Abajo Mountains, 

and descended "Canon Colorado" (Indian Creek) to its 

junction with the Grand (Colorado). The homeward 

route was down "Rito de la S. Abajo" (Recapture 

Creek or Montezmna Creek) and up the San Juan to 

Canyon Largo. The descriptions given by Macomb 

and by Newberry,1 geologist of the expedition, supplemented by colored reproductions of sketches made in 

the. field, portray for the first time the outstanding 

geographic features of southeastern Utah.

In connection with the work of the Hayden Survey, 

Jackson 2 made an exploratory traverse that included 

the San Juan Valley to the mouth of "DeChelly Creek"

i Newberry, J. S., Geological report, in Report of the exploring expedition from 

Santa Fe, N. Mex., to the junction of the Grand and Green Rivers of the great 

Colorado of the West in 1859, pp. 83-109,1876.

'Jackson, W. H., Ruins of southwestern Colorado and adjacent territory: U. S. 

Qeol. and Geog. Survey Terr. 10th Ann. Rept., pp. 411-130, 1878.

(Chinle Creek), "Epsom Creek" (Comb Wash), and 

the south base of the Abajo Mountains, and Holmes 3 

made a reconnaissance of northern Sage Plain and the 

Abajo Mountains. Interesting geographic, archeologic, 

and geologic features in Utah are shown on the map of 

Colorado issued by Hayden in 1878. The niap retains 

"Sierra Abajo" and "Sage Plain" as used by Macomb 

(1859) and for the first time applies the terms "McElmo", "Montezuma", "Recapture", and "Macombs" 

(now Cottonwood) to tributaries of the San Juan.

The topographic features of all southeastern Utah 

are depicted in generalized fashion on the Abajo and 

Henry Mountains reconnaissance maps of the United 

States^Geological Survey, made by P. Holman in 1884. 

On these maps the new names applied are "Cottonwood Wash" (for Macombs Creek of Hayden), "Butler 

Wash", "Comb Wash", "Elk Ridge" (Bears Ears Plateau of Holmes), and "Clay Hill Divide."

The first known exploration of the San Juan canyons 

was made by E. L. Goodridge, an oil prospector who, 

in 1882, descended the river in a boat from Bluff to 

Lees Ferry, investigating on the way the "oil seeps" 

reported by the Piutes as issuing from "white rock" 

between the mouths of tributaries now mapped as Lime 

Creek and Slickhorn Gulch. Reports of gold in gravel 

bars along the river gave rise to much detailed exploration of the San Juan Canyon during and after the 

"Bluff excitement" of 1892. During 1893 and 1894 

Bert Loper explored the river by boat between Chinle 

Creek and Nokai Creek, and in 1894 and 1895 Walter 

E. Mendenhall, a gold prospector, made two trips down 

the San Juan from "Mendenhall Cabin", about 3 miles 

below the Goodridge bridge. Some detailed explorations of the San Juan Valley were made in 1909 by 

Gregory and by Woodruff, but not until 1921 39 years 

after its first traverse were adequate maps and 

descriptions of the river from Comb Wash to its 

mouth provided. In that year a party of the United 

States Geological Survey in charge of K. W. Trimble 

spent 3 months in a detailed study of 140 miles of its 

interesting canyon.

In part contemporaneous with these reconnaissance 

surveys, studies of other kinds have added much to the 

geographic and geologic knowledge of the eastern part 

of the Colorado Plateau province. In 1921 the Colorado 

River and its main eastern tributary, the San Juan, 

were surveyed in detail by field parties under the general direction of E. C. La Rue 4 to ascertain "the facts 

regarding available water supply and all known dam 

sites." The resulting maps and geographic descriptions gave for the first time an adequate description of 

the alinement and gradient of these rivers and of the

«Holmes, W. H., Report on the geology of the Sierra Abajo and West San Miguel 

Mountains: U. S. Geol. and Geog. Survey Terr. 10th Ann. Rept., pp. 187-195,1878.

< La Rue, E. C., Water power and flood control of Colorado River below Green 

River, Utah: U. S. Geol. Survey Water-Supply Paper 556,1925.
INTRODUCTION

topography of their canyons. The geologists associated 

with these river surveys studied the structure, stratigraphy, and physiography of areas theretofore unknown 

and amplified the records made by previous investigators. During the course of their field work "the geology 

of the canyons of Colorado and San Juan Rivers and 

of the lower parts of tributary canyons was examined 

continuously, and reconnaissance work was done in 

the country back from the rivers." Among the resulting publications a paper by Longwell and others 5 

deals chiefly with regional stratigraphy, and papers by 

Miser 6 afford a comprehensive geographic and geologic 

study of the San Juan Canyon.

To determine the mineral value of public lands a 

third type of Government survey has been in progress. 

In these studies chief attention has been appropriately 

given to plane-table mapping, stratigraphy, and structure. Among the projects in central and eastern 

Utah that have involved detailed areal work by many 

geologists have been studies of the coal resources of 

the Wasatch Plateau by Spieker 7 and of the Book 

Cliffs by Clark 8 and Fisher.9 The oil possibilities of 

the Moab district and of the part of Utah south of the 

San Juan River have been described by Baker, 10 of 

the San Rafael Swell by Gilluly,11 of the Circle Cliffs 

by Moore,12 and of the Green River district by Baker. 13 

Special stratigraphic studies made during the course of 

the economic surveys have been described by Gilluly 

and Reeside 14 and by Baker and his field associates. 15

Insofar as they bear on the interpretation of the 

geology of the San Juan country the papers resulting 

from the Colorado River survey and the wider-range 

economic surveys have been incorporated in this report. 

The results of the work by Cross and Howe,16 Coffin, 17 

Baker and Reeside,18 Butler,19 and Thorpe 20 have also 

been utilized.

4 Longwell, C. R., Miser, H. D., Moore, R. C., Bryan, Kirk, and Paige, Sidney, 

Rock formations in the Colorado Plateau of southeastern Utah and northern Arizona: U. S. Qeol. Survey Prof. Paper 132, pp. 1-23,1925.

6 Miser, H. D., The San Juan Canyon, southeastern Utah: U. S. Qeol. Survey 

Water-Supply Paper 538,1924; Geologic structure of San Juan Canyon and adjacent 

country, Utah: U. S. Oeol. Survey Bull. 751, pp. 115-155,1925; Erosion in San Juan 

Canyon, Utah: Qeol. Soc. America Bull., vol. 36, pp. 365-378,1925.

' Spieker, E. M., The Wasatch Plateau coal field, Utah: U. S. Geol. Survey Bull. 

819, 1931.

8 Clark, F. R., Economic geology of the Castlegate, Wellington, and Sunnyside 

quadrangles, Carbon County, Utah: U. S. Geol. Survey Bull. 793,1928.

» Fisher, D. J., The Book Cliffs coal field in Emery and Grand Counties, Utah: 

U. S. Geol. Survey Bull. 852,1936.

10 Baker, A. A., Geology and oil possibilities of the Moab district, Grand and San 

Juan Counties, Utah: U. S. Geol. Survey Bull. 841,1933; Geology of the Monument 

Valley-Navajo Mountain region, San Juan County, Utah: U. S. Geol. Survey Bull. 

865,1936.

11 Gilluly, James, Geology and oil and gas prospects of part of the San Rafael Swell, 

Utah: U. S. Geol. Survey Bull. 806, pp. 69-130,1929.

12 Gregory, H. E., and Moore, R. C., The Kaiparowits region, a geographic and 

geologic reconnaissance of parts of Utah arid Arizona: U. S. Geol. Survey Prof. Paper 

164, pp. 154-157, 1931.

18 Baker, A. A., Preliminary map showing geologic structure of parts of Emery, 

Wayne, and Garfield Counties, Utah, U. S. Geol. Survey, 1933.

"Gilluly, James, and Reeside, J. B., Jr., Sedimentary rocks of the San Rafael 

Swell and some adjacent areas in eastern Utah: U. S. Geol. Survey Prof. Paper J50, 

pp. 61-110,1928.

18 Baker, A. A., Dobbin, C. E., McKnight, E. T., and Reeside, J. B., Jr., Notes 

on the stratigraphy of the Moab region, Utah: Am. Assoc. Petroleum Geologists 

Bull., vol. 11, pp. 785-808.1927. 

145824 38 2

1 ACKNOWLEDGMENTS

It is a pleasure to acknowledge the cooperation given 

by officials of the Forest Service, the Indian Bureau, 

and the General Land Office, both in Washington and 

in the field, and the assistance'of the stockmen who 

make their homes in Monticello, Blanding, and Bluff. 

In laying out preliminary routes of travel and selecting 

the season for visiting various localities, the knowledge 

and assistance of friendly "old timers" was invaluable. 

The interest taken in tne field work by such men as 

Parley Redd, Jacob Adams, John Adams, Gory Perkins, 

Marion Hunt, H. E. Blake, E. Z. Black, and A. L. 

Raplee made it possible to procure camp assistants and 

supplies at reasonable cost and with little loss of tune. 

The resourcefulness and cheerful acceptance of hardships by John Wetherill, Joseph Adams, Zeke "Junior" 

Johnson, and Lloyd Young, who served as guides in a 

region much of which they had not previously traversed, 

are recalled with pleasure.

To R. C. Coffin, chief geologist of the Midwest Oil 

Co., I am indebted for a structure map of Elk Ridge and 

for geologic information that facilitated field work in 

areas immediately adjoining Colorado.

The value of my investigation has been enhanced by 

conference with A. A. Baker and E. T. McKnight at 

Elk Ridge and at localities north of the Abajo Mountains and by discussions of terminology and regional 

correlation during traverses along the San Juan River 

and southward in company with A. A. Baker, James 

Gilluly, and John B. Reeside, Jr.

SUGGESTIONS TO TRAVELERS

Southeastern Utah seems destined to have many 

visitors who are attracted by the scenery of a region 

remote from main lines of travel. In anticipation of 

lucrative tourist travel the highway from northern 

Utah and western Colorado through Moab, Monticello, 

and Blanding to Bluff is in process of much improvement, and plans have been made for reconstructing 

the road from Bluff across the San Juan at Goodridge 

and south through the Navajo country to join the 

transcontinental highway that parallels the Atchison, 

Topeka & Santa Fe Railway. When this route is made 

suitable for automobiles, it will have few rivals as a 

scenic highway. A good road leads from Monticello 

to the Indian reservation at Alien Canyon and, except 

during the winter, is passable as far west as the Natural 

Bridges, in White Canyon. Most of the San Juan

19 Crosse, Whitman, and Howe, Ernest, Red beds of southwestern Colorado and 

their correlation: Geol. Soc. America Bull., vol. 16, pp. 447-498,1905.

17 Coffin, R. C., Radium, uranium, and vanadium deposits of southwestern Colprado: Colorado Geol. Survey Bull. 16,1921.

is Baker, A. A., and Reeside, J. B., Jr., Correlation of the Permian of southern 

Utah, northern Arizona, northwestern New Mexico, and southwestern Colorado: 

Am. Assoc. Petroleum Geologists Bull., vol. 13, pp. 1431-1448, 1929.

i» Butler, B. S:, Loughlin, G. F., Heikes, V. C., and others, Ore deposits of Utah:. 

U. S. Geol. Survey Prof. Paper 111, 1920.

w Thorpe, M. R., Structural features of the Abajo Mountains, Utah: Am. Jour. 

Sci., 4th ser., vol. 48, pp. 379-389,1919.
THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

country, however, like the Kaiparowits region to the 

west and the Navajo country to the south, is as yet 

inaccessible to automobiles; and few places off the 

main highway can be reached by wagons. For a 

distance of 140 miles but one bridge crosses the San 

Juan. There are no bridges or ferries across the 

Colorado in this region, and the only rowboats are the 

makeshift affairs of prospectors, constructed from time 

to time as needed. The region is distinctly a "foot 

 and horseback country": most of it is accessible only 

by pack train. Even with a pack train, traverses west 

of Elk Ridge and Grand Gulch should not be undertaken without careful preparation. Horses accustomed to rough country can make their way up steep 

slopes, across deep canyons, over bare rock, and through 

piles of drifting sand and under skilful guidance can 

reach seemingly inaccessible spots. But forage is 

nearly everywhere insufficient for horses that have 

only the night in which to search for food; for pack 

trains grain must be carried. Here, as in other semiarid regions, the recognized routes are streamways or 

trails that lead across uplands from one spring to 

another. "Off the trail" is away from water. The 

greatest difficulty is presented by the inconvenient 

spacing of water supplies. Immediately after rains 

water is plentiful in rock pockets and in ephemeral

streams; at other times the valley flats and mesas are 

almost bare of water holes, and supplies are obtainable 

only in the bottoms of canyons, which are very difficult 

to reach. At any time of year it is possible, by making 

long daily rides, to obtain water on the old Mormon 

trail to the Hole in the Rock and along the poorly 

marked trails across Red Rock Plateau or down White 

Canyon. Trips to the Sipapu Natural Bridge, to 

points about Elk Ridge and the Abajo Mountains, and 

to the cliff ruins in Montezuma Canyon and Grand 

Gulch present few difficulties, and with experienced 

guides the exceptionally interesting trail through the 

Clay Hills, Castle Wash, Wilson Mesa, and across the 

San Juan to Navajo Mountain, and the trail down 

White Canyon across the Colorado, through the Henry 

Mountains and the Kaiparowits region to Escalante, 

are feasible for adventurers who place unusual experiences above daily comforts. Except under the direction of men acquainted with the topography of the 

plateau province and experienced in finding water 

holes, tourists are advised to limit their travels to 

areas reached by automobile or by frequently used 

trails. In diversity, beauty, and grandeur the scenery 

thus reached is fortunately a counterpart of the scenery 

viewed by the scientific explorer whose routine duties 

lead him to places difficult of access.
CHAPTER 1. GEOGRAPHY

LOCATION, EXTENT, AND ACCESSIBILITY

As denned in this paper the San Juan country lies 

between the San Juan River and the north base of the 

Abajo Mountains and extends from the Colorado line 

westward to Glen Canyon. (See pi. 1.) It is the part 

of San Juan County, Utah, that in records of the Mormon Church, in popular literature, and in generalized 

scientific writings has long been known as the San 

Juan country, as a ready means of distinguishing it 

from the Dry Valley district, the Indian Creek country, 

and the La Sal country, in northern San Juan County, 

and from the Utah strip and the Navajo country, 

south of the San Juan River. The average distance 

across the region in an east-west direction is about 85 

miles, in a north-south direction about 45 miles; the 

area is therefore approximately 3,800 square miles. 

The commercial center of the area is Blanding, midway 

between the county seat, Monticello, and the pioneer 

settlement of Bluff. For the convenience of farmers, 

post offices are maintained at Lockerby and Urado. 

At Goodridge (Mexican Hat), 25 miles west of Bluff, a 

store is intermittently operated, mainly for trade with 

Navajos-who live south of the San Juan River. Trading pdsts are main tamed also at Aneth and in Montezuma Canyon.

Of the routes to the San Juan country the original 

Hole in the Rock road used by the missionary party 

in 1879-80 was abandoned the year it was made, and 

its place was taken by one that crossed Glen Canyon 

on a ferry at the mouth of Halls Creek and joined the 

old road in Lake Canyon. This road in turn was soon 

superseded by one that crossed the Colorado at Dandy 

Crossing (Hite) and led up White Canyon, across the 

head of Grand Gulch, and down Comb Wash. For 

some years a traverse of this route was the only means 

of bringing the people of central Utah into touch with 

their friends in far-away Bluff. Soon after the settlements on the San Juan River were made, a trail over 

which wagons might be taken was constructed from 

Bluff to Moab and thence to Salt Lake City, but for 

many years the chief trade route ran along the San 

Juan River and McElmo Creek from Bluff to Mancos 

and on to Albuquerque. To reach the ranches east of 

Elk Ridge a wagon road was constructed across Bluff 

Bench to the floor of Cottonwood Canyon. After 

Monticello was established (1886) the Bluff-MoabThompson road was improved and later relocated to 

include Blanding. During the development of the 

San Juan "oil field" a road was constructed from Bluff 

across Comb Ridge and Comb Wash, up Snake Canyon,

and down Lime Creek, and a makeshift bridge was built 

across the San Juan at Goodridge (1910?). In 1926-27 

the old road from Blanding through the Indian settlement at Alien Canyon to Elk Ridge was made suitable 

for automobiles. In 1928 it was extended to the 

Natural Bridges, in White Canyon. At present (1934) 

the main artery of travel, the only "good road", runs 

from Bluff through Blanding, Verdure, Monticello, 

and Moab to the railroad at Thompson (140 miles), 

with a branch from Monticello east to Dolores and 

Cortez (65 miles). Automobiles can be driven from 

Bluff westward through Goodridge and the Navajo 

Reservation to Flagstaff (200 miles); from a junction 

with the Bluff-Blanding road across Recapture Canyon, 

McCracken Mesa, and Montezuma Canyon to McElmo 

and Cortez; to some of the farms on Sage'Plain, and to 

Aneth by way of Cortez. Points along the San Juan 

River above Bluff and below Goodridge, along the 

Colorado River, and about the Abajo Mountains are 

accessible only on horseback. A few trails are kept 

open by cattlemen, and in many places topography 

marks out feasible routes for pack trains, but for most 

of southeastern Utah travel consists of rough scrambles 

in and out of canyons at places that seem at the time 

most favorable.

NOTE ON THE MAP

The existing maps of the San Juan country inadequately picture the geographic features; those based 

on detailed surveys cover but a small part of the region. 

The General Land Office has mapped the Natural 

Bridges National Monument, the "oil fields" of Lime 

Creek Valley, and most of the area between Cottonwood Canyon and the Colorado State line. Maps 

showing township lines and drainage on and about Elk 

Ridge have been made by the Forest Service. Accurate 

maps are available for the San Juan canyons below 

Bluff and for the entire Colorado River. The Abajo 

and Henry Mountain reconnaissance topographic maps, 

made by P. Holman in 1884 and published by the 

United States Geological Survey, include the San Juan 

country. They show the mountains, the larger ridges 

and valleys, and such features as could be seen from 

selected viewpoints on Elk Ridge and on highlands 

along the San Juan River. Unfortunately, in this 

region of deep meandering canyons and interlacing 

ridges and plateaus, the trend of many drainage lines, 

the position and size of tributaries, and the distinction 

between mesa face and canyon wall cannot be determined in distant views. The 1884 maps are therefore 

of little practical use.

5
6 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

On the base map constructed for this report (pi. 1) 

the features of Sage Plain, of the San Juan canyons, of 

the Colorado canyons, and of the eastern edge of Grand 

Gulch Plateau are reproduced from modern surveys. 

West of Comb Wash and Elk Ridge the map is a record 

of field traverses checked here and there by instrumental measurements. The names on the map include 

those on older maps and those locally in common use. 

To facilitate description of geographic districts and 

prominent topographic features, new names have been 

added. When maps become available on which to 

represent them, many more interesting features in this 

little-known region can appropriately be named.

TOPOGRAPHIC OUTLINE

The San Juan country is part of the Colorado 

Plateau province; its larger topographic features are 

duplicated in the Navajo country, to the south, and 

in the Kaiparowits region, to the west. Throughout 

most of the region the rocks are flat-lying or slightly 

tilted and are cut into great sections by steep-walled, 

deep canyons. East of Comb Wash and the prominent Comb Ridge the topographic pattern is simple; 

the surface is formed of a single stratum of sandstone 

into which are sunk canyon trenches of uniform pattern 

and above which rise a few inconspicuous mounds. 

West of Comb Wash the landscape is much varied. 

The flat dome of Grand Gulch Plateau is bordered on 

the west by the Red House Cliffs, a precipitous terraced 

sandstone wall that marks the beginning of deep, steepsided, meandering gorges tributary to Glen Canyon. 

Elk Ridge is a mesa capped by a stratum of resistant 

sandstone that terminates abruptly at the box head of 

small canyons. The historic landmarks the Bears 

Ears are two of the many buttes that project above 

its general surface. The lofty Abajo Mountains consist of a laccolithic mass that reproduces the topographic 

features of the Henry and La Sal Mountains.

About 50 percent of the San Juan country lies between 6,000 and 7,000 feet above sea level. The areas 

below 5,000 feet are the benchlands and stream valleys 

along the San Juan and Colorado Rivers, and those 

below 4,000 feet are narrow strips within the canyons 

of these master streams. Elk Ridge stands 8,000 feet 

above sea level, and the Abajo Mountains are still 

higher. The extremes of regional relief are Abajo 

Peak, 11,445 feet, and the mouth of the San Juan, 

3,286 feet. The general surface slopes of the area are 

southward to the San Juan and westward to the 

Colorado.

Except for a few small meadows and tiny highland 

ponds the region is thoroughly drained by well-defined 

channels. Streams entering the San Juan carry the 

run-off from about two-thirds of the area in canyons, 

some of which, especially at their mouths, broaden into 

washes. Streams entering the Colorado directly carry

the remaining drainage in channels that retain their 

canyon form throughout. Only the San Juan and the 

Colorado are through-flowing. Twice in the last half 

century even the San Juan ceased to flow below 

Aneth. Many of the streams are perennial at their 

heads and at favorable places along their courses; many 

others flow only in direct response to rainfall. During 

most of the year the stream channels, except at their 

heads, are dry beds of sand, boulders, or bare rock; yet 

the coarse detritus and the driftwood perched on the 

valley sides testify to the strength of the occasional 

floods.

Erosion is vigorously active. Most streams at their 

headwaters are keeping their channels clear of normal 

rock waste and are rapidly removing the materials piled 

in by landslides; farther down their courses they are 

digging out and transporting the enormous masses of 

sand and gravel deposited during a previous physiographic epoch. Talus is piled deep on the slopes of the 

Abajo Mountains, along White Canyon, and around 

the south rim of Elk Ridge, and it forms a basal border 

along the east wall of Comb Wash. Elsewhere it is 

irregularly present and inconspicuous; many slopes and 

most canyon walls present bare rock. On interstream 

areas, particularly along the San Juan River and west 

of Grand Gulch, erosion has outlined flat domes, huge 

angular mesas, and circular buttes that rise above the 

plateau tops. In many places along the canyon walls 

soft beds underlying hard beds have been removed to 

form caves with overhanging roofs, and the massive 

beds of sandstone have been carved into alcoves, 

fluted columns, natural bridges, and a variety of miniature features picturesque alike in form and in color. 

There are no large areas of dunes, but most of the region 

below the 6,000-foot contour is unevenly coated with 

wind-blown sand. Outside the high level areas forest 

vegetation is insufficient to conceal the rocks. The 

color of canyon walls and plateau tops is the color of 

the rock red, tan, white, replaced here and there by 

variegated bands miles in length.

GEOGRAPHIC DISTRICTS

BASIS OF SUBDIVISION

Though the San Juan country is a division of the extensive Colorado Plateaus, its .diversified features are 

not readily grouped within a single geographic unit. 

As regards possibility of future utilization, the parts 

of the area are decidedly unlike, and such problems as 

water development, forestation, agriculture, and transportation can best be understood with the local condi^ 

tions in mind. For this reason it seems desirable to 

divide the region into geographic districts on the basis 

of topography, vegetation, water supplies, and other 

features that affect the human population. The 12 

districts thus outlined are described on the following 

pages. (See pi. 1.)
GEOGRAPHIC DISTRICTS

SAGE PLAIN

That part of southeastern Utah lying east of Comb 

Wash, upper Cottonwood Canyon, and the flanks of the 

Abajo Mountains is essentially a plain, about 1,200 

square miles in area, the western half of the flat surface 

that extends to the Dolores River and the Mesa Verde 

in Colorado. To this extensive area of flat land, one 

of the largest in the plateau country, Newberry 21 gave 

the name "Sage Plain." He speaks of it as "an arid 

expanse", a scene of "dreary monotony", an "orderly 

and unbroken arrangement of underlying jocks."

From Surouaro [near the Dolores River] to the base of the 

Sierra Abajo the physical aspects of the country are everywhere 

the same a great plain, to the eye as limitless as the sea; the 

monotonous outline of its surface varied only by two or three 

small islandlike mountains so'distant as scarcely to rise above the 

horizon line.

Surface profiles drawn in an east-west direction 

across almost any part of the plain reveal only small 

departures from horizontality, but north-south profiles 

show a regional slope of about 2,000 feet in a distance 

of less than 50 miles, from 7,000 feet above sea level 

in the region east of Monticello to 5,000 feet near the 

mouth of Montezuma Creek. Almost any point on 

Sage Plain affords uninterrupted views of distant 

features. From the highway between Blanding and 

Bluff, Lone Cone of the San Miguel Mountains, the 

wall of the Mesa Verde, and Ute Mountain rise prominently on the sky line 70 miles to the east; and at the 

base of the Carrizo Mountains Ship Kock appears as a 

vessel far out at sea. To the south and southwest 

the bluffs of the San Juan River are in plain sight, and 

beyond them the towers of Monument Valley and the 

precipitous walls of Black Mesa, in the center of the 

Navajo country. Even from the old Indian trail that 

crosses the northeast corner of Sage Plain the Spanish 

scouts of early days recognized the Sierra Abajo, 

Orejos del Oso (Bears Ears), Calabasa Mountains 

(South Comb Ridge, the Monuments, and Skeleton 

Mesa?), Lava Negra (Agathla Needle), and even Sierra 

Panoche (Navajo Mountain), more than 100 miles 

distant. Though the remarkably even surface of 

Sage Plain is surmounted only by scattered low mounds 

of shale, it is deeply dissected by stream ways that begin 

as canyons and continue as canyons all the way to the 

San Juan. Even the narrow shallow channels in the 

least dissected parts of the plain are vertical-walled, 

for the initial trench is cut through a thick bed of 

resistant sandstone. To cross the center of the plain 

in an east-west direction is a difficult undertaking; 

canyons 100 feet to more than 500 feet deep appear 

without warning and can be crossed only at the few 

places where the tops of their enclosing walls are 

broken by cracks or fringed with talus.

« Newberry, J. S., Geological report, In report of exploring expedition from Santa 

Fe, N. Mex., to the junction of the Green and Grand Rivers of the great Colorado of 

the West in 1859. p. 89.1876.

The road from Blanding to the San Juan is on the flat 

divide between Cottonwood and Recapture Canyons, 

which at one point is only 30 feet wide. The road 

from Blanding to Alien Canyon, which replaces the 

long road up the sandy floor of Cottonwood Wash, 

crosses four deep canyons and some shallower ones 

where expensive construction was required; and the 

highway between Blanding and Monticello, though it 

crosses only the headwater tributaries of Recapture and 

Montezuma Creeks, is a series of costly fills and graded 

slopes. To construct the much desired road from 

Blanding directly east to railroad points in Colorado 

would involve crossing no less than 25 canyons, 10 of 

them within the first 15 miles. Of the highways that 

now connect Blanding and Bluff with Dolores and 

Cortez, one follows the circuitous route around the 

heads of tributaries to the Montezuma, and the other 

crosses Recapture and Montezuma Canyons at places 

not far from their mouths, where the floors of the canyons are broad and their rims somewhat broken down. 

The canyons of Sage Plain are much alike in form. 

Starting at the top with a formidable "rim rock", the 

wall descends by steps or talus-covered slopes to a floor 

of detritus, below which lies the sandy stream -bed. 

The lower third of Butler Wash occupies a rock-floored, 

V-shaped trench, and here and there in other canyons 

the water flows over bare rock between high narrowly 

spaced walls. But most of the canyon floors consist of 

alluvium in which are embedded huge blocks dropped 

from the walls. Much of it has been reworked by 

floods and wind.

In places where water is permanent and the soil 

suitable the canyon bottoms have long been cultivated. 

In all the larger canyons and in many tributaries, 

particularly in the Montezuma, are groups of ruins on 

the floor, on the rim, and on low spurs within the canyon 

walls. Here and there are remnants of ancient cornfields. Jackson speaks of "a band of Wiminuche Utes" 

in middle Montezuma Canyon who "have considerable 

corn planted." Present-day Piutes practice agriculture 

in Cottonwood Wash, and some of them return to their 

old homes in Montezuma and McElmo Canyons, 

especially in the winter. Most of the efforts of the 

Mormon pioneers to "farm the washes" have proved 

unprofitable. At Verdure and a few other places near 

the Abajo Mountains where streams have permanent 

flow, grain and alfalfa are profitably grown. Agriculture at Blanding and at Monticello depends on irrigation water drawn from the mountain tributaries of. 

Recapture and Montezuma Creeks.

On the surface of Sage Plain (pi. 2, A) sagebrush is. 

present everywhere, and within the canyons it seems to 

be dominant. At Verdure, south of Blanding, between 

Cottonwood and Montezuma Canyons, near Lockerby,. 

and west of McElmo Canyon it constitutes almost pure 

stands 3 to 5 feet high. On the floors and lower slopes 

of canyons it grows in places to a height of 8 feet, form-
8 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

ing almost impenetrable thickets. Pinon and jumper 

in constant association are likewise widely distributed. 

As single trees or small groves they occupy canyons and 

interstream flats. As viewed from Blanding, continuous forests of pinon and juniper extend westward to 

the Alien Canyon country and eastward to Colorado. 

These trees supply fuel for homes and for the small 

gristmills and sawmills. Oak brush, which is conspicuous on the lower slopes of the Abajo Mountains, appears 

in the canyons of Sage Plain in small, widely separated, 

dense groves. On the floors of canyons vigorously 

growing cottonwoods are abundant.

As an agricultural region Sage Plain, though by no 

means worthless, offers no' large promise. On alluvial 

slopes extending some miles from the Abajo Mountains 

and on flat lands where disintegrated shale is sufficient 

in depth the soil is suitable for most crops, but on much 

of the plain bare rock is exposed or is thinly coated with 

highly siliceous materials. Scant precipitation and a 

short growing season prevent the full utilization of 

favorable soil. Dry farming in this region at an altitude 

of 5,000 to 7,000 feet and with an annual rainfall of 8 

to 18 inches is likely to be profitable only in times of 

unusually high prices. Agricultural development depends upon the amount of water that can be brought 

without prohibitive cost from streams on the Abajo 

Mountains and from wells sunk deep to water-bearing 

strata. Land at present irrigated is yielding satisfactory returns, and though the produce raised is prevented 

by transportation costs from competing in the general 

market, the local demand is supplied at prices.far below 

those charged for materials brought in.

As a grazing country Sage Plain has small and decreasing value. Stock water is sufficient and spaced at 

convenient intervals, but much of the grass, perennial 

plants, and brush suitable for forage has been destroyed 

as the result of overgrazing, especially by sheep. The 

region serves mainly as winter range when the highland 

pastures are buried in snow.

ABAJO MOUNTAINS

The Abajo Mountains rise from Sage Plain with a 

slope of 500 feet to the mile between the contour lines 

of 7,000 and 9,000 feet, 1,000 feet to the mile between 

the contours of 9,000 and 10,000 feet, and then more 

steeply to eight independent summits (pi. 2, A). 

Below 8,000. feet the mountains constitute a single mass 

about 16 miles long and 10 miles wide, scalloped by 

radial valleys except on the west, where the flat-topped 

Elk Ridge abuts against its flanks. Above 9,000 feet 

and covering an area of 90 square miles are four groups 

of peaks a southern group, including South Peak 

(11,000+ feet) and Abajo Peak (11,445 feet); a western 

group, dominated by Mount Linnaeus (11,300+ feet); 

a northern group, including North Peak (11,350 feet), 

Horsehead Peak (11,000+ feet), and Twin Peak 

(11,000+ feet); and at the northwest the isolated mesalike Shay Mountain (10,000+ feet). The peaks constituting these groups are much alike in form and 

structure* Their tops are rounded, some of them 

nearly flat; their sides slope steeply and evenly and not 

far from the summit develop into long spurs, which 

likewise have broad tops and smooth sides. There are 

no deep, sharply cut canyons, no steep precipices, and 

no bold masses of naked rock; the features associated 

with mountain ruggedness are absent. Trails between 

South Peak and Mount Linnaeus and between Twin 

Peak and Abajo Peak present no difficulties. Wagons 

traversing the road from Monticello to the pass between 

Abajo and Horsehead Peaks have mainly steepness to 

contend with.

At altitudes of about 9,000 feet the general smooth 

outlines of the mountains are replaced by a belt of rough 

country. Here the sandstones of Sage Plain, which 

formerly covered the mountains, terminate with steeply 

upturned edges, forming disconnected hogbacks that in 

places have been broken up into huge blocks. In this 

zone also are extensive and thick accumulations of talus 

from the igneous rock above. (See pi. 2, A.)

The Abajo Mountains give rise to many permanent 

streams that head in swampy meadows high on the 

slopes or emerge from the talus lower down. Those 

flowing south and east unite to form the tributaries of 

Montezuma Creek, Recapture Creek, and Cottonwood 

Canyon, all draining to the San Juan River. Those 

rising on the north slopes form Indian Creek and Harts 

Draw, which enter the Colorado River. Except for the 

San Juan River, these headwater tributaries constitute 

the only reliable supply of water adequate for irrigation. 

In fact, the rills and brooks of the Abajo Mountains are 

the life of southeastern Utah. Without them the villages 

of Monticello, Verdure, and Blanding, the ranches about 

the base of the mountains, and the Indian reservation 

in the Alien Canyon country could not be maintained.

Except in areas of unstable talus (slide rock), where 

only lichens and small tufts of alpine grasses grow, the 

entire mountain mass is clothed with forest or grass. 

(See pi. 2, A, B.) In general, dense forests cover the 

northern and northwestern slopes and terminate 

abruptly at the crests of spurs and ridges; grasses cover 

the southern and eastern slopes. At the heads of the 

highest valleys and in favorable places down to an 

altitude of 8,000 feet are groves and individual trees of 

spruce and balsam fir. Below them is a forest zone in 

which yellow pine is dominant, then a zone of pinon 

and juniper merging down-slope with the vegetation 

characteristic of the Sage Plain. Aspens seem most at 

home-among the yellow pines and the spruces, but 

groups grow also with the pinons. About the swampy 

stream heads are willows, maples, and alders, meadow 

grasses, and a wealth of flowering annuals. Sagebrush 

reaches up to the 9,000-foot contour line; oak and service 

berry likewise seem to be distributed with little regard 

to altitude or soil.
GEOGRAPHIC DISTRICTS 9

Vegetation, climate, and scenery combine to make the 

mountain meadows and groves at altitudes of 8,000 to 

9,000 feet delightful camping places. Jackson 22 writes:

The southern, eastern, and northern flanks of the Sierra Abajo 

* * * without exception, the most pleasant spot we have 

touched since leaving La Plata. Clear and cold mountain streams 

ripple down through ravines overhung by groves of willow, 

maple, and quaking aspen, with splendid oaks and stately pines 

scattered over the uplands, and an abundance of rich, nutritious 

grass everywhere, that our poor, half-starved animals knew well 

how to appreciate. The blacktail deer and grouse were in goodly 

numbers, starting up from under our very noses and leading our 

hunters many a long chase.

The view from the top of Abajo Peak is of unusual 

interest. The prominent features of the marvelously 

carved and marvelously colored Colorado Plateaus 

within a radius of 100 miles are plainly visible. On 

clear days the sweep of vision is limited eastward only 

by the San Miguel and La Plata Mountains, southward 

by Black Mesa, westward by Kaiparowits and Aquarius 

Plateaus, and northward by the Book Cliffs. In distant views the La Sal Mountains, Henry Mountains, 

Ute Mountain, and Navajo Mountain, companions of 

the Abajo Mountains in structure and setting, appear 

on the horizon as solitary peaks dwarfed in size by the 

enormous expanse of surrounding flat surface. The 

general course of the San Juan can be traced and 

Cataract Canyon and Glen Canyon located with reference to adjoining features. By aiming its projecting 

teeth the Comb monocline can be followed with the eye 

far into the Navajo country. Immediately at hand to 

the west can be seen the forest-covered flat-topped Elk 

Ridge, from which rise the brilliantly colored Bears 

Ears and Woodenshoe Buttes and below which toward 

the southwest is the intricately eroded area at the head 

of Comb and Butler Washes. Looking south and east 

the eye follows down the forested slopes of the Abajo 

Mountains out across the dull-colored, scantily wooded 

Sage Plain to stretches of bare rock terminating at 

Carrizo Mountain, south of the San Juan River in 

Arizona.

As a grazing area and a source for timber, the Abajo 

Mountains have high value, and it is not difficult to 

foresee the time when they will become a center of 

scenic interest. Of all the high isolated mountains 

affording extensive views of the plateau country this 

group is the most easily accessible.

SAN JUAN VALLEY

Throughout its course in Utah the immediate valley 

of the San Juan River consists of two unlike parts. 

Between the Colorado boundary and Butler Wash the 

river occupies a wide flood plain bordered by gravel 

terraces that form steps in front of low enclosing walls. 

(See pis. 2, C; 3, (7.) At Butler Wash the river enters 

a remarkably meandering canyon and except for short

"Jackson, W. H., Report on ancient ruins examined in 1875 and 1877: U. S. Oeol.and 

Qeog. Survey Terr. 10th Ann. Rept., p. 426,1878.

stretches at Comb Wash, Goodridge, and Clay Hill 

Crossing continues to the Colorado between close-set 

waUs 1,000 to 2,500 feet high. (See pi. 3, A, B.) Like 

the master stream, the mouths of most of its tributaries 

are set deep in rock gorges. Within the canyon the 

alluvial materials consist of piles of boulders and gravel 

and patches of sand deposited and removed in response 

to floods. Except for tiny fields near Clay Hill Crossing and Comb Wash the arable lands in the San Juan 

VaUey are the strips of flood plain above the mouth of 

Cottonwood Creek, most of them on the north side of 

the river.

Stone-built villages under the ruins of the canyon 

walls and potsherds on gravel terraces point to long 

occupation by agriculturists of pueblo times, and 

hogans and wickiups, some of them habitable, others 

in decay, show intermittent use of these lands by 

Navajos and Piutes. These flood-plain lands, cultivated by the Indians and by Cliff Dwellers before them, 

were the lure that brought the Mormon pioneers to 

southeastern Utah. (See pp. 31-33.)

During the last 20 years great changes have taken 

place in the San Juan Valley. The destruction of arable 

land, the result of changes in the river's current and 

the neglect of irrigation ditches, has reached a stage 

where barely 200 acres remains; abandoned machinery 

and huts mark the sites of "placer mines" and "oil 

fields"; coarse brush and fields of introduced weeds 

have replaced the grass and flowering shrubs. Because 

of intermittent floods it has been found impracticable 

to maintain a road along the river above Bluff. At low 

stages of water pack trains can go along the banks for 

most of the distance from Bluff to Aneth and can cross 

the river at several places; the difficulties encountered 

are quicksand and precipitous walls rather than depth 

and strength of current. Below Bluff the river can 

be reached at few places. Between Bluff and Goodridge 

the topography forces a long, sinuous detour that leads 

to a suspension bridge below the mouth of Lime Creek 

the only highway crossing in Utah. Below Goodridge 

the short road on the north side cf the river is high on 

the canyon rim; that south of the river is far back. At 

favorable stages of water the. lower -canyon can be 

crossed by pack train at the mouth of Copper Creek 

and at the mouth of Wilson Creek.

ELK RIDGE

Except for the Abajo Mountains, Elk Ridge is the 

most conspicuous topographic feature in the San Juan 

country. It is plainly visible from the Mesa Verde in 

Colorado-, from Monument Valley, Arizona, and from 

the Henry Mountains, west of the Colorado River. 

From Blanding it is an impressive sight a huge flat 

block from which rise the Bears Ears (pi. 4, A) and 

about which winds a crenulated wall, in places brilliantly colored. From Grand Flat its outstanding feature 

is a series of long, narrow, steep-sided, flat-topped ridges
10 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

that project from the main mass and terminate abruptly 

like capes on a rugged seacoast. Elk Ridge is a plateau 

or mesa like the Kaiparowits or Mesa Verde, and the 

term "Bears Ears Plateau" as applied by Holmes is 

much more appropriate than the name now in use. 

It is a forest-covered surface about 20 miles long and 15 

miles wide at an altitude of 7,500 to 8,000 feet above sea 

level and 1,000. to 2,000 feet above its basal slopes. 

On the east its bordering wall is a series of cliffs alternating with steep slopes; on the south and west the wall 

is precipitous; on the northwest it is flanked by slopes 

broken by steps that descend to Cataract Canyon; on 

the northeast its surrounding wall is interrupted by the 

Causeway, which connects Elk Ridge with the Abajo 

Mountains. At first sight the surface seems flat and 

even, except for the beautifully colored buttes that rise 

above it. Instrumental measurements show a long, 

flat dome in fact, two domes separated by a shallow 

swale with a top at 8,400 feet. The culminating 

feature is the Bears Ears, 9,040 feet.

The plateau is deeply dissected by streams that flow 

in profound canyons and divide the surface into segments of very irregular outline. The master drainage 

line is Dark Canyon, whose tributaries extend from 

the west nearly across the plateau. The head of Dark 

Canyon has reached and broken down the eastern wall, 

producing the "Notch", which separates South Elk 

Ridge from North Elk Ridge and forms the narrow 

divide between canyons leading to the San Juan and 

to the Colorado. Near Kigalia ranger station the 

vertical walls of Kigalia Canyon, tributary to Dark 

Canyon, are less than 3 miles from the box heads of 

Hammond Creek and Arch Canyon, draining to the 

San Juan. Peavine Canyon and Woodenshoe Creek, 

the longest tributaries of Dark Canyon, head within a 

few miles of the precipitous south wall of Elk Ridge. 

Parts of the plateau are poorly drained. Some of the 

streamways are merely shallow depressions revealed 

by the presence of water-loving plants. Standing 

water appears in small swampy areas immediately 

under the cap rock and in such shallow ponds as Duck 

Lake on the road to the Bears Ears and the "lake" near 

Gooseberry ranger station. Several springs and also 

the headwaters of streams that lead out from the plateau 

rim are perennial. They supply water of excellent 

quality sufficient to meet the needs of stockmen.

Forests of yellow pine cover Elk Ridge and extend 

down the plateau slopes to points where they are replaced by juniper and cedar. With the pines, in 

detached areas and on the borders of open parks, quaking aspen, oak, scrub maple, and willow are conspicuous. 

Such shrubs as the service berry, manzanita, sagebrush, and checkerberry and many grasses serve to 

increase the ground cover within and outside the dense 

growth of pine. Many of the most attractive flowers 

common to the plateau province grow in abundance. 

(See pp. 23-24; pi. 4, A.)

Elk Ridge is part of the south or Monticello division 

of the La Sal National Forest. In addition to timber 

for local use it provides forage for several thousand, 

cattle and horses during the months when lands at 

lower altitudes are without water sufficient for stock.

During the summer Kigalia and Gooseberry ranger 

stations and some cabins built long ago are intermittently occupied. During the winter the entire plateau 

surface is deeply covered with snow.

The southern part of Elk Ridge (the "South Elks") 

was made accessible to the early settlers of San Juan 

County by the construction of a road from Cottonwood 

Canyon to the flat lands about the Bears Ears a road 

much better adapted to pack trains than to wagons. 

Through the combined appropriations of the State, the 

county, and the Forest Service, part of this road was reconstructed and extended to Blanding. In 1926-27 

the Midwest Refining Co. constructed an expensive 

road from the Junction, near Kigalia, through the 

Notch, down the walls of Kigalia Canyon, and along 

the floor of Dark Canyon to its deep well in Reservoir 

Canyon. The "North Elks" can be reached by horse 

trails from the Blanding-Kigalia road or from trails 

that pass around and over the Abajo Mountains and 

across the Causeway; even wagons have been dragged 

over the trail from the Notch. In 1927-28 the old road 

from Kigalia to the Bears Ears was reconstructed and 

extended over the plateau rim and along the flats bordering Armstrong Canyon to the Natural Bridges, thus 

making accessible an exceptionally interesting region. 

After a few hours' ride from Blanding a delightfully cool 

camp on Elk Ridge may be made among tall forest 

trees near attractive springs, in the home of flowers and 

birds. Short walks from camp to the rim of the plateau 

reveal scenery of surprising beauty and grandeur. To 

the east the great Sage Plain extends from the base of 

the Abajo Mountains far away into Colorado and the 

Comb Ridge traverses the country like a turreted wall; 

to the south Grand Gulch Plateau presents a seemingly 

unbroken surface, terminated only by the steep face of 

Red Rock Plateau and by the towering buttes beyond 

the San Juan, 50 miles away. Westward the view 

ranges across the brightly colored White Canyon, Red 

Canyon, and Clay Hills to the mesas, buttes, and ridges 

of the Castle Wash and Moki Canyon region and on to 

the Henry Mountains, the Kaiparowits country, and 

Navajo Mountain beyond the Colorado. Immediately 

at the rim is the head of the inaccessible Arch Canyon, 

formed by beautifully carved red-topped white walls 

that descend 1,000 feet to a mysteriously hidden floor. 

Within the whole region from Comb Wash to Dark 

Canyon, 90 degrees of arc and extending as far as vision 

permits, the only evidences of human inhabitants are 

the mummies and skeletons of the Basket Makers and 

Cliff Dwellers, buried in the sand of washes or resting 

among the ruined structures in wall recesses of the profound canvons.
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 188 PLATE 1

GARFIELD CO 

KAN E CO

EXPLANATION

SEDIMENTARY ROCKS

Dakota (?) -sandstone. In

places overlain by Maneos

Chlnle (Upper Triassic), ShinaI'unip (Upper (?) Triaasie), and 

Moenkopi (Lower Triassie) formations

De Chelly aiifl Organ Book 

members of Cutler formation

Cedar Mesa sandstone member of Cutler formation and 

outliers of Organ Rock 

member 011 Grand Gulch 

Plateau

Halgalto member of Cutler

formation, Rico formation,

and in deep canyons HerIgneous rocks

Strike and dip of bods

Axis ol anticline

Axis of syncline

t ________ f

Axis of monoclinal fold

MONUMENT UPWARP

Woodenshoe

Butte ELK RIDGE Comb monoclir

Section nearly east and west through Woodenshoe Butte

s,ooo'-\

Balanced Rock 

anticline MONUMENT UPWARP 

GRAND GULCH PLATEAU

Comb monocline

-g-S Comb Black

SAGE PLAIN DOWNWARP

Section through Wilson Mesa and Black Mesa

\ooo3,000'

RECONNAISSANCE GEOLOGIC MAP AND GENERALIZED SECTIONS OF THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

1938
GEOLOGICAL SURVEY PROFE

A. ABAJO MOUNTAINS FROM WESTERN EDGE OF SAGE PLAIN. 

Viewed at a distance of 8 miles. Panoramic photograph by L. M. Gould.

it. LAKE ON FLANK OF ABAJO MOUNTAINS BETWEEN JOHNSON AND RECAPTURE

CREEKS.

Depression in a sheet of intrusive rock. Photograph by M. R. Thorpe.

i.. >AN JUAN RIVER 1 MILE BELOW MOUTH 

Lookiag upstream toward Aneth, middle distance. Shows part o

Morrison strata capped by gravel t
GEOLOGICAL SUKVEY PROF

A. SAN JUAN CANYON A1JOVE HONAKER TRAIL. 

Permian and Pennsylvania!! strata. Photograph by R. N. Alien.

B. SAN JUAN CANYON 6 MILES HELOW 

Navaio and Kayenta strata in middle distance; Wingate sandst

by R. N. Alien.

C. VIEW LOOKING SOUTH ACROSS SAN JUAN RIVER AT HLUFF. 

Foreground, top of Bluff bench developed on Bluff sandstone. In distance, Bluff sandstone underlain by Summerville (?) and Entrada formations. Photograp
GEOLOGICAL SURVEY PROF

"I IS.'

4. BEARS EAHS ON SOUTH EDGE OF ELK PLAILAl. 

Flat in foreground shows general surface of the plateau developed in Shinarump conglomerate; buttes composed of Chinle shale capped by Wingate sandstone. Ph

B. MEXICAN HAT.

An erosion remnant of Halgaito strata preserved in the Mexican Hat syncline in Lime Creek Valley. 

Raplee anticline in background. Photograph by R. N. Alien.

C. LIME CREEK VALLEY SHOWING EROSION SUR

Butte of Halgaito sandslone in middle distance. South face of C

by E. G. Woodruff.
GEOGRAPHIC DISTRICTS 11

ALIEN CANYON COUNTRY

The head tributaries of Cottonwood Canyon 23 drain 

an area of relatively low land walled about by the edge 

of the Sage Plain, the base of Mount Linnaeus, the 

Causeway, and the rim of Elk Ridge. These tributaries Dry Wash, Alien Canyon, Hammond Canyon, 

and their many short branches and the Cottonwood 

itself rise at the base of encircling cliffs and, after 

gathering run-off from the bordering steep slopes, flow 

southward to form a single stream that emerges at the 

point where the walls have been broken down. All these 

tributary streams have about the same gradient and 

drain areas of about the same size, but the canyons 

they have developed differ widely in width, depth, and 

continuity. The area drained by them has been known 

as the Alien Canyon country.234

The east bank of Dry Wash is a terraced wall about 

800 feet high; the west bank is a dissected lowland. 

Hammond Canyon crosses a series of ridges. Alien 

Canyon and especially its branches, Chippean, Deep, 

and many less conspicuous gorges, have cut deep 

crooked trenches into massive red rock. Cottonwood 

Canyon, in part of its course, is enclosed in high walls, 

but for long stretches only its eastern wall is prominent; 

its western tributaries are narrowly spaced, sharply cut 

canyons that start as box heads beneath the rim of Elk 

Ridge. The south end of the highlands between Dry 

Wash and Alien Canyon is carved into brightly banded 

buttes, capped columns, and mounds of red rock locally 

known as "Beehives." Mancos Jim Butte is the 

dominating feature. Farther north the highland, 

coated with alluvium spread by streams from the Abajo 

Mountains, becomes an area of flat land (Bailey's 

pasture) suitable for cultivation. The northwest 

corner of the Alien Canyon country is intricately dissected. The short wall-like ridges, rounded mesas, and 

especially the columns of sandstone have suggested the 

local name "Chimney Park." The massive red walls of 

Alien and Cottonwood Canyons display niches, pockets, 

and roofed recesses used as dwellings and storehouses by 

prehistoric inhabitants.

The attractiveness of the basin is enhanced by the 

vegetation. The great differences in soil, in altitude, 

in water supply, and in exposure to sun have produced 

conditions that favor the development of spots of 

unlike vegetation in close proximity. In a small section of canyon, yellow pine, pifion, sage, oak, box 

elder, willow, cottonwood, squaw bush, roses, clematis, 

ferns, and many grasses and flowering annuals are at 

home. At the box heads oak brush forms almost 

impenetrable thickets. In the large groves of cottonwood many trees are 4 to 6 feet in diameter.

» On some maps the name "Cottonwood Canyon" is applied to a short stream that 

rises in the Causeway near the head of Alien Canyon and trends north to Indian 

Creek. Locally "Cottonwood Creek" is known as Gundlock Creek.

>3» As the Alien Canyon country includes lands reserved for use by Piute Indians 

it has also been known as "Piute Park" and "Piute Basin."

The Piute village at Alien Canyon is one of the oldest 

settlements in Utah. Water, patches of rich soil, protection from wind, house sites in canyon walls, and adjoining hunting grounds made it a desirable spot for 

Basket Makers and Cliff Dwellers. The Piutes and 

Utes found the stream flats suitable for planting corn, 

and early white settlers were attracted by the pasturage 

and the favorable conditions for small-scale irrigation. 

The obvious injustice of taking from the Indians land 

which they had used continuously for many generations 

led to the present arrangement; the agricultural land in 

Hammond, Cottonwood, and Alien Canyons and in Dry 

Wash is allotted to the Indians; the other lands in the 

Alien Canyon country form part of the national forest, 

in which the Indians have preferential grazing rights. 

GRAND GULCH PLATEAU

Comb Ridge, the San Juan River, Red House Cliffs, 

and the south wall of Elk Ridge outline an area of 

about 1,000 square miles here called Grand Gulch 

Plateau. It is a unit with respect to its topography, 

its drainage pattern, and its vegetation. Essentially 

the surface of the plateau is a single stratum of sandstone on which stand a few low flat-topped mesas and 

some rounded sandstone "haystacks." It slopes upward from the west and from the east to a broad flat 

axis, which in turn slopes southward from an altitude 

of 7,000 feet near Elk Ridge to 5,000 feet in Cedar 

Mesa, overlooking the San Juan. From viewpoints on 

Elk Ridge and on mesas in the Red House region the 

surface of Grand Gulch Plateau seems continuous. In 

fact, some extensive areas like Grand Flat, Polly Mesa, 

and those about the heads of Steer Gulch and Road 

Creek have remarkably unbroken floors on which 

drainage channels are so faintly outlined that in places 

water stands after, rains. But attempts to traverse 

the plateau except along carefully selected routes proved 

futile: the surface is trenched by impassable canyons 

that reveal their presence only when their rims are 

reached. The floors of the canyons that, cut the 

eastern slopes of the plateau are accessible only at the 

canyon mouths. Though the white rocks in which the 

natural bridges and windows in Arch Canyon are 

carved are in plain view from the road on Elk Ridge, 

they can be reached only by a trail from Comb Wash. 

Likewise the deep trenches of Johns Canyon and Slickhorn Gulch, which cut the southern edge of the plateau, 

are passable only on worked trails along the banks of 

the San Juan River. The chief obstacle to traverse is 

Grand Gulch, which divides the plateau into an eastern 

and a western part. Though less than 1,000 feet deep, 

its walls begin with a vertical drop of 30 to 60 feet and 

continue downward as a series of undercut steps 10 to 

40 feet high and 5 to 10 feet broad, impossible to descend, even on foot, except with great caution and at 

wisely chosen places. Throughout its course the 

parallel canyon walls wind in and out as a series of 

closely placed meanders and rise almost vertically from
12 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

a floor which in few places exceeds 500 feet in width. 

No trails cross Grand Gulch. Access to its floor from 

the east is impossible except at one point. From the 

west it may be reached by an artificial trail near 

Dripping Spring Gulch, at Collins. To avoid Grand 

Gulch the abandoned wagon road from Bluff to the 

Colorado River the only road ever built across the 

plateau leads up Road Canyon to the plateau surface 

bordering Fish Canyon and then north nearly to the 

base of Elk Ridge, where shallow Kane Gulch, the chief 

head tributary, is crossed by dugways.

During the winter and immediately after rains in 

spring and summer, water may be found in broad, 

shallow streamways on Grand Flat and in pockets 

scattered over the plateau surface. Water remains 

throughout the year in Kane Gulch, Dripping Spring 

Gulch, and Snow Flat and in places on the floors of the 

larger canyons. Over most of the plateau bare rock is 

exposed. What little soil is produced by weathering is 

blown by winds into low dunes, which provide footing 

for sagebrush, various low shrubs, and grasses. Pinon 

and cedar thinly spread over the surface send their 

roots deep into rock cracks and serve as centers for 

small piles of wind-blown sand.

During times when water is present Grand Gulch 

Plateau is a grazing ground for small bands of stock. 

Otherwise it is not utilized. That it was once the 

center of a considerable population is amply shown by 

ruined structures and agricultural fields on the canyon 

floors and walls, and to a less extent on their runs. 

The steep walls of Grand Gulch appear to have presented little difficulty to the ancient Basket Makers 

and Cliff Dwellers. Lines of toe holes leading from 

watered fields on the canyon floor to houses tucked away 

on shelves and in recesses of the walls and other lines 

leading to the plateau surface above demonstrate the 

skill with which the ancient inhabitants gained access 

to water, to arable ground, to building materials, and to 

wild animals that might serve as food. Miser 24 

describes the lowermost mile of Grand Gulch as presenting "some of the wildest scenery.along the San 

Juan. It is a dark narrow canyon, with vertical red 

walls several hundred feet in height, at whose base lie 

heaps of huge boulders and great piles of driftwood."

LIME CHEEK VALIEY

At its southeastern edge Grand Gulch Plateau overlooks Lime Creek Valley, a lowland area sharply defined 

on the north and west by the curved wall of Cedar Mesa, 

on the east by the domelike ridge that borders Comb 

Wash, and on the south by the San Juan Canyon. 

Lime Creek and its score of western tributaries rise 

abruptly hi the wall-like face of Cedar Mesa and, when 

water is sufficient, flow throughout their courses with 

moderate gradient in meandering, vertical-walled, 

shallow trenches. Tributaries from the east are short,

« Miser, H. D., op. cit. (Water-Supply Paper 538), p. 10. 

steep, angular grooves, cut into the flanks of the remarkably banded Raplee Ridge. The valley includes 

no towering mesas or deep canyons. Essentially it is 

a plain broken into irregular tables and short, flattopped ridges from which rise here'and there picturesque erosion remnants Mexican Hat, Setting Hen, 

Bell Butte, Garden of the Gods cut in red sandstone 

and shale.

Lime Creek Valley (pi. 4, B, O) is an inhospitable 

region -dry throughout the, year and hot in the 

summer. During most of the year a small amount of 

potable water may be obtained from a spring on the 

Cedar Mesa rim, but the only reliable source is the 

muddy San Juan. Lime Creek water is alkaline. 

Though the altitude of the valley exceeds 4,000 feet, 

the annual precipitation is probably less than 8 inches. 

In favorable spots scattered pinons maintain themselves in rock cracks, but the general vegetation consists of shadscale and other tough, low brush characteristic of arid regions. Fully three-fourths of the 

surface is destitute of plant cover. Though much of 

the bedrock is limestone, the formation of soil is prevented by the sweep of sudden showers.

Lime Creek Valley afforded no attractions to the prehistoric inhabitants of Utah, nor to the Piutes or 

Navajos. To the white pioneers it was a necessary 

part of the route to the well-watered Johns Canyon and 

to grazing lands beyond. The spring near the head of 

Lime Creek was a camp site for prospectors who used 

the overland route to places in San Juan Canyon below 

Goodridge. During the "oil boom" that began in 

1908 with the completion of a weU on the bank of the 

San Juan and continued for several years the valley 

enrolled a considerable population. A road was constructed from Bluff, a bridge built across the San Juan, 

and in the mushroom village of Mexican Hat, near 

Goodridge, three stores did a profitable business with 

drillers and with Navajo visitors from beyond the 

San Juan. Since the field has been abandoned by 

drillers and real-estate speculators, a trading post 

has been intermittently maintained at Goodridge, and 

in the winter small flocks of sheep graze on the sparse 

vegetation.

DARK CANYON PLATEAU

Cattle trails from the northwest edge of Elk Ridge 

lead out to the Dark Canyon country, a plateau that 

slopes gently westward to the Colorado River, where it 

terminates abruptly in the walls of Cataract Canyon. 

(See pi. 5, A.) At the south the plateau terminates in 

the giant rock steps that border White Canyon. Toward the north it extends to the gorge that carries to 

the Colorado the drainage of Beef Basin. The dominant feature of the plateau is Dark Canyon, a deep, 

narrow, meandering watercourse whose headmost tributaries have cut far into Elk Ridge. Below the mouth 

of Woodenshoe Creek the walls of Dark Canyon are 

continuous and nearly vertical, and its floor descends
GEOGRAPHIC DISTRICTS 13

to the Colorado as a series, of steps into which waterfalls have cut irregular grooves. Attempts to traverse 

the canyon on horseback proved futile, but passage 

on foot is possible with the aid of ropes. The characteristic vegetation of Dark Canyon Plateau is that common 

to highlands of the San Juan country above altitudes of 

5,000 to 7,000 feet mile after mile of sagebrush interrupted by groves of pinon and juniper. During seasons 

when rain is sufficient small widely spaced water holes 

permit the use of the plateau as grazing ground for

cattle.

WHITE CANYON

White Canyon is the best-known region along the 

east side of the Colorado between Moab and Lees 

Ferry. There is reason to believe that it was explored 

by prospectors as early as 1870, and since Dandy 

Crossing (Hite), near its mouth, was discovered, in 

1880, it has served as the route for pack trains and 

wagon trains that have found occasion to take a direct 

course from the San Juan country to the settlements hi 

central Utah. Frey Cabin, Soldiers Crossing, Duckett, 

Blue Dike, and Rasp Trail are historic spots.

In its topographic expression White Canyon is 

unlike the other drainage channels in southern Utah. 

Except near its mouth, where the run-off passes through 

a narrow, sharply meandering gorge, the canyon is a 

broad, flat floor bordered on the south by almost 

continous high cliffs and on the north by cliffs alternating with broad areas of lowland buttes, mesas, and 

ridges. As seen from Elk Ridge, it appears as a roadway of white rock 2 to 5 miles wide that leads indefinitely 

westward between walls of banded red rock. Into the 

white rock that constitutes this floor the present White 

River and its tributaries have cut remarkably sinuous 

defiles 200 to 500 feet deep canyons within a canyon. 

(See pis. 5, B; 6, A; 23, 5.) Some tributary canyons 

are vertical-walled or even undercut trenches much 

deeper than wide and give no indication of their presence until their very rims are reached. The floor of 

the inner canyon can be reached by following down 

the bed of Armstrong Canyon, also by trails constructed 

at Soldiers Crossing and Duckett. Along the pioneer 

trail down White Canyon interesting erosion features 

appear at three levels. On the south rim of the outer 

canyon stand huge mesas of red sandstone, the Tables 

of the Sun, and west of them smaller mesas extend in 

a broken line to the Colorado. On the north rim 

Jacobs Chair, the Cheesebox, and other picturesque 

buttes interrupt the otherwise even sky line formed by 

spurs that lead to Dark Canyon Plateau. The floor 

of the outer canyon, particularly below Soldiers Crossing, is studded with low mesas, buttes, and mounds. 

The inner canyon is wonderfully carved. High on 

the walls and down near the stream bed are long 

roofed shelves, alcoves, tunnels, windows, pocketlike 

niches, and a bewildering variety of miniature-erosion 

forms. Undercut walls are common. In three places

natural bridges have been developed. (See p. 103.) 

Along White Canyon pinon, juniper, and sage constitute 

the dominant vegetation. At the heads of tributary 

canyons yellow pine appears, and immediately along 

the streams cottonwood, willow, boxelder, flowering 

vines, and many annuals grow vigorously. Because of 

the suitable sites for dwellings, abundant water supply, 

patches of fertile soil, and convenient hunting range, 

upper White Canyon was the home of many Cliff 

Dwellers. The structures built by them, some still 

undisturbed, are features of interest to tourists who 

visit the Natural Bridges National Monument. At 

present the White Canyon region has no inhabitants. 

Prospecting has revealed no valuable minerals, and the 

historic road from Dandy Crossing to Bluff has been 

long abandoned. As grazing ground it has value 

when forage on the surrounding highlands is buried 

in snow.

RED, ROCK PLATEAU

The little known "red-rock country" along Glen 

Canyon, "beyond the Clay Hills", is a highland area 

bounded by White Canyon, Red House Cliffs, San Juan 

Canyon, and Glen Canyon. For this region of mesas, 

domes, and canyons, walled about by lines of cliffs, the 

term "Red Rock Plateau" seems appropriate. It is an 

isolated region and difficult of access. From White 

Canyon the plateau surface may be reached by the 

Frey trail, at the head of Frey Canyon, and by the 

Rasp trail, near the Colorado River. From Glen 

Canyon a stock trail has been constructed up Trail 

Cliff, near the mouth of Red Canyon, and other difficult 

trails lead to the plateau surface at Lake Canyon and at 

a point opposite the Hole in the Rock. From the San 

Juan River a trail runs up Castle Wash, and opposite 

Navajo Mountain a trail climbs to the plateau about 

1,000 feet in 2 miles. From the east, access to the 

plateau top presents no great difficulty; the wall formed 

by the Red House Cliffs is broken down at Red House 

and at the Clay Hills. From Red House, Red Canyon 

may be followed to its mouth, but access to the high 

country is blocked by cliffs. From the Clay Hills, however, trails lead to the plateau surface at places where 

travel in all directions is feasible. In fact,,Clay Hills 

Pass, discovered and used by the members of the San 

Juan Mission as part of their memorable route from 

Escalante to Bluff, is the only entrance to the plateau 

that could be developed as a wagon road without 

prohibitive expense. (See pi. 6, B.)

Over the part of the plateau between Castle Wash and 

Red Canyon the surface is made uneven by mounds, 

short ridges, and flat tables, few of which rise more than 

100 feet above a general level. In this part of the 

plateau travel is made difficult by the deep-cut Mold, 

Cedar, and Knowles Canyons with their innumerable 

short canyon tributaries, rather than by surface irregularities. Between Red. Canyon and White Canyon 

lines of high-walled mesas dominate the topography.
14 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

South of Clay Hills Pass and back of Ked House Cliffs 

the country rises into high domes and mesas among 

which wind box-headed canyons that lead the drainage 

down precipitous channels south to the San Juan and 

west to lower Castle Wash. Along a line paralleling 

Lake Canyon the surface of Red Rock Plateau curves 

upward, forming the Step, west of which the plateau 

continues at a higher level nearly to the Colorado 

River. Of the separate plateau thus formed only 

Gray Mesa remains. The rest of it has been eroded by 

short tributaries to the Colorado and the San Juan to 

such an extent that canyons alone seem to constitute 

the landscape. Traverse about the junction of the 

Colorado and the San Juan is possible only on foot, by 

scrambling in and out over smooth sandstone walls 

and following little crooked defiles whose floors break 

off in terraces toward the river. In a day's walk, 

covering 2 miles, 25 canyons were crossed. It is a 

region of bare rock towers, alcoves, arches, and deep 

vertical-walled grooves the roughest country seen in 

the plateau province. (See pi. 6, C, D.)

The streamways traversing Red Rock Plateau vary 

much in form and in details of erosion. Red Canyon is 

a broad, sheer-walled trench throughout most of its 

course. Moki Canyon is a narrow gorge with walls 

1,000 feet high, unscalable except where sand dunes or 

landslides have obliterated the cliffs. The upper part 

of Castle Wash is a wide, open valley, bordered on the 

north by low sloping walls and on the south by benchlike sandstone cliffs that lead back to high country. 

The lower part of the wash is a canyon more than 500 

feet in depth joined by tributaries equally deep. The 

tributary along the base of the Step, locally known as 

Johnny Hole, is a particularly narrow, rough-walled 

trench, into which a trail descends over the edges of 

irregularly broken strata. Near its mouth Castle Wash 

widens, though still hemmed in by walls. This part of 

the wash, heretofore mapped as an independent canyon 

(Spring Gulch), presents areas of flat floor and a permanent spring-fed stream. It has been utilized by the 

Piutes for winter camps.

Lake Canyon, like most of the other stream channels 

of Red Rock Plateau, is a trench defined by sandstone 

walls and joined by short, box-headed gulches. At a 

place near its head the floor of bare rock and sand, 

usually dry, is replaced by a stretch of meadow land. 

This is the spot to which "Providence directed" the 

San Juan Mission in 1879-80, the only place on the long 

traverse where water and stock feed were abundant. 

Though Hermit Lake, which cheered the tired scouts, 

has since disappeared, the meadow remains an attractive 

feature that contrasts sharply with surrounding areas of 

bare rock. Its bordering walls are beautifully carved 

into alcoves and overhanging arches; its alluvial floor 

is a field of grasses, ferns, wild roses, violets, and 

mallows, among which grow willows and cottonwoods.

Though most of Red Rock Plateau has an altitude

exceeding 5,000 feet and receives annually about 20 

inches of rainfall, it is comparatively treeless. Widely 

spaced pinons and junipers are rooted in rock cracks on 

the plateau top, on the edges of mesas, and on canyon 

walls and together with rare willows form small groves 

in depressions floored with sand that from time to time 

is soaked with rain. Sage, buckbrush, and cactus, 

growing as individuals or as groups, seem equally at 

home on the plateau surface and in canyons. Grass of 

various kinds and a surprising.number of annuals grow 

in the wind-made flats, low dunes, and mounds built at 

the base of trees and brush. Outside the canyons the 

soil is predominantly shifting sand. There are large 

areas of bare rock continuously swept clean by rain 

wash and wind.

Red Rock Plateau is a lonely region and doubtless 

has always been so. The cliff houses in Lake Canyon, 

Moki Canyon, Knowles Canyon, and elsewhere are few, 

small, and crudely built. They seem to be the temporary homes of migratory bands or of pioneers who 

found the situation unfavorable. As remarked by 

Judd,25 "These ancient folk, safely cloistered in murky 

canyons, tarried but a short while; then moved to a 

happier environment." For the Piutes and Navajos 

the plateau is a hunting ground for deer and mountain 

sheep. For white men it is a feeding ground for cattle. 

But as a cattle range its use is restricted. There is 

enough forage for several thousand cattle and enough 

water to supply their needs. The permanent water 

supplies, however, are unfavorably placed. Over about 

800 square miles of surface there are few perennial 

springs, and the best grasslands have none. Access to 

seeps on the canyon bottoms is possible at few places. 

After rains water stands for days in rock pockets and'in 

favorable seasons may last for weeks. During most 

years fall rains and winter snow provide sufficient water 

for livestock. The critical season is summer. By June, 

or even May, water is no longer available. The stock 

that can be accommodated in the national forest is 

driven to Elk Ridge, and the remainder started on the 

100-mile trail to the railroad at Thompson.

WILSON MESA

West of the S>tep and north of the Great Bend of the 

San Juan River the characteristically rough surface of 

Red Rock Plateau is replaced by a level, undissected 

floor. On the east it terminates just back of the Step; 

its north and west edges are defined by the box heads 

of canyon tributaries to the Colorado; its south edge 

overlooks the San Juan River, 2,000 feet below. To 

this remarkable feature, the only stretch of flat land 

along Glen Canyon, the San Juan Mormon band gave 

the name "Gray Mesa", hi recognition of the color of 

its rock floor and in contrast with the red-rock country 

north and west of it. In recent years, however, the 

terms "Wilson Mesa" and "Rustlers Flat" have comeJudd, N.'M., Beyond the Clay Hills: Nat. Geog. Mag., vol. 45, p. 279,1924.
CLIMATE 15

into use. "Wilson Mesa is a distinct geographic unit. 

No pinons, junipers, or other trees grow on the mesa; 

grass and low, hardy brush cover the surface. As a 

point from which to view the stupendous work done by 

the Colorado and Sail Juan Rivers, "Wilson Mesa vies 

with Navajo Mountain and the Kaiparowits Plateau. 

In traverses across its surface there was no opportunity 

to trace the boundaries of "Wilson Mesa. The outline 

shown on the map is therefore highly generalized.

GLEN CANYON

Throughout most of its course in Glen Canyon the 

Colorado flows close to the base of its massive sandstone walls 800 to 1,200 feet high. (See pi. 7, A, B, 

(7.) In places the walls are undercut. At low water 

stages mud flats are exposed here and there at the base 

of cliffs, and in the river itself sand bars appear. There 

are also gravel bars above the reach of high water 

the sites of placer claims. Most of the tributaries to 

Glen Canyon enter through narrow gashes in the walls 

and join the master stream without passing over flats 

or deltas. At their mouths their depth and width are 

about the same as farther back. In fact, in passing 

through the canyon it is difficult to tell whether some 

of the vertical grooves in the towering walls are local 

features or the exits of long streams. Red Canyon and 

White Canyon join Glen Canyon less abruptly; the 

last half mile of their courses is a gravel-strewn flat. 

In general, the color of the canyon walls is the color of 

the rock, little changed by* a coating of vegetation. 

Only a few pinons and junipers seem to maintain a 

foothold. At the heads of alcoves and in recesses 

about water seeps, oak, ferns, and brush of various 

kinds grow vigorously. The high-level bars support 

cottonwood, willow, and tamarisk, and the bars exposed 

at low water are thickly covered with young trees.

Glen Canyon was known to the prehistoric peoples, 

whose presence is recorded in ruins and picture writing. 

It has been thoroughly explored by prospectors, who 

in 1883 to 1900 and intermittently thereafter were at 

work on placer claims. Compared to Cataract Canyon, 

above, and Marble Gorge and Grand Canyon, below, 

Glen Canyon is a quiet stretch of water many times 

traversed by explorers, miners, and tourists, who reach 

it from the settlements in central Utah. The trip by 

boat from Hite to Lees Ferry is a memorable experience 

attained in a few days' time with little necessary 

discomfort. At present no one lives in the canyon. 

Mining has proved unprofitable, and the routes that 

made use of crossings at Hall Creek and Hite have been 

abandoned. Except for its scenic interest, its future 

economic usefulness lies in the possibility of developing 

water power.

BEEF BASIN

As viewed from Horse Mountain the Beef Basin 

country appears as a flat dome, about 20 miles long and

8 miles wide, extending northwestward from the base of 

Elk Ridge. Into the northern and eastern flanks of the 

dome tributaries to Indian Creek have cut deep boxheaded canyons. Along its south border Beef Basin 

extends westward as a wide valley and is joined by 

tributary canyons that reach north to and beyond the 

crest of the dome and south into the flanks of Elk Ridge. 

Springs at several canyon heads, in particular Home 

Spring, provide a perennial water supply that makes 

possible the utilization of the basin as a grazing area 

even in summer. Along canyon walls near the springs 

cliff houses are numerous. In general viewrs from high 

points the region appears as an enormous expanse of 

white sandstone, carved in places deep enough to expose 

the red beds and dotted by buttes. Toward the west 

Beef Basin Canyon rapidly deepens, and from the 

mouth of Fable Valley to Cataract Canyon it is a gorge 

1,000 to 2,000 feet deep.

In the San Juan country, as in other parts of the plateau province, the climate is controlled only generally 

by latitude and the passage of cyclonic storms. In a 

broad sense, the westerly winds of the winter and the 

southwesterly winds of July, August, and September, 

rather than the more variable winds of other seasons, 

provide conditions favorable for precipitation; but these 

factors are greatly modified and in some places nullified 

by altitude and topography. The result is a group of 

local climates, each with its peculiar distribution of 

rainfall and temperature. Thus at Bluff, in the San 

Juan Valley, the mean annual precipitation is about 

7 inches; at Blanding, on Sage Plain 27 miles to the 

north, about 15 inches. At Monticello southeast winds 

prevail throughout the year; at Blanding, 22 miles 

distant, the wind is south for 10 months of the year, 

southwest for 1 month, and north for 1 month.

Rain showers are short and far apart. Most showers 

last for an hour or less and furnish rain to a few square 

miles. The number of days in a year on which rain is 

lacking or is less than 0.01 inch is 323 at Aneth, 314 at 

Blanding, 327 at Hite, and 311 at Monticello, the wettest 

station for which records are available. Many of the 

recorded small monthly rainfalls are in reality the 

records of single showers, and the larger monthly means 

may comprise but a few heavy downpours. But during 

these infrequent showers water seems to be everywhere; 

the bare rocks are coated, waterfalls drop over the canyon rims, and the dry washes become turbulent, muddy 

streams. Most of the brief showers of summer and 

early fall are accompanied by lightning. Bolts from a 

cloud mass perhaps the only one in an otherwise clear 

sky -strike savagely at trees or bare rocks. The precipitation from these showers is slight; it sprinkles the 

ground with scattered drops or with a few hailstones.
THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

During July and August 1921 Miser 26 experienced 23 

thunderstorms, yet the precipitation recorded for those 

months at the nearest station (Bluff) was only 1.65 

inches.

As is to be expected, the low-lying canyon settlements Hite, Bluff, and Aneth experience higher mean 

annual temperatures than the plateau villages Blanding 

and Monticello, yet the highest temperature recorded 

in San Juan County is at Blanding (110°) and the 

lowest at Aneth ( 29°). Except in deeper canyons, 

snow is expected any time between October 1 and June 

1. Even in the San Juan Canyon at Aneth the annual 

snowfall of 5 inches is distributed through 5 months. 

Snow may fall on Elk Ridge (altitude 8,000 feet) at 

any time between September and June and on the 

Abajo Mountains (altitude 11,000 feet) during every 

month of the year. Extensive snowbanks were encountered near the Bears Ears in May. About Abajo 

Peak and Mount Linnaeus snow chokes the canyon 

heads until late hi June and supplies water to streams 

until late in August. During most winters snowdrifts 

block the Monticello-Blanding highway and make the 

Blanding-Kigalia road impassable.

Characteristic features of the San Juan climate are 

the great range of diurnal temperature and the prevalence of clear skies. During summer and autumn a 

daily range of 50° is not unusual. Hot days are followed by cool nights beginning soon after sunset. 

Even in deep canyons during the hottest part of the 

year few nights are comfortably spent without a covering blanket. On Elk Ridge in July uncomfortably 

hot days may be followed by nights during which water 

freezes in camp buckets.

At Hite, Bluff, and Goodridge days with cloudless 

skies number probably 200 a year. At Blanding the 

approximate means for the years 1922-27 are, clear, 

133 days; partly cloudy, 153; cloudy, 79. Of 'the, 

cloudy and partly cloudy days, those with rain number 

about 50 at Blanding and perhaps 40 at Aneth, Hite, 

and Bluff. West of Elk Ridge and along the San Juan 

many clear days are to be expected in every month of 

the year. In spring and fall they may be continuous 

for 1 or 2 weeks, and throughout the San Juan country 

days with scattered clouds greatly exceed those with 

overcast skies. It is estimated that southeastern Utah 

as a whole receives 85 percent of the possible sunshine.

Because of its clear skies, its low humidity, its large 

range of daily and annual temperature, and its almost 

constant gentle winds, the climate of the San Juan 

country is invigorating. Though the heat of spring

* 6 Miser, H. D., The San Juan Canyon of southeastern Utah; a geographic and 

hydrographic reconnaissance: U. S. Qeol. Survey Water-Supply Paper 538, p. 16, 

1924.

and summer days is great, it is not oppressive; it is 

dry heat, and the coolness of night is equally dry. To 

escape the discomfort of the hottest days spent traversing the bare ledges and sand-floored washes, it is 

only necessary to seek the shade of a rock. The edge 

of a shadow is the dividing line between heat and 

delightful coolness.

PRECIPITATION 

RECORDS

Since the settlement of the San Juan country in 1880, 

facts about floods and droughts, the tune of killing 

frosts, snowfall, and ice in the San Juan and the Colorado have been recorded in archives of the Church of. 

Jesus Christ of Latter Day Saints. Diaries and the 

recollections of old-tuners are additional sources of information. Instrumental measurements of the amount 

and distribution of rain that falls between the ColoradoUtah boundary line and the High Plateaus, 100 miles 

west, have been made by volunteer observers.

At Aneth the records are complete for 9 years, 7 of 

them consecutive (1901-7); at Hite, for 12 consecutive years (1902-14); at Bluff, for 14 years, scattered 

through a period of 24 years. At Monticello the records are substantially complete for 17 years (1911-19, 

1924, 1928-34), and when supplemented by measurements at Verdure, 7 miles south of Monticello, and at 

the nearby Baker ranger station, give a reasonably accurate record of the rainfall for 33 years (1902-34). 

The most satisfactory records are those at Blanding, 

which, except for the years 1910 and 1911, are complete and consecutive for 29 years (1905-34).

Unfortunately these six stations are so located as to 

give information for only a small part of southeastern 

Utah. Bluff, Blanding, and Monticello are in a northsouth line; Baker ranger station is close to Monticello; 

Aneth has substantially the same situation as Bluff; 

and Hite obviously records peculiar conditions. For 

the higher lands, for the lower San Juan Canyon, and 

for the great stretch of country between Comb Wash 

and the Colorado measurements of climatic factors 

are lacking. Of the records published, those for 

Blanding are believed to represent best the conditions 

on the plateau lands, and Bluff those of the canyon 

floors.

Though the instrumental records are obviously too 

fragmentary for detailed climatic studies, when supplemented by observations on streamways and vegetation 

they give a generalized picture of the climate and 

indicate the amount and distribution of rainfall in 

those parts of the San Juan country that are adapted 

for agriculture. (See fig. 1.)
CLIMATE 17

24

23 

22 

21 

20 

19 

16 

17 

16 

15

toOz 13 z

-1 12 

Z"

9 8

7 

6 

5 

4 

3 

2 

1 0

-nHtHh -U

... ...... -1 (- n

HH

-1 h

H [

 +1 

H > 

Hi

EXPLANATION

Wettest year

Mean

Driest year

H r 

H h

 +1= 

 -Ih 

"H H

"H 1- 

'H 1-

-| h-j (. 

H hj (.

 tl 

-1 H

 tl 

4 

 1

__ ^

H 

-ij

-1 

 -11

r- -* c-w-fe ^F^ ^-^ ^w^ | 

" § 1 - I -c E = £ T E - 1 r E = t- T E =

.= O- D "m <- Q_ 3 (0 --CO-DOT --r CL 3 (0 vr Q- 3 BJ 

^ CO CO U_ S 10 10 U- StOCOLu ? CO CO li- StOtOU.

H h -j H

if i <[!

H t- <f * H h- 2^| 

1 L _1H I-"1 , ^

H h < H N I §

H h D'-l K, f ^ 

H H Z H h\ &

H f- ' Z ^ K i S H h r- < ol 1 h- if ^' '

] , -j j. H H 1 £

^ JL ^-,-1^ ^HHH^^ 

Hi- H H h | $^

if n IKt IN

^ 0- 1] ^H, |||

nT j h ii H Hj~!: H be\ 

HI- ^ t- ^ H h'J | ^ ^

jt " ^ M^ H 

H - M j t [ H H i- h-n- 1 ^ WS IT ^ ^ 

M^

H tJ [ ~T H N *" ^8^^ $^ H h ]r Hf" HHh g|^$ ^ ^

H H^-_ H H -) H h p | | | | ^

al 1' nl ! ll

11! 1 111! iff! If

H H/S ^ > ^ ^ 'y tfi - in

n -Th if HI

11 i|^f HI

\\ llTl III 1 III 111

-H r

Lhh

$ 11- 

^ II- 

^ Lk

^ II- h

h h

^ 1- 

^ t-

/ \

X \

/ \

/ s

s \

^ \ 

y X 

y 1

^ ^

\ '$

y ^

f rainfa

a o

"S

J3

d annual distri

05

 5 n

CD 

W.

bo

't>g 0A

G 

S3$S1GURE 

ft

ANETH BLUFF BLANDING MONTICELLO HUE I U. CD O UJ 

H U. z -J h

<flQ <| 

CD n
18 THE SAN JUAN COUNTRY, SOUTHEASTERN. UTAH

Precipitation in the San Juan country

Anelh (altitude 4,800 feet)

Year

lonn

1901.. 

1902 

1903.. 

1904 

1905 

1906 

1907...... 

1910 

1911 

1912...... 

1913 

Mean..

January

1.06 

.06 

.11 

.05 

1.67 

.29 

.85

.51 

.09 

25

'.49

February

0.86 

.19 

.50 

.07 

1.71 

T. 

.41

.83 

.05 

1 12

.57

J3 

§ 

%

0.33 

.46 

1.54 

.10 

1.02 

1.06 

.72

.85 

1.57 

.68

.83

cL 

 <

0.18 

.01 

.59 

.03 

1.40 

.55 

.52

.40 

.28 

10

.41

& 

§

0 05

.30 

.37 

.12 

.62 

.39 

.25 

.85

.00 

.04 

.20

.29

<u

a 3- i-s

1 00

.51 

.00 

.51 

T. 

T. 

.00 

.54

.29 

.02 

00

.26

t>> "3

Hs

0 00

1.05 

.19 

.38 

.50 

.37 

1.20 

.49

2.40 

.56 

 1.02

.74

s <<

0.02

1.46 

1.22 

.04 

.85 

.07 

.54 

2.39

.71 

.30

.76

September

1,88

.00 

.35 

.93 

1.25 

1.95 

2.00 

.35

2.08 

.00

1.08

October

0,40

.36 

00 

.06 

.50 

.00 

.11 

.61

2.48 

.97

.55

November

1 01

.00 

1.36 

.00 

.00 

1.96 

1.01 

.55 

45

.12 

.02

.60

December

T

.01 

1.09 

.02 

.28 

.20 

1.08 

1.25 

.45

.16 

.10

.42

Annual

6.12 

5.30 

4.80 

4.25 

10.74 

8.09 

9.53

10.83 

4.00

7.00

Bluff (altitude 4,200 feet)

1911 

1912 .

1913 

1914 .

1915 

1916 

1917 

1918 -.

1919 ...

1920 

1921 .

1922 ..

1923 

1924 -

1925 

1926 

1927 .

1928 

1929 .

1930......

1931 

1932 

19S3 ..

1934 .

Mean..

T.

0.43

2.06

.99

29

55

1.52

.49

.22

10

.28

.11

.10

1.02

.10

.78

.62

.17

.55

T.

0.91

.70

.80

05

2.32

.20

.10

46

1.78

1.07

.54

.41

1.27

.96

.14

.89

.74

2.03

.58

,17

.05

19

.56

.85

.36

1 1?

30

1.28

1.11

.50

.31

.81

.17

.02

.00

.58

.25

.10

.10

1.00

74

.45

.21

1.15

.05

.11

? 99

T.

.17

.22

.72

.62

.64

.38

1.17

.58

0.05

.00

11.50

45

58

.56

.42

.07

T.

T

1 50

T.

.93

.33

.17

.38

.13

.23

.97

.44

0 ?3

.02

.00

1.20

03

00

.80

.41

T.

?8

,03

2.15

.03

.00

.36

.05

.11

.08

.04

.25

?, ?1

1.19

.61

1.07

.75

,55

.04

.15

.88

.07

.23

2.11

.17

2.37

.28

.28

1.02

.88

.04

.78

1,04

.51

.04

1.57

T.

.64

59

.23

1.50

T

10

.10

.66

39

1.02

.27

.64

.34

.39

.93

.17

.70

.54

l.Rfi

.00

.00

.00

.50

5?

,57

.33

.00

00

.39

1.47

2.12

.55

1.98

.71

1.56

.53

1.16

.46

.74

1.80

.45

.00

.00

on

69

1.17

.75

T

1.01

.62

2.42

.96

.20

1.27

.43

.24

.03

.67

0 00

.01

.09

.00

.03

1,75

.54

.04

T.

95

.16

.50

1.05

.00

.83

1.85

.00

.41

.82

.48

0 35

.05

.87

.75

1.61

.15

.37

.30

.41

1.19

1 39

.86

.83

.08

.00

1.51

1.03

.21

.57

.70

4.56

3.63

7.43

8.65

6.26

4.46

12.72

8.71

7.72

5.35

10.09

6.73

4.54

5.86

6.91

Interpolated.

Blanding (altitude 6,400 feet)

1904......

1905 

1906......

1907 -.

1908 

1909 

1910 

1911 -.

1912......

1913 

1914 

1915 ...

1916 .

1917 

1918 

1919......

1920 __

1921 

1922......

1923 

1924 

1925......

1926 

1927 

1928 

1929. -

1930 

1931 .

1932 .

1933 

1934 ..

Mean..

i 1.25

3.21

2.60

1.03

3.65

.20

1.78

1.25

1.27

4.09

2.45

3.60

1.93

.91

.05

1.97

.47

1.92

.88

.90

.31

.32

.69

.34

1.28

1.54

T.

.77

1.40

.27

1.34

i .75

T.

.55

2.93

2.70

.70

13.43

.30

3.87

2.15

3.72

.60

.60

.25

1.31

2.91

T.

2.25

.79

.20

1.02

.33

2.88

1.68

1.70

.73

1.47

2.27

.14

1.41

1.49

2.27

3.72

1.23

.50

.90

1.80

1.88

i 3.00

.75

.40

.28

1.28

.20

2.08

1.71

1.22

.70

1.57

1.20

1.35

1.41

.80

1.86

.97

.19

.71

.80

T.

.12

.05

1.13

2.87

1.69

1.73

T.

T.

.60

1.31

1.40

.65

.04

2.79

.65

2.22

.20

.25

.05

.98

.35

.73

.25

.79

4.35

.17

.40

.59

1.65

.73

1.00

1.26

.66

.95

1.40

1.10

1.42

.63

.55

T.

i.OO

1.08

.00

.55

1.78

.39

,79

T.

1.15

1.54

1.74

.70

.70

.08

.04

2.62

T.

1.86

.48

.39

.32

.37

1.33

.93

.76

0.30

.00

.43

.20

.00

1.25

1.60

.03

.10

1.88

.35

.00

.00

.83

T.

.76

.74

.21

.08

T.

.80

.23

2.47

.22

.00

.40

.39

.67

.24

.05

.44

1.25

1.38

1.05

.80

2.00

.05

13.25

2.78

.19

3.55

1.43

.70

2.03

1.36

1.51

T.

2.68

1.22

2.11

2.81

.98

1.03

1.50

.54

1.05

.66

.42

1.43

1.39

.25

1.38

0.15

1.23

3.28

1.80

3.78

1.60

12.00

1.17

1.75

.99

1.70

2.05

.43

.20

1.44

1.76

2.38

1.52

3.25

.13

1.20

.51

1.73

1.85

2.21

1.82

.46

1.57

.85

.57

1.48

2.89

2.81

.60

2.30

1.40

1.30

1 2.80

.00

1.42

.16

1.50

.48

.40

1.15

.67

.79

.01

.15

.68

.85

2.02

1.27

4.80

.15

1.92

2.55

1.98

1.72

2.61

.28

1.36

0.02

.20

1.59

2.80

.40

i 2.10

i 4.50

4.75

.78

2.99

T.

7.01

T:

.87

1.77

1.28

1.65

.10

.85

1.32

1.89

.79

1.18

3.96

.21

.34

2.14

.37

1.52

.15

1.58

4.17

4.31

.75

1.15

2.80

i 1.60

1.10

.42

2.84

.06

.76

.03

.10

.91

3.35

1.65

.51

2.30

1.93

.20

.45

.22

.78

1.76

.00

1.90

2.17

.00

1.22

1.28

1.32

0 53

.25

4.15

1.63

6.20

6.43

i 1.20

i 1.50

.50

1.69

1.51

3.24

.84

.00

2.38

.25

.47

2.64

1.50

 2.11

1.97

.60

2.90

1.30

.99

T.

.00

2.90

1.02

.55

1.17

1.69

18.57

23.80

16.86

20.34

24.61

9.48

20.15

13.68

15.31

18.37

20.00

17.63

8.70

11.14

13.46

14.40

14.50

13.79

15.31

10.06

11.51

15.37

19.36

14.72

9.63

12.69

13.78

11.19

12.63

7.07

14. 94

Interpolated.

Monticello (altitude 7,400 feet) 

[Record for 1905 at Verdure, 7 miles south of Monticello]

1902 

1903 . 

1904 

1905 

1906 .. 

1907...... 

1908 

1909 

1910 

10.75 

T. 

.01

2.37 

2.75 ~i~.il

J.54

'0.50 

.65 

.09

.41 

.55

'§."80 

'.88

10.75 

2.61 

1.53

5.12

"i.'io

U.50

T. 

0.77 

.12

2.31

.61 

1.10 1.58

1.13 

.46 

1.67

1.24

Toe

0.35 

1.72 

.35 

.21 

.00 

.11 "T."

11.41

0.12 

1.44 

1.32 

1.12 

2.29

1.54 

1.72 

1.95

1.72 

.30 

3.91 

.50 

1.06 

1.98 

2.06 

2.29 1.80

2.09 

1.17 

1.37 

2.92 

2.86 

1.96

TTO

0.02 

.00 

1.36

.70 

2.00

r~2~.l3

3.28 

.00 

i .00 

3 93

2.96 

.47 

1.00

i"l~87

0.49 

.00 

1.65

1.99 

1.23 

2.25

i"l"50

11.20 

9.12 

12.38

23.31 

~ii~92

Precipitation in the San Juan Country Continued 

Monticello Continued

Year

1911......

1912 

1913... 

1914 

1915 

1916 -

1917 

1918 

1919 

1920 

1921 ..

1922 

1923 

1924 -

1925 -

1926 

1927 ,..

1928 

1929. ..

1930 

1931 -.

1932 

1933 

1934 

Mean..

1"

I

1.75

.20

1.30

i 2.50

2.70

2.70

1.81

.83

.15

1.30

1.95

12.72

i 1.20

.64

.44

.48

1.77

3?

1.84

4.35

T.

2.10

2.36

.54

1.33

05

3

®

PH

3.73

1.50

3.50

1.55

2.45

.47

1.90

.60

1.65

4.55

1.29

i 1.15

i 1.22

.12

1.10

1.00

i 4.30

1 70

1.04

.64

.99

3.18

.50

1.15

1.62

S3 

o

1

1.04

6.45

1.30

.41

.32

2.25

.85

6.00

2.25

1.75

i 1.05

i 2.75

i.93

1.93

i 1.25

1.80

 2.70

2 29

.19

.48

.41

.23

.39

T.

1.69

D,

.36

1.36

1.32

.24

2.70

1.22

4.05

1.12

.57

.69

1.02

1.70

1.67

.98

1.92

3.35

1.29

1.10

.97

.91

1.04

.72

1.41

1.19

1.11

03

.00

.03

.10

1.49

1.56

.30

2.07

.00

1.44

1.46

i 1.61

1.90

1.92

.16

1.05

2.33

MS

1.45

.82

.69

.78

.42

.67

.49

.84

<D

a

.91

1.17

.59

2.21

.80

.00

.25

.1.52

.12

1.19

.44

1.09

1.22

.04

1.87

.55

i 3.15

.78

.28

.35

1.34

.18

.14

.07

.70

"3

3.95

3.11

1.08

3.10

1.75

3.96

1.73

1.38

1.65

.00

2.27

1.15

i 1.42

1.49

1.71

1.27

i 1.40

1.06

2.52

2.36

1.36

2.37

1.61

.21

1.67

1

a

2.24

.52

.73

2.58

.30

1.92

2.01

1.68

2.60

1.13

2.98

i 1.04

i 2.90

.97

4.99

1.64

12.90

? 34

2.93

2.11

.90

2.68

1.37

1.35

1.83

itember

CO

2.91

.02

2.51

.05

1.55

.37

.96

.00

1.24

i .92

.54

1.43

2.36

.98

2.61

i 1.46

5.63

09

2.89

1.49

2.14

1.66

3.02

.55

1.60

1 

o

O

6.31

4.97

1.80

3.25

.00

7.25

.00

1.63

i 2.00

»2.72

i 2.00

1.72

.80

1.65

2.99

i 1.85

1.13

4 25

.16

.92

2.43

.24

1.42

.11

1.89

1

i

1

.10

.28

2.45

.10

.99

.05

.15

1.15

5.94

12.44

1.50

i 1.40

1 1.40

.25

1.34

MO

.39

2.72

.18

2.76

2.00

.00

2.02

1.51

1.30

53

£>

1

Q

1.60

1.20

i 1.50

1.85

4.50

1.28

.15

i 1.65

.95

i 1.02

i 1.85

i 1.70

i 1.70

3.88

.50

12.56

1. 35

1.21

.12

T.

2.65

1.00

.74

1.04

1.42

3

a

a

23.90

19.81

18.18

18.33

19.62

21.77

15.93

16.36

20.56

19.17

15.50

13.75

15.74

13.09

18.77

16.39

24.19

19 31

13.94

17.06

16.04

14.78

15.65

8.21

16. 72

i Interpolated.

Kite (altitude 3,500 feet)

1900 

1901------

1902 -

1903 

1904 

1905--. -.

1906 -

1907......

1908 

1909 

1910 

1911 .

1912 

1913 

1914 

Mean..

0.30

.30

.10

.76

.74

.53

.31

1.27

.97

.78

.08

.31

2.12

.66

0.60

.24

.60

1.52

.22

.45

1.43

.84

.21

.78

.34

.81

.82

.68

T

T.

0.64

.45

1.31

1.42

.51

.84

.43

.87

.53

2.28

.28

.19

.70

T.

0.26

T.

.98

.39

.82

.20

.63

.12

.35

.44

.14

.37

.36

.40

0.23

.84

1.58

.45

1.41

.28

.06

T.

.00

.12

T.

1.10

.50

T

0.00

.50

.08

T.

T.

.48

.14

.00

.77

1.22

.03

.05

1.06

.31

0 00

T

.09

.63

.15

.45

.45

1.21

1.06

.36

T.

.64

.47

.44

1.41

.49

0.12

35

.87

T.

1.06

.19

1.28

1.31

1.14

1.05

.58

.26

.14

.50

.63

0 00

.65

.32

.55

1.59

1.84

.21

.63

1.70

.22

1.12

.08

.62

.....

.73

T.

T.

0.36

.15

.11

.62

1.29

T.

.67

2.92

2.25

.58

.....

.75

1.29

.00

.00

3.83

1.75

.45

.18

.10

.85

.15

.14

.66

.....

.78

0.20

.00

.25

T.

.76

.30

1.83

2.27

.74

.68

.48

..77

-----

.69

4.40

3.12

4.44

12.36

9.41

8.30

9.33

8.71

6.00

9.43

6.85

5.16

......

7.28

GEOGRAPHIC DISTRIBUTION

All of Utah east of the Wasatch Mountains is deficient 

in rainfall. In Kane, Garfield, Wayne, Emery, Carbon, 

and Duchesne Counties, west of the Colorado River, 

and San Juan, Grand, and Uinta Counties, east of the 

river, the 35 meteorologic stations record as much as 

20 inches of rain arid snow only at Alton, on the High 

Plateaus of Kane County, and Winter Quarters, near 

the crest of the Wasatch Mountains in Carbon County. 

At 29 stations less than 15 inches is recorded, and at 

19 stations less than 10 inches. With respect to total 

rainfall, San Juan County, with an-annual mean of 

about 12 inches, is more favored than its neighbors. 

Grand County receives 7.88 inches; Wayne County, 

6.85 inches; Garfield County, 10.30 inches; and Kane 

County (except for a small area on Paunsaugunt 

Plateau), about 8 inches.

A comparison of rainfall records of the different 

stations shows clearly the influence of geographic 

position. At Hite, Bluff, and Aneth, stations in 

canyons at altitudes of 3,500, 4,200, and 4,800 feet, 

the mean annual rainfall is respectively 7.28, 6.97, and 

7.00 inches. The mean totals for Bluff and Aneth 

probably fairly represent conditions in the San Juan 

Valley east of Comb Wash but, to judge from field
CLIMATE 19

experience and amount and kind of vegetation, are 

too high for the region about Goodridge and for the 

^stretches of canyons farther west. The position of 

Hite, at the base of the Henry Mountains, seems to 

give it a rainfall greater than that believed to be characteristic of Glen Canyon. For the stations about the 

Abajo Mountains, Blanding (altitude 6,400 feet) 

receives 14.94 inches and Monticello (altitude 7,400 

feet) 16.72 inches. Records kept for 3 years (1921-23) 

indicate that somewhat more rain falls at Lockerby, 

near the Utah-Colorado line, than at Blanding or 

Monticello. On the higher lands the precipitation 

undoubtedly exceeds that recorded for any station. 

The forests, meadowlands, springs, and small bodies 

of standing water on Elk Ridge and the Abajo Mountains indicate an annual precipitation certainly exceeding 20 inches and perhaps as much as 25 inches. For 

Kigalia ranger station A. C. Folster, forest supervisor, 

estimates the precipitation as 23 inches, including the 

equivalent of the snow, which during most years covers 

the ground to a depth of about 3 feet from December 

to April.

VARIATION FROM YEAR \TO YEAR

The precipitation at stations in the San Juan country 

shows a wide annual range, though somewhat less than 

that recorded for the Navajo country to the south or 

the Kaiparowits region to the west. The variation 

is less at the canyon stations (Aneth, Bluff, and Hite) 

than at those at greater altitudes. At Hite, where the 

annual mean is 7.28 inches, 12.36 inches of rain fell 

in 1905 and 3.12 inches in 1903, a year during which 

November and December were rainless. At Bluff the 

extremes are 12.72 inches in 1927 and 3.63 inches in 

1913; at Aneth, 10.83 inches in 1911 and 4.00 inches in 

1912. At Blanding precipitation of 20 inches or more 

is recorded for 1906, 1908, 1909, and 1915. The rainfall at Blanding for 1909 (24.61 inches), the heaviest 

recorded for San Juan County, was two and one-half 

times that of the following year (9.48 inches) and still 

greater than that for 1917 (8.70 inches) and 1934 

(7.07 inches). In 1906 and 1911 Monticello received 

more than 23 inches of rain; in 1903, only 9.12 inches; 

and in 1934, 8.21 inches. The records show that 1903 

and 1934 were dry years at all stations in San Juan 

County, that 1913 was another dry year at Aneth and 

Bluff though not at Blanding or Monticello, that 1905 

was a wet year at three stations, and that 1906, 1909, 

1911, 1915, 1916, and 1927 were wet years at two 

stations.

Long before instrumental records were made the 

pioneers experienced years of heavy rain and years of 

drought. As related in diaries it "rained for a solid 

month" in the summer of 1884, and during the "great 

drought" of 1896 the San Juan at Bluff could be crossed 

dry-shod. Dying fish in pools scattered along its sandy 

bed were caught by Navajos and sold as food. Hot 

southwest winds caught up the sand from the river

bed and swept cultivated fields bare of soil down to the 

base of plow furrows. In areas adjoining the San 

Juan intermittent streams ceased flowing, large springs 

decreased in volume, and small springs disappeared. 

Except on the mountains the fodder of pasture lands 

was deficient in amount and quality. In 1934 the 

San Juan country in common with adjacent regions 

witnessed extreme aridity. In July the bed of the 

San Juan River was dry.

Some years of abnormal precipitation in the San 

Juan country correspond with those in other parts of 

the plateau province. Others show wide differences. 

The year 1903 was dry in the Kaiparowits region but 

unusually wet at Fort Defiance; in 1913 Holbrook and 

Chinle were dry, but most other stations experienced 

heavy rams, and Fort Defiance received one of its 

heaviest rainfalls. The year 1905 was wet at stations 

in the Navajo country and at Alton and Cannonville, 

in the Kaiparowits region, and 1911 was exceptionally 

rainy over most of northern Arizona and southern 

Utah. Lake wise at most stations the precipitation for 

1906,1909,1915, and 1916 was somewhat above normal. 

The records available give no indication of cycles. At 

many stations exceptionally wet years are immediately 

followed or preceded by exceptionally dry years.

As the maximum annual precipitation in the San 

Juan country is insufficient for ordinary agriculture 

and in places even for grazing, and as the possibility 

of irrigation for any year depends upon the rain and 

snow that fall on the Abajo Mountains, these great 

variations from year to year limit the utilization of the 

abundant unoccupied land.

SEASONAL DISTRIBUTION

In the San Juan country the seasonal distribution of 

rainfall is unfavorable for ordinary farming and for 

the vigorous growth of forage plants. For all stations 

March is a relatively wet month, but the combined 

mean rainfall during April, May, and June is 2.63 

inches for Monticello, 2.15 inches for Blanding, 1.27 

inches for Bluff, and 0.96 inch for Aneth. In 2 years 

at Monticello and 3 years at Blanding, Bluff, and Aneth 

no rain fell during June. Part of even this inadequate 

supply is unavailable; evaporation during these dry, 

hot months is great. In a few favored areas the moisture from fall rams, kept intact during the winter and 

supplemented by the small supplies of spring, is sufficient in some years to bring field crops to maturity, but 

in most of the San Juan country the success of irrigated 

crops depends upon the rains of July.

During 30 years at Blanding the July rains amounted 

to 0.05 to 0.98 inch for 9 years, 1.00 to 2.00 inches for 

13 years, and more than 3 inches only in the "good 

years" of 1911 and 1914. During 32 years Monticello 

recorded only 9 years with a July precipitation exceeding 2.00 inches. July rains exceeding 1.00 inch fell 

in 3 out of 15 years at Hite, 3 out of 19 at Bluff, and 

4 out of 11 at Aneth. In general the nonirrigated
20 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

crops for years having July rains of less than 2.00 

inches are raised at a loss.

The range in monthly rainfall from year to year is 

large even for semiarid regions. The figures for Blanding during 30 years, in inches, are: January, trace to 

4.09; February, trace to 3.87; March, trace to 3.72; 

April, trace to 4.35; May, trace to 2.62; June, 0.00-2.47; 

July, 0.05-3.55; August, 0.13-3.78; September, 0.01- 

4.80; October, trace to 7.01; November, 0.20-4.31; 

December, 0.00-6.43. October 1916, which had the 

heaviest monthly rainfall recorded (7.01 inches), was 

preceded and followed by Octobers with only a trace. 

Corresponding variations appear in the records of other 

stations. Obviously, agriculture based on an expectation of rain for a certain month or a group of consecutive 

months and stockraising that depends on ephemeral 

water supplies are speculative industries.

Except for a relatively dry season that includes April, 

May, and June, which is characteristic of the plateau 

province, the meteorologic records for the San Juan 

country show no uniform seasonal rainfall. In amount 

of precipitation the seasons rank at Aneth, fall, summer, 

spring, winter; at Hite, fall, winter, spring, summer; at 

Bluff, winter, summer, spring, fall; at Blanding, winter, 

fall, summer, spring; at Monticello, fall, spring, summer, winter. The wettest month of the year is September at Aneth, November at Hite, July at Bluff, 

December at Blanding, March at Monticello, and April 

at Baker ranger station. At Bluff November is nearly 

as dry as June; at Blanding the November rainfall is 

three times that of June. The distribution of rainfall 

during the wettest and driest years of record is shown

in figure 1.

TEMPERATURE

As shown by a comparison of the tables for the meteorologic stations in the San Juan country, the mean annual temperature varies with altitude; but in order of 

the amount of heat experienced, the position of the 

months differs considerably. The warmest months 

have the rank July, August, June, September, May. 

The coldest months have the rank January or December; February or November; March, November, or. 

February.

At Monticello, the coldest station, the thermometer 

rarely records as much as 90°, and the highest recorded 

temperature during 32 years was 98°. At the other 

stations in San Juan County temperatures exceeding 

100° are normal for June, July, August, and September. 

The maximum figures are,'for Aneth,-106°; Bluff, 109°; 

Blanding, 110°; Hite, 115°. The difference in mean 

monthly temperature from year to year, though not 

abnormal, is greatest in September and January. The 

September variation is a factor of some importance in 

agriculture. Temperatures below zero have been 

recorded at.all stations; at Monticello and Blanding 

they may occur at any time during November, December, January, and February. At Bluff temperatures

below zero are expected late in December. Because of 

some local conditions not understood, Aneth, otherwise 

a warm station, has experienced the lowest temperature ( 29°) recorded for San Juan County.

Each year the soil is frozen to depths of 1 to 4 feet 

and the Colorado and San Juan Rivers freeze over in 

places. During some years the ice is sufficiently solid 

to support teams and wagons.

The annual ranges of temperature are great. The 

maximum ranges recorded are, for Monticello, 119° 

(98° to -21°); for Blanding, 133° (110° to -23°); 

for Hite, 116° (115° to -1°); for Aneth, 135° (106° 

to 29°), the highest range recorded for the plateau 

province and among the highest known.

The daily range of temperature, except on canyon 

floors, is probably 40° to 50°. Hot days are followed 

by cold nights, and passing thunder showers lower the 

temperature abruptly.

As given in the reports of the United States Weather 

Bureau, the average period without killing frosts is 145 

days (May 17 to Sept. 29) at Blanding, 154 days (May 

5 to Sept. 26) at Aneth, 224 days (Mar. 24 to Nov. 3) 

at Hite, 118 days (May 29 to Sept. 24) at La Sal, and 

128 days (May 26 to Oct. 1) at Monticello. In exceptional years killing frosts come later in the Spring or 

earlier in the fall, or both later and earlier, thus reducing 

the length of the growing season disastrously. During 

certain years days without killing frosts numbered 130 

at Aneth, 90 at Blanding, 179 at Hite, and 78 at 

Monticello.

As corn requires, on the average, 90 to 150 days, and 

fruit an even longer period to reach maturity, it is 

obvious that crops suitable for the San Juan country 

must be selected with discrimination and that crop 

failures are to be expected.

Temperature (°F.) at stations in the San Juan country 

[From records of U. S. Weather Bureau]

ANETH '

July 

HITE '

April 

July 

Annual _ ... ...

Maximum

43.2

51.3

59.4

69.6

78.6

89.4

94.5

93.5

83.7

71.8

67.1

41.4

69.7

46.8

54.7

65.1

74.2

83.4

94.2

99.5

97.7

88.5

75.4

60.9

46.1

73.9

Mean

Minimum

17.5

24.3

33.0

39.9

47.6

55.6

61.7

61.1

51.3

39.3

28.0

17.7

39.8

24.7

30.0

37.3

44.3

52.9

61.3

68.8

67.9

56.4

43.9

34.1

24.3

45.5

Monthly

30.4

37.8

46.2

64.7

63.1

72.2

78.1

77.3

67.5

50.5

42.6

31.1

54.3

35.7

42.4

51.1

59.2

68.2

77.7

84.2

82.8

72.5

59.7

47.5

35.2

69.7

Highest

63

77

83

86

93

105

104

106

100

88

74

67

106

66

81

86

94

104

111

115

110

104

91

76

76

115

-29

2

14

19

31

38

45

42

28

22

10 -2

-29

1

6

18

28

35

40

44

51

39

29

19 -1

-1
SOIL 21

Temperature (°F.) at stations in the San Juan country Contd.

BLUFF

February _ __ "... __

April.. ...........

July....... ...........

October. ____ ... _ .

BLANDING

April..... . __ .......

July.......... ...........

August ..................

MONTICELLO

April........ ............

July ................

August ..................

November. ... ..........

Mean

Maximum

39.1 

50.0 

60.1 

69.6 

79.8 

90.8 

94.4 

91.9 

83.7 

71.0 

55.0 

40.0 

68.8

37.0 

44.3 

52.6 

61.5 

70.2 

81.7 

86.0 

84.5 

- 76.5 

66.0 

52.6 

39.1 

62.7

34.4 

39.4 

46.6 

57.3 

65.3 

76.5 

81.4 

79.8 

72.6 

62.7 

48.8 

36.1 

58.4

Minimum

16.1 

26.6 

33.0 

40.3 

49.7 

57.5 

65.6 

62.3 

53.4 

40.8 

30.2 

18.6 

41.2

15.4 

21.5 

27.5 

34.2 

41.0 

50.3 

57.6 

55.5 

47.4 

37.1 

26.8 

18.0 

36.0

12.5 

18.3 

24.7 

32.1 

38.4 

47.1 

53.4 

51.7 

44.0 

34.8 

25.2 

15.1 

33.1

Monthly

27.5 

38.3 

46.5 

55.0 

64.7 

74.0 

80.0 

77.1 

68.4 

56.0 

42.6 

29.3 

55.0

26.3 

32.9 

40.0 

47.8 

55.6 

66.0 

71.8 

70.0 

61.9 

51.5 

39.7 

28.4 

49.3

23.4 

28.8 

35.6 

44.7 

51.8 

61.8 

67.4 

65.7 

58.3 

44.2 

37.0 

25.6 

45.4

Highest

62 

72 

80 

88 

95 

 105 

109 

104 

99 

89 

85 

60 

109

62 

71 

86 

88 

91 

110 

109 

106 

100 

99 

74 

65 

110

57 

80 

81 

80 

85 

97 

97 

98 

89 

80 

70 

58 

98

Lowest

-20 

-13 

16 

20 

28 

 38 

40 

40 

29 

20 -1 

-18 

-20

-15 

-23 

4 

10 

15 

28 

42 

40 

20 

12 -7 

-11 

-23

-12 

-21 

2 

4 

14 '27 

35 

37 

21 

12 

-6 

-14 

-21

1 Length of record, 10 years. 

1 Length of record, 14 years.

WIND

At Monticello the recorded direction of prevailing 

wind was consistently southwest for a 9-year period. 

At Blanding it was prevailingly south, except for December (southwest) and January (north), for the years 

1904-20 and 1923-27, and southwest during 1921-22. 

These regional directions are those common to the 

plateau province and are reflected in the shape of trees 

in exposed positions and in the alinement of dunes and 

wind-borne debris on the flat surfaces of Sage Plain and 

Grand Gulch Plateau. But for most of the region the 

winds are highly variable in direction, strength, and 

continuity. They blow in and out of canyons, up 

canyons, down canyons, and around buttes and mesas. 

They blow up over the box heads of canyons during 

the day, only to return down canyon at night. During 

the hot summer days they seem to head from all directions toward sand flats and stretches of naked rocks. 

The rugged country west of Red House Cliffs provides 

no long sweeps for the wind, and on the flatter plateaus 

any material available for wind transportation has long 

ago been carried eastward and added to the soil of 

Colorado. Consequently, there are no large areas of 

dunes, and severe dust storms are infrequent. The 

most annoying one experienced during field work 

originated in the plowed fields about Blanding.

SOIL

For the San Juan country as a whole soil is deficient 

in amount and in fertility. Over large areas it is merely 

shallow filling of disintegrated material in depressions 

between projecting rocks, sand temporarily holding its 

position on wind-swept rocks, or deposits left by storm 

floods only to be moved by succeeding floods. The 

patches of soil on canyon and mesa walls, in mountain 

gullies, and on isolated mesa tops are unfavorably 

located for utilization. Large areas have no soil at all.

Most of the flat-lying surface rock is siliceous sandstone deficient in mineral plant food. The patches of 

shale on Sage Plain are small, and the limestones of the 

"oil fields" are too continuously dry to permit the formation of residual clays. In local parlance the land 

west of the Clay Hills is "a lot of rocks, a lot of sand, 

more rocks, more sand, and wind to blow it away." 

On the whole agricultural soil derived directly from the 

decomposition of rock in place covers probably not 

more than 5 percent of San Juan County. The low 

ground-water tables, the short-lived heavy showers, 

and the scanty vegetation are unfavorable for the 

decomposition of rocks and the retention of soil in place.

Nearly all the soil suitable for agriculture is transported soil, carried and deposited in its present position 

by running water. The soil about Blanding, Verdure, 

and Monticello, in Mormon Pasture, and along the 

headwaters of Indian Creek and Alien Canyon is the 

result of erosion in the Abajo Mountains, which has 

provided material for transport by the streams that 

spread from the mountain base. Because this soil is the 

product of igneous rocks and shale, as well as of sandstone, it includes the necessary inorganic plant foods. 

The soils about Bluff and Aneth, at the mouth of Red 

Canyon, and in Montezuma, McElmo, Cottonwood, 

Comb, and the many other narrow valleys are the tops 

of flood plains and terraces built by the San Juan, the 

Colorado, and their tributaries out of materials derived 

from nearby and distant sources. During the last 50 

years most of the soil in these valleys has been carried 

away by floods. (See p. 102.)

That these transported soils are fertile is shown by 

the vegetation. Thick sagebrush and oak occupy parts 

of the alluvial fans about the Abajo Mountains, and 

groves of cottonwood and willows and dense stands of 

weeds appear along the San Juan, the Colorado, and 

most of the wider washes. The ruins of small gardens 

and cornfields are common about the sites formerly 

occupied by Cliff Dwellers. At the present settlements, 

even without irrigation, potatoes and melons are raised, 

and in favorable seasons wheat yields fairly satisfactory 

crops. In many places where the soil is suitable in 

depth and quality lack of water prevents profitable 

agriculture.
22 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

VEGETATION

In describing plants collected by the Hayden Survey, 

Brandegee 27 speaks of the San Juan Valley above 

Montezuma Creek as "a line of green a mile wide 

* * * winding through the gray desert" and flanked 

by mesas "very barren of vegetation. * * * there 

are large areas with absolutely nothing growing upon 

them, and often, even along the streams, our day's 

journey would be lengthened 4 or 5 miles before grass 

could be found sufficient for a camping place." He 

expressed surprise that the cactus are neither abundant 

nor large; "the country along the San Juan River has 

not a single additional species of cactus and lacks very 

nearly all the species of the eastern (Rocky Mountain) 

slope." Also "the genus Astragalus is represented by 

few species, and these are not very abundant." On the 

other hand, "Eriogonium is well represented in species, 

and the plants are very abundant * * * nine 

annual species grow in San Juan Valley; in the Arkansas 

Valley but three are found and in northern Colorado 

but one." Eastwood 28 and also Rydberg 29 have pointed 

out certain exceptional features in the flora of the San 

Juan country, which in general shows a distribution and 

relative abundance of species common to the Colorado 

Plateaus.

In the San Juan country, as elsewhere in the plateau 

province, types of vegetation are related to altitude but 

are also closely related to topographic features and 

available water supply. In general the distribution of 

plant life resembles that of the Kaiparowits region,30 

but the altitude zones defined in terms of temperature 

and rainfall are locally much modified by the conditions 

of isolation imposed by position and height of canyon 

walls and by the wide range in altitude" of the prevailing 

sandstone soils. Except in forested areas the vegetation 

is gray, and in places its color is less conspicuous than 

that of the rocks on which it grows; bright-green plants 

constitute but dots and short ribbons disposed here 

and there in the landscape.

Forests of tall trees cover parts of the Abajo Mountains and Elk Ridge, trees of stunted growth cover the 

plateau stretches at intermediate altitudes, and the 

lower lands have a sparse and specialized flora. Dense 

thickets make the heads of many canyons impassable, 

and masses of reeds grow about little-used springs; but 

in general the trees are widely spaced, the shrubs grow 

in clumps, and the grass in separate bunches. (See 

pis. 2, B; 4, A; 5, B; 6, A; 11, C; 16, B, C\ 18, A.) 

Continuous turf was seen only in Lake Canyon and in 

small meadows on Elk Ridge and the Abajo Mountains. 

Vegetation characteristic of salt flats and of alkali lands

17 Brandegee, T. S., The flora of southwestern Colorado: U. S. Qeol. and Qeog. Survey Terr. Bull., vol. 2, no. 3, pp. 227-248,1876.

28 Eastwood, Alice, Report on a collection of plants from San Juan County, in southeastern Utah: California Acad. Sci. Proc., 2d ser., vol. 6, pp. 271-329,1896.

» Rydberg, P. A., Report of a trip to southeastern Utah in the summer of 1911: 

New York Bot. Garden Jour., vol. 12, pp. 237-253,1911.

80 Gregory, H. E., and Moore, R. C., The Kaiparowits region: U. S. Qeol. Survey 

Prof. Paper 164, pp. 24-27,1931.

grows along Lime Creek and in a few other places. 

(See pis. 4, B,C;16,D.)

Southward from the Abajo Mountains vegetation 

becomes less and less abundant and the plants decrease 

in size as the San Juan River is approached, but few 

areas exceeding an acre are devoid of trees and shrubs; 

even the canyon walls are partly clothed. Over large 

parts of Grand Gulch Plateau and of the region between 

the Red House Clift's and Glen Canyon, however, plant 

life is poorly represented. Widely spaced individual 

small trees rise from the plateaus; shrubs and grasses 

and weeds appear along valley bottoms and in rock 

cracks; in places only sand dunes provide the conditions 

necessary for plant growth. Miles of bare canyon walls 

and broad stretches of bare surface rock are conspicuous. 

(See pis. 6, C, D; 12, D; 13, A, B; 18, A.) A peculiar 

feature is the absence from Wilson Mesa of the pinon 

and juniper.

For most of the San Juan country the conspicuous 

vegetation consists of pinon, juniper, sagebrush, and 

cottonwood. Except at altitudes above about 8,000 

feet, pinon and its running mate, Utah juniper 

("cedar"), are nearly everywhere in sight. On the flat 

lands separating streams leading from Elk Ridge and 

the Abajo Mountains, on knolls rising above Sage Plain, 

and on some valley sides they form continuous, vigorously growing forests of closely set trees; "Cedar Flats" 

and "Cedar Mesa" are local names for scores of benches 

and flat-topped plateau remnants. (See pis. 2, C; 3, C; 

5, B; 6, A; 8, A; 12, A; 13, C; 16, B.) Sagebrush is even 

more widely spread. Growing with piiion and juniper 

or standing alone it seems to be the dominant plant at 

altitudes between 6,000 and 7,000 feet, but it grows well 

also high on the slopes of the Abajo Mountains and 

down in the canyons of the San Juan and the Colorado. 

It forms clumps 5 to 8 feet high at the base of many 

canyon walls. (See pi. 2, A.) Cottonwoods grow in the 

alluvial soil of most canyon bottoms. Along the upper 

San Juan, except where their supporting ground has 

been removed by floods, cottonwoods form groves of 

big trees; above Bluff they are continuous for 2 miles. 

Likewise in upper Glen Canyon cottonwoods are common on the higher stream flats, and thousands of seedlings are crowded on sandbars and close to the banks of 

the river. On the floors of the long dry washes leading 

from the Abajo Mountains and Elk Ridge, cottonwoods 

standing alone or with a few companions extend their 

friendly branches as protection from the scorching sun. 

Many of them are old gnarled trees with trunks 4 to 6 

feet in diameter. The piles of driftwood along these 

streams consist chiefly of cottonwood. (See pis. 2, C; 

3, C; 9, A)

Like juniper, pinon, sagebrush, and cottonwood, oak 

brush is widely distributed. Small thickets of these 

tough trees, which the explorer soon learns to go around 

instead of through, grow in valleys, on ridges, and 

plateau tops, and particularly near the heads of can-
VEGETATION 23

yons. At places about the base of the Abajo Mountains oak brush forms almost pure stands several acres 

in extent.

Certain trees and shrubs and annuals are somewhat 

definitely localized. Except for a few individuals in 

exceptionally favorable spots, fir, spruce, balsam, aspen, 

manzanita, birch-leaf mahogany, Oregon grape, myrtle 

brush, snowberry, serviceberry, chokecherry, currant, 

gooseberry, and raspberry were seen only at altitudes 

exceeding 7,000 feet. Yellow pine, though attaining its 

greatest abundance and largest size in this zone, grows 

also in canyons at much lower altitudes. On the Abajo 

Mountains the forests of fir and pine cover the northern 

slopes of spurs and ridges; grass covers the top and the 

southern slopes. In addition to pinon and cedar and 

sage the most noticeable vegetation of the plateaus, 

broad canyon bottoms, and rock benches at altitudes 

between 5,000 and 7,000 feet consists of rabbitbrush, 

bitterbush, squawbush, bullberry, boxelder, alder, scrub 

maple, old man, and brigham tea. The rare and 

beautiful purple sage was found growing in dunes near 

Moki Canyon. Willows, rushes, some of the sedges, 

and ferns grow wherever there is water, regardless of 

altitude and soil.

High on the canyon walls along the San Juan River 

and Butler Wash the spring line at the base of the bare 

Bluff sandstone is marked by a band of green vegetation formed by plant species that seem out of place 

in the present scheme of distribution. In contrast to 

the vegetation common to theo Upper Sonoran zone, 

growing along the river below and on the mesa tops 

above, the plants tucked away in moist niches on the 

cliffs include Aquilegia micrantha, Primula farinosa, 

Solidago canadensis, Mimulus cardinalis, Oenothera 

biennis var. grandiflora, Shepherdia rotundifolia, and 

Epipactis gigantea. Eastwood 31 speaks of this habitat 

as "a boreal oasis in the midst of a Sonoran desert", perhaps dating from a time when the climate of the whole 

San Juan region was colder.

Flowering plants are widely distributed. In appropriate seasons roses, daisies, asters, larkspurs, dandelions, phlox, snapdragons, sego lilies, and Indian paintbrush are abundant. Among the yellow pines of Elk 

Ridge buttercups, fireweed, green dock, harebell, 

blue gentian, columbine, meadowrue, mint, stonecrop, 

strawberry, tansy, yarrow, bluebell, and yellow umbel 

find a congenial home. At lower altitudes evening 

primroses appear, and along most trails honeysuckle, 

plantains, sunflowers, peppergrass, and wallflowers are 

common. The yellow and purple beeflower (Cleome) 

lines the washes for miles. Here and there the conspicuous Jimson weed stands out from bare rock walls.

In the La Sal National Forest, a large highland area 

that includes the Abajo Mountains and Elk Ridge, six 

vegetation types have been outlined. In brief, their 

features are as follows:

11 Eastwood, Alice, Report on a collection of plants from San Juan County In 

southwestern Utah: California Acad. Sci. Proc., 2d ser., vol. 6, pp. 271-328,1896.

1. Spruce-balsam type. Limited to the high rugged 

mountainous areas between altitudes of 7,500 and 

11,500 feet, where both the soil and the air contain a 

large amount of moisture. The predominant tree is 

Engelmann spruce, with which grow balsam and some 

Douglas fir.

2. Yellow-pine type. Characteristic of all high plateaus, between altitudes of 6,700 and 9,000 feet. It 

grows best on deep soils of sandstone origin; on clay 

soils it produces open stands and parks. On the Abajo 

Mountains this type covers about 56,500 acres.

3. Pinon and juniper type. Altitude 5,000 to 8,000 

efet. Consists chiefly of pinon and Utah juniper, with 

yellow pine, mahogany, oak, and serviceberry, growing 

on benches and plateaus.

4. Brushland type. Grows regardless of altitude, 

soil, or exposure, except 'under fairly dense stands of 

trees. Oak and serviceberry are dominant, though 

manzanita, snowberry, buckbrush, and sage are present. 

This type covers about half of the area classed as 

"forest."

5. Sagebrush type. At altitudes below 9,000 feet 

sagebrush is commonly associated with the species 

that constitute the brushland type. Over areas of considerable size it is the dominant shrub.

6. Mountain meadow type. Range in altitude is 

7,600 to 11,000 feet. Found mainly in the form of 

open grassy parks, consisting of blue, gramma, and pine 

grasses, bluestem, white clover, sedge, wire grass, and 

many species of weeds. This type covers less than 1 

percent of the highland areas.

Outside the boundaries of the national forest pinon, 

juniper, and sagebrush continue as the conspicuous 

vegetation at altitudes above 5,000 feet. Below that 

altitude, on benches and flats overlooking the San Juan 

River, shadscale and rabbitbrush are common. At still 

lower altitudes greasewood and the alkali-loving saltgrass and pickleweed constitute the plant life in a few 

places.

The following list of plants collected on Elk Ridge and 

the Abajo Mountains and in areas at lower altitudes 

west of Elk Ridge has-been submitted by Orange F. 

Olson, of the United States Forest Service:

Plants found at 8,000 to 10,000 feet on Elk Ridge and the Abajo 

Mountains

TREES

Abies concolor (white fir, black balsam). 

Abies lasiocarpa (alpine fir, white balsam). 

Picea engelmanni (Engelmann spruce). 

Pinus flexilis (limber pine). 

Pinus ponderosa (western yellow pine). 

Populus tremuloides (quaking aspen). 

Pseudotsuga taxifolia (Douglas fir, red pine).

SHKTJBS

Acer glabrum (?) (scrub maple). 

Amelanchier alnifolia (serviceberry). 

Arctostaphylos uva-ursi (manzanita, bearberry).
24

Artemisia tridentata (sagebrush). 

Ceanothus velutinus (chaparral). 

Cercocarpus parvifolius (birch-leaf mahogany). 

Chrysothamnus sp. (rabbitbrush). 

Grossularia sp. (gooseberry). 

Lonicera utahensis (twinberry). 

Odostemon repens (Oregon grape). 

Pachystima myrsinites (myrtle brush). 

Peraphyllum ramosissimum (wild apple). 

Prunus demissa (chokecherry). 

Purshia tridentata (bitterbush). 

Quercus gambelii (Gambel oak). 

Ribes saxosum (currant). 

Rubus strigosus (raspberry). 

Salix (several species) (willow). 

Sambucus melanocarpa (elderberry). 

Symphoricarpos vaccinioides (snowberry).

GRASSES

Agropyron smith ii (bluestem). 

Agropyron spicatum (spiked wheatgrass). 

Agropyron tenerum (slender wheatgrass). 

Agrostis alba (redtop). 

Agrostis hiemalis (tickle grass). 

Bouteloua gracilis (grama grass). 

Bromus marginatus (bromegrass). 

Bromus polyanthus (bromegrass). 

Bromus porteri (bromegrass). 

Calamagrostis rubescens (pinegrass). 

Carex (several species) (sedge grass). 

Deschampsia caespitosa (tufted hairgrass). 

Juncus (several species) (rush grass). 

Koeleria cristata (Koeleria). 

Phleum alpinum (mountain timothy). 

Poa fendleriana (Fendler poa). 

Poa sandbergii (Sandberg poa). 

Sitanion hystrix (squirreltail grass). 

Stipa minor (needlegrass). 

Stipa occidentalis (porcupine grass).

HERBS

Achillea lanulosa (yarrow). 

Aconitum columbianum (monkshood). 

Allium (several species) (wild onion). 

Aquilegia sp. (columbine). 

Aragalus (several species) (locoweed). 

Arenaria canadensis (flower grass). 

Arnica sp. (arnica).

Balsamorrhiza sagittata (balsam root). 

Bursa bursa-pastoris (shepherd's purse). 

Calochortus nuttallii (sego-lily). 

Castilleja sp. (Indian paintbrush). 

Chamaenirion angustifolium (fireweed). 

Chenopodium album (lambsquarters). 

Claytonia sp. (springbeauty). 

Clematis douglasii (harebell). 

Cogswellia sp. (parsley). 

Collomia linearis (collomia). 

Crepis sp. (mountain dandelion). 

Delphinium barbeyi (larkspur). 

Erigeron (several species) (fleabane). 

Eriogonum (several species) (Indianroot). 

Erysimum asperum (wallflower). 

Fragaria americana (strawberry). 

Frasera jamesiana (elk weed). 

Gayophytum sp. (kitchen weed). 

Gentiana elegans (fringed gentian). 

Geranium viscosissimum (crowfoot).

Gymnolomia multiflora (mountain sunflower .

Helenium hoopesii (sneezeweed).

Heracleum lanatum (cow cabbage).

Heuchera (red root).

Lapula floribunda (stickseed).

Lathyrus leucanthus (pea).

Leontodon taraxacum (common dandelion).

Linum lewisii (flax).

Lupin us alpestris (wild bean).

Mentha (several species) (mint).

Mertensia (several species) (bluebell).

Mimulus longsdorfii (monkeyflower).

Pentstemon (several species) (snapdragon).

Phacelia sp. (phacelia).

Phlox (several species) (phlox or sweet-william).

Plantago (2 species) (plantain).

Polemonium (several species) (skunkweed).

Polygonum aviculare (knotweed).

Polygonum douglasii (knotweed).

Potentilla filipes (cinquefoil).

Pseudocymopterus tiedestromii (yellow umbel).

Ranunculus sp. (buttercup).

Rumex mexicanus (sour dock).

Sedum gormania (stonecrop).

Senecio (several species) (butterweed).

Solidago sp. (goldenrod).

Sophia incisa (tansy mustard).

Thalictrum fendleri (meadowrue).

Trifolium (several species) (clover).

Urtica gracilis (nettle).

Washingtonia sp. (sweet anise).

Wyethia amplexicaulis (green dock).

Plants found at 4,000 to 8,000 feet between the Colorado River and 

Elk Ridge

TREES

Acer negundo (boxelder).

Alnus tenuifolia (alder).

Cercocarpus parvifolius (mountain-mahogany).

Juniperus monosperma (red cedar).

Juniperus scopulorum (white cedar).

Juniperus utahensis (Utah cedar or juniper).

Pinus edulis (pinon).

Pinus ponderosa (western yellow pine).

Populus angustifolia (cottonwood).

Populus tremuloides (aspen, around 8,000 feet)

SHRUBS

Acer sp. (scrub maple). 

Artemisia aromatica (aroma sage). 

Artemisia tridentata (sagebrush). 

Atriplex canescens (saltbush or shadscale). 

Betula sp. (birch). 

Ceanothus velutinus (chaparral). 

Chrysothamnus (several species) (rabbitbrush). 

Coleogyne racemosissima (blackbrush). 

Cornus sp. (dogwood). 

Cowania neomexicana (bitterbush). 

Crataegus sp. (hawthorn).

Ephedra antisyphilitica (mountain rush or brigham tea). 

Eurotia lanata (white sage). 

Peraphyllum sp. (wild apple). 

Petradora sp. (Petradora or stone bush). 

Purshia tridentata (bitterbush). 

Quercus sp. (live oak). 

Salix (several species) (willow). 

Sarcobatus vermiculatus (greasewood).
VEGETATION 25

(bullberry bush). 

(old man). 

(silver leaf). 

(squaw bush).

GRASSES

Agropyron smithii (bluestem).

Bouteloua gracilis (grama grass).

Carex sp. (slough grass).

Elymus condensatus (giant ryegrass).

Festuca (numerous species) (fescue grass).

Juncus confusus (wire grass).

Oryzopsis exigua (ricegrass or sandgrass).

Poa (numerous species) (bluegrass).

Sporobolus (dropseed).

Stipa comata (needle-and-thread grass).

Achillea lanulosa (yarrow).

Aragallus (several species) (loco).

Arenaria congesta (flower grass).

Aster sp. (aster).

Balsamorrhiza sagittata (balsamroot).

Calochortus nuttalli (sego-lily;.

Carduus drummondi (Canadian thistle).

Castilleja sp. (Indian paintbrush).

Chenopodium album (pigweed or lambsquarters).

Cleome lutea (yellow beeilower).

Cleome serrulata (purple beeflower).

Delphinium arizonicum (low larkspur).

Equisetum arvense (horsetail).

Equisetum robustum (horsetail).

Erigeron (several species) (daisy).

Eriogonum (several species) (Indianroot).

Erodium cicutarium (filaree).

Erysimum asperum (wallflower).

Bucephalus engelmanni (tall aster).

Gayophytum sp. (kitchen weed).

Gilia aggregata and others (honeysuckle).

Gutierrezia sp. (snakeweed).

Gymnolomia multiflora (sunflower).

Lappula sp. (stickseed).

Leontodon taraxacum (dandelion).

Lepidium ramosum (peppergrass).

Ltithospermum pilosum.

Malva rotundifolia (common mallow).

Onagrasp. (evening-primrose).

Orthocarpus purpureus albus (orthocarpus).

Pentstemon (several species) (snapdragon).

Phlox (several species) (phlox).

Physaria lesquerella (bladderpod).

Plantago sp. (plantain).

Polygonum aviculare (knotweed).

Polygonum douglasii (knotweed).

Salsola pestifer (Russian thistle).

Senecio (several species) (butterweed).

Yucca (3 species) (Indian soapweed).

Zygadenus sp. (deathcamas).

Along the San Juan River between Aneth and Goodridge, Eastwood 32 recorded the following plants in July 

1895:

Abronia cycloptera (sandverbena). 

Abronia fragrans. 

Abronia turbinata var. marginata. 

Actinella leptoclada.

3J Eastwood, Alice, Report on a collection of plants from San Juan County, in 

southeastern Utah: California Acad. Sci. Proc., 2d ser., vol. 6, pp. 271-328,1896.

Adiantum capillus-veneris (maidenhair fern).

Allionia incarnata.

Ambrosia (ragwe'ed).

Ampelopsis quinquefolia (woodbine).

Amsonia angustifolia var. texana.

Amsonia brevifolia.

Andropogon scoparium.

Aplopappus gracilis.

Apocynum cannabinum (Indian hemp).

Aquilegia micrantha (columbine).

Arenaria f endleri (starwort).

Argemone intermedia (thistle poppy).

Aristida purpurea.

Asclepias involucrata var. tomentosa (silkweed).

Asclepias stenophylla.

Aster canescens var. aristatus.

Aster laevis.

Aster multiflorus.

Aster spinosus (aster).

Astragalus preussii (locoweed).

Astragalus sabulonum (locoweed).

Astragalus subcinereus (locoweed).

Atriplex (saltbush).

Atriplex canescens (saltbush).

Atriplex caput-medusae (saltbush).

Atriplex confertifolia (saltbush).

Atriplex cornuta (saltbush).

Atriplex powellii (saltbush).

Atriplex truncata (saltbush).

Berberis fremontii (barberry).

Blepharidachene kingii.

Bouteloua oligostachya.

Castilleja linariaefolia (Indian paintbrush).

Celtis occidentalis (hackberry).

Chara sp.

Chenopodium fremonti (goosefoot).

Chenopodium leptophyllum.

Chrysopsis villosa var. scabra (golden-aster).

Cladothrix lanuginosa.

Clematis ligusticifolia (clematis).

Cleome integrifolia (beeweed).

Cnicus rothrockii var. diffusus (thistle).

Coldenia hispidissima.

Comandra umbellata (toadflax).

Cordylanthus wrightii (snakehead).

Cowania mexicana (cliffrose).

Cuscuta arvensis (dodder).

Cycloloma platyphyllum (tumbleweed).

Datura meteloides (thorn apple). . Dicoria brandegei.

Dicoria paniculata.

Elymus canadensis.

Encelia frutescens.

Epipactis gigantea (stream orchid).

Equisetum laevigatum (scouring-rush).

Erigeron bellidiastrum (daisy).

Erigeron canadensis.

Erigeron sparsifolius.

Eriogonum alatum.

Eriogonum cernuum.

Eriogonum cernuum var. umbraticum.

Eriogonum divaricatum.

Eriogonum flexum.

Eriogonum inflatum.

Eriogonum jonesii.

Eriogonum mearnsii.

Eriogonum microthecum var. rigidum.

Eriogonum ramosissimum.
26 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

Eriogonum wetherillii.

Euphorbia fendleri.

Euphorbia flagelliformis (spurge).

Eurotia lanata (winterfat).

Forestiera neomexicana (ironwood).

Franseria hookeriana.

Fraxinus anomala (1-leaved ash).

Frasera utahensis.

Galium acutissimum (bedstraw).

Gaura coccinea (red gaura).

Gilia aggregata (gilia).

Gilia congesta var. nuda (gilia).

Gilia gunnisoni (gilia).

Gilia haydeni (gilia).

Gilia inconspicua (gilia).

Gilia leptomeria (gilia).

Gilia longiflora (gilia).

Gilia multiflora (gilia).

Gilia pumila (gilia).

Gilia subnuda (gilia).

Grayia brandegei.

Grayia, polygaloides.

Grindelia squarrosa var. nuda.

Grindelia stylosa (gumweed).

Gutierrezia californica.

Hedeoma drummondii (pennyroyal).

Helianthus petiolaris var. canescens (sunflower).

Heliotropium convolvulaceum (birdseed).

Hilaria jamesii.

Houstonia saxicola.

Hymenatherum pentachaetum.

Hymenopappus filifolius.

Juncus xiphioides (rush).

Juniperus occidentalis var. monosperma.

Krynitzkia jamesii.

Lepidium alyssoides (peppergrass).

Lesquerella fendleri.

Linum aristatum var. subteres (yellowflax).

Lycium andersoni.

Lycium pallidum.

Lygodesmia exigua.

Malvastrum coccineum (red mallow).

Malvastrum leptophyllum (red mallow).

Mentzelia pterosperma.

Mentzelia pumila.

Mimulus cardinalis.

Oenothera biennis var. grandiflora.

Oenothera brevipes (evening-primrose).

Oryzopsis cuspidata.

Oxybaphus angustifolius var. viscidus.

Oxytenia acerosa.

Panicum bulbosum.

Pentstemon bridgesii (red pentstemon).

Petalostemon candidus (prairieclover).

Phacelia crenulata.

Physalis fendleri (groundcherry).

Poliomintha incana.

Polygala acanthoclada var. intricata.

Populus fremontii var. wislizeni (cottonwood).

Primula farinosa (cliff primrose).

Psoralea juncea.

Psoralea micrantha.

Quercus gambelii (oak).

Quercus undulata (oak).

Rhamnus purshiana (cascara).

Rhus canadensis var. simplicifolia (Ute lemonade).

Rosa fendleri (wild rose).

Sslix cordata (willow).

Salix lasiandra var. fendleriana (willow).

Salix longifolia (willow).

Sarcobatus vermiculatus (greasewood).

Senecio multilobatus (ragwort).

Shepherdia rotundifolia (buffalo berry).

Sida hederacea (Alaki mallow).

Solidago canadensis (goldenrod).

Sporobolus airoides.

Stanleya pinnatifida.

Stephanomeria pentachaeta.

Suaeda torreyana (sea blite).

Talinum brachypodium.

Thelesperma gracile.

Thelypodium sp.

Townsendia incana.

Wyethia scabra (compassplant).

Of the 444,348 acres that constitute the national forests of San Juan County, 221,773 acres is classed as 

timber land, on which it is estimated there are about 

99,000,000 board feet of yellow pine, 50,000,000 feet of 

Engelmann spruce, 690,000 feet of Douglas fir, 8,.700,000 

feet of other conifers, 460,000 cords of aspen, and 14,000 

cords of pinon and juniper. Some yellow pine is sawed 

into timber for local use, but the trees are cut chiefly for 

poles and for firewood.

ANIMAL LIFE

The San Juan country is part of the zoologic province 

that includes southern Utah, southwestern Colorado, 

northern Arizona, and northwestern New Mexico, 

and its indigenous animal life is essentially that described for these regions by Coues,33 Alien,34 Cooke,36 

Gilman,36 Barnes,37 Woodbury,38 and others. The fauna 

is chiefly that of the upper Sonoran, transition, and 

Canadian zones as defined by Bailey.39 Its species are 

more closely related to those in the Great Basin region 

than to those within and east of the Rocky Mountains.

During the field work the mammals most frequently 

noted at lower altitudes were several kinds of rats, 

grasshopper mouse, white-footed moiise, harvest mouse, 

meadow mouse, pocket mouse, prairie dog, spotted 

squirrel, banded squirrel, pocket gopher, rock chipmunk, jack rabbit, cottontail rabbit, and cave bat. A 

few coyotes, skunks, and ring-tailed cats were seen on 

Sage Plain, muskrats and beavers along the San Juan 

River, and otters in Glen Canyon. Mountain sheep, 

reported as plentiful in the eighties, seem now to be 

restricted to lower Dark Canyon, the south end of Grand

33 Coues, Elliott, and Yarrow, H. C., Report upon the collections of mammals made 

in portions of Nevada, Utah, California, Colorado, New Mexico, and Arizona during 

the years 1871,1872,1873, and 1874: U. S. Geog. and Geol. Expl. W. 100th Mer. Kept., 

vol. 5, pp. 37-129, 1875.

3< Alien, J. A., List of mammals collected by Mr. Chas. P. Rowley in the San Juan 

region of Colorado, New Mexico, and Utah, with descriptions of new species: Am. 

Mus. Nat. History Bull., vol. 5, pp. 69-84, 1893.

3s Cooke, W. W., The birds of Colorado: Colorado State Agr. Coll. Bull. 37, 44, and 

56, 1897-1900.

3' Gilman, M. F., Birds of the Navajo Reservation in New Mexico: Condor, vol. 10, 

pp. 146-152,1908.

s? Barnes, C. T., Mammals of Utah: Utah Univ. Bull., vol. 12, no. 15, pp. 1-166, 

1922.

as Woodbury, A. M., Reptiles of Utah: Utah Univ. Bull., vol. 21, no. 5,1931.

»' Bailey, Vernon, Life zones and crop zones of New Mexico: U. S. Bur. Biol. Survey 

North Amerinan Fauna, no. 35,1913.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 188 PLATE 5

/I. CATARACT CANYON. 

View looking upstream at mouth of Dark Canyon. Carboniferous strata.

B. VIEW LOOKING NORTHWEST FROM HEAD OF ARMSTRONG CANYON. 

View across flat into which upper White Canyon and its tributaries are cut- Photograph by W. T. Leo,
GEOLOGICAL SURVEY PROFES

A. WHITE CANYON BETWEEN ROCK SPRINGS AND SOLDIERS CROSSING.

Floor of outer canyon developed in Cedar Mesa strata into which (foreground) the inner canyon is sunk 300 feet. Wall of outer canyon (distance) consists of Permian and Triassic strata topped by buttes of Jurassic.

B. CLAY HILLS.

Passage through Red House Cliffs on the Hole in the Rock road f

formation. Photograph by A. A. Kcr

C. ENTRANCE TO MOKI CANYON AT RED CONE SPRING.

Navajo sandstone capped by strata of San Rafael group. Dimensions indicitnd by comparison with

pack train.

D. CASTLE III 111; ON DIVIDE BETWEEN WHITE CAN

Chinle strata capped by Wingate sand
GEOLOGICAL SURVEY PROFESS

A. VIEW LOOKING UPSTREAM AT JUNCTION OF COLORADO AND SAN JUAA RIVERS.

Kayenta and Navajo strata.

B. \IK\\ LOOKING SOUTHWEST ACROSS THE CANYON AT IIITK.

Wall includes Permian (Organ Rock), Triassic, and Jurassic (?) (Wingateand Kayenta). The Colorado 

River flows between buildings and base of cliff. Photograph by M. R. Thorpe.

GLEN CANYON.

C. VIEW LOOKING DOWNSTREAM AT MOUTH 

Wall of Nava.jo sandstone 1,600+ feet h
GEOLOGICAL SURVEY PROFESS

A. RUINS OF CUFF HOUSE, HOVENWEEP NATIONAL MONUMENT. li. RUINS OF CLIFF DWELLERS' HOUSE, BUT

Navajo sandstone. Photograph by H. D. M

C. CLIFF HOUSE IN WHITE CANYON. 

Cedar Mesa strata. Photograph by W. H. Hopkins.
INHABITANTS 27

Gulch Plateau, and the almost inaccessible mesas between White Canyon and Red Canyon. Miser saw 

seven along.the San Juan Canyon between the Honaker 

trail and Oljeto Creek. The Piutes tell of large herds of 

antelopes that ranged throughout southern Utah until 

exterminated by the whites. They speak also of a 

"big hairy cowlike creature" that suggests the buffalo. 

On the higher forested areas, in addition to squirrels, 

chipmunks, rats, mice, and snowshoe rabbits, there are 

many porcupines, foxes, bobcats, some mountain lions, 

timber wolves, lynxes, and a few brown bears. Deer, 

which are fairly common on Elk Ridge and the Abajo 

Mountains in summer, are protected by laws that seem 

to restrain the white man but not the Piutes and Navajos. Elk, which are reported as once abundant, 

"have not been seen for 40 years."

Of the reptiles some half dozen varieties of lizards, also 

garter snakes, bull snakes, and rattlesnakes and one 

box turtle were noted on sand flats and among the 

rocks. But lizards are much less common than in 

regions south of the San Juan River, and harmful 

snakes are surprisingly rare. On long traverses during 

four field seasons only six rattlesnakes were seen.

Of insects, the most continuously annoying are the 

flies about the villages, corrals, and Indian encampments, and the ants, which seem always at home on 

sand bars, the floors of washes, rock slopes, and forested 

areas. Mosquitoes were found troublesome only in a 

few swampy areas about water holes, but there they 

are incredibly numerous. As if resenting the lack of 

opportunity to live elsewhere, they swarm over the 

pack train and prevent making camp in their vicinity. 

Scorpions and centipedes, though not abundant, seem 

to be where they are not welcome, and tent caterpillars 

in June force campers into the open. Crickets and 

many varieties of beetles are common.

The breeding birds most commonly seen are the 

magpies, mourning doves, piiion jays, sage sparrows, 

canyon towhees, catbirds, rock wrens, house wrens, 

sage thrashers, bluebirds, swallows, and chickadees. 

But the list includes mountain eagles, ravens, ducks, 

woodpeckers, meadow larks, blackbirds, turkey buzzards, cranes, finches, sapsuckers, flycatchers, grouse, 

swifts, humming birds, and various warblers. Hawks 

seem to be always in the sky, and the hoot of owls is 

the commonest of night sounds. These birds find abundant nourishment in prairie dogs, squirrels, and mice. 

Sagehens provided food for the early settlers at Bluff.

"West of the Clay Hills and along canyons leading 

from Elk Ridge to the Colorado River are a few wild 

horses and wild long-haired cattle, remnants of the 

herds brought from New Mexico about 1885. Members of the Hayden Survey found the Indians in Montezuma Canyon the proud possessors of scrub ponies and 

dogs. Nowadays herds of cattle and flocks of sheep 

move from water hole to water hole and from summer 

to winter grazing ground.

145824 38 3

Because of the great losses sustained by the stockmen 

a vigorous and successful campaign has been waged 

against predatory animals. Trapping is a profitable 

occupation. Seth Shummway, Government trapper, 

states that the big wolves and cougars formerly abundant are now nearly exterminated, but that about 100 

wildcats (lynx cats) and 150 coyotes are caught each 

year.

MINERAL WEALTH

Search for valuable metals in the San Juan country, 

though thorough, has proved to be unprofitable; nowhere have ores of high commercial value been located. 

A little gold has been taken from placers on the San 

Juan" River and from mines in the Abajo Mountains, 

and gravel in Glen Canyon has at times yielded enough 

to cover the cost of mining. The many copper mines 

and radium mines have had short lives. Wells drilled 

in search for oil in the'Lime Creek Valley, in Johns 

Canyon, in Soda Basin, in Dark Canyon, and at 

Boulder Knoll, east of Monticello, have been abandoned 

after an expenditure for explorations estimated as 

$2,000,000. Thin seams of coal about Monticello have 

proved unsatisfactory for general use. (See p. 110.)

Before America was known to Europeans the San 

Juan country was the seat of a flourishing population. 

Abandoned farms, burial grounds, dams and ditches for 

conserving water, agricultural and household implements, and the ruins of well-made dwellings point to a 

people well adjusted to the region chosen for their home 

and indicate a long period of residence. The densest 

settlements and those with the longest continuous 

history are in the drainage basin of Montezuma Creek, 

Recapture Creek, Cottonwood Canyon, and Grand 

Gulch, but well-made buildings appear along the San 

Juan River, Butler Creek, Comb Wash, Alien Canyon, 

the upper tributaries of White Canyon, Lake Canyon, 

Mold Canyon, Castle Wash, and sporadically elsewhere 

on canyon walls, mesas, and plateau rims. This area 

of ancient settlements extends into Colorado, where 

villages and isolated dwellings are abundant along the 

McElmo, Mancos, La Plata, and Animas Rivers 

northern tributaries to the San Juan and into New 

Mexico and Arizona, where streams entering the San 

Juan from the south mark the sites of the remarkable 

ancient villages in Chaco, De Chelly, Del Muerto, 

Carrizo, and Segihatsosi Canyons. The San Juan 

drainage basin, like the basin of the Rio Grande, seems 

to have been fully occupied by these old people. The 

San Juan Basin appears also to mark the northern 

boundary of the area densely inhabited by the pioneer 

tribes. Except for the large village in Indian Creek 

Valley, some houses in Fable Valley, and a ruin of considerable size near Moab, few sites are known north of
28 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

the Abajo Mountains. At the west, along Cataract 

Canyon and Glen Canyon, the scattered ruins suggest 

outposts and hunting lodges designed for temporary 

occupation. Like the present inhabitants, the ancient 

colonizers seem to have found their routes blocked by 

these profound gorges.

Within the area formerly inhabited the ruins are 

grouped, not evenly distributed. On Sage Plain, on 

the bench lands along the San Juan, on Grand Gulch 

Plateau, on most of the high mesas between the Clay 

Hills and the Colorado River, on forested Elk Ridge, 

and on the Abajo Mountains many sherds of pottery are 

strewn over the surface, but structures are few and 

inconspicuous. Along Recapture Creek they- are 

bunched in two large settlements. On Montezuma 

Creek a large group near the mouth of Boulder Canyon 

is continued downstream as houses on both sides of the 

valley. Along San Juan Canyon ruined houses and 

abandoned fields appear near the mouths of Butler 

Wash, Slickhorn Gulch, and Wilson Creek, and interesting petroglyphs have been found at Clay Hill Crossing. 

In Grand Gulch scores of cavelike recesses are occupied 

by houses or burial grounds, most of them smaU and 

relatively inconspicuous. In some canyons they are 

placed like farm houses along a country highway.

The buildings, artifacts, and skeletal remains in the 

San Juan country reveal the presence of two cultures 

that of the Cliff Dwellers, superposed upon a more 

primitive type that of the so-called Basket Makers. 

Since the existence of a culture older than that of the 

Cliff Dwellers was recognized by Prudden 40 and its 

salient features described by Pepper 41 as the result of 

collections made in Grand Gulch, much has been 

learned of the mode of life and distribution of these 

interesting people. Unlike the Cliff Dwellers, the 

Basket Makers built no permanent stone houses. 

Their dwellings seem to have been brush hogans and 

skin or brush tepees that were abandoned or rebuilt 

as temporary needs required. For storage of grain, 

shelter from storms, from cold, and from wild animals, 

and for burials they utilized natural recesses in the 

canyon walls, modifying them somewhat by digging 

pits into their floors. The skeletons were placed in 

stone-lined cists or in graves dug in soft rock. They 

show no deformation of the head. The Basket Makers 

were skilled in making fur cloth and in the use of skins 

of deer, mountain sheep, badgers, rabbits, and prairie 

dogs, also feathers, for clothing. They made nets of 

Indian hemp (Apocynum cannabinum) and had special 

forms of sandals and cradles. Instead of the bow and 

arrow they used the stone-pointed dart and the spear 

thrower (atlatl). They knew little of stonework and 

pottery. The rare pieces of unglazed pottery are 

extremely crude in design and workmanship and could 

have served no particular purpose. In general the

« Prudden, T. M., An elder brother of the Cliff Dweller: Harpers Mag., June 1897. 

<' Pepper, O. H., The ancient Basket Makers of southeastern Utah: Am. Mus. 

Nat. History Jour., vol. 2, no. 4, suppl., pp. 3-26,1902.

place of pottery was taken by coiled-work baskets 

remarkable alike for number, variety, and design. 

There are trays, platters, dishes, sifters, carrying 

baskets, and storage baskets of many forms. Corn 

cobs and squash seeds appear among the ruins, but 

there is no evidence of cultivation of the bean or of 

cotton.

The Basket Maker was doubtless the original pioneer 

in the plateau province, but whether he was replaced 

by the Cliff Dweller or merely represented an early 

stage in the development of Cliff Dweller culture 

remains to be demonstrated. Either because he was 

a pioneer, unfamiliar with his new home, or because 

he represented a weak race, incapable of meeting the 

demands of an exacting environment, he was not fully 

adjusted to an arid region. He seems not to have 

understood the storage of water and its use in agriculture or the advantages of a well-built house, and he 

had no adequate means of capturing the larger wild 

animals for food: in all these respects strongly contrasting with men of the Cliff Dweller and Pueblo 

tribea.

The Cliff Dweller culture in the San Juan country is 

represented by pottery of remarkable abundance and 

variety and by structures of many kinds in many 

different settings. There are houses built of selected 

and fitted slabs of sandstone and limestone with little 

adobe mortar, houses built of irregular stones and 

steam-worn boulders with much adobe mortar, stone 

houses without mortar, houses built entirely or almost 

entirely of adobe, and houses of jaral (loosely woven 

withes thickly plastered with adobe). Some of them 

stand in unprotected places on mesas and valley floors, 

but commonly they are in niches or rock shelves on 

canyon walls, behind big talus boulders, on tops of 

steep-sided buttes, and on the points of narrow mesas 

overlooking the canyon floors. The dwellings are 

isolated or distributed in small compact clusters, in 

rambling groups or in large communal pueblos. Except 

for watch towers and small structures that may have 

served as temporary outposts or hunting lodges most 

of the house groups have three elements in common 

rooms for sleeping and storage, a ceremonial kiva or 

estufa, and a burial ground placed south of the dwelling constituting what Prudden 42 aptly terms "the 

unit type." (See pis. 8, A, B, C; 25, A, B, C, D; 

26, A, B; fig. 4.)

In selecting dwelling sites, access to water, arable 

land, and exposure to the sun seem to have been considered essential; many sites otherwise attractive have 

never been occupied. Accessibility and room for expansion seem not to have been considered. The sites 

of the large groups of rums and of most of the smaller 

ones are along the perennial tributaries of intermittent 

streams, at the heads of box canyons, and at places

« Prudden, T. M., The prehistoric ruins of the San Juan watershed in Utah, 

Arizona, Colorado, and New Mexico: Am. Anthropology, vol. 5, pp. 334-335, 1903.
INHABITANTS 29

along the larger streams where permanent water flows 

through alluvial valley bottoms. Along narrow, steepwalled canyons and the dry lower parts of broad washes 

ruined structures are absent or rare; farther headward 

they are abundant. Along the San Juan the absence of 

ruins at low levels seems to imply a knowledge of the 

destructive overflows resulting from seasonal floods.

With the distribution of the ancient settlements in 

mind, there seems no reason for assuming that the Cliff 

Dwellers were not adjusted to their geographic environment or that the climatic conditions during the days of 

their greatest expansion were more favorable than now. 

For an agricultural people living on corn, beans, and 

squashes, supplemented by piilon nuts, grass seed, and 

the flesh of prairie dogs, badgers, and rabbits, the San 

Juan region today affords a favorable location, and 

before much of the alluvial bottom lands had been 

destroyed and the deer, mountain sheep, and antelope 

driven out, the conditions were still more favorable. 

It is probable that the Cliff Dwellers had plenty of 

accessible water. Abandoned ditches and check dams 

show that they knew something of water conservation 

and irrigation. Some home sites are near springs, and 

small seeps of water appear inside some of the communal 

dwellings. Near many cliff houses arable land is no 

longer accessible, but no sites were seen where lack of 

water would prevent reoccupation.

The antiquity of the ruins of Basket Maker and Cliff 

Dweller and the density of the population are difficult to 

determine. As might be expected, the better-built 

houses are the better preserved, and those in protected 

places are less dilapidated than those in exposed places. 

Many ruins protected from rain and snow by overhanging ledges appear remarkably fresh. Some houses 

in exposed positions retain roof timbers well preserved. 

On the other hand, some houses in caves have fallen 

into decay, and many on mesa tops and valley floors are 

mere heaps of rocks. Some houses are buried in sand 

dunes, in talus, and in stream gravel. Some have been 

built on the ruins of others. Examination of building 

sites at which hewn beams, adobe mortar, baskets, 

sandals, and skeletons have decomposed or crumbled 

to dust even in this dry climate gives an impression 

of great age. The fact that the Spanish in 1540 could 

learn of no pueblo inhabitants north of Walpi and 

Moenkopi suggests that few if any Cliff Dwellers were 

living along the San Juan at that time. Trees at least 

200 years old are growing on burial sites where soil 

marks of stumps point to still older trees. Yet some 

of the adobe-plastered walls, timbers with bark, corn 

cobs, squash seeds, strong textiles, and bright baskets 

give the impression that the families have merely 

gone on a long visit.

Although there is no reason to assume that all or even 

a large part of the ancient dwellings were occupied 

simultaneously, the number of ruins and their obvious 

fitness for accommodation of many people suggests a

relatively large population for a semiarid region. It 

seems probable that during their most prosperous days 

the number of CM Dwellers in the San Juan country 

was twice the present population, and that the larger 

settlements accommodated more people than are now 

living at Bluff. The cause for the disappearance of 

this group of perhaps 4,000 people is unknown. Climatic changes, struggles with nomadic tribes, epidemics 

from introduced diseases, and absorption by neighboring 

tribes doubtless all played a part. But as there is no 

tradition of large-scale migration or slaughter, it seems 

not unlikely that the race after reaching a stationary 

culture gradually deteriorated the death rate overtook 

the birth rate, and, like the present Hopis, they acquired 

a psychology of hopelessness that served to hasten their 

extinction.

PIUTES, UTES, AND NAVAJOS

The Cliff Dwellers and Pueblo people have entirely 

disappeared from the San Juan country; their culture is 

carried on by the remnant tribes in northern Arizona 

and northern New Mexico the Moenkopi, Hopi, Zufii, 

and the pueblo dwellers of the Rio Grande- Valley. The 

place of the ancient agricultural communities has been 

taken by nomadic tribes Piutes, Utes, and Navajos. 

Just when these vigorous tribes took possession of the 

lands bordering the San Juan and which of them were 

the first comers no one knows. The accounts, especially of the Piutes, are meager and conflicting. As the 

Spanish priests and soldiers seem not to have visited 

the San Juan country, reliable knowledge of its Indian 

inhabitants dates only from the days of pioneer settlement most of it within the last half century.

Newberry met camps of Utes (Piutes?) on his traverse 

down the San Juan in 1859, and the work of the Hayden 

Survey in 1871-77 was several times interrupted by the 

hostilities of these tribes. Jackson 43 states that the 

Navajos occupied southwestern Colorado and southwestern Utah "within the remembrance of the older 

persons" and "were driven beyond the San Juan by 

the onslaughts of the aggressive Utes." The relations 

of the Mormon pioneers in San Juan County were with 

Utes, Piutes, and Navajos. In general it may be said 

that the prospectors, trappers, and Government exploring parties of the period 1840-70 found the Utes and 

their linguistic relatives, the Piutes, firmly established 

in Utah, Nevada, western Colorado, southern Oregon, 

and southeastern California, and that the Navajos together with their cousins, the Apaches, dominated New 

Mexico and Arizona. The San Juan River, continued 

by Glen Canyon and Grand Canyon of the Colorado, 

seems to have separated two hunting areas or at least 

two "spheres of influence." During the time immediately preceding settlement by the whites, Navajo visits 

north of the San Juan seem to have been warlike raids 

or short-time hunting and trading excursions permitted

« Jackson, W. H., U. S. Qeol. and Geog. Survey Terr. 10th Ann. Rept., p. 428,1878.
30 THE SAN JUAN COUNTEY, SOUTHEASTERN UTAH

by the Utes, and Ute visits to the Navajo country were 

governed by the same conditions. Tradition records 

many warlike raids back and forth across the San Juan. 

Descendants of Navajo slaves among the Piutes and of 

Piute slaves among the Navajos are evidence of hostile 

relations. Obviously the boundaries of tribal areas 

were not sharply denned. Piutes have long lived in 

Piute Canyon, south of the San Juan, and Navajos at 

Ute Mountain, in Colorado; Kigalia ranger station, on 

Elk Ridge, was the home of a Navajo chieftain.

The Mormon pioneers who settled at Bluff in 1880 

found Indian communities in Alien Canyon, Cottonwood Canyon, and Montezuma Canyon and a few 

families along the San Juan. In accordance with their 

traditional attitude, these representatives of the Church 

maintained friendly relations with the natives and refrained from occupying the lands which the Indians 

claimed. Even the fertile Alien Canyon and the 

choicest bits of soil on the floors of other canyons, 

though little used by the Piutes, were recognized as 

"Indian land." In keeping with the traditional GUST 

toms of their tribe these Piutes roamed rather freely in 

small independent bands, each under the nominal direction of a chief. During the growing season they 

remained near permanent water, caring for their small, 

poorly cultivated fields of corn, squash, and melons and 

herding their goats and ponies on nearby grass lands. 

During the colder weather many of them relocated as 

families or groups in places where snow and cold winds 

could be avoided and where bright sunshine provided 

warmth not given by fires in their loosely constructed 

brush and mat wickiups. (See pi. 9, A.} To supplement the meager food supply obtained from cultivated 

red and blue corn, the men of the tribe hunted deer, 

mountain sheep, prairie dogs, badgers, rats, and especially the rabbit, which were killed with the "rabbit 

stick" or trapped with the ingeniously constructed 

"flax" twine rabbit net described by Powell 44 as in use 

by the Piutes of the Uinkaret Plateau. The women 

and children and at times the men gathered pinon nuts, 

acorns, berries, and seeds of grass and herbs especially 

Oryzopsis ("mountain rice"), Chenopodium, and Coreocarpus. A Piute "biscuit" is a small, hard, red, unsalted 

mass of ground-up bullberries, squawberries, grass 

seed, weed seed, and corn baked in ashes.

Like other Piute tribes on the border of the great 

Ute region, those in the San Juan country seem to have 

adapted themselves to only the most obvious features 

of natural environment and to have borrowed freely 

from their neighbors. Their homes are modified forms 

of the tepee of the plains Indians; the rabbit net, the 

skillfully made and attractively decorated storage and 

carrying baskets, and the remarkably practicable 

pitch-coated, wicker water bottles resemble those of 

the ancient Basket Makers, the aboriginal inhabitants 

of the Piute fields. Like the Basket Makers, the

 «« Powell, J. W., Exploration of the Colorado River, p. 127, Washington, 1875.

Piutes know little about pottery, a characteristic feature of Cliff Dweller culture. It is interesting to note 

that the Hopis and the San Juan Piutes are of the same 

linguistic stock.

For nearly 40 years after the first white community 

settled on the San Juan River no official attention was 

given to the Indians. Though petty thieving and 

killing -of stock caused periodic friction that led to calling in troops from Fort Lewis, the Piutes were permitted 

to roam at will. Some were given work by the pioneers 

and in time of famine were fed from their scant stores 

of provisions, and the Indians on their part refrained 

from any organized opposition. On the whole the 

relations were tolerable, if not always pleasant. With 

the increase in white population, especially of cattlemen, 

the Ute and Piute leaders seemed to feel that their 

lands were no longer safe. Many disagreements arose 

between stockmen and Indians. In 1923 a trouble 

developed that called for governmental action. As 

related by E. Z. Black, the local representative of the 

Bureau of Indian Affairs, a band of Piutes caught 

robbing a sheep camp were arrested and sentenced to 

jail. After a bloody riot the prisoners broke away 

from the sheriff and, aided by their friends, escaped to 

the canyons bordering their ancestral homes. A posse 

was then formed to round up all the Indians and to 

"teach the robbers a lesson." After a tiresome hunt 

one Indian was killed. The leader, "Old Posey", 

though wounded, refused to surrender and died in an 

abandoned cave protected by his faithful followers. 

In the meantime word had gone to Washington, and a 

conference was arranged under the direction of General 

Hugh L. Scott, who was well known among all the 

tribes of Utah and Arizona and whose wise and just 

attitude toward the Indians had been many times 

tested. The proposal that future trouble be forestalled 

by removing the Indians to lands south of the San 

Juan or to the Ute Reservation in Colorado was met 

with the stoical reply, "Our fathers have always slept 

here." Recognizing that only superior force .could 

drive the Indians from their hereditary homes, the conference reached the decision that the two bands of 

Piutes and Utes who acknowledged the leadership of 

"Old Posey" and "Polk" should be allotted lands in 

Cottonwood Canyon and its tributaries, Hammond 

Canyon, Alien Canyon, and Dry Wash, and Whiskers 

Creek. Each allotment consists of 40 acres of irrigable 

land, 80 acres of dry-farm land, or 160 acres of grazing 

land that may not be sold or leased without the consent 

of the Indian Bureau. The 45 allotments made comprise all the suitable areas within this region.

At the present time the Indians who make their home 

in San Juan County number about 180. Most of them 

are Piutes, but among them are perhaps a score of Utes 

and a few Navajos. Their official residence is at the 

Indian village at Alien Canyon, where they are encouraged to develop their allotments and to utilize their
INHABITANTS 31

grazing rights on Elk Ridge. They are supposed to 

work their lands, to cut timber, and to supply themselves with food from their crops and livestock, but it 

has been found impracticable to discontinue food 

rations. Under a capable superintendent, who is wise 

enough to treat a little crop as a "big crop" and a 

straggling band of sheep as a "herd", the Indians are 

making some progress, but supervised industry and a 

fixed abode afford little attraction. They want to live 

their lives in their own way. In particular they resent 

the Government decision to keep their children in school 

100 miles away, in Colorado.

WHITE SETTLEMENTS 

HISTORY

The history of white settlements in southeast Utah 

is the record of explorations and of systematic attempts 

to utilize some 5,000 square miles of grazing and agricultural land. The exploratory adventures of Posada 

and Rivera (1761) and of Escalante (1776) in eastern 

Utah and .western Colorado were not followed by 

Spanish settlements, and the pioneer journey of the 

American Wolfskill (1830) seems to have been soon 

forgotten.

The topographers of the Hayden Survey in 1874 

found "Parrott City" (two log houses) on the La Plata 

River, "the only white settlement in southwest Colorado." They reported no white men in the area now 

constituting San Juan County. Doubtless a few 

adventurous trappers and prospectors found their way 

along the San Juan River and to the base of Abajo 

Mountains during the decade 1870-80. It is known 

that in 1879 Patrick O'Donnell occupied a hermit 

cabin near the present Monticello, that Peter Shirts, a 

roving trapper, was camped at the mouth of Montezuma Creek, and that the Mitchells, the first white 

family in southeastern Utah, were living at the mouth 

of McElmo Creek. But the recorded history of the 

San Juan country begins with the settlement of Bluff 

in 1880.

From unpublished records made accessible by the 

historian of the Church of Jesus Christ of Latter Day 

Saints, from a manuscript history of San Juan County 

by Albert Lyman, from information furnished by Truman Jones, Bishop Redd, and other old-timers, the 

salient features of this outstanding adventure in 

pioneering have been assembled. While working 

among the Navajos in the region east of Marsh Pass, 

Jacob Hamblin and other missionaries investigated 

opportunities for irrigation, farming, and stock raising 

along the San Juan River north of Carrizo Mountain. 

Their favorable report led to a decision by the church to 

establish a settlement as near as possible to Four 

Corners, "but in Utah." Leaving Cedar City April 14, 

1879, the party consisting of about 30 men (2 with 

their families), 20 wagons, arid many saddle horses 

under the leadership of Silas S. Smith, proceeded by

way of Panguitch, Kanab, Lees Ferry, Moenkopi, 

Marsh Pass, and Boundary Butte and reached the San 

Juan at "Allan Bottom", between Montezuma and 

McElmo Creeks, on June 1, 1879. On the way they 

were forced to build roads, dig wells on dry wash bottoms, and overcome as best they could the suspicion 

and opposition of the Indians. There was particular 

trouble with the Navajo chief "Peogament", who 

"claimed the river and all the lands north." With 

Allan Bottom as a base the river was explored down to 

Butler Wash (John Builer) and up to Alamosa, and the 

base of the Abajo Mountains was studied as a source of 

water, timber, and forage. As a site for a settlement 

a stretch of meadowland 2 miles above the mouth of 

Montezuma Creek was chosen. For protection a 

stockade, Fort Montezuma, was built. Claims were 

staked for 18 miles along the San Juan. Leaving two 

families (Harriman and Davis) at the "fort", the party 

returned to Cedar City by constructing a road up 

Recapture Creek, across the headwaters of Montezuma 

Creek, down Peters Hill, across Dry Valley, over the 

pass to Moab, thence on across the Colorado and Green 

Rivers and the High Plateaus. During the period 

April 14 to September 17 more than 1,000 miles of 

little-known country had been traversed and 400 miles 

of new wagon road had been made. The enthusiastic 

reports of Silas Smith met with an equally enthusiastic 

reception. A picturesque region rich in farm land and 

grazing land, supplied with timber and water, and 

occupied only by a few Indians awaited settlement. 

Within a few weeks a call of the church was issued to 

settle the San Juan country.

The proposed new colony was peculiarly isolated. 

To the north across Utah the only white people were a 

few families at Moab, 110 miles distant; eastward was 

the small settlement at Mancos, 70 miles away; southward for 160 miles was the Navajo country; westward 

the nearest settlement was Escalante, 115 miles distant. The nearest markets and reliable sources of 

supplies were Albuquerque, 225 miles distant, and Salt 

Lake City, 350 miles distant. But the church authorities who planned the settlement on the San Juan were 

fully aware of the economic and social difficulties incident to isolation and were prepared to pay the price; 

in their opinion sacrifices that resulted in permanent 

occupation of "desirable places" were justified. It 

was obvious, however, that unless the proposed new 

settlement was to be entirely self-contained, roads 

suitable for wagons must be built to connect it with, 

existing settlements. The natural connection is with 

Colorado, up the San Juan or across the level Sage 

Plain. The topography is favorable for roads planned 

to reach the Spanish settlements on the Mancos and 

the La Plata and, farther on, Albuquerque.

But the geographic advantages of nearness and ease 

of travel were outweighed by the call for a "compact 

population of adherents to the Church of the Latter
32 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

Day Saints." To the leaders of the church it seemed 

highly desirable that the outlying settlements should 

be brought into social and political contact with the 

"Saints" in Utah rather than with the "Gentiles" in 

Colorado.

To put into effect this desire for closer union involved 

the construction of roads from the High Plateaus of 

central Utah to the spots chosen for colonization on the 

middle San Juan River. Three routes were possible 

a northern one, across the Wasatch Mountains, down 

the Price River, and southward along the UtahColorado line; a southern one, through Arizona; and a 

central one, directly eastward from Panguitch and 

Escalante. The northern route involved the crossing 

of the Green River and the Colorado River and a long 

traverse through country inhabited only by hostile 

Utes. The southern route involved crossing the Colorado River at the mouth of the Paria or of the Virgin 

and a traverse of 150 miles through rough country 

held by the Navajos. The central route required a 

crossing of the forbidding Glen Canyon and of long 

stretches of exceedingly rough and arid country on 

both sides of the Colorado. Partly because of its 

shorter distance and its freedom from hostile Indians 

and partly because the "Saints called to settle on the 

San Juan" were residing in Cedar City, Parowan, and 

Panguitch, the central route was chosen a decision 

which led to the construction of the Escalante-Bluff 

road, in many respects the boldest pioneer adventure 

in the history of the plateau country.

With only a knowledge of the country west of the 

Colorado and the report of Charles Hall that a crossing 

of Glen Canyon at Hole in the Rock, an old Indian trail, 

was feasible, 25 wagons constituting the vanguard of the 

San Juan mission left Cedar City and the scattered 

settlements about Panguitch in October 1879. In 

November they were camped at 40-mile spring and 

50-mile spring, on the Escalante Desert at the base of 

the Kaiparowits Plateau. Here they were joined by 

others who had responded to this "call" until about 80 

wagons and. some hundreds of horses, the means of 

transport for 60 men, most of them with families, were 

gathered in these inhospitable places. The situation 

was desperate. Scouts had reported that the Hole in 

the Rock crossing was formidable and the country east 

of the river was so intricately cut by deep canyons in 

solid rock as to make traverse with wagons impossible. 

But though months of the hardest work lay ahead and 

provisions were nearing exhaustion, a return to the 

settlements was extremely difficult; heavy snow blocked 

the trails across the High Plateaus, and the scant season's forage had been eaten up by the hundreds of horses 

and cattle that accompanied the expedition. In council 

the leaders decided to go ahead. Albert Lyman states 

that on December 14 most of the party moved to the 

Hole in the Rock, a region without wood or water, and in 

the cold of winter, men, women, and children were engaged in "working out a shute" down to the river. On 

January 26, 1880, 24 wagons were taken through the 

Hole and ferried across the river on a boat made of lumber sawed out at Escalante. The crossing was completed on February 10, and 7 days was spent in getting 

the wagons up a canyon in the east wall of "the river. "It 

took four to seven span of horses or the same number of 

oxen to move one wagon." After traversing the rough 

sandstone gorges adjoining the Colorado and the flattopped Wilson Mesa beyond, they spent "7 cold, wet, 

windy days" in making a road for wagons down "slick 

rocks", the wall of a tributary leading northward to the 

Colorado. On February 28 the party reached Hermit 

Lake, in Lake Canyon, thence proceeded along Castle 

Wash, and completed a road down the Clay Hills on 

March 12. (See pi. 6, B.} Finding the road east of 

the Clay Hills and along the San Juan blocked by 

impassable canyons, they selected a route northward 

across the head of Grand Gulch, thence southeastward 

over the Grand Gulch Plateau to Comb Wash, and 

down Comb Wash to the San Juan, which was reached 

on March 31. Four days was spent in making a "dugway through the Comb" (mouth of Butler Wash) 

(pi. 9, A). On April 5 the party reached the mouth of 

Cottonwood Creek and established camp. Though 

their proposed destination was Fort Montezuma, 18 

miles up the San Juan, they could go no farther. The 

225 men, women, and children, who had survived the 

continuous hardships for 170 days, were exhausted, and 

the diminished herds of horses and cattle were "barely 

able to move." Contact was made with Fort Montezuma by sending scouts with provisions for the families 

left there the previous year. 45

My traverse of the Escalante-San Juan road on foot, 

on horseback, and by swimming makes it easy to understand why it was used but once.

West of the Colorado is the almost waterless "50-mile 

desert" (Escalante Desert). Hole in the Rock is 'a 

difficult and dangerous crossing the worst on the 

Colorado. Though the river here is favorable for 

boats or for swimming with horses, the only access 

from the west is through a crooked, smooth-sided slit 

in a towering wall.46 East of the river the road 

ascends a bench, then enters a maze of knobs, pits, 

boxes, shelves, and "dry waterfalls" that constitute 

features of interlacing big and little high-walled 

canyons. Among the many dry stream channels leading to the plateau above, only one can be ascended, 

and that one only after building trails over and around 

bare rock shoulders. Topography of this type continues to a point some 12 miles from the river, where the 

flat top of Wilson Mesa furnishes an easy route. But 

the descent from the mesa must be made over the bare

45 According to Mr. Albert Lyman, of Blanding, the statement that the entire party 

of emigrants reached Fort Montezuma is based on erroneous information. (See 

Gregory, H. E., U. S. Geol. Survey Prof. Paper 164, p. 11, 1931.)

49 Gregory, H. E., and Moore, R. C., The Kaiparowits region: U. S. Geol. Survey 

Prof. Paper 164, pp. 11-12, 1931.
INHABITANTS 33

surface of sandstone knobs whose steep sides lead 

downward to deep, narrow gorges. Only by cutting 

steps and building up retaining walls on the "slick 

rocks" is passage with wagons possible. Even on 

horseback the road is dangerous. Hermit Lake is a 

delightful oasis of water and grass in a region of bare 

rocks. In making the road from the lake to the Clay 

Hills only sand dunes on the uplands and the irregularity of canyon floors need be overcome, but Clay 

Hills Pass presents difficulties. It is easy to understand that "a company of 60 men with horses and 

scrapers" needed 3 days to construct a passage through 

a mile of slippery clay heaped with huge talus blocks. 

From the Clay Hills up Grand Flat, across the head 

tributaries of Grand Gulch, and down Comb Wash to 

the San Juan the road makers encountered no serious 

obstacles. The chief work was shaving down the sides 

of narrow gullies, building runways to ledges, cutting 

brush, and assisting teams through sand. To take the 

wagons up the San Juan River from the mouth of 

Comb Wash it was necessary to build a roadway hi 

rock around the end of Comb Ridge, thence up and 

across Butler Canyon. It seems clear that missionary 

zeal rather than a knowledge of topography guided 

this heroic but futile undertaking.

Fortunately an examination of the bottom lands 

along the San Juan had shown that the wide alluvial 

flats at the mouth of Cottonwood Canyon the place 

where exhaustion had ended the long, arduous journey 

of the San Juan mission was the best place in the 

valley for an agricultural settlement. Without delay 

preparations were made for planting a crop an urgent 

necessity if starvation was to be avoided later in the 

year. From 8 to 20 acres of farm land was assigned 

to each family, in addition to unrestricted grazing rights 

and a 1-acre lot in the village, organized April 6, 1880, 

as "Bluff City." Local government had already been 

provided: by an act of the legislature (Feb. 17, 1880) 

San Juan County had been established and the leaders 

of the mission band appointed as its officers when as yet 

it had no inhabitants.

Life at Bluff during the first few years must have been 

discouraging. Official reports and personal records 

speak of "continuous trouble with irrigation ditches"; 

"floods from the Cottonwood covered fields with mud"; 

as protection from Indians "women and children lived 

in a fort"; "stock had to be herded to prevent stealing"; 

crops for 1880, 1881, 1882 were "very poor"; 10 

families moved to the mouth of Montezuma, Wash, 

others to the mouth of Recapture Creek; in the fall of 

1880 "about half of the population moved away"; 

in 1880 and again in 1883 the desire of the settlers to 

"abandon the place" was overruled by the church 

officials.

"The church had a definite object and purpose in 

settling a colony in this wild region"; money was made 

by trading with the Indians and by working as teamsters in Colorado; the "great flood" of June 1884 

drowned the farm lands above Bluff, destroyed the 

settlement at Fort Montezuma, and "changed the 

meadows on Cottonwood Creek into sand flats"; in 

1885 more farm land was destroyed; by 1886 "20 miles 

of farms along the San Juan in 1880 had become at 

most 700 acres served by one ditch at Bluff." At one 

time it was proposed to set aside San Juan County as 

an Indian reservation.

Though the people of dwindling Bluff accepted the 

decision of the church that the mission be held in spite 

of hardships, "for the sake of more fruitful places", 

their experience had proved that farming in the San 

Juan Valley was unprofitable. Exploration of the 

lower San Juan, Castle Wash, Red Canyon, White 

Canyon, and the "little valleys" east of Elk Ridge 

showed that these places' also lacked land and water 

suitable for irrigation farming but that forage for stock 

was abundant. Beginning about 1885, stock raising 

replaced agriculture as the primary industry. Sheep 

were introduced, cattle ranches owned by men from 

Bluff were established in Alien Canyon, Dark Canyon, 

and Comb Wash, and the right to graze stock on Elk 

Ridge was purchased from the Indians.

The opportunities to supplement summer forage in 

the Abajo Mountains by raising alfalfa and grain on 

dry farms and fields irrigated by headwater tributaries 

of the Montezuma attracted settlers from Bluff and 

from Mancos and led to the organization of the "tough 

cattle town" of Hammond (now Monticello) in 1887, 

Carlisle in 1889, and Verdure in 1894 and to the starting of ranches in Strawberry Creek (Mormon Pasture), 

Cottonwood Canyon/6* and Indian Creek. In the 

hope of success from dry farming a few settlers took up 

land east of Monticello and on Sage Plain at Lockerby, 

Ucolo, and a few other places. The last important 

shift in population came with the establishment of 

Blanding (formerly Grayson) in 1905, the largest village in San Juan County.

Blanding owes its existence to the foresight and persistence of Walter C. Lyman, the father of the irrigation project that brought the waters of the Abajo 

Mountains to some 3,000 acres of favorably lying land 

on "White Mesa." The site had been prepared by 

constructing a ditch line (in 1903), clearing of rank 

sagebrush, and harvesting an experimental crop. In 

1905 the first settlers arrived chiefly those whose 

farms had been ruined by the San Juan River at Bluff 

and those driven from Mexico by political and religious 

persecution.

Three ephemeral events have interrupted the normal 

development of settlement in the San Juan country 

the gold excitement on the San Juan (1890-92), the 

mining boom in the Abajo Mountains (1892-93), and 

the oil boom at Mexican Hat, which reached its height 

between 1907 and 1910. The unverified report of Bill

4»» See footnote 23, p. 11.
34 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

Williams that rich placer gravel "was strewn all along 

San Juan Canyon" brought "about 2,000 people through 

Bluff" in 1892, and the shift of the disillusioned miners 

to stream bottoms and ledges of the Abajo Mountains 

still left Bluff as the outfitting point. "Forty to fifty 

miners passed in a day." "Bluff was amazingly prosperous." In 1909 and the next few years work in the 

oil fields temporarily increased the population of Bluff 

and built up a small settlement at Goodridge (Mexican 

Hat).

The history of white settlement in southeastern Utah 

is the record of a systematic attempt to make use of 

some 5,000 square miles of agricultural and grazing 

lands and to exploit possible mineral resources. The 

region has proved disappointing. On the San Juan 

River less than 100 people at Bluff, 1 family at Goodridge, and 1 at Aneth constitute the present population; elsewhere on the river the former population of 

farmers, traders, missionaries, miners, and oil men has 

disappeared. On Sage Plain east of Recapture and 

Montezuma Creeks abandoned farms are more numerous than occupied farms. West of the Abajo Mountains and Cottonwood Creek no white man maintains 

a residence. This vast region is visited in summer by 

cattlemen, forest rangers, and a few tourists and in 

winter by trappers and now and then a prospector. 

Essentially the "population centers in the villages of 

Monticello and Blanding two oases that owe their 

existence to streams from the Abajo Mountains. The 

fluctuation in population during the 50 years since the 

first settlers arrived is shown in the following table:

Population of San Juan County, 1880-1930

Bluff___ ........._

Blanding. ____ ____

La Sal.. __.-._.._.

Settlements and

Total whites. __

Indians. _-__--__._

Total... _.._._

1880

225

225

1890

190

115

60

365

365

1900

*3l5

180

97

271

863

160

1,023

1910

160

385

375

39

959

959

1920

150

1, 072

768

287

231

2,508

871

3, 379

1930

70

1,001

763

2 211

221

2,266

s 1, 230

3,496

1 Includes about 150 prospectors.

2 La Sal, at the base of the La Sal Mountains, though in San Juan County, is not 

included in the "San Juan country."

3 Includes about 1,000 Indians in the "Utah strip", part of the Navajo country south 

of the San Juan River.

For 10 years after its establishment the pioneer settlement Bluff contained almost the entire population of 

San Juan County and, nearly half of the population of 

Utah east of the Colorado and Green Rivers. Growth 

of the population began with the coming of farmers and 

stockmen to lands bordering the Abajo Mountains and 

continued with marked increase to a peak in 1921. 

Since 1918 small settlements have grown up at Lockerby, Cedar Point, and Summit Point. On the other

hand, the 53 inhabitants of Indian Creek in 1900 were 

represented in 1934 by one family. The former settlements on the San Juan above Bluff, including 168 people 

in the McElmo precinct, have dwindled to two families, 

and the oil-boom population of Goodridge and Mexican 

Hat is represented by the keeper of a trading post.

Like the rest of Utah in general, San Juan County 

has a remarkably virile population of almost pure 

Nordic stock. As shown by the census for 1920, the 

population exclusive of Indians consists of native-born 

whites and foreign-born whites from Great Britain, 

Canada, Scandinavia, and Germany. The list includes 

3 Mexicans but no orientals or negroes. For all census 

years the males exceeded the females; children under 7 

years of age constituted about one-third o± the population, and those under 14 years more than half.

After 50 years of settlement the white population of 

San Juan County was 2,266, or about 0.3 person to the 

square mile. Yet this small number is probably all 

that the country can support under present conditions. 

More and more the outlying farms and ranches are 

being abandoned and the population is becoming concentrated on irrigated tracts, particularly at Blanding 

and Monticello. Increase in population would involve 

fuller utilization of the streams issuing from the Abajo 

Mountains, the sinking of deep wells, the development 

of small suitably placed water supplies in the grazing 

districts, and the selection of grains and roots appropriate for dry farming.

INDUSTRIES

FARMING

Experience covering half a century has demonstrated 

that few areas in the San Juan country are adapted to 

farming and that without irrigation the raising of food 

and forage crops is unprofitable. The floors of canyons in Grand Gulch, Red Rock, and Dark Canyon 

Plateaus have few patches of arable land, and most of 

the canyon floors in Sage Plain lack both suitable land 

and adequate water. The broad alluvial flats, that attracted the pioneers to the San Juan and the Cottonwood have been largely destroyed by shifting floods. 

Of the "20 miles of farms" once grouped along the San 

Juan, there remain about 40 acres at Aneth and 200 

acres at Bluff, in part irrigated by artesian wells. Three 

irrigated patches of alfalfa along Indian Creek, one in 

Comb Wash, a garden patch at the mouth of Red Canyon, and small plots intermittently cultivated in Piute 

Park and in Montezuma Canyon complete the list of 

"farms" on alluvial bottom lands. It is interesting to 

note that the canyon floors found suitable for cultivation by white men are those used by the Indians and by 

the Cliff Dwellers and Basket Makers before them.

Dry-land farming on Sage Plain east of Montezuma 

Creek started in 1887 and was vigorously developed 

during the war period, when more than 100,000 acres 

of previously unoccupeid land was taken up as farms.
INHABITANTS 35

The crop for 1919 was the largest and most valuable 

and covered the largest acreage of those recorded for 

San Juan County. During that year the value of farm 

lands and buildings exceeded $3,500,000, more than 

five times that of 1910 and twice that of 1925 or 1930. 

These dry-land farms demonstrated that much of the 

region between the Abajo Mountains and the Colorado 

line is well adapted for the production of oats, corn, and 

dry-land wheat. Prof. A. Merrill, of Utah Agricultural 

College, says that "without question San Juan County 

ranks as the best dry-farming county in the State." 

But the cultivation of dry-land farms has proved to be 

unprofitable under normal conditions. Except in an 

inflated market, the cost of hauling grain '100 miles to 

the railroad at Thompson prohibits export. At present 

few dry-land farms justify continued cultivation; 

failures outnumber successes. More than half of those 

occupied in 1920 have been abandoned.

Farming for profit in the San Juan country is essentially restricted to the outer slope of the Abajo Mountains, round about Blanding, Verdure, Monticello, and 

Carlisle, where headwater tributaries of Recapture and 

Montezuma Creeks are available for irrigation. Unfortunately the amount of water during "good years" 

is sufficient for covering but a small part of the land 

otherwise suitable for farming, and in dry years fields 

distant from the head ditches receive no water during 

part of the growing season. The land considered 

available for irrigation by the existing systems of canals 

is estimated as 14,158 acres. In 1920, 13,469 acres 

was irrigated; in 1930, 9,525 .acres, a decrease of 29.3 

percent. For Blanding, the largest irrigation district, 

the land accessible to water has ranged between 

7,500 acres in 1921 and 4,000 acres in 1928.

For all San Juan County (nearly 5,000,000 acres) 

the area of land classed by the Census Bureau in 1930 

as "farms" was 110,477 acres. Of this amount 25,183 

acres was "crop land", 55,964 acres "pasture land", 

and 29,330 acres "other land" that is, land on which 

no crop was planted and land on which the crop failed 

to mature. Of the "crop land" 15,832 acres was 

harvested. During the decade 1920 to 1930 the farm 

land decreased from 167,639 to 110,477 acres, but the 

number of farms increased; in 1930 about one-fourth 

of all farms in the county comprised less than 20 acres 

each. The average value of farm land is reported as 

about $20 an acre in 1920 and $12 in 1930.

As at present practiced, farming in San Juan County 

consists of raising wheat, potatoes, fruit, and garden 

vegetables for family use and oats, barley, alfalfa, and 

corn for stock feed. The production of more than 

50,000 bushels of wheat, 1,000 bushels of apples, and 

large quantities of peaches gives a surplus of these 

crops for export. The alfalfa grown is insufficient for 

local needs, and each year many tons of oats are 

imported. The cultivation of food crops and orchards 

on irrigated lands has yielded satisfactory returns.

145824 38 4

STOCK RAISING

San Juan County, Utah, which includes the area 

described in this paper, is essentially a grazing district a great expanse of free range. The villages 

serve primarily as homes and supply points for cattlemen and sheepmen. The chief business of the farms is 

to supply feed for cattle, horses, and sheep. Of a total 

area of 7,761 square miles, 4,988 square miles of grazing 

land is unappropriated, most of it unsurveyed, and 

890 square miles of grazing land is reserved for the use 

of Navajos and Piutes. This large area is further 

increased by 723 square miles included within the 

national forest, the chief, purpose of which is to provide 

feed for stock during the summer season. Over most 

of the free-range lands the grass and "browse", though 

scarce and unevenly distributed, is very nutritious. 

In large parts of the area 1 square mile can supply forage 

for about 6 head of cattle or 20 head of sheep, provided 

due attention is given to the selection of feeding grounds 

in dry years. The region west of Comb Wash and Elk 

Ridge seems not to be overstocked; water from rain 

and snow is sufficient in late fall, winter, and early 

spring, but it is wholly insufficient in summer. During 

most years the herds must leave the lower country in 

May, and those which cannot be accommodated on the 

national forest must be sent to market. The lands 

along Comb Wash, Cottonwood Canyon, and Recapture 

and Montezuma Creeks and out on the mesas beyond 

Lime Creek have been overgrazed; their present carrying capacity is much less than that for the period 

1880-1900, and some sort of periodic reservation seems 

necessary to bring the range back to more profitable 

use. Were it not for the national forest, stock 

raising in San Juan County would be a hazardous 

undertaking except where supplemented by irrigation 

farming.

In response to the annual variations in the condition 

of the range, the amount and distribution of water, and 

the state of the market for beef, mutton, and wool, the 

number of cattle and sheep shows a wide range. Census 

figures are as follows: 

1910....... ._........ ...._...........

1920.. _._......_._._.._._.._...._..

1925... _.--__...._...__........._..

1930_ ______________________________

Cattle

20, 316

15, 764

26, 184

13, 527

Sheep

92, 507

44, 060

109, 482

i 60, 200

i Estimated.

Stock raising is the most important source of income. 

For the years 1920-30 the value of sheep averaged 

about $230,000, of cattle about $395,000, and of the 

wool clip about $90,000. A small amount of butter, an 

important source of revenue in the early days of settlement, is manufactured for export. Cream is shipped 

regularly from Blanding and Lockerby.
CHAPTER 2. SEDIMENTARY ROCKS

GENERAL STRATIGRAPHIC RELATIONS

Nearly all the consolidated sedimentary rocks in the 

San Juan country are of Permian, Triassic, Jurassic, and 

Cretaceous age. For short distances in San Juan, 

Dark, and Cataract Canyons strata of Pennsylvanian 

age are exposed, and drill holes that reached "mica 

schist" at a depth of 4,422 feet in Reservoir Canyon, 

Elk Ridge, and 3,633 feet at Soda Basin, in the San 

Juan Canyon, penetrate great beds of limestone and of 

resistant sandstone and shale 'that probably represent 

most of the lower Paleozoic of the plateau province. 

The youngest strata (Mancos shale) appear on the surface of the synclinal Sage Plain and in the broken roof 

of the laccolithic Abajo Mountains; the oldest (Hermosa 

formation) in Dark Canyon and Cataract Canyon and 

in the Raplee and Mitten Butte anticlines where these 

are trenched by the San Juan. All the formations 

mapped in the San Juan country, also the absent 

Tertiary and uppermost Cretaceous, are represented in 

adjoining regions, and some of the Triassic and Jurassic 

formations are approximately coextensive with the Colorado Plateaus. For example, the Navajo sandstone, 

which may be traced almost continuously across southern Utah and southward into Arizona, shows everywhere closely similar lithology, peculiarities of weathering, and topographic expression; the Chinle retains its 

characteristic features at exposures in Utah, Arizona, 

and Nevada; the remarkable Shinarump conglomerate 

show& little change over thousands of square miles, and 

the Moenkopi of Red Rock Plateau is but the eastern 

extension of that formation in the Escalante, Paria, 

Kanab, and Virgin River Valleys, Utah; the Little Colorado Valley, Arizona; and the Muddy Mountains, 

Nevada. On the other hand, in lithology and sequence 

the Permian beds of southeastern Utah are unlike those 

farther west. Of the Grand Canyon formations the 

Coconino is absent and the Kaibab, Hermit, and Supai 

are not clearly represented. Their place in the time 

scale is occupied by the Cutler and Rico formations. 

The general stratigraphic features of formations in the 

San Juan country are summarized in the accompanying 

table. (See also pi. 10.)

Generalized section of the rock formations in the San Juan country

System

Cretaceous.

Jurassic.

Series

Upper Cretaceous.

Upper Jurassic.

Group, formation , and member

Mancos shale.

Dakota (?) sandstone.

Morrison formation

A

o

t-, 

bO

1303 "53 &

a

eS 

CQ

Brushy Basin shale 

member.

Westwater Tank 

sandstone member.

Recapture shale 

member.

Bluff sandstone member.

Summerville (?) formation.

Entrada sandstone.

Carmel (?) formation. 

 Unconformity 

Character

Steel-gray to brown argillaceous and sandy shale 

and irregularly bedded sandstones; some coal; contains Ostrea, Exogyra, Gryphaea, and other fossils; 

forms mounds and badlands. -

Gray to nearly white sandstones, conglomerates, and 

sandy shales, quartz, lime, and iron cement; irregularly bedded; contains coal; forms cliffs.

Brightly banded shales, thin limestones, conglomerates, and sandstones; forms slopes. Dinosaur 

remains.

White to buff coarse sandstones; very irregularly 

bedded; many lenticular beds of conglomerate, 

sandy shale, and sandstone; contains chert, concretionary clay, fragments of petrified wood, and 

dinosaur bones; forms cliffs and benches.

Dark-red and variegated calcareous and gypsiferous 

shales and thin white siliceous sandstones; overlapping beds; forms slopes and low steps.

White to gray-brown massive or thick-bedded, crossbedded sandstone; in places thin-bedded; includes 

quartz aggregates, clay balls, and mudstones; 

forms cliffs and platforms.

Varicolored thin calcareous sandstone and mudstone, cross-bedded and lenticular; gypsiferous 

and calcareous shale; includes lime pellets and 

chert concretions; forms banded cliffs.

Brick-red to orange-brown fine, even-grained sandstone; some irregularly bedded sandstone and 

shales form benches; weathers into round-edged 

ledges, spools, and "rock babies."

Red and white earthy, lumpy, unevenly bedded sandstone and red mud shale; some arenaceous limestone; weathers in short steps and slopes.

Thickness (feet)

0-350

92-200 +

350-470

222-295

100-300

100 (?)-350

42-132

8-80

0-17

36
SEDIMENTARY ROCKS

Generalized section of the rock formations in the San Juan country Continued

37

System

Jurassic (?)

Triassic.

Carboniferous.

Scries

Upper Triassic.

Upper (?) Triassic.

Lower Triassic.

Permian.

Pen nsyl vanian .

Group, formation, and member

a 

ot-i

bO

C

o 

>>

a

6

a<u

O

Navajo sandstone.

Kayenta formation.

Wingate sandstone.

Chinle formation.

Shinarump conglomerate.

Moenkopi formation.

 Hoskinnini member.

Cutler formation

De Chelly sandstone 

member.

Organ Rock member.

Cedar Mesa sandstone member.

Halgaito member.

Rico formation.

Hermosa formation.

Character

Cream-yellow to buff-white (?) cross-bedded sandstone; one massive stratum and thick bed separated 

by sandy shale; includes lenses of dense limestone; 

weathers as mounds, alcoves, and niches.

Dark red-maroon coarse-grained sandstone; maroon, 

brown, and lavender sandy shales; dense limestone 

and limestone conglomerate; all in thin irregular 

beds; weathers as a banded slope.

Reddish-brown massive cross-bedded sandstone; 

crops out commonly as prominently jointed vertical 

cliffs.

Highly variegated calcareous friable shale ("marl") ; 

red-brown and gray fine-grained sandstone most 

abundant at the top; limestone and limestone conglomerate; contains petrified wood; weathers as 

banded, benched slope.

Gray to yellow coarse-grained to conglomeratic sandstone; grades locally into sandy shale; irregularly 

bedded and highly variable in thickness; contains 

fossil wood; commonly forms prominent benches.

Chocolate-brown to yellow shale and sandstone 

dominantly thin-bedded, platy, and ripple-marked; 

includes locally thick-bedded sandstone, limestone, 

and conglomerate of clay balls; weathers as a 

ribbed slope.

Red sandstone and shale.

Gray sandstone, in part cross-bedded, and associated 

conglomerate of quartz, clay balls, lime pellets, 

and shale fragments; appears as gray band on cliff 

faces.

Red sandstone and sandy shale, uniformly finegrained and calcareous; lower part thin-bedded, 

weathering as slope; upper part thicker, more 

resistant beds, weathering as fluted wall.

Cream-white to yellow-brown calcareous sandstone, 

very fine-grained, cross-bedded; red and brown 

shale in thin lenticular beds; includes lenses and 

dense limestone and limestone conglomerate; 

weathering produces platforms, arches, windows, 

and "biscuits."

Light-red to brown-red thin fine-grained calcareous 

shaly sandstones, irregularly bedded in detail; 

subordinate thin, dense gray limestones; at base in 

places conglomerate of limestone fragments; 

weathers a steep benched slope.

Red and gray thick- and thin-bedded calcareous 

sandstones; sandy shales; resistant gray limestones;, 

contains oil and fossils; weathers as nights of steps.

Drab hard cherty limestones, thicker and more 

numerous at the base; gray, buff, and red calcareous sandstones and sandy shales; fossiliferous; . 

alternating hard and soft beds; weathers as stairways on canyon walls.

Thickness (feet)

300-880

40(?)-220

300 ±

400(?)-856

0-120

186-290

0-50

4-90

250-421

400-1, 250

203(?)-464

300-325

436-1, 086 (?)

CARBONIFEROUS FORMATIONS

HISTORY AND CORRELATION

In the plateau province and adjacent regions the 

Carboniferous has long been recognized. Strata of this 

age on Coconino and Kaibab Plateaus, in Grand 

Canyon, Marble Gorge, and Cataract Canyon, in the 

Zufii Mountains, and in the San Juan Mountains are 

described in publications by Marcou (1856), Newberry

(1861), Powell, Button, Gilbert, and Marvine (1875- 

85), and Holmes and other members of the Hayden 

Survey (1874-78). In the Grand Canyon region the 

work of the early geologic explorers has been carried 

on by Noble, Darton, Robinson, and others, with the 

result that the subdivisions called "Lower Carboniferous" ("Redwall limestone"), "Upper Carboniferous" 

("Aubrey sandstone" and "Aubrey limestone"), and
38 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

"Permo-Carboniferous" have been reclassified as five 

formations Redwall limestone (Mississippian) and 

Supai formation, Hermit shale, Coconirio sandstone, 

and Kaibab limestone (Permian). Likewise the Carboniferous strata of southwestern Colorado, classified 

by the Hayden Survey as "Carboniferous", "Middle 

Carboniferous", "Upper Carboniferous", and "red beds 

below the Trias" have been redefined by Cross and his 

coworkers as three formations: Hermosa (Pennsylvanian), Rico (Permian), and C\itler (Permian). The 

formations thus established in the San Juan Mountains, 

Colorado, and the Grand Canyon, Ariz., have remained 

standards for the correlation of stratigrapliic sections 

in Colorado, Utah, Arizona, and Nevada. In the 

region between these guideposts recent field work has 

brought to light other areas of Carboniferous rocks. 

Along San Juan Canyon, Pennsylvanian and Permian 

formations, reported by Gregory,47 have been studied 

in detail by Woodruff,48 Miser,49 and Baker and Reeside.60 In the Moab region the extension of the Pennsylvanian and Permian formations of Colorado has 

been established by Baker and his coworkers.51 Permian 

formations of the Grand Canyon type in the San Rafael 

Swell have been described by Gilluly and Reeside,52 

and those at Circle Cliffs and Paria Valley by Gregory 

and Moore.53

Throughout the vast region that lies between the 

San Juan Mountains, Colo., and the Muddy Mountains, Nev., the Carboniferous lies unconformably below 

Triassic beds Moenkopi (Lower Triassic) in Utah, 

Arizona, and Nevada and. Chinle (Upper Triassic) in 

Colorado. In the Grand Canyon and the Muddy 

Mountains the lowest Carboniferous beds (Mississippian) lie unconformably above the Devonian; elsewhere 

in the plateau province the base of the system is not 

exposed. But although the stratigraphic limits of the 

Carboniferous are generally recognized, there is a wide 

range of interpretation regarding the number, lithology, 

sequence, and age of formations at different localities.

The difficulties of satisfactory correlation are great. 

Two faunal provinces and widely diverse conditions 

of sedimentation are involved; most of the beds are 

unfossiliferous and, like bedded terrestrial deposits 

elsewhere, lack continuity; and the areas of type out41 Gregory, H. E., The San Juan oil field, San Juan County, Utah: U. S. Qeol. 

Survey Bull. 431, pp. 11-25, 1911.

« Woodruff, E. G., Geology of the San Juan oil field, Utah: U. S. Geol. Survey 

Bull: 471^ pp. 76-104, 1912.

<» Miser, H. D., Geologic structure of San Juan Canyon and adjacent country, 

Utah: U. S. Geol. Survey Bull. 751, pp. 115-155, 1924.

«o Baker, A. A., and Reeside, J. B., Jr., Correlation of the Permian of southern 

Utah, northern Arizona, northwestern New Mexico, and southwestern Colorado: 

Am. Assoc. Petroleum Geologists Bull., vol. 13, pp. 1413-1438, 1929.

« Baker, A. A., Dobbin, C. E., McKnight, E. T., and Reeside, J. B., Jr., Notes 

on the stratigraphy of the Moab region, Utah: Am. Assoc. Petroleum Geologists 

Bull., vol. 11, pp. 787-808, 1927.

a Gilluly, James, and Reeside, J. B., Jr., Sedimentary rocks of the San Rafael 

Swell and some adjacent areas in eastern Utah: U. S. Geol. Survey Prof. Paper 150, 

pp. 15-21, 1928.

83 Gregory, H. E., and Moore, R. C., The Kaiparowits region, a geographic and 

geologic reconnaissance of parts of Utah and Arizona: U. S. Geol. Survey Prof. 

Paper 164, pp. 38^5,1931.

crops are far apart. In southeastern Utah the fossiliferous marine limestones in the lower walls of San 

Juan Canyon near Goodridge are now identified as 

belonging to the Hermosa formation (Pennsylvanian) 

of southwestern Colorado and are also correlated with 

formations of that age in the Mississippi Valley. 

Likewise the limestones and red shales that rim the 

canyon between Comb Wash and Grand Gulch are 

now identified as belonging to the Rico formation 

(Permian) of southwestern Colorado. These two 

formations are believed to extend northeastward without significant change for about 75 miles beneath covering beds. West of outcrops in the San Juan country 

the Carboniferous includes no formations like the 

Hermosa and the Rico, and fossils in the Permian limestone (Kaibab) belong to a western province perhaps 

Asiatic. Somewhere beneath the 140-mile stretch of 

existing post-Permian rocks is the boundary between 

two regions in which during Pennsylvanian time and 

at least part of Permian time the topography and faunas 

were unlike.

The Permian strata that lie above the fossiliferous 

Rico present even greater difficulties of correlation. 

In southwestern Colorado these beds constitute a single 

unit (Cutler), described by Cross 54 as "red beds" 1,000 

to 2,000 feet thick. In the Moab region, Utah, these 

beds, here also assigned to the Cutler,55 are 400 to 600 

feet thick and include not only red beds but, toward 

the west, white sandstone at the base and the top. 

Along the Kaibab trail, in the Grand Canyon, Permian 

red beds (Supai and Hermit), 825 feet thick, have much 

the same stratification and composition. In the San 

Juan country the outstanding feature of the Permian 

beds above the Rico is a thick-bedded, cross-bedded 

white sandstone (Cedar Mesa) that at Elk Ridge is 

more than 1,000 feet thick. Red beds below this 

sandstone resemble in a general way both the Cutler 

and the Supai but include limestones at several horizons. 

The beds above the Cedar Mesa likewise are dominantly 

thin sandstones, mudstones, and sandy shale of various 

shades of red but include massive red beds, gray shales, 

limestone conglomerates, and white sandstones. Both 

the upper and lower series of red beds include many 

unconformities.

In such diverse sediments, in which guides for subdivisions are color, texture, and composition rather 

than fossils, only broad subdivisions can be recognized 

with profit. Minor subdivisions, though clearly exposed 

at one place, may be almost or quite different at places 

20 miles distant.

Satisfactory regional correlation has been hindered 

by the interpretation of the paleontologic evidence 

many times revised. Of the Colorado faunas, that in

'« Cross, Whitman, and others, U. S. Geol. Survey Geol. Atlas, Telluride folio 

(no. 57), 1899; La Plata folio (no. 60), 1899; Rico folio (uo. 130), 1905; Engineer Mountain folio (no. 171), 1910; and Silverton folio (no. 120), 1905.

" Baker, A. A., Dobbin, C. E., McKnight, E. T., and Reeside, J. B., Jr., op. cit, 

pp. 794-796
CARBONIFEROUS FORMATIONS 39

die Rico was formerly classed as Pennsylvania!! 56 ; 

then as "Permo-Pennsylvanian" with the statement 

that "no unequivocal Permian fauna has come to 

light"57 ; again as Pennsylvanian 58 ; and finally as 

doubtful Permian by some paleontologists and true 

Permian by others. Reporting on the fossils in strata 

from top to bottom of the Honaker trail, San Juan 

Canyon, Schuchert 59 states that "all the lots are of 

the Pennsylvanian", and Girty 60 writes, "With one 

exception all the collections are clearly of Pennsylvanian 

age, and that lot (165) [51 feet above the base] is an 

exception merely because it is not sufficiently diagnostic 

to show that it is not Mississippian." As the strata 

comprising the San Juan section obviously are not the 

equivalents of those in any Pennsylvanian formation 

elsewhere, they were grouped by Woodruff 61 in the 

fOoodridge formation 6* (Pennsylvanian) a procedure 

followed by Gregory 63 and by Miser.64 A restudy. of 

the collections led Girty 65 to the conclusion that

The Goodridge formation, as described by Woodruff, comprises 

two widely different faunas. The lower fauna, which contains 

almost no true Mollusca, changes abruptly at bed no. 55 of his 

transverse section to one that contains almost nothing else.

* * * The general faunal resemblance would tend to correlate the upper part of the Goodridge with the Rico formation

* * * and the lower part with the Hermosa. * * * 

Developments of the last 10 years have brought about the 

assignment of the Rico formation to the Permian (?).

These conclusions were strengthened by a study of 

collections from the Carboniferous of the Moab region, 

regarding which Girty 66 states:

Few paleontologists would question the Pennsylvanian age of 

the older fauna (Hermosa) in these collections * * *. In 

my judgment the later faunas (Rico) * * * may be assigned to the Permian, * * * though the assignment 

should be recognized as provisional.

Giving full value to existing paleontologic and stratigraphic evidence, we may place the Rico without question in the Permian. There is little doubt that the 

limestones and associated strata at the Honaker trail 

are appropriately correlated with the Hermosa and 

Rico of Colorado. The term "Goodridge formation" 

is therefore discarded.

89 Cross, Whitman, and others, U. S. Qeol. Survey Geol. Atlas, Silverton folio (no. 

120), 1905.

" Cross, Whitmanandothers, U. S. Oeol. Survey Geol. Atlas, Rico folio (no. 130), 1905.

s8 Cross, Whitman, andothers, U. S. Geol. Survey Geol. Atlas, Engineer Mountain 

folio (no. 171), 1910.

M Schuchert, Charles, in Gregory, H. E., The San Juan oil field, San Juan County, 

Utah: U. S. Geol. Survey Bull. 431, p. 19, 1911.

«« Girty, G. H., in Woodruff, E. G., Geology of the San Juan oil field, Utah: U. S. 

Geol. Survey Bull. 471, p. 83,1912.

« Woodruff, E. G., op. cit., pp. 80-85.

61 A dagger (t) preceding a geologic name indicates that the name has been abandoned or rejected for use in classification in publications of the U. S. Geological Survey. Quotation marks, formerly used to indicate abandoned or rejected names, are 

now used only in the ordinary sense.

63 Gregory, H. E., Geology of the Navajo country, a reconnaissance of parts of 

Arizona, New Mexico, and Utah: U. S. Geol. Survey Prof. Paper 93, p. 20, 1917.

04 Miser, H. D., Geologic structure of San Juan Canyon and adjacent country, Utah: 

U. S. Geol. Survey Bull. 751, pp. 119-121,1924.

«J Girty, G. H., in Longwell, C. R., Miser, H. D., Moore, R. C., Bryan, Kirk, and 

Paige, Sidney, Rock formations in the Colorado Plateau of southeastern Utah and 

northern Arizona: U. S. Geol. Survey Prof. Paper'132, pp. 7-23, 1923!

M Girty, G. H., in Baker, A. A., Dobbin, C. E., McKnight, E. T., and Reeside, 

J. B., Jr., op. cit., p. 792.

The unfossiliferous Cutler, 1,000 to 2,000 feet thick, 

which embraces nearly all the red beds of southwestern 

Colorado, was long assigned to the Triassic, then pro-r 

visionally referred to the Permian with the remark "but 

may prove to belong to the Pennsylvanian." 67 The 

fact that in lithology, in number and position of limestone beds, and in sequence the red beds that overlie 

the Rico of San Juan Canyon resemble more closely the 

Supai and Hermit than the Cutler, led Miser 68 to 

designate these beds the "Supai (?) formation" and 

in most reports relating to exploration for oil the term 

"Supai" is applied to red beds underlying white sandstone at Cedar Mesa, on Elk Ridge, and along the Colorado canyons.

Harrison 69 assigned to the Cutler the formations then 

known as the "Coconino", "Moenkopi", and "De 

Chelly" and termed the beds below them "Rico or 

Supai." He described as "Moenkopi" all the "red 

sandstones and shales" that lie above the Coconino; 

and the Shinarump as a sandstone above the De Chelly.

Prommel,70 who used the term "Moenkopi-Cutler", 

remarked that in the series between the Shinarump and 

the Rico, "1,300 to 1,400 feet thick", "the lower portion *. * * resembles very closely the Cutler 

formation of Colorado, while the upper part is very 

similar to the Moenkopi as described by Gregory."

For some 30 years after the description by Walcott 

of faunas in Kanab Valley the Permian was thought to 

include the group of fossiliferous shales, sandstones, and 

limestones that unconformably underlie the Shinarump 

conglomerate and overlie the Kaibab limestone (where 

present). These beds where exposed in the Little 

Colorado Valley were described by Ward 71 as the 

"Moenkopie" [Moenkopi formation], with the remark, 

"It is very probable that the lower portion of the 

Moenkopie beds belong to the Permian." Guided by 

these paleontologic conclusions, Gregory classed some 

200 feet of imbricated,, ripple-marked, slabby, thinbedded red and chocolate-brown shales, sandstones, and 

limestones near Fort Defiance as Moenkopi (Permian?).72 Likewise in San Juan Valley Woodruff 73 and 

Gregory 74 included in the Moenkopi all beds betweeen 

the Shinarump and the limestone of the Goodridge oil 

field, then thought by Girty 75 as possibly at the same 

"geologic level" as the Kaibab. They recognized that 

in composition, color, and sequence of beds the lower 

part of the Moenkopi of southeastern Utah is unlike that 

in the Little Colorado Valley and that in stratigraphic 

position it corresponds with the Cutler of Colorado.

67 Cross, Whitman, and others, op. cit. (Folio 171).

es Miser, H. D., op. cit. (Bull. 751), p. 121.

6" Harrison, T. S., Colorado-Utah salt domes: Am. Assoc. Petroleum Geologists 

Bull., vol. 11, p. 115, 1927.

70 Prommel, H. W. C., Geology and structure of portions of Grand and San Juan 

Counties, Utah: Am. Assoc. Petroleum Geologists Bull., vol. 7, p. 389, 1923.

7 > Ward, L. F., Geology of the Little Colorado Valley: Am. Jour. Sci., 4th ser., 

vol. 12, pp. 403-404, 1901.

7J Gregory, H. E., op. cit. (Prof. Paper 93), pp. 27-29.

« Woodruff, E. G., op. cit. (Bull. 471), pp. 86-88. 

74 Gregory, H. E., op. cit. (Prof. Paper 93), pp. 29-31.

75 Girty, G. H., in Woodruff, E. G., op. cit., p. 83.
40 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

A restudy of fossils from Arizona and southern Utah 

by Girty and others resulted in transferring the Moerikopi formation from the Permian to the Triassic, thus 

restricting the Permian and establishing for the plateau 

province a formation of Lower Triassic age. Using 

this new classification, Miser 76 recognized the Supai 

and the Coconino as subdivisions of the Permian of 

the San Juan Valley, and more recent study has added 

other subdivisions. The regional unconformity below 

the accepted Moenkopi has been traced throughout 

most of the plateau province, and Permian fossils have 

been found below it. In the San Juan country between 

this pre-Triassic unconformity and the top of the 

Hermosa formation (Pennsylvanian) lie four thick, 

well-differentiated series of beds, a fifth thin but persistent series, and in places a sixth series less well 

defined. (See pp. 46-47.)

PENNSYLVANIAN FORMATION

HERMOSA FORMATION

Beds assigned to the Hermosa formation crop out in 

the San Juan Canyon at the Honaker trail and Soda 

Basin, in Dark Canyon, and in other tributaries to 

Cataract Canyon. Along the San Juan the base of 

the formation is not exposed. In Dark Canyon all 

the formation, also formations below, are represented 

in the well drilled by the Midwest Refining Co. Starting in the Rico formation this well penetrates 4,422 

feet of strata, of which about 70 percent is limestone, 

and terminates in schist just below "blue hard sandy 

shale."

As the Hermosa beds combine with the overlying 

Rico to form a single wall in which no marked change 

in topography or lithology is observed, the boundary 

between these formations is drawn at the horizon 

where a dominantly brachiopod fauna (Hermosa) 

changes abruptly to one characterized by abundant 

pelecypods. Fortunately the measured sections of the 

fGoodridge formation are so related to the faunas that 

the division line can be drawn with assurance. Thus 

the Hermosa part of the fGoodridge formation at the 

Honaker trail is 1,086 feet as measured by "Woodruff 77 

and 975 to 985 feet as measured by Miser. (See sec. 

1, p. 65.) At the mouth of Slickhorn Gulch the 

Hermosa exposed measures 436 feet ,and in the Raplee 

anticline as much as 600 feet. The thickness of the 

Hermosa in exposures of fGoodridge in Dark Canyon 

(400 to 1,000 feet) and in Cataract Canyon (1,500 feet) 

has not been determined.. (See pi. 5, A)

The Hermosa consists of conformably interbedded 

limestones, sandstones, and shales a series of alternating hard and soft beds which on erosion produce the 

remarkable steps shown in photographs of canyon 

walls. In the lowest one-third of all outcrops examined 

limestone is dominant. Beginning as beds 20 to 40

'»Miser, H. D., op. cit., fig. 18, pp. 121-122. 

" Woodruff, E. Q., op. cit., pp. 81-82.

feet thick, separated by shales and thin calcareous 

sandstones, the limestone continues upward, progressively decreasing in number and thickness of beds. 

As analyzed by Woodruff,77 the lowest 725 feet of the 

Hermosa at the Honaker trail contains 652 feet of 

limestone, 493 feet of which is in six beds. The limestones are predominantly drab, with shades of gray 

and of blue. Most of them are massive, hard, and 

crystalline and include nodules and lenses of red, gray, 

and jet-black chert. The top and the base of some 

massive limestone beds are coated with limestone 

conglomerate.

The sandstones are commonly gray but include buff, 

greenish, white, and (toward the top) red beds. They 

appear as massive beds 3 to 15 feet thick and as groups 

of thin beds that grade along the strike into shale. 

Most of them are fine-grained and consist chiefly of 

rounded quartz fragments cemented by lime.

The shales, like the sandstones, are dominantly 

gray, but there are black, green, and yellow beds and 

near the top of the formation shades of red are common. 

Most of the shale, particularly that of the red beds, is 

arenaceous and highly calcareous. In composition it 

differs little from the shaly sandstone and sandy limestone. The thinly foliated black shales are argillaceous; 

a few are bituminous. In sections measured along the 

San Juan, shale constitutes about 50 percent of the 

uppermost 200 feet and 15 percent of the lowermost 

200 feet.

Fossil marine organisms collected from several beds 

and determined by Girty establish the Pennsylvanian 

age of beds in San Juan Canyon and serve as a means of 

correlating these beds with the Hermosa of Colorado. 

The faunal correlation is strengthened by similarity in 

composition and stratigraphic sequence, which indicates like conditions of deposition.

PERMIAN FORMATIONS 

RICO FORMATION

Strata of the Rico formation are continuously exposed 

on the crests and flanks of the Raplee and Mitten Butte 

anticlines, where the topmost thin limestone forms the 

surface over large areas. They constitute the rim rock 

of the San Juan and tributary canyons between Comb 

Wash and Slickhorn Gulch, except along Lime Creek, 

where they are lost to view in the Mexican Hat syncline. The Rico is exposed in Dark Canyon, Beef 

Basin, and Fable Valley, and beds provisionally assigned 

to this formation appear in Mule, Arch, and Hammond 

Canyons. In the walls of canyons and gulches the 

limestone and hard sandstones interbedded with shale 

and soft sandstones form flights of colored steps that 

lead from the bottom to the top. On steep structural 

slopes bright-red sandstone is revealed by scores of 

meandering gullies that have cut through the cover of 

blue-gray limestone. Viewed from the west, the
CARBONIFEROUS FORMATIONS 41

Raplee anticline is an exceptionally attractive feature 

(pis. 3, A; 11, A).

The Rico is made up of sandstones, shales, and limestones. The sandstones are prevailingly "red" 

bright red, dark red, pink, purple but a few beds are 

brown, gray, or white. They include massive beds 10 

to 20 feet thick and series of thin, lenticular beds. They 

are calcareous fine- to medium-grained rocks composed 

of quartz, calcite, some mica, and a little feldspar. The 

gray cross-bedded pitted sandstones that constitute the 

four oil sands in the Rico near Goodridge consist of 

clear quartz grains cemented by lime, the removal of 

which has produced a porosity favorable for the accumulation of disseminated petroleum. The shales are sandy 

and differ from the sandstones chiefly in thinness of 

bedding. They might be classed as thin, irregularly 

bedded, lenticular, in places cross-bedded sandstone 

units that lose their identity in short distances along 

the strike. The limestones are blue-gray, resistant, 

fossiliferous rocks that form benches. They are continuous and impervious enough to form caps for water 

and oil under pressure beneath. In sections measured 

at the Honaker trial four beds of limestone constitute 

about 11 percent of the rock exposed.

The bottom of the Rico is the top of the Hermosa 

the place in the f Goodridge formation where a Pennsylvanian fauna changes to one characteristic of the Permian. The top of the R'co is arbitrarily defined as the 

highest bed of limestone in the walls of San Juan and 

Johns Canyons, which generally is the highest fossiliferous stratum in the region. As thus limited, the Rico 

in the walls of the San Juan Canyon is 300 to 325 feet 

thick.

Beds assigned to the Rico in the San Juan country 

have the same relation to the underlying Hermosa as 

at Rico, Colo. Permian fossils from the Honaker trail 

are characteristic of the type Rico, but those from Dark 

Canyon contain suggestions of the Manzano fauna. 

In lithology, considerable differences appear. As 

described by Cross 78 the sandstones in the Rico of 

Colorado

are mostly coarse or conglomeratic, always showing grains of 

fresh feldspar mixed with mica flakes and quartz. When conglomeratic the pebbles are chiefly of schists and quartzite. 

* * * The shales, aside from the sandy varieties, are of two 

kinds the fine-grained, unlaminated red marly beds * * * 

and the equally fine-grained, laminated clay shales of a green 

color.

In Utah the sandstone beds are finer-grained and less 

arkosic and contain oil; the shales show less variation in 

bedding and composition.

Except for the fossils and the larger numbers of persistent limestone beds in the Rico there is little to distinguish that formation from the overlying Cutler. 

Both are Permian red beds, both are dominantly calcareous, irregularly bedded, more or less arkosic sandstones with considerable range in texture. Were it not

" Cross. Whitman, op. cit. (Folio 130), pp. 3-4.

for established usage the Rico and the lowest Cutler 

(Halgaito member) might be combined in one formation 

that derived its sediments from Colorado high lands 

and deposited them westward in shallow sea waters 

that intermittently withdrew. The periods in which 

the land provided red sediments seem to have increased 

progressively in length during the whole tune represented 

by the Hermosa, the Rico, and the Halgaito.

The section of the Hermosa and Rico formations 

shown on pages 64-65 (sec. 1) is representative of several that accompany the descriptions of the fGoodridge 

formation by Woodruff, Miser, and Gregory already 

cited. (See also sec. 2, p. 66.)

CUTLER FORMATION

TERMINOLOGY

As defined by Cross 79 the Cutler formation is that 

division of the Permian red beds that overlies the Rico 

and unconformably underlies the Dolores (Chinle in 

part). In Colorado it has been treated as a unit within 

which the differences in litholog}T and the unconformities are not sufficiently persistent nor diagnostic to 

justify separation into members. Where beds above 

the Rico reappear in southeastern Utah, some 75 miles 

west of the typical Cutler outcrops, four or in places 

five clearly marked Permian subdivisions and two 

Triassic subdivisions occupy the Rico-Chinle interval.

Field work by Baker and Reeside 80 and the investigation on which the present paper is based have resulted in the separation of the Permian and the Triassic 

and demonstrated that post-Rico Permian time in the 

San Juan country and neighboring districts is represented by a lower series of red beds, a great thickness 

of white sandstones, and an upper series of red beds 

and may include also a persistent bed of gray conglomerate along White Canyon and a thin series of red shales 

leading upward in turn to the Permian-Triassic unconformity at the base of the Moenkopi. The rank that 

should be.given to these lithologic subdivisions and 

their correlation with unlike sediments recognized 

elsewhere are necessarily matters of opinion. The few 

fossil plants and bone fragments indicate Permian age, 

but the parts of this long period represented by the 

formations and the relations of the strata to established 

Permian formations in Colorado and west of Glen 

Canyon are imperfectly known.

In the present paper the series of Permian beds above 

the Rico are assigned to the Cutler formation and 

divided into five members, in ascending order the 

Halgaito, Cedar Mesa, Organ Rock, De Chelly, and 

Hoskinnini. As these names have been published by 

Baker and Reeside for subdivisions south of the San 

Juan River, they are here used for the region north of 

the river, where substantially the same units are represented. Of the five members assigned to the Cutler by 

Baker and Reeside all except the Halgaito .are. here

" Cross, Whitman, op. cit. (folio 130), p. 4. 

* Baker, A. A., and Reeside, J. B., Jr.,^op. cit.
42 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

considered as doubtfully corresponding to the Cutler 

formation as represented in Colorado. (See sees. 2 to 

13, pp. 66-72.)

HALGAITO MEMBER

The Halgaito member (Halgaito tongue of Baker 

and Reeside) of the Cutler formation is that division 

of the Permian red beds that immediately overlies the 

Rico formation. In Lime Creek Valley it forms the 

base of Mexican Hat, Bell Butte, and other picturesque 

erosion remnants (pis. 4, B, C; 9, (7). Westward 

along the San Juan River it is well displayed in Cedar 

Mesa and the steep walls of Johns Canyon and Slickhorn Gulch. North of Lime Creek Valley it forms 

an undetermined part of Rico-Cutler sections in 

Fish, Road, Mule, and Arch Canyons, tributary to 

Comb Wash, in Hammond Canyon, and in branches 

of Dark Canyon north of Elk Ridge. Viewed from a 

distance, low cliffs and long steep slopes of Halgaito 

strata appear as uniform horizontal layers of alternating hard and soft red sandstone banded with purple 

and gray, but the bedding is irregular. Sandstone in 

beds 2 to 10 feet thick, sufficiently massive and resistant to form a protruding ledge, changes in short distances along the strike to shaly beds that on weathering 

form slopes. Most of the sandstone splits readily into 

sheets 2 to 6 inches thick not susceptible of further 

subdivision; the shale into beds about an eighth of an 

inch thick. The bedding planes are commonly lumpy 

with overlapping plasters of mud, though a few are 

smooth and glistening. Some show ripple marks and 

mud cracks; others show shallow erosion channels and 

depressions filled with the material of the overlying 

beds. Measured sections include three to seven widely 

spaced beds of gray limestone as uniform and continuous as the sandstones. They also include thin beds 

or bands of white sandstone that in composition are 

like the red beds and perhaps are red beds from which 

the iron cement has been leached by ground water.

Here and there at the base of the formation is a thin 

conglomerate composed of fragments of red sandstone 

or of pebbles, slabs, and angular chunks of gray, blue, 

and black limestone. It suggests a plane of unconformity between the Rico and the Halgaito and is so 

interpreted by Miser.81

The massive and shaly sandstone alike include lenses 

of limestone conglomerate, iron, lime, and sand concretions. Some strata are cross-bedded, and many 

include dark areas surrounded by white or blue zones 

that suggest leaching of vegetable matter. ' (See sees. 

3 to 6, pp. 67-69.)

As typically exposed in the San Juan Valley the 

materials classed as sandstone and shale are essentially 

alike in color and composition. In general the shale 

is brighter red, more uniformly fine-grained, and 

slightly less calcareous, but all the red beds range in

81 Miser, H. D., Geologic structure of San Juan Canyon and adjacent country, 

'Utah: U. S. Geol. Survey Bull. 75!, p. 120, pi. 15, 1924.

color from light red to brown, consist mostly of grains 

too small to be distinguished with the unaided eye, 

and are so calcareous that the local term "red limestone", the source of the name "Lime Creek", seems 

reasonably appropriate. The chief constituents are 

poorly rounded grains of clear quartz, calcite or dolomite, and iron as cement and scattered particles. 

Muscovite and gypsum are present in small amounts, 

also microscopic bits of feldspar, magnetite, and 

garnet (?). Near the top of the formation in Johns 

Canyon are slightly carbonaceous beds.

The top of the Halgaito is marked by the lowest bed 

of sandstone typical of the Cedar Mesa member. Its 

base is marked by the highest limestone bed in the Rico. 

As thus limited it is 380 feet thick at Slickhorn Gulch, 

464 feet in Johns Canyon, 425 feet near Cedar Point, 

392 feet at the head of Lime Creek, 402 feet at Navajo 

Springs, Comb Wash, and 203 feet in Fish Creek 

Canyon. Northward about Elk Ridge its limits have 

not been definitely established, and it may be absent.

The strata here described as the Halgaito member 

of the Cutler were included in the Moenkopi formation 

(then recognized as Permian) by Woodruff 82 and 

Gregory 83 and classed as the Supai (?) formation by 

Miser 84 and most geologists of oil companies. Though 

its lithology is like that of the Supai or, even more, 

the Hermit shale, it is correlated with the Cutler of 

Colorado chiefly because of its relations to the underlying Rico. Fragmentary bones in the limestone 

conglomerates and plants in formations above prove 

its Permian age.

CONTACT OF HAtGAITO AND CEDAR MESA MEMBERS

At outcrops where both members are well displayed 

the red, shaly, slope-forming Halgaito strata terminate 

abruptly at the base of a prominent cliff composed of 

buff to white thick-bedded massive Cedar Mesa sandstone. In sections measured at Polly and Cedar 

Mesas the contact is marked (1) by an irregularly continuous bed of conglomerate composed of clay mud 

balls and lozenges, concretionary limestone, and fragments of sandstone, (2) by an earthy nodular limestone 

including clay pellets, short shale lenses, and coarse 

grains of quartz, or. (3) by thin even beds of fairly 

coarse sandstone with hardened and ripple-marked 

surfaces. The wavy contact is the zone of springs and 

seeps. Unconformity is further suggested by the 

study of sections exposed in the Monument up warp. 

In Fish Creek Canyon strata assigned to the Halgaito 

are about half the thickness of those 10 miles farther 

south and are weathered at the top. In Arch Canyon 

the contact of Cedar Mesa sandstone with underlying

" Woodruff, E. G., Geology of the San Juan oil field, Utah: U. S. Geol. Survey 

Bull. 471, pp. 8ft-88,1912.

83 Gregory, H. E., The Navajo country: U. S. Geol. Survey Prof. Paper 93, pp. 

29-30,1917.

81 Miser, H. D., Geologic structure of San Juan Canyon and adjacent country. 

Utah- U. S. Geol. Survey Bull. 751, p. 121.1924.
GEOLOGICAL SURVEY PEOPBS

A. NAVAJO SUMMER HOUSE NEAR MOUTH OF BUTLER WASH.

Dugway on old Escalante-Bluff road cut in Navajo sandstone of Comb Ridge. Photograph by R. N. Alien.

B. RED HOUSE CLIFFS, 4 MILES NORTH OF S

Organ Rock member of the Cutler formation: Lower part (division 

(division B), resistant sandstone. Chinle and Wiiigate covered 

C. WALL OF JOHNS CANYON NEAR ITS HEAD.

Halgaito strata (lower half) and Cedar Mesa strata (upper half). Top bed of Rico formation in foreground.

D. SANDSTONE AND SHALE IN ARMSTRO

Upper part of Cedar Mesa member of the Cu
GEOLOGICAL SURVEY PROFESSIONAL PAPER 188 PLATE UP

Cretaceous

Jurassic 

Cretj?)

Rafael Sangroup

Jurassic (?)Canyon Glen group

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Mancos shale 3,000 ft.

(^ Dakota (?) sandstone 0-l5ft. 

Morrison formation 563ft. 

^ Summerville formation 90ft,

Entrada sandstone 1,070ft.

Carmel formation 450±ft.(?)

Navajo sandstone 1,350ft.

Todiltol?) formation 175ft.

Wingate sandstone 300ft.

Chinle formation 475ft.

Shinarump conglomerate O-l25ft. 

Moenkopi formation 304-500 ft.

Coconino sandstone, and 

SupaK?) formation 

1,700 ft.

Goodridget?) formation 1,582ft.

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Mancos shale O-350ft. 

Da kota(?) sandstone 92~200ft.

Morrison formation 772-l,l82ft.

/ Summervillet?) formation 42-l32ft.

"" Entrada sandstone 8-80 ft.

^ Carmel (?) formation 0-107 ft.

Navajo sandstone 400-880ft.

^ Kayenta formation 40-220 ft.

Wingate sandstone 300 ±ft.

Chinle formation 400-856ft.

' Shinarump conglomerate 0-120 ft. 

Moenkopi formation 186-390 ft.

N. Hoskinnini member 0-50 ft. 

\ DeChelly sandstone member 4-9Oft. 

 Organ Rock member 250-421 ft

Cedar Mesa sandstone member 

400-1,250 ft.

Halgaito member 203-464 ft.

Rico formation 300-325ft

Hermosa formation 15004 ft.

Cretaceous

Jurassic

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iferous 

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Dakota sandstone 100-250 ft.

McElmo formation 400-l,000ft.

La Plata sandstone 250-500 ft.

Dolores formation 400 ft.

Cutler formation 1,600 ft.

Rico formation 300 ft.

Hermosa formation 1,800-^OOOft.

B

COLUMNAR SECTIONS.

A. Kaiparowits region (after Gregory and Moore, Prof. Paper 164).

B. San Juan country.

C. Southwestern Colorado (after Cross and Spencer, Geol. Atlas, Rico folio no. 130).
CARBONIFEROUS FORMATIONS 43

red beds is a surface of erosion on which lie large diskshaped cherts, irregularly disposed lenses of clay shale, 

black carbonaceous sandstone, and strings of quartz 

pebbles. Only a few feet of red beds lie between the 

plane of unconformity and limestones that contain a 

fauna which has the facies of the Rico formation. 

In Hammond Canyon no typical Halgaito beds were 

seen. In Dark Canyon the few red beds among the 

gray sandstones and fossiliferous limestones that lie 

below the Cedar Mesa are quite unlike those in the 

Halgaito of the San Juan Valley. On the Spanish 

trail, near the mouth of the Green River, Prommel and 

Crum 85 noted an erosion surface at the base of the 

Coconino [Cedar Mesa] the result of "an up warp at 

the close of Rico-Supai time." The contact of the 

Halgaito and the shaly phase of the Cedar Mesa 

member in Road Canyon is shown in plate 11, B.

The stratigraphic significance of this unconformity 

is not clearly understood. If the northward thinning 

and final disappearance of the Halgaito can be explained 

as the result of erosion, the unconformity represents a 

considerable interval of time. On the other hand, if 

the Halgaito is thought of as the western extension of 

the lowermost Cutler of Colorado not everywhere 

deposited and the Cedar Mesa merely a modified 

form of the typical Cutler, no important lapse of time 

need be predicated. Baker and Reeside 86 treat the 

Halgaito and the Cedar Mesa as conformable members 

of the Cutler that grade laterally into each other. 

They consider that the variation in thickness of the 

red Halgaito records the degree to which it has been 

replaced by the white Cedar Mesa.

CEDAR MESA SANDSTONE MEMBER

Overlying the "lower red beds" (Halgaito member) 

and underlying the "upper red beds" (Organ Rock 

member) of Permian sections in the San Juan country 

is the series of sandstones and subordinate shales and 

limestones here identified as the Cedar Mesa sandstone 

member of the Cutler formation.

This member is widely displayed. Along the San 

Juan River it is the cap rock of mesas between Comb 

Wash and Clay Hill Crossing and of erosion remnants 

in Lime Creek Valley and at Zahns Camp. It forms 

the surface of Grand Gulch Plateau and continues 

along the White River and its tributaries nearly to the 

Colorado River as a white floor into which the canyons 

are cut and above which rise red cliffs. About Elk 

Ridge it is prominently exposed in Dark Canyon, Fable 

Canyon, and Beef Basin and at the heads of canyons 

tributary to Cottonwood Canyon and Comb Wash. 

(See pis.' 5, B; 6, A;'8, C; 9, D; 11, <7.)

M Prommel, H. W. C., and Crum, H. E., Salt domes of Permian and Pennsylvanian 

age in southeastern Utah and their influence on oil accumulation: Am. Assoc. Petroleum Geologists Bull., vol. 7, pp. 384-390, 1923.

M Baker, A. A., and Reeside, J. B., Jr., Correlation of the Permian of southern 

Utah, northern Arizona, northwestern New Mexico, and southwestern Colorado: 

Am. Assoc. Petroleum Geologists Bull., vol. 13, p. 1432,1929.

In thickness the Cedar Mesa ranges from about 400 

feet on the south face of Grand Gulch Plateau to 600 

to 1,000 feet in canyons that head in Elk Ridge. Warren 

0. Thompson, of the Midwest Refining Co., gives a 

maximum thickness of 1,250 feet ("Coconino sandstone and massive limestone, white"). For some 20 

miles in Grand Gulch and 30 miles in White Canyon 

the streams have cut 200 to 500 feet into the member 

without reaching its base.

The sandstone that constitutes the bulk of the member 

appears in beds 20 to 40 feet thick, some as much as 80 

feet thick, that retain their individuality for miles. 

Many thick beds change along the strike into a group of 

thin beds, and some beds appear as long lenses. Few 

beds are even and smooth at their tops or bottoms. 

Cross-bedding is common but varies much in amount, 

kind, and distribution. An outcrop about 150 feet 

thick in Hideout Canyon includes no cross-bedded 

strata, but below Collins all beds examined in the wall 

of Grand Gulch are cross-bedded. In Cedar Mesa 

and Polly Mesa the basal strata are much less crossbedded than those at the top; in a branch of Cottonwood Canyon cross-bedded strata underlie and overlie 

a series that lacks this feature. Few thick beds are 

cross-bedded throughout. Most of the cross-bedding 

is angular; sets of parallel oblique laminae terminate 

sharply at a horizontal line. Near Sipapu Natural 

Bridge and elsewhere some beds show long curves that 

gradually flatten .and become tangent to a basal plane. 

In general, cross-bedding in the Cedar Mesa seems 

neither so prominent nor so uniform, as that in the 

Coconino and resembles little the great curves and fine 

scroll work of the Navajo.

The sandstone consists chiefly of quartz cemented by 

lime. The grains in some of it are distinguishable with 

the eye, but in most of it they are revealed only by the 

microscope, which shows rounded grains of clear 

quartz, some fragments of calcite, and black bits of iron 

cemented by calcite (and dolomite?) that seems to 

have been generously supplied. It weathers to a powderlike substance readily swept away by winds. The rock 

includes many hard limestone concretions, some white 

and red chert, and here and there cavities shaped like 

cross sections of coral. Two shell casts were found. The 

amount of lime varies widely. Of fragments tested, 

some are nearly pure quartz sandstone; others nearly 

pure limestone. Most of them effervesce freely with 

acid and give the impression that as a comprehensive 

term "arenaceous limestone" is about as good as 

"calcareous sandstone." No consistent regional distribution of the less calcareous material was noted, but 

in general the upper beds are somewhat more calcareous 

than the lower, and outcrops near Glen Canyon more 

calcareous than those farther east. In color the sandstone is cream white and weathers buff tan or yellow 

brown. In contrast with the red rocks above, it is
44 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

white and is so thought of in naming "White Canyon", 

"white arches", "white peaks", and "white road."

The shale that separates the beds of sandstone is 

microscopically fine-grained lime silt with sufficient iron 

to produce various shades of red and brown. In places 

it is well stratified and fissile, but generally it is lenticular in detail, and beds a few inches to 8 feet thick thin 

and thicken along the strike in a seemingly capricious 

manner. Interbedded with the shale are lenses of 

thin blue-gray limestone, strings of red and white chert 

in flattened masses 1 to 8 inches in diameter, and plasters of fairly large quartz grains.

Limestone in the Cedar Mesa appears not only with 

the red shales but also in the sandstones, where it is 

represented by very thin beds of hard gray rock and of 

concretionary conglomerate that extend for a few tens of 

feet and by isolated fragments. A limestone bed 2 

feet, thick in Fable Valley is exceptional. (See sees. 

6 and 7, pp. 69-70.)

Because the sandstone beds are dominantly finegrained and calcareous, the outcrops are rounded; 

straight-edged steps and sheer vertical cliffs are rare. 

As the shale weathers more readily than the sandstone, 

most canyon walls are like grooved moldings outwardcurving and inward-curving elements in parallelism. 

Deeply recessed grooves high on canyon walls serve as 

trails for animals and as sites for cliff houses. Vertical 

joints that cross individual sandstone strata combine 

with bedding seams to outline masses which on weathering appear like a row of elongated biscuits placed on the 

canyon run. Joints that traverse the whole formation 

in Arch Canyon, in lower Notch Canyon ("Chimney 

Park"), and elsewhere outline towers detached from 

canyon walls. Joints aided by cross-bedding have 

developed arches, windows, and natural bridges in 

White Canyon and Arch Canyon, "haystacks" on 

Grand Gulch Plateau, and picturesque erosion remnants 

at many other places.

As pointed out by Woodruff,87 the thick-bedded 

Cedar Mesa sandstone that caps Cedar Point loses its 

characteristic features in passing southeastward.

To the south it is composed chiefly of soft light-pink sandy 

shale, with darker shaly sandstone interbedded. To the north 

* * * [it] consists of massive tan-colored sandstone beds 

forming Cedar Mesa. * * * The transition of the shale of 

the south into the sandstone of the north begins * * * southwest of Navajo Spring. In this area the shale beds that predominate to the south are interstratified with thin sandstone lenses 

which thicken rapidly to the north and replace the shale.

Along lower Comb Wash the Cedar Mesa member, as 

represented elsewhere, is scarcely recognizable. The 

dominant resistant sandstones give way to weak strata 

and, in consequence, the usual cliffs are replaced by 

slopes and mounds of crumbling rock. As shown in 

section 4 (p. 68) the Cedar Mesa here includes not only 

beds of white sandstone but also red-pink gypsiferous

« Woodruff, E. G., Geology of the San Juan oil field, Utah: U. S. Geol. Survey Bull. 

471, p. 86,1912.

shales, brown shaly sandstones, conglomeratic and 

even-bedded dense limestones, chert, and much gypsum. 

Though the section includes beds of typical tan-colored 

Cedar Mesa sandstone, the thickest measures only 22 

feet. Most of them are sheets a few inches to a few 

feet thick that appear as if inserted between layers of 

shale, of shale and gypsum, and of limestone and darkred thin sandstones. Some of them taper to extinction; others grade laterally into thin beds or thick beds 

that differ from the type only in color; still others grade 

along the strike and down the dip into gypsiferous or 

arenaceous shales with or without change in color. 

South of the San Juan River strata approximately in 

the stratigraphic position of those along Comb Wash 

include only red beds; deposits of Cedar Mesa time, if 

ever present, have lost their identity. These evidences 

of "transition" first noted by Woodruff 88 suggest that 

the Permian white beds of southeastern Utah merge 

gradually into the Permian red beds of Colorado; that 

the Cedar Mesa sandstone should be treated as part of 

the Cutler formation. This interpretation seems not 

to take sufficiently into consideration the erosional unconformity at the base of the Cedar Mesa and the 

conspicuous unlikeness in lithology between this member 

and any part of the typical Cutler in Colorado as described by Cross.89 Furthermore, casts of fossils, the 

type of cross-bedding, and arrangement of subordinate 

beds in the Cedar Mesa suggest conditions of sedimentation not applicable to the Cutler.

Northward from Navajo Springs the gypsiferous 

beds thin to disappearance, the beds of white sandstone 

thicken, and the red shale becomes more prominent until 

at Fish Creek, Texas Canyon, and Arch Canyon the 

canyon walls show the alternating white sandstone and 

red shale characteristic of the Cedar Mesa. (See 

sees. 4 and 6, pp. 67-68, 69.)

Beds comprising the Cedar Mesa member at its 

southernmost outcrops were included in the Moenkopi 

by Woodruff 90 and Gregory.91 They were classed as 

Coconino sandstone in a published paper by Miser 92 

and in manuscript reports by other geologists. The 

member has generally been described as the eastern 

continuation of the Coconino or as having closely 

similar lithologic features. But the Coconino and the 

Cedar Mesa have little in common. Unlike the stratified Cedar Mesa, the Coconino appears as a single 

massive bed of uniformly fine-grained, well-rounded 

quartz with a cement so siliceous that the rock does not 

effervesce with acid. It includes no division planes 

of shale or other material.' At all exposures examined 

it makes strong vertical cliffs or hogbacks characterized by persistent angular cross-bedding that separates 

the rock into huge wedges. Furthermore, as shown by

it Woodruff, E. G., op. cit.

«« Cross, Whitman, U. S. Geol. Survey Geol. Atlas, Rico folio (no. 130), 1905. 

 « Woodruff, E. G., op. cit. (Bull. 471), pp. 86-88. 

81 Gregory, H. E., op. cit. (Prof. Paper 93), pp. 29-30.

M Miser, H. D., Geologic structure of San Juan Canyon and adjacent country. 

Utah: U. S. Geol. Survey Bull. 751, pp. 121-122, 1924.
CAEBONIFEROUS FORMATIONS 45

Gregory and Noble,93 the Coconino of Grand Canyon, 

330 feet thick, thins northward and northeastward 

across Kaibab Plateau and is absent from sections 

measured in Kaibab Gulch. East of the Paria Valley 

no unmistakable Coconino has been recognized. Even 

in upper Marble Gorge, where both formations are fully 

exposed in a single wall, limits of the Coconino and the 

Kaibab have been recognized with doubt; in substantially the same section near Lees Ferry recorded thicknesses of the Coconino range from 57 to 300 feet. In 

part the difficulty seems to lie in the general view that 

the Coconino is a "cross-bedded sandstone" and the 

Kaibab a "regularly bedded limestone." But though 

the typical Coconino is noncalcareous and strongly 

cross-bedded, the Kaibab is everywhere arenaceous 

and much of it is cross-bedded.

Thus Noble 94 shows that of 562 feet of the Kaibab at 

the Bass trail, 136 feet is "buff and reddish fine-grained 

sandstone" and 134 feet "buff sandstone and limestone 

in alternating beds"; and that a section 717 feet thick 

at Kaibab Gulch includes 272 feet of "sandstone" and 

445 feet of thin-bedded limestone with which are incorporated beds of "calcareous sandstone." Gregory 95 

describes the Kaibab of the Little Colorado Valley as 

ranging between an arenaceous limestone and a calcareous sandstone. Gilluly and Reeside 96 state that the 

Coconino [Kaibab?] of San Rafael Swell "is dominantly 

lime-cemented and somewhat friable. * * * The 

basal 40 feet of the thickest exposure * * * is 

chiefly limestone." At the Waterpocket Fold, as 

reported by Gregory and Moore,97 "the Coconino 

sandstone * * * differs in no respect from the 

sandstone in the lower part of the Kaibab." Additional proof, of the invalidity of the correlation of the 

Cedar Mesa with the Coconino is presented in a recent 

paper by McKee.98

The Cedar Mesa member is here considered to occupy 

the stratigraphic position of the combined Coconino and 

Kaibab formations of the Kaibab Plateau and to be 

partly equivalent in lithology to the Kaibab. Substantially it is the sandy phase of the Kaibab, which, 

extending eastward, constitutes an increasingly large 

part of the formation and finally the whole.

' Gregory, H. E.( and Noble, L. F., Notes on a geological traverse from Mohave, 

Calif., to the mouth of the San Juan Eiver, Utah: Am. Jour. Sci., 5th ser., vol. 5, 

pp. 229-238,1923. Noble, L. F., A section of the Kaibab limestone in Kaibab Gulch, 

Utah: U. S. Geol. Survey Prof. Paper 150, pp. 43-46,1928.

84 Noble, L. F., A section of the Paleozoic formations of the Grand Canyon at the 

Bass trail: U.S. Geol. Survey Prof. Paper 131, p. 26,1923; A section of the Kaibab limestone in Kaibab Gulch, Utah: U. S. Geol. Survey Prof. Paper 150, pi. 12,1928.

M Gregory, H. E., Geology of the Navajo country, a reconnaissance of parts of Arizona, New Mexico, and Utah: U.S. Geol. Survey Prof. Paper 93, p. 20,1917.

M Gilluly, James, and Reeside, J. B., Jr., Sedimentary rocks of the San Rafael Swell 

and some adjacent areas in eastern Utah: U. S. Geol. Survey Prof. Paper 150, p. 63, 

1928.

97 Gregory, H. E., and Moore, R. C., The Kaiparowits region, a geographic and 

geologic reconnaissance of parts of Utah and Arizona: U. S. Geol. Survey Prof. Paper 

164, p. 40,1931.

88 McKee, E. D., The Coconino sandstone its origin and history: Carnegie Inst. 

Washington Pub. 440, pp. 77-115,1933.

CONTACT OF CEDAR MESA AND ORGAN ROCK MEMBERS

An unconformity at the top of the Coconino was 

noted by Miser 99 in San Juan Valley and by Prommel l 

in Cataract Canyon. About the mouth of the Fremont 

River, where the Coconino [Cedar Mesa] is overlain by 

maroon and red shales of the lower Moenkopi [Organ 

Rock member], Longwell 2 found that "the resistant 

Coconino preserves large areas of the pre-Triassic erosion surface almost unchanged. * * * Recent canyons are cut through the contact, revealing it as a distinct wavy line overlain by conglomerate in which all 

the pebbles are sandstone." In the San Juan country 

the contact plane of the Cedar Mesa and Organ Rock 

members ranges in unevenness from slightly wavy surfaces to those that have a relief of 5 to 10 feet within 

areas of about a quarter of a square mile. In some 

places the overlying red shales occupy the depressions, 

but commonly beds or patches of conglomerate intervene. In lower White Canyon the conglomerate consists chiefly of fragments of white and red sandstone, 

red shale, quartz grams, and flattened pellets of gray 

clay limestone, associated with which are huge limestone concretions and some chert, probably of secondary 

origin. At a place between Fish and Mule Creeks the 

conglomerate shows angular limestone fragments and 

chert embedded in coarse sand, all firmly cemented by 

lime and iron. It rests in hollows eroded in the top of 

a thick bed of white sandstone. At places on Grand 

Flat and northward along Steer Gulch the conglomerate, composed chiefly of fragments of limestone and 

clay mud balls, rests on a mud-cracked surface of shaly 

calcareous sandstone.

The regional extent and stratigraphic significance of 

the unconformity at the top of the Cedar Mesa member 

are not known. Obviously it is not the erosion surface 

that separates the Lower Triassic Moenkopi from Permian formations, for that lies some 300 feet higher in 

the same sections. The conclusion of Longwell 3 and 

others that the erosion surface at the top of the Coconino [Cedar Mesa] marks the division between Permian 

and Triassic time and that the unconformity "about 

400 feet" higher records but an interruption in Triassic 

deposition is opposed by the fact that plants of Permian 

age appear in the ' 'lower Moenkopi.'' If the unconformity represents but a brief and somewhat localized interruption of Permian sedimentation, the red beds above 

it constitute deposits of Kaibab age quite unlike those 

elsewhere in the plateau province.

68 Miser, H. D., Geologic structure of San Juan Canyon and adjacent country, 

Utah: U. S. Geol. Survey Bull. 751, p. 120, 1924.

i Prommel, H. W. C., Geology and structure of portions of Grand and San Juan 

Counties, Utah: Am. Assoc. Petroleum Geologists Bull., vol. 7, pp. 384-390, 1923.

' Longwell, C. R., Miser, H. D., Moore, R. C., Bryan, Kirk, and Paige, Sidney, 

Rock formations in the Colorado Plateau of southeastern Utah and northern Arizona: 

U. S. Geol. Survey Prof. Paper 132, p. 8,1923.

»Idem, pp. 9, 10.
46 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

Baker and Reeside 4 define the Cedar Mesa sandstone 

as an integral part of the Cutler formation, conformable 

with red beds above and below.

ORGAN ROCK MEMBER

The sedimentary rocks here classed as the Organ 

Rock member of the Cutler formation comprise a series 

of dominantly red sandstones and sandy shales that 

rests on the Cedar Mesa sandstone and extends upward 

to a gray band of sandstone and conglomerate of the 

De Chelly sandstone member, which in most of the 

area unconformably underlies the Moenkopi formation. 

The member is exposed in cliffs and canyon heads about 

Elk Ridge, in cliffs along the east face of Red Rock 

Plateau from the head of Steer Gulch southward to 

points beyond the San Juan, and as outliers on Grand 

Gulch Plateau. Along White Canyon and its tributaries the Organ Rock member constitutes a red bordering wall that contrasts sharply with the white platform 

into which the canyon is sunk. At the mouth of White 

Canyon it is displayed at the base of walls on both 

sides of the Colorado River. For many miles along 

the Red House Cliffs and White Canyon the topographic 

expression of the Organ Rock member is much the same. 

The lower part (division A) begins as a thin cover on 

the white Cedar Mesa sandstone and as a slope of red 

rocks broken by minor steps extends upward in thin 

beds to the base of a vertical red cliff (division B), 50 to 

120 feet high, that in places seems massive but generally 

appears as a series of relatively resistant thick beds cutby strong vertical joints. Between these divisions in 

places are thin beds of white sandstone and of finegrained limestone conglomerate. (See pis. 9, B; 12, 

A,B.)

The Organ Rock member is 310 feet thick in Hideout 

Canyon, 347 feet at Soldiers Crossing, 259 feet near 

Red House, 280 to 350 feet along Armstrong Canyon, 

421 feet at the head of Arch Canyon, 360 feet at the 

head of Comb Wash, 278 feet at the Rasp trail, 320 feet 

at the south end of Elk Ridge, and 270 feet at Rock 

Springs. Along Glen Canyon, according to Longwell, 

it is about 400 feet. Miser gives measurements of 450 

feet at Zahns Camp, on the San Juan River, and 500 

feet 3 miles southeast of Piute Farms.

In general view the bedding in the Organ Rock is 

regular. The shalelike beds of the lower part and the 

thicker sandstone beds above are parallel to a degree 

remarkable for sedimentary strata that otherwise show 

evidence of fluviatile origin and rapid deposition. In 

detail, however, the beds show many irregularities. 

The shales are nonfissile and in part lenticular and 

weather into angular chunks. Their surfaces are made 

uneven by overlapping flakes of hardened mud. The 

sandstone in some beds is massive, with or without 

cross-bedding, and retains its thickness for a long dis-

< Baker, A. A., and Reeside, J. B., Jr., Correlation of the Permian of southern 

Utah, northern Arizona, northwestern New Mexico, and southwestern Colorado: 

Am. Assoc. Petroleum Geologists Bull., vol. 13, p. 1432, 1929.

tance, but most of it breaks irregularly into thinner 

beds. It weathers with rounded surfaces, from which 

curved slabs and chips peel off. About a mile north of 

the San Juan a section- includes 4-inch b.eds of white 

calcareous sandstone 230 and 280 feet above the base, 

and similar beds were observed at Comb Wash and 

elsewhere. In places the formation is streaked with 

seams of gray-white gypsiferous sandstone. Except 

in bedding and firmness of cement, the upper and lower 

parts of the Organ Rock are much alike. They consist 

essentially of microscopic grains of quartz with some 

specks of iron, calcite, and muscovite held together by 

lime-iron mud. All parts tested effervesce vigorously 

with acid.

The uniformly fine grain and high calcareous content 

of the Organ Rock number are unfavorable for the 

production of sheer cliffs, angular recesses, or big subordinate steps. Guided by bedding planes and joints, 

weathering has produced horizontal and vertical flutings rounded in cross section. If the protecting cap 

were removed, further weathering would develop 

erosion remnants like the picturesque Organ Rock, in 

the Navajo country. (See se^cs. 4, 8-11, and 13, pp. 

67-68, 70-72, 72-73.)

The strata comprising the Organ Rock were included 

in the Moenkopi (Permian?) by Gregory 5 and described 

by Longwell 6 as "lower Moenkopi (Triassic)." They 

are the northward extension of the beds that make up 

the Organ Rock tongue of the Cutler as defined by 

Baker and Reeside. 7

The De Chelly (de-shay') sandstone, with features 

characteristic of typical outcrops in the Navajo country,8 appears southwest of Navajo Springs as a bed about 

80 feet thick that thins northward and finally is lost to 

view in the floor of Comb Wash. Generally in the 

San Juan country its stratigraphic position is held by 

gray medium- to coarse-grained, in part cross-bedded 

sandstone with associated conglomerate. In most 

places these gray beds, a few niches to some 20 feet 

thick, overlie the Organ Rock and directly underlie the 

Moenkopi, but in the cliffs south of Clay Hills Pass 

30 to 50 feet of red shales and sandstone like those in 

the Organ Rock lie between the gray beds and the 

Moenkopi and constitute a northward continuation 

of the beds called Hoskinnini tongue (of the Cutler 

formation) by Baker and Reeside. 9

The De Chelly varies much in texture and arrangement of beds. Along White Canyon for some 20 miles

 Gregory, H. E., Geology of the Navajo country, a reconnaissance of parts of Arizona, New Mexico, and Utah: U. S, Geol. Survey Prof. Paper 93, p. 30,1917.

« Longwell, C. R., Miser, H. D., Moore, R. C., Bryan, Kirk, and Paige, Sidney, 

Rock formations in the Colorado Plateau of southeastern Utah and northern Arizona: 

U. S. Geol. Survey Prof. Paper 132, p. 10,1923.

7 Baker, A. A., and Reeside, J. B., Jr., Correlation of the Permian of southern Utah, 

northern Arizona, northwestern New Mexico, and southwestern Colorado: Am. 

Assoc. Petroleum Geologists Bull., vol. 13, pp. 1421-1422, 1929.

s Gregory, H. E., op. cit., pp. 31-33.

» Baker, A. A., and Reeside, J. B., Jr.. op. cit., pp. 1431-1432.
TRIASSIC FORMATIONS 47

above its mouth this conspicuous horizon marker is in 

many places conformable with the Organ Rock; in some 

places a plane of unconformity lies within the gray 

mass between sandstone conformable with the Organ 

Rock and overlying conglomerate. In the walls of 

Glen Canyon between White and Red Canyons a thin 

conglomerate rests in hollows on top of massive sandstone about 10 feet thick. At the head of Arch Canyon 

and in Hammond Canyon this gray band is merely a 

stratum of coarse cross-bedded sandstone about 2 feet 

thick; near Red House it includes a few pebbles of 

concretionary limestone; at the head of Comb Wash it 

is chiefly a conglomerate of small black and white quartz 

grains, calcite, and iron; in Hideout Canyon about 90 

percent of the pebbles are lime pellets and white and 

red clay balls; at the Rasp trail and elsewhere near 

the mouth of White Canyon it is a lenticular mass of 

angular white chert and sandstone pebbles one-fourth 

to 1 inch in diameter, firmly embedded in a coarse 

quartz grit .(pi. 12, C}. Longwell 10 found that west of 

the Colorado this gray band consists of cross-bedded 

sandstone a few inches to 60 feet thick, which he correlated with the De Chelly sandstone lentil, unconformable below conglomerate a few inches to 25 feet 

thick that marks the base of the upper member of the 

Moenkopi. Northward through Cataract Canyon the 

sandstone appropriately called the "White Rim" may 

prove to be an extension of the De Chelly. (See sec. 

4, p. 68.)

PERMIAN-TRIASSIC EROSION INTERVAL

In the San Juan country, as elsewhere in the plateau 

province, the Permian beds unconformably underlie 

Triassic beds. The contact is a surface of erosion, 

which in places is merely an uneven surface but generally .shows pits, channels, and broad depressions 

filled with conglomerate. The unconformity is further 

shown by the relation of the lowest Triassic formation 

(Moenkopi) to formations below. Near the San Juan 

River the Moenkopi rests on thin beds (Hoskinnini?) 

associated with the Organ Rock; along White Canyon 

and the Colorado River it rests on the De Chelly; 

farther west it rests on the Kaibab. Near Moab all 

the Permian beds have been cut out, and the Moenkopi 

rests on the Hermosa (Pennsylvanian). n

TRIASSIC FORMATIONS

REGIONAL RELATIONS

The Triassic of the San Juan country embraces three 

subdivisions the Moenkopi formation, Shinarump 

conglomerate, and Chinle formation. All of them extend into adjoining regions. In composition, color, 

and manner of erosion they differ little from correspond10 Longwell, C. R., Miser, H. D., Moore, R. C., Bryan, Kirk, and Paige, Sidney, 

op. cit., p. 10.

« Baker, A. A., Dobbin, C. E., McKnight, E. T., and Reeside, J. B., Jr., Notes 

on the stratigraphy of the Moab region, Utah: Am. Assoc. Petroleum Oeoloeists 

Bull., vol. 11, p. 796, 1927.

ing units that are exposed in the Navajo country and 

westward across northern Arizona and southern Utah 

into Nevada. In many places the three formations 

constitute a single steep slope in which the red and 

brown Moenkopi shales, the dark-gray band of the 

Shinarump, and the brilliantly colored Chinle are readily 

distinguished. In other places they appear as two 

slopes: the lower one includes the Moenkopi resting 

unconformably on Permian red beds and capped by a 

vertical cliff of Shinarump; the upper one consists of 

Chinle beds set far back on the Shinarump platform 

and capped by Jurassic (?) sandstone.

The geologists of the Powell and Wheeler surveys 

treated the strata here classed as Moenkopi, Shinarump, 

and Chinle as undefined parts of a f Shinarump group, 

tentatively assigned to the Triassic. No doubt has 

been cast on the Triassic age of their "upper Shinarump" 

[Chinle], but its fossil fish scales, saurian bones, and 

plants are now regarded as Upper Triassic types. The 

Shinarump conglomerate includes fossil plants like 

those in the Chinle and is therefore probably of Upper 

Triassic age; and it is regarded as the basal conglomerate 

of the series of beds that make up the Chinle. The 

"lower Shinarump" [Moenkopi] of the early geologists, 

originally included in the Triassic, was assigned to the 

Permian after Walcott had described "Permian fossils" 

from shale beds below the Shinarump conglomerate in 

Kanab Valley. A restudy of this fauna by Girty, 

however, proved its equivalence with that which characterizes the Triassic of Idaho, and evidence from several 

sources seems ample to prove the Lower Triassic age of 

the Moenkopi.

The descriptions here given are .supplementary to 

the detailed discussions of the composition, stratigraphy, 

distribution, and age of the Triassic formations in regions 

bordering the San Juan country as included in published 

reports. 12

MOENKOPI FORMATION (LOWER TRIASSIC)

The Moenkopi formation is part of all Triassic outcrops between Comb Ridge and the Colorado River 

and appears on the walls of the Glen Canyon at the 

mouths of Red Canyon and White Canyon. At Elk 

Ridge and its capelike projections that border White 

Canyon, Grand Gulch, and Mule Canyon, it is almost 

continuously exposed as a steep slope just below the 

cap rock of Shinarump conglomerate. Down Comb 

Wash it may be traced to the San Juan River as a 

series of upturned beds. Most sections of Moenkopi

» Gregory, H. E., Geology ol the Navajo country, a reconnaissance of parts of 

Arizona, New Mexico, and Utah: U. S. Geol. Survey Prof. Paper 93, pp. 35-50,1917. 

Miser, H. D., Geologic structure ol San Juan Canyon and adjacent country, Utah: 

U. S. Geol. Survey Bull. 751. pp. 122-124, 1924. Longwell, C. R., Miser, H. D., 

Moore, R. C., Bryan, Kirk, and Paige, Sidney, Rock formations in the Colorado 

Plateau of southeastern Utah and northern Arizona: U. S. Geol. Survey Prof. Paper 

132, pp. 9-11, 1923. Gregory, H. E., and Moore, R. C., The Kaiparowits region, a 

geographic and geologic reconnaissance of parts of Utah and Arizona: U. S. Geol. 

Survey Prof. Paper 164, pp. 46-58, 1931. Baker, A. A., Dobbin, C. E., McKnight, 

E. T., and Reeside, J. B., Jr., Notes on the stratigraphy of the Moab region, Utah: 

Am. Assoc. Petroleum Geologists Bull., vol. 11, pp. 796-801.1927.
48 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

are easily recognized; they lie between formations 

marked by different color and topographic expression, 

but where the gray-white bands of De Chelly sandstone 

and the gray-brown Shinarump conglomerate are 

poorly developed the lower and upper limits of the formation are not easy to define. As shown in sections 

4, 8, and 14 (pp. 68, 70, 73), the greater part of the 

M oenkopi is thin-bedded fine-grained sandstone. Groups 

of shalelike beds weather easily into slopes and in some 

exposures show considerable thickness of slightly gypsiferpus variegated shales that crumble into fluffy masses 

somewhat like the "marls" in the Chinle formation. 

Some of the sandstones, commonly those in the middle 

of the formation, are 2 to 10 feet thick, remain massive 

for some hundreds of feet or split into thinner, even or 

lenticular beds, and are resistant enough to form cliffs. 

Thin lenses of conglomerate composed of clay mud 

balls and fragments of shale and sandstone appear in 

many sections. Beds with-ripple-marked, sun-hardened surfaces may be numbered by the hundreds. 

They are characteristic of the formation and indicate 

deposition in shallow water of rivers, lakes, or the sea 

and intermittent exposure to the atmosphere. (See pi. 12, a)

In color the Moenkopi is dominantly chocolate 

brown but includes a few white sandstones, and some 

fresh surfaces are banded red and green gray.

Though no fossils were found in the Moenkopi of 

southeastern Utah, its stratigraphic relations and lithologic features permit correlation with the type Moenkopi 

of the Little Colorado Valley, Ariz., and with beds in 

Kanab Valley, Virgin Valley, and elsewhere that carry 

marine fossils of Lower Triassic age. As interpreted by 

Miser, Longwell, and others, the series of beds here 

called Moenkopi is the uppermost member of a threefold 

Moenkopi that included the De Chelly sandstone and 

the red shales below (Organ Kock, Permian).

In the San Juan country measured sections of the 

formation range in thickness from 200 to more than 

400 feet.

MOENKOPI-SHXNARUMP EROSION INTERVAL

The top of the Moenkopi is an erosion surface over 

which is spread the Shinarump conglomerate. In the 

development of this surface parts of the Moenkopi and 

perhaps higher beds not now anywhere represented were 

removed from large areas of the plateau province. 

Erosion continued until both flat-lying beds and tilted 

beds were worn down to a surface of low relief that 

marked the end of a physiographic cycle. For beginning 

a succeeding cycle the conditions were suitable for the 

deposition of sheets of conglomerate (Shinarump). 

Where the stratification of the two formations is essentially parallel, shallow channels carved in red-brown 

shales are filed with gray grits. Where the dip of the 

Moenkopi beds differs from that of the Shinarump, 

the grits extend more or less evenly across beveled edges

of shale beds. In most places the Moenkopi-Shinarump 

contact is not conspicuous, and where the Shinarump is 

poorly represented and the topmost Moenkopi beds are 

colored shales it seems gradational.

SHESTARUMP CONGLOMERATE

Though the thickness of the Shinarump conglomerate 

in few places exceeds 100 feet, it is a remarkably persistent formation. In southeastern Nevada, southern 

Utah, and northern Arizona it is an unmistakable horizon marker and generally a maker of prominent cliffs 

and platforms. Throughout the plateau province its 

exposures are much alike massive units of coarse 

cross-bedded sandstone interbedded with lenses of 

conglomerate that exhibit the same wide range in 

thickness, texture, color, bedding, and composition.

In the San Juan country the Shinarump is exposed 

on the eastern flank of the great Monument upwarp, 

in the bed of Comb Wash and northward along upper 

Cottonwood Creek and down Mormon Pasture Creek. 

It is likewise exposed on the western flank of the upwarp, in the Red House Cliffs from the San Juan River 

northward to Armstrong Canyon and westward down 

White Canyon to the Colorado River. On the crest of 

the upwarp many square miles of Shinarump form the 

surface of Elk Ridge and its capelike projections. The 

formation varies widely in thickness and composition. 

At the head of Comb Wash the exposed part of the 

Shinarump, 64 feet thick, is about three-fourths coarse 

gray sandstone and one-fourth conglomerate with 

pebbles as much as a quarter of an inch in diameter of 

black and red quartzite, gray chert, shale lumps, and 

worn wood. It includes plant impressions and broken 

logs. The Shinarump that caps Elk Ridge to a thickness of 60 to 120 feet is chiefly gray grit composed of 

glistening grains of rounded and angular quartz. It 

appears as huge cross-bedded lenses separated by irregularly deposited yellow-gray fine sandstone. Generally 

at the base and here and there at higher levels are lenses 

and stringers of conglomerate composed chiefly of 

pebbles of red and black quartzite, white quartz, and 

white chert an eighth to half an inch hi diameter. Near 

Soldiers Crossing most of the 35 feet of Shinarump is 

yellow-gray sandstone and ripple-marked brown mud 

shale with plant impressions, fragments of wood, and 

big iron concretions that resemble tree trunks. Below 

Duckett Tanks much of the fossil wood is stained green, 

and some of it is replaced by copper minerals. At the 

head of Frey Canyon the Shinarump is exceptionally 

coarse, consisting almost entirely of cross-bedded lenticular grits that include concretionary masses of limestone 

1 to 8 inches in diameter, slabs of sandstone 3 to 8 inches 

long, big chips of petrified wood, and pebbles of white 

chert, and gray, black, brown, and white quartz and 

quartzite more than an inch across.

In and near Clay Hills Pass the Shinarump is a coarse 

lenticular ash-gray sandstone only 1 to 8 feet thick that
TBIASSIC FORMATIONS 49

consists of aggregates and strings of subangular quartz, 

quartzite, and chert pebbles; in places it is preserved 

only in depressions carved in the underlying Moenkopi. 

Along White Canyon it is less than 50 feet thick and 

shows an unusual assemblage of grits, ripple-marked 

sandy shales, green shales, clay-lime balls as much as 1 

inch in diameter, and widely scattered small pebbles of 

quartz. In some places it is represented by plasters of 

quartz, limestone, and chert less than 1 foot thick; in 

others by lenticular coarse sandstone and limestone 

conglomerate. It is quite possible that some of these 

outcrops may have been mistaken for beds in the Chinle. 

"Where the plane of unconformity is inconspicuous 

and shales lie both above and below the thin conglomerate the sequence appears gradational and the contacts 

are somewhat arbitrarily drawn. (See sees. 11 and 12, 

pp. 71-72.)

Pebbles of quartz, quartzite, chert, limestone, and 

petrified wood and beds of green-gray shale are features 

common to all outcrops examined, but in general the 

Shinarump in the San Juan country appears to be less 

thick and less conglomeratic and to contain less fossil 

wood and quartzite but more clay, limestone, and chert 

than in regions south of the San Juan River and Glen 

Canyon.

The physiographic conditions under which the Shinarump was deposited are difficult to visualize. What 

conditions could be so persistent and so uniform as to 

permit the deposition of a thin sheet of material essentially alike over thousands of square miles in Utah, 

Arizona, and Nevada? The lenticular bedding, the 

abrupt lateral and vertical change in composition and 

texture, and the absence of thick deposits point to a 

land surface of slight relief over which intermittent 

and ephemeral streams, perhaps also perennial streams 

of fluctuating,, volume, all flowing in poorly defined 

channels, transported and deposited material available 

for distribution. After the coarse material was exhausted in filling depressions in the Moenkopi surface 

and building above them, the streams deposited sand 

in increasingly broader, more regular, and finer-grained 

beds, until with change in climate the conditions became favorable for the deposition of the marl-like shales 

and fresh-water limestones of the Chinle formation. 

The Shinarump marks the beginning of the cycle of 

deposition that followed the cycle of erosion represented 

by the Moenkopi-Shinarump unconformity. It seems 

to be the basal conglomerate of the Upper Triassic 

Chinle formation.

The unsolved problem of Shinarump lithology is the 

source of the pebbles in the conglomerate. The slabs 

of sandstone and clay balls may have come from underlying beds, the cycads doubtless grew where their 

fossils are found, and the petrified trees are probably 

driftwood. Some of the limestone fragments may 

represent beds in a once much thicker Moenkopi; others 

may have come from places like Moab, where preShinarump erosion has locally exposed the Hermosa 

formation. But no Triassic or Carboniferous formation 

so far mapped includes material that might supply the 

varicolored quartz and quartzite. The quartzites 

differ in no essential from those in the pre-Cambrian, 

of Utah and Arizona.

CHINLE FORMATION

Strata assigned to the Chinle formation in the San 

Juan country are exposed in San Juan Canyon at the 

mouths of Clay Gulch, Castle Wash (Spring Gulch), 

Piute Creek, and Wilson Creek. North of the San 

Juan River they form part of the prominent cliff that 

extends to Armstrong Canyon and down the south wall 

of White Canyon and terminates in Castle Butte overlooking the Colorado. Bears Ears, Woodenshoe'Buttes, 

Horse Mountain, and similar landmarks on the plateaulike Elk Ridge, also Jacobs Chair and other isolated 

buttes between White Canyon and Dark Canyon, consist of Chinle beds resting on Shinarump conglomerate 

and capped by remnants of Wingate sandstone. Partial 

or complete sections of the formation are exposed in 

Comb Ridge and in canyon branches of Cottonwood 

Canyon. Here and there on Red Rock Plateau 

streams tributary to the Colorado have cut through the 

overlying sandstones and exposed Chinle beds. (See 

pis. 6, B, D; 12, D; 13, A.}

The position of the relatively soft Chinle between 

two cliff makers accounts for its preservation in a region 

where erosion is vigorous. Where combined with the 

Wingate in a single steep slope the formation displays 

its full thickness for miles, but with the removal of its 

protecting cover it weathers into a mass of fluffy-topped 

mounds and benches that resist neither rain wash nor 

streams. In many places the lower part of the formation is covered by landslides.

Like the Shinarump conglomerate, the Chinle formation is nearly coextensive with the plateau province and 

presents at all exposures much the same lithology and 

erosion forms. Its outstanding features are fossil 

wood, a peculiar limestone conglomerate, and series of 

richly colored variegated shales gray, red, pink, 

lavender, yellow, green that weather in the manner 

of marls. In the San Juan country, as in regions 

immediately adjoining, measured sections of the Chinle 

show four rough subdivisions (1) at the base, brown 

and gray sandstones that weather into steps and 

benches; (2) variegated sandy and calcareous shales or 

"marls" that weather as mammillary mounds and 

immature mesas with typical badland expression;

(3) light-red, dark-red, and mottled shales and massive 

or conglomeratic limestone in alternating beds, weathering as a stepped slope on which the resistant limestone 

forms the top of long, narrow benches and small mesas;

(4) red and brown sandstone and sandy shale, weathering as a cliff that, continued upward, includes the 

Wingate sandstone. Although these subdivisions are
50 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

generally recognizable and the beds that compose them 

combine to give the Chinle an appearance unlike that of 

the formations above and below, the variation in composition, texture, color, and order of deposition is 

.extreme. In no two sections are the relative amounts 

of sandstone, limestone, and shale or the position of 

these strata in the series the same. Most beds are 

lenses that within short distances along the strike are 

replaced by rock of other kinds. Near the head of 

Cottonwood Canyon the limestones and the variegated 

"marls" are concentrated near the base, and at Clay 

Hills Pass these beds rest directly on the Shinarump. 

At the head of Comb Wash a single bed of limestone 

conglomerate 4 feet thick caps the friable "marls." 

In Moki Canyon the top 164 feet of the Chinle is 

mostly'red sandstone; near the mouth of Red Canyon 

shales and limestones immediately underlie the Wingate. 

In nine sections measured the limestone ranges, in 

round numbers, from 3 to 20 percent, the shale from 30 

to 70 percent, and the sandstone from 10 to 20 percent. 

Fossil wood appears generally in the lower half of the 

formation but is not abundant. (See sees. 11, 12, 16, 

and 17, pp. 71-72, 73.)

Measured sections of the Chinle range in thickness 

from 580 to 856 feet. It is thinnest at the mouths of 

Red Canyon and White Canyon and thickest along the 

San Juan River. As a whole the Chinle of southeastern Utah is thinner, is less brilliantly colored, and 

contains less petrified wood and seemingly less red 

sandstone than at typical exposures in northeastern 

Arizona and southwestern Utah. No "fossil forests" 

were discovered, and the great sandstone ledges in the 

middle of the Chinle on the Virgin River are lacking.

In detail, published descriptions of the lithology of 

the Chinle in the Navajo country and in the Kaiparowits region apply equally well to exposures of this formation in the San Juan country and need not be repeated here. Correlation with the Chinle at its type 

locality and with part of the Dolores formation of 

Colorado is made with assurance.

CHINLE-WINGATE CONTACT

At most places where the two formations are in 

contact the massive, strongly cross-bedded, vertically 

jointed Wingate seems to overlie conformably 30 to 60 

feet of regularly bedded sandstone. In tracing the 

contact, however, evidences of a lithologic break and 

of a surface of erosion appear. Near the head of Clay 

Hills Pass the Wingate rests on a wavy surface that 

slightly truncates beds of brown sandstone and white 

limestone conglomerate, red shale, and blue-gray clay. 

The contact is a horizon for springs and seeps. In the 

walls of the Tables of the Sun the lowermost beds of 

Wingate are lenticular and conglomeratic and fill 

depressions in the underlying Chinle. Along the north 

side of Red Canyon the contact is marked by discontinuous accumulations of limestone concretions, mud

balls, and pellets of clay; at the head of Comb Wash, 

by ripple-marked and mud-cracked shale. Though in 

color, mass composition, and general texture the sandstones above and below the contact are much alike, 

the differences suggest that the Wingate sands were 

derived in part from disintegrating Chinle, in part from 

the same source as the Chinle, and in part from other 

sources. The evidence is sufficient to show that the 

topmost Chinle was exposed to erosion before the 

Wingate was laid down.

JURASSIC FORMATIONS

GENERAL FEATURES

Newberry 13 speaks of "Jurassic or Triassic rocks" 

north of Abajo Mountains, and in the Atlas of the 

Hayden Survey fJura-Trias red beds are shown in 

middle Montezuma Valley and along the San Juan. 

The outcrops noted by these pioneer geologists are but 

samples of the Jurassic beds conspicuously displayed in 

the San Juan country on both sides of the San Juan 

River from Aneth to its mouth, in many canyons heading in the Abajo Mountains, and in the region of cliffs 

and mesas between Elk Ridge and the Colorado River. 

The Jurassic rocks in these areas are in turn but large 

samples of formations widely exposed in southern Utah, 

northern Arizona, and western Colorado. The descriptions by Baker, 14 Cross, 15 Coffin, 16 Gregory,17 Miser, 18 

Longwell, 19 and others apply substantially to the 

Jurassic of the San Juan country. Though many 

differences appear in thickness and continuity of individual formations and some in texture and bedding, the 

major divisions and the age are broadly the same, and 

the physical conditions controlling deposition seem to 

have been common to the whole region.

The Jurassic of the San Juan country is essentially a 

series of brightly colored sandstones. It includes beds 

nearly 1,000 feet thick and beds as thin as cardboard, 

but massive beds and shaly beds alike are composed 

predominantly of quartz grains. Beds of organic 

material are absent, limestone and gypsum are rare, 

and most of the beds described as shale might equally 

well be termed thin sandstones. True argillaceous 

shale is represented chiefly by patches and thin irregular 

lenses associated with local unconformities. Cross13 Newberry, J. S., Geological report, in Report of an expedition from Santa Fe, N. 

Mex., to the junction of the Grand and Green Rivers of the Colorado River of the 

West in 1859, p. 99,1876.

14 Baker, A. A., Dobbin, C. E., McKnight, E. T. and Reeside, J. B., Jr., Notes on 

the stratigraphy of the Moab region, Utah: Am. Assoc. Petroleum Geologists Bull., 

vol. 11, no. 8, pp. 785-808,1927.

is Cross, Whitman, and others, U. S. Geol. Survey Geol. Atlas, Telluride folio 

(no. 57), 1899; La Plata folio (no. 60), 1899; Rico folio (no. 130), 1905; Engineer Mountainfolio (no. 171), 1910; Silvertonfolio (no. 120), 1905.

'« Coffin, R. C., Radium, uranium, and vanadium deposits of southwestern Colorado: Colorado Geol. Survey Bull. 16, pp. 61,77,79,83,86-92,95,1921.

17 Gregory, H. E., Geology of the Navajo country, a reconnaissance of parts of Arizona, New Mexico, and Utah: U. S. Geol. Survey Prof. Paper 93. pp. 50-68,1917.

is Miser, H. D., Geologic structure of San Juan Canyon and adjacent country, 

Utah: U. S. Geol. Survey Bull. 751, pp. 124-125,1924.

» Longwell, C. R., Miser, H. D., Moore, R. C., Bryan, Kirk, and Paige, Sidney, 

Rock formations in the Colorado Plateau of southeastern Utah and northern Arizona: 

U. S. Geol. Survey Prof. Paper 132. pp. 11-14,1923.
JURASSIC FORMATIONS 51

bedding and lenticular structure are characteristic features. Except for the rare lenses of siliceous limestone 

and the few beds of dense calcareous sandstone, the 

Jurassic rocks are friable. Unlike the limestones of the 

Pennsylvanian and Permian, the Shinarump conglomerate in the Triassic, and the sandstones in the Cretaceous, the Jurassic strata are not conspicuous as overhanging rim rocks or as level plateau floors. In making 

the high Jurassic cliffs weathering has been influenced 

chiefly by texture and minor structural features. 

Accumulations of talus from Jurassic rocks are nowhere 

large. The weakly cemented fragments pried from the 

ledges by frost soon disintegrate and form materials 

readily removed by torrential rains.

As here tentatively delimited the Jurassic embraces 

an assemblage of strata that lie between the Chinle 

formation (Upper Triassic) and the Dakota (?) sandstone (Cretaceous), but it is recognized that the age 

of the Glen Canyon group has not been proved and 

that it well may be uppermost Triassic. Outside the 

San Juan country the Carmel formation, in the middle 

of the succession, carries in places unmistakable basal 

Upper Jurassic fossils; the Curtis contains middle 

Upper Jurassic fossils; and the Morrison contains late 

Jurassic dinosaurs and mammals. The formations present combinations of physical features unlike those that 

characterize the known Cretaceous formations above 

and the known Triassic below, and they are remarkable 

for extent, continuity, thickness, composition, and 

color. Doubts regarding the assignment of the whole 

series to the Jurassic rest on the lack of satisfactory 

paleontologic evidence rather than on field observations 

that would justify a different assignment. But though 

the evidence for a common age and sedimentary history 

seems strong, it is quite possible that paleontologic 

studies may result in placing the lower boundary within 

or above the Glen Canyon group and the upper boundary definitely at the top of the Morrison. >

CORRELATION

Correlation of the Jurassic formations mapped in 

the San Juan country with those west of Glen and Cataract Canyons presents no special difficulties. With 

the exception of the fossiliferous Curtis formation, all 

subdivisions of the Jurassic in the Kaiparowits region 

and San Rafael Swell are recognizable in Butler Valley, 

in the Alien Canyon country, and north of the Abajo 

Mountains. But in the Jurassic of southwestern Colorado and western New Mexico none of these subdivisions 

have been established with assurance. It is therefore 

not surprising that attempts to establish in Utah, Arizona, and Neva.da the equivalents of the Jurassic formations in Colorado and New Mexico have led to unlike 

conclusions. >

In his systematic study of the San Juan Mountains 

and adjacent territory Cross 20 found it desirable to

*° Cross. Whitman, U. S. Oeol. Survey Geol. Atlas, Telluride folio (no. 57), p. 3, 

1899.

give formation names to the two very unlike parts of 

the Jurassic, both of which were included in the 

fGunnison formation of Eldridge.21 For "the alternating sandstones and variously colored marls and 

shales of the upper part of the section" the term f"McElmo" was chosen in consequence of a report by Gane 

that rocks of this kind were well exposed in McElmo 

Canyon and had been mapped by the Hayden Survey. 

The "heavy sandstones of the lower portion" of the 

fGunnison (prominent in the La Plata Mountains) 

were called fLa Plata formation and defined as "two 

massive sandstones with an intermediate ^member of 

more thinly bedded sandstones and a variable amount 

of bluish fresh-water limestones." The fMcElmo and 

fLa Plata were consistently mapped as the two formations that constitute the Jurassic, in the Telluride, 

La Plata, Rico, and Engineer Mountain quadrangles. 

During a reconnaissance traverse from Dolores, Colo., 

through Monticello to Moab, Utah, Cross 22 recognized 

the "McElmo beds in characteristic development" 

in Dry Valley, Utah, a region from which Newberry 

(1859) had obtained skeletal remains of Dystrophaeus 

riaemaiae Cope in rocks described as Jurassic (?). 

Cross recognized also the fLa Plata formation, regarding which he states that "the upper sandstone of the 

La Plata, * - * * about 300 feet in thickness," 

forms "low mesas or ridges between the branches of 

Dry Valley"; that the "main floor" of the valley is 

"near the upper surface of the lower La Plata sandstone," which is "about 250 feet thick"; and that "the 

middle calcareous member" comprises less than 100 

feet of thin-bedded sandstone "with shaly and impure 

calcareous layers between."

With the knowledge then available, the correlation 

of- strata (Navajo, Carmel, Entrada) along the Monticello-Moab road through Dry Valley with the fLa 

Plata formation at Rico was reasonable, even though 

exposures are many miles apart. In both areas two 

massive red sandstones, separated by about 100 feet 

of calcareous sandstones and shale, are overlain by 

the tMcElmo formation. Cross had no reason to suspect the existence of a third massive red sandstone and 

a second series of calcareous shales within the stratigraphic zone occupied by the fLa Plata. Correlation 

by Cross of the upper fLa Plata with the f White Cliffs 

sandstone (Navajo) of central Utah also seemed reasonable.

To ascertain the westward extension of the Jurassic 

of Colorado, Gane,23 who assisted Cross in mapping 

the Telluride and La Plata quadrangles, traversed a 

route down McElmo Canyon, along the San Juan 

River, and across Red Rock Plateau to Glen Canyon. 

He recognized the "massive La Plata sandstone" in 

San Juan Valley and states that "opposite Waterpocket

21 Eldridge,.G. H., U. S. Geol. Survey Geol. Atlas, Anthracite-Crested Butte folio 

(no. 9), 1894.

22 Cross, Whitman, Stratigraphic results of a reconnaissance in western Colorado 

and eastern Utah: Jour. Geology, vol. 15, pp. 639-640, 1907. 

M Idem, pp. 638. 642, 643.
52 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

Fold the canyon of the Colorado, * * * mainly 

cut in La Plata beds, is 1,000 feet or more deep." 

Obviously Gane correlated the fLa Plata with beds 

now classed as Navajo and Wingate.

A study of the Jurassic outcrops along the Dolores 

River and in McElmo Canyon in 1909 gave Gregory 

a basis for adopting fLa Plata and fMcElmo as stratigraphic terms applicable to northeastern Arizona. For 

the Navajo country the Navajo sandstone was correlated with the upper member of the fLa Plata, the 

Todilto formation with the middle member, and the 

Wingate sandstone with the lower member. As the 

mapping was carried westward in 1915, it was found 

that, particularly about Navajo Mountain and along 

lower Glen Canyon, the characteristically calcareous 

Todilto became dominantly arenaceous and in places 

inconspicuous or absent, that the Navajo was capped 

by a fossiliferous limestone, and that a massive red 

sandstone above the limestone became increasingly 

prominent until north of Glen Canyon it vied with the 

Navajo as a cliff maker. These observations led to 

combining the strata in the walls of Glen Canyon into 

a Glen Canyon group and treating the calcareous shale 

and limestone (Carmel) immediately above the Navajo 

and the massive sandstone (Entrada) above the limestone as two formations not previously recognized.

In traverses across the Kaiparowits Plateau, Waterpocket Fold to San Rafael Swell, and through the 

Henry Mountains, Elk Ridge, .and the Abajo Mountains to Monticello and Moab (1915, 1918) Gregory 

found that the post-Navajo strata along Glen Canyon, 

now classed as Carmel, Entrada, and Morrison, also 

the Wingate, Todilto (?), Navajo, and strata similar 

to the fMcElmo, were displayed on both sides of the 

Colorado. At the end of the traverse in northern 

San Juan County a perplexing problem was presented. 

Church Rock, between Monticello and Moab, which 

tracing had shown to occupy a stratigraphic position 

above the Navajo sandstone, had been correlated by 

Cross with the upper |La Plata, which in turn had been 

correlated with the Navajo. In reconciling these 

diverse conclusions it was thought possible that the 

sandstone (Entrada) represented by this erosion remnant lost its identity or disappeared in passing beneath 

covering beds in the 80-mile stretch between Dry 

Valley and'Rico. The assumption derived support 

from the fact that in the San Juan country the Entrada 

and other formations in the San Rafael group thin 

out, change in composition, or disappear as they are 

traced southeastward. As they were deposited near 

the margin of a Jurassic basin, progressive changes in 

lithology were to be expected.

In reports of the geologists 24 associated with engineering parties in a survey of the Colorado canyons in 1921, 

the Wingate, Todilto (?), Navajo, and fMcElmo are

« Longwell, C. R., Miser, H. D., Moore, R. C., Bryan, Kirk, and Paige, Sidney, 

Rock formations in the Colorado Plateau of southeastern Utah and northern Arizona: 

U. S. Oeol. Survey Prof. Paper 132, pp. 1-23, 1923.

described as formations and two unnamed groups of 

strata between the Navajo and the fMcElmo are listed.

Field work by Gregory and Moore 25 (in the Kaiparowits region) (1918-24) and by Gilluly and Reeside 26 

in the San Rafael Swell (1924-26) resulted' in subdividing the strata between the Navajo sandstone and the 

Dakota (?) into the Carmel, Entrada, Curtis, Summerville, and Morrison formations. It was recognized 

that these five formations occupy the stratigraphic 

position of the fMcElmo as defined by Cross and by 

Gregory 27 ; that the topmost formation (Morrison) is 

equivalent to the upper part of the fMcElmo; but that 

some if not all of the other formations are older than 

any beds in the type fMcElmo. As the upper part of 

the fMcElmo is similar to the type Morrison of eastern 

Colorado, the term "Morrison" was adopted for corresponding lithologic units in Utah, and t"McElmo" 

as a formation name was discarded.

After exploratory studies by Prommel, Harrison, 

Crum, and other geologists of oil companies (1920-24), 

members of the Geological Survey mapped the stratigraphy and structure of the sedimentary formations in 

parts of Emery, Grand, and San Juan Counties, Utah, 

and for correlation with formations in adjoining regions 

made reconnaissances of type localities in the San Juan 

Mountains and in the San Juan River Valley. As 

interpreted in their reports 28 the hitherto accepted 

correlation of the Jurassic formations of Utah and 

Arizona with those described in Colorado is probably 

erroneous. As stated with doubt by Lee but with 

assurance by Baker and others, the fLa Plata formation 

is the equivalent of the Navajo, Carmel, and Entrada, 

not of the Wingate, Todilto (?), and Navajo. Lee and 

his coworkers regarded the Wingate as possibly the 

equivalent of sandstone at the top of the Dolores, and 

the jMcElmo as the equivalent of the combined 

Summerville and Morrison formations. The uncertainty in the correlation of these unfossiliferous beds is 

well shown in the radically different interpretations of 

boundaries, thicknesses, and sequence in essentially the 

same sections.

For the Glen Canyon group- differences in correlation relate in part to the stratigraphic position of the 

Todilto (?), which has been treated as equivalent to the 

middle fLa Plata, to the Carmel, and to some undetermined part of the Morrison. Recently Baker, Dane,

K Gregory, H. E., and Moore, R. C., The Kaiparowits region, a geographic and 

geologic reconnaissance of parts of Utah and Arizona: U. S. Qeol. Survey Prof. 

Paper 164, pp. 69-89, 1931.

*« Gilluly, James, and Reeside, J. B., Jr., Sedimentary rocks of the San Rafael 

Swell and some adjacent areas in eastern Utah: U. S. Geol. Survey Prof. Paper 150, 

pp. 73-82, 1928.

« Gregory, H. E., Geology of the Navajo country, a reconnaissance of parts of 

Arizona, New Mexico, and Utah: U. S. Geol. Survey Prof. Paper 93, p. 59, 1917.

w Lee, W. T., Gilluly, James, Boyer, W. W., Baker, A. A., McKnight, E. T., 

Dobbin, C. E., and Reeside, J. B., Jr., Geology and oil in southeastern-Utah: U. S. 

Dept. Interior Press Mem., July 29, 1927. Lee, W. T., Continuity of formations in 

western Colorado and eastern Utah (U. S. Geol. Survey manuscript on file, 1925). 

Baker, A. A., Dobbin, C. E., McKnight, E. T., and Reeside, J. B., Jr., Notes on the 

stratigraphy of the Moab region, Utah: Am. Assoc. Petroleum Geologists Bull., 

vol. 11, no. 8. pp. 785-808. 1927.
JURASSIC FORMATIONS 53

and Reeside 29 have expressed the opinion that the type 

Todilto lies above the Navajo sandstone, and that 

"Todilto" should therefore be discarded as the formation name for the limestones, calcareous sandstones, 

and shales "that separate the Wingate and Navajo." 

For the unit between the Wingate and Navajo they have 

introduced the term "Kayenta formation."

All these views of the stratigraphic position of the 

Todilto (?) are necessarily tentative. The obstacles that 

hinder satisfactory correlation of the Jurassic of Utah 

and Arizona with type sections in Colorado and New 

Mexico are many. For 60 miles east of Bluff and 40 

miles southeast of Todilto Park the Glen Canyon and 

San Rafael groups are covered by younger beds. Where 

they reappear at Rico and McElmo Canyon, Colo., 

and Fort Wingate, N. Mex., some members are lacking 

and others are much modified or absent. Some 3,500 

feet of strata embracing seven formations in southcentral Utah are represented in Colorado 'by 300 to 750 

feet of unfossiliferous strata that constitute three units 

of one formation (the |La Plata). The great sandstone 

beds of the tentative Jurassic Wingate, Navajo 

Entrada, and La Plata are so alike in range of composition, structure, color, and manner of weathering that 

hand specimens are practically indistinguishable, and 

outcrops in the field can be recognized with certainty 

only where the whole series is present in the same or 

nearby exposures. Likewise the intervening shaly 

beds Kayenta, Carmel, and Summerville have many 

features in common.

In the plateau province as a whole the Jurassic is 

most fully represented in the north-south strip of country that includes the San Raf ael Swell, the Waterpocket 

Fold, the Kaiparowits Plateau, and the Rainbow 

Plateau. Of the eight Jurassic formations in the 

Kaiparowits region only the Navajo and the Carmel 

are clearly identifiable in western Utah and only the 

Morrison (fMcElmo) in Colorado. That the Wingate 

of New Mexico and the fLa Plata of Colorado are 

equivalents of some part of the combined Glen Canyon and San Rafael groups is shown by the presence 

of Chinle beds below them and Morrison beds above. 

Possibly they are deposits on the border of a widespread 

Jurassic basin, thus lacking the lithologic, stratigraphic, 

and paleontologic features of the great accumulations 

exposed in Glen Canyon and along the rim of the 

Paunsaugunt and Markagunt Plateaus. . The subdivisions of the Jurassic as outlined by geologists for 

regions immediately adjoining the San Juan country 

are shown in plate 15. The extent, age, and relationship of the formations assigned to the Jurassic of the 

plateau country are discussed in a recent paper.30

» Baker, A. A., Dane, C. H., and Reeside, J. B., Jr., Correlation of Jurassic formations of portions of Utah, Arizona, New Mexico, and Colorado: U. S. Qeol. Survey 

Prof. Paper 183, pp. 5, 17, 1936.

"Baker, A. A., Dane, C. H., and Reeside, J. B., Jr., op. cit.

MAJOR DIVISIONS OF THE JURASSIC

The major divisions of the Jurassic established for 

the Kaiparowits region and elsewhere in the plateau 

province are represented in the San Juan country. Of 

these the Glen Canyon group, of Jurassic (?) age, 

including the Wingate, Kayenta, and Navajo formations, is unmistakable; the San Rafael group, of Upper 

Jurassic age, though somewhat differently constituted, 

is readily recognized; and most of the beds classed as 

Morrison retain their characteristic features. The 

plane of separation between the Glen Canyon and San 

Rafael groups is an unconformity, probably of regional 

extent, but the division between the San Rafael and the 

Morrison has not been satisfactorily established. 

These groups of strata include many unconformities 

and show near their contact wide variation in composition and structure of beds. The thickness of the 

Jurassic in the San Juan country is about 3,000 feet.

The subdivisions and descriptions that follow are 

presented as an analysis of present knowledge regarding 

the Jurassic of southeastern Utah.

Glen Canyon group (Jurassic?}. In massiveness, 

uniformity, and boldness of sculpture the Glen Canyon 

stands first among groups of strata in the San Juan 

country. Its essential components are two huge 

brightly colored cross-bedded sandstones the Wingate 

below and the Navajo above. In most places these 

great beds are separated by a variable thickness of 

shaly calcareous sandstones and thin, dense, lenticular 

limestones that constitute the Kayenta (formerly 

Todilto?) formation. Though the Wingate and Navajo 

have some individual general features, they are so much 

alike in composition, color, and texture that in the 

absence of the Kayenta they appear as a single bed, 

1,000 feet or more in thickness. The Glen Canyon of 

the San Juan country is the stratigraphic equivalent of 

the Glen Canyon group of the Kaiparowits region, to 

the west, and of the fLa Plata group as defined for the 

Navajo country. (See pis. 7, A, C; 13, A, B.}

San Rafael group (Upper Jurassic}. The San Rafael 

group embraces the strata lying between the Navajo 

sandstone and the Morrison formation. In the San 

Rafael Swell, where all formations are represented, the 

base of the group is the Carmel formation, above which 

in turn lie the Entrada, the Curtis, and the Summerville 

formations. As it extends eastward and southeastward from the San Rafael Swell, its type locality, the 

group as a whole loses some of its salient features but 

continues to include massive and shaly sandstone, thin 

limestones, chert, and gypsum. In the San Juan 

country the beds identified as probably Carmel are 

unfossiliferous and include more shale than limestone; 

the Entrada sandstone, elsewhere conspicuous for 

thickness, massiveness, and large-scale sculptural forms, 

is less than 100 feet thick; the Curtis has not been recog-
54 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

nized; and the beds identified as Summerville, where 

present, are thin, are somewhat indefinitely bounded, 

and only in position and mass composition resemble 

those well displayed west of Colorado River. The 

formations comprised in the San Rafael group form the 

base of the fMcElmo as that term is used by'Gregory 

for the Navajo country and part of the fMcElmo and 

perhaps also part of the fLa Plata as defined by Gross 

for southwestern Colorado. (See sees. 18-22, pp. 74-76.) 

Morrison formation (Upper Jurassic}. The sloping 

cliffs of variegated shaly sandstone that characterize 

the Morrison at its many outcrops in Colorado, New 

Mexico, and Arizona are reproduced as conspicuous 

topographic features in Utah. In the San Juan country 

these brightly colored shales lie at the top of the Morrison. Below them and also prominent as a cliff maker 

is a series of discontinuous, coarse, lenticular gray 

sandstones that appear to have the position of the Salt 

Wash sandstone, as that bed is defined in geologic 

descriptions of areas in Grand and Emery Counties, 

Utah. Below this sandstone in turn are two distinctive stratigraphic units a series of calcareous and 

gypsiferous shales interbedded with thin hard sandstones, and a massive cliff-forming sandstone. For 

convenience of description these four groups of strata 

that constitute the Morrison as here defined are given 

local names derived from the places where they are well 

exposed for study. In descending order they are the 

Brushy Basin shale member (Brushy Basin Wash), 

Westwater Canyon sandstone member (West Water 

Canyon), Recapture shale member (Recapture Creek), 

and Bluff sandstone member (village of Bluff). The 

upper two members are believed to be regional in 

extent. The lower two, though also termed "members" 

in accord with prevailing terminology, are subdivisions 

that may prove to be restricted to .the San Juan Valley. 

The Morrison was included in the fMcElmo as defined 

by Cross and Gregory. Parts of it were correlated with 

the San Rafael group by Lee and his coworkers. (See 

sees. 23-26, pp. 76-78.)

GLEN CANYON GROUP (JURASSIC?)

The most prominent outcrops in southern Utah are 

the red, tan, and white sandstones of the Glen Canyon 

group. They can be traced almost continuously from 

the Virgin River, along the rim of Markagunt and 

Paunsaugunt Plateaus, the base of Kaiparowits Plateau, 

and up the Colorado River to points beyond Moab. In 

the San Juan country they form Comb Ridge and Red 

Rock Plateau, border the Abajo Mountains on the 

west and north, and extend northeastward toward the 

La Sal Mountains. Remnants of these brightly colored 

formations appear as mesas on Elk Ridge and along 

White Canyon. Except at the Rincon and a few other 

places where the underlying beds have been exposed by 

erosion, the whole of Glen Canyon and many of its 

tributaries are but gashes cut in rocks of this group.

Throughout this great area the Glen Canyon red beds 

seem everywhere in view, and in some places they constitute the entire visible landscape.

WINGATE SANDSTONE

As displayed in the San Juan country, the Wingate 

sandstone is characteristically a single ledge of finegrained cross-bedded massive sandstone that maintains 

an average thickness not far from 300 feet. It is cut 

by strong vertical joints that outline huge blocks and 

facilitate the making of vertical cliffs. Many buttes 

and small mesas, capped by Wingate sandstone, are 

rimmed about with a palisaded wall of vertical columns 

impossible to climb. In most cliffs that include the 

whole Glen Canyon group the faces of the Wingate are 

more nearly vertical and continuous than those of the 

much thicker Navajo. The Wingate consists almost 

entirely of uniformly fine, round grains of white quartz. 

The cement consists of lime and iron oxides that give 

to weathered surfaces a prevailing red-brown color. In 

some places the lowermost few beds of the Wingate are 

lenticular, conglomeratic, or for short distances regularly bedded, but as a whole the formation is crossbedded on a scale that ranges from markings revealed 

only by weathering to conspicuous oblique truncated 

laminae arranged in a crisscross pattern.

The Wingate is exposed in the walls of San Juan 

Canyon at Comb Ridge and below Clay Hill Crossing. 

Complete or partial sections appear in upper Cottonwood Wash and its western tributaries that cut deeply 

into tilted beds along the flanks of Elk Ridge. Castle 

Wash, Moki Canyon, Cedar Creek, and other gorges 

that carry the drainage of Red Rock Plateau to the 

San Juan and the Colorado reveal the Wingate, and 

many mesas on the divide between Red Canyon and 

White Canyon, likewise the Bears Ears, Woodenshoe 

Buttes, and other picturesque landmarks on Elk Ridge, 

are capped with this rock. (See pis. 4, A; 13, A)

KAYENTA FORMATION

In most sections that include all three formations of 

the Glen Canyon group the Kayenta is easily recognized. Even at a distance it appears as a dark-red, 

maroon, or lavender band of thin-bedded material 

between two thick, massive, cross-bedded strata of buff, 

tan, or light-red color. Its position is also generally 

marked by a topographic break. Its weak beds form 

a bench or platform developed by stripping the Navajo 

sandstone back from the face of the Wingate cliffs. 

The Kayenta is made up of beds of sandstone, shale, and 

limestone, all lenticular, uneven at their tops, and discontinuous within short distances. They suggest 

deposits made by shifting streams of fluctuating volume. 

The sandstone beds, from less than 1 inch to more than 

10 feet thick, are composed of relatively coarse, wellrounded quartz grains cemented by lime and iron. The 

thicker beds are indefinitely cross-bedded. The shales
JURASSIC FORMATIONS 55

are essentially fine-grained, very thin sandstones that 

include lime concretions and balls of consolidated mud. 

The limestone appears as solid gray-blue beds, a few 

inches to a few feet thick, and as lenses of limestone 

conglomerate. Most of the limestone lenses are less 

than 25 feet long, but two were traced for nearly 500 

feet and one for 1,650 feet. On the Hammond trail, 

which crosses Comb Ridge opposite the mouth of Arch 

Canyon, a conglomerate of lime mud balls that weather 

into a spongy mass is a distinctive feature. In Moki 

Qanyon interbedded limestone lenses and shales that 

contain fragments and concretionary masses of limestone make' up a calcareous zone as much as 50 feet 

thick. In places along Castle Wash the Kayenta is 

obscure; the upper two-thirds of a continuous wall is 

marked off from the lower third by thin beds and fat, 

short lenses of blue, green, and white limestone. On 

lower Cedar Creek the Kayenta is exceptionally well 

displayed as the floor of an esplanade that 100 feet above 

the stream extends back from the canyon rim nearly a 

mile. Here the basal beds are sandstones and limestone 

conglomerates in long, thin lenses and thick, short, 

stub-ended masses that are replaced along the strike by 

dark-red mudstone decorated with green bands that 

mark joints and incipient faults. The middle part is a 

series of 10 massive, friable, cross-bedded layers 2 to 5 

feet thick marked on bedding surfaces by mud cracks. 

Less than a mile distant the limestones occur only at 

the top.

In different sections the limestone beds range from 

5 to 18 in number and constitute 9 to 25 percent of the 

material. The formation is 200 feet thick at the head 

of Comb Wash, 140 feet thick on the Hammond trail, 

160 feet in Castle Wash, and 220 feet in Cedar and 

Knowles Canyons. Immediately west of the Colorado 

and along the lower San Juan thicknesses ranging from 

125 to 249 feet are recorded.

Viewed as a whole the Kayenta is readily distinguished 

from the formations above and below it. It is unlike 

them in composition, color, manner of bedding, and 

sedimentary history. Obviously the conditions of 

sedimentation changed in passing from the Wingate 

to the Kayenta and from the Kayenta to .the Navajo, 

but the nature and regional significance of the changes 

have not been determined. In some measured sections 

the transition from Wingate to Kayenta is gradual; 

the material in the basal Kayenta beds seems to have 

been derived from the Wingate immediately below and 

redeposited with only the discordance characteristic 

of fluviatile sediments. But in many sections the contact between the two formations is unconformable; the 

basal Kayenta consists of conglomerate and lenticular 

sandstone that fills depressions eroded in the underlying beds. In Moki Canyon near Red Cone Spring 

nearly 10 feet of Kayenta limestone" conglomerate rests 

in a long meandering valley cut in Wingate. Likewise, the contact between the Kayenta and the Navajo

in places seems to be gradational, but generally a thin 

jumbled mass of sandstone and shales, chunks of shale 

and limestone, mud balls, and concretions of lime and 

iron lies at the base of the fine-grained, cross-bedded 

Navajo. Mud cracks, a few ripple marks, and incipient drainage channels were observed in the topmost 

bed of the Kayenta on Red Rock Plateau; and west of 

Glen Canjron wide sand-filled cracks appear at this 

horizon. These features indicate that, in places at 

least, the Wingate and Kayenta were exposed to erosion 

before their overlying formations were deposited, and 

it may be that the range in thickness of the Kayenta 

is thus in part accounted for. However, unconformities within and between formations are so common 

in the Mesozoic of the plateau province that the field 

geologist hesitates to give regional significance to breaks 

in sedimentation that have not been correlated with 

changes in faunas arid large-scale tectonic movements.

NAVAJO SANDSTONE

In the San Juan country the Navajo sandstone is 

exposed in the east and west flanks of the broad Monument upwarp. The .sandstone forms the crest and 

eastern slope of the "Comb", the prominent ridge that 

crosses the San Juan and extends northward between 

Comb Wash and Butler Wash as a steeply dipping 

monocline, and continues to crop out along the east base 

of Elk Ridge and across the Causeway into the Indian 

Creek country.31 The walls and mosques and alcoves 

that make the "wonderland" of the Alien Canyon 

country are chiefly exposures of Navajo sandstone.

In the remote Red Rock Plateau the Navajo is 

magnificently developed. The plateau is essentially 

one great sheet of sandstone, cut into huge segments 

by the San Juan, Castle, Moki, Red, and Colorado 

Canyons. On this plateau the Navajo shows its characteristic features of erosion. Along canyons and at 

their boxlike heads it forms vertical or even undercut 

walls sheer cliffs 400 to 600 feet high that can be 

ascended only at fracture zones or on sand dunes that 

extend from the bottom to the rim. A traverse of 

miles of canyon floor may reveal no place where the 

walls can be climbed. Though the Navajo stands first 

among cliff makers in the plateau province, it does not 

form platforms or mesa tops. Unlike the Dakota(?) 

of Sage Plain and the Shinarump of Elk Ridge, which 

form extensive nearly horizontal plateaus, the Navajo 

shows very uneven surfaces. Its composition, texture, 

and structure combine to produce smooth or ribbed 

mounds on which streamways are poorly defined. 

Between the San Juan River and upper Castle Wash 

and at the junction of the San Juan and the Colorado 

the surface of Red Rock Plateau is a maze of domes 

and saucerlike depressions. The intricate network of

81 Through an error in drafting the geologic map accompanying the report on the 

Navajo country (U. S. Qeol. Survey Prof. Paper 93, pi. 2,1917), the Navajo formation 

is represented as extending some miles east of Bluff. Fortunately the error is obvious; 

the formations are prominent and distinctive and the relations unmistakable.
56 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

narrow, deep canyons that carry the run-off from bare 

slopes seems to be arranged with little regard to surface 

topography.

The published descriptions of the Navajo sandstone 

in the Navajo country and in the Kaiparowits region 

apply equally well to the San Juan country and need 

only be generalized here. In fact, the composition, 

structure, texture, and style of bedding of the Navajo 

are remarkably alike throughout the Colorado Plateaus: 

the differences relate chiefly to thickness, color, and 

degree of massiveness. Essentially the Navajo is a 

single massive bed of fine-grained, marvelously crossbedded sandstone composed of crystal-clear grains of 

quartz cemented by lime and iron. Cross-bedding is a 

scroll work of curves and parallel lines etched on the 

surface and strengthened here and there by projecting 

seams of quartz and rows of cylindrical iron concretions. 

The Navajo sandstone includes lenses of thin regularbedded sandstone and lenses of resistant limestone a 

few inches to 5 feet thick and a few hundred feet Iong4 

On the run of Lake Canyon dense blue-gray dolomitic 

limestone near the top of the Navajo caps low mesas 

and provided building materials for the walls of prehistoric structures. Numerous vertical and oblique 

joints outline slabs on cliff faces and in conjunction 

with cross-bedding determine the position and shape 

of buttresses, recesses, and alcoves on canyon walls 

and the caves once occupied by Cliff Dwellers. (See 

pis. 6, C; 13, J5.)

As most of the Navajo in the San Juan country has 

been long exposed to erosion, its original thickness has 

been reduced. At Comb Ridge and in the Alien 

Canyon country 300 to 600 feet remains. In the south 

wall of Wilson Mesa, where the Navajo is overlain by 

younger strata, a complete section measured 880 feet. 

At most places west of the Colorado River measured 

thicknesses exceed 1,000 feet; at Zion Canyon, nearly 

2,500 feet.

SAN RAFAEL, GROUP (UPPER JURASSIC)

DISTRIBUTION

The San Rafael group, typically exposed in the San 

Rafael Swell and a prominent assemblage of strata in 

the Kaiparowits region, is poorly displayed in the San 

Juan country. Of its four constituent formations the 

beds that appear to represent the Carmel (elsewhere in 

part a richly fossiliferous marine limestone) consist of 

calcareous shales and sandstones. The Entrada, a 

great cliff maker west of the Colorado and to the north 

about Moab, is here a thin though characteristic bed; 

the fossiliferous Curtis formation is not recognizable; 

and the beds tentatively assigned to the Summerville 

lack clear-cut diagnostic features and perhaps should be 

classed as Morrison. Apparently the group, 600 to 

2,000 feet thick at the San Rafael Swell, 385 to 625 feet 

at Moab, and 420 to 800 feet along Glen Canyon, thins 

southeastward and disappears in the neighborhood of

Bluff. Beds exposed on the floor of Montezuma 

Canyon at the mouth of Verdure Creek, tentatively 

assigned to the San Rafael, measured about 80 feet. 

(See sees. 18 to 22, pp. 74-76.)

In the San Juan country the group is best represented 

in a narrow band that, beginning at the base of Tank 

Mesa, extends northward along Butler Wash and middle 

Cottonwood Wash into and beyond the Alien Canyon 

country, where in canyon walls and rims of mesas it 

contrasts sharply with the underlying Navajo and the 

overlying Morrison. The lowermost beds of the group 

form the cap of Wilson Mesa and flat-topped remnants 

near Lake Canyon and Knowles Canyon.' Elsewhere 

in the wide belt between the Comb monocline and Glen 

Canyon all members of the San Rafael have been 

stripped away.

CARMEL (?) FORMATION

As its type locality in Parunuweap Valley, near 

Mount Carmel village, the Carmel formation measures 

222 to 269 feet, of which about 100 feet is limestone 

that contains a marine fauna of Upper Jurassic age. 

Northeastward from Mount Carmel the formation 

maintains its thickness and stratigraphic features at 

places as far distant as the San Rafael Swell, but southeastward across the Paria River and along the base of 

the Kaiparowits Plateau it thins gradually and loses its 

limestone, until near the mouth of Rock Creek it is 

represented by some 50 feet of calcareous sandstone 

with which is interbedded 2 inches of unfossiliferous 

hard, brittle limestone. As represented in the San 

Juan country the Carmel consists of red and white 

earthy, lumpy, unevenly bedded sandstones and earthy 

red mud shales that range in total thickness from 107 

feet to the vanishing point.

Near the mouth of Alien Canyon the formation 

embraces 10 to 40 feet of friable red imbricated shales 

that weather into chips. At the head of Butler Wash 

it consists of 24 feet of red thin-bedded slabby sandstone. Southward along the wash the formation is 

thicker and includes not only sandstone and shales of 

various shades of red and wide range in bedding and 

composition, but also beds of white sandstone. On 

Wilson Mesa the highest bed is a knobby arenaceous 

limestone that weathers like caliche.

In the San Juan country, as elsewhere in the plateau 

province, the Carmel where present rests unconformably 

on the Navajo sandstone. The top surface of the 

Navajo is uneven and in most places is coated with 

particles of lenticular, nodular, even conglomeratic red 

shales and sandstone. In the Alien Canyon country 

masses of lumpy red, gray, and yellow shale occupy 

depressions and channels in the Navajo as much as 25 

feet deep. In places the curved laminae in the Navajo 

were truncated before the lowest bed of Carmel was 

deposited. Though this unconformity may mark the 

division between the Lower or Middle Jurassic and the
JURASSIC - FORMATIONS 57

Upper Jurassic, it probably does not indicate a long interval of erosion. (See sees. 18, 20, and 22, pp. 74, 75-76.)

ENTEADA SANDSTONE

The Entrada sandstone is the most conspicuous formation of the San Rafael group. West of the Colorado 

River, where its thickness is measured in hundreds of 

feet, it resembles the Navajo sandstone in massiveness, 

structure, and boldness of sculpture. In the San Juan 

country the formation maintains the characteristic 

composition and erosion features, though diminished 

in thickness to less than 100 feet. Exposures in Dry 

Canyon, in the walls of Cottonwood Wash, and southward along Butler Wash show a conspicuous band of 

brick-red or orange-red rock that contrasts strongly 

with the dark-red and green-gray Morrison above and 

the tan-colored Navajo below (pi. 13, (7). Essentially 

the Entrada is a fine, even-grained sandstone with subordinate amounts of bright-red shale. In some places it 

is a single massive, strongly cross-bedded ledge; in other 

places a series of thick-bedded sandstones or sandstones 

interbedded with shales, within which are local unconformities. The rock consists chiefly of round and 

angular grains of quartz, a little feldspar, and a few 

flakes of biotite. The cement is commonly calcite and 

ferric iron, in proportions that determine the color tone. 

Because the cement is weak and the grains small and 

nearly uniform in size, the Entrada where massive 

weathers into low domes and round-edged ledges. 

Where lenses of relatively resistant materials make up 

part of the bed, erosion produces forms like spools, hour 

glasses, and "rock babies." The "Beehives" along Dry 

Canyon, the "Goblet of Venus" (pi. 14, B) on the Blanding-Kigalia road, and the "hoodoos" at the head of 

Buck Canyon, west of Bluff, are representative features. 

In most sections the beds at the base of the Entrada 

grade downward through a series of red sandstones to 

the Carmel beneath. In other sections an erosional 

unconformity, separates the two formations and doubtless accounts for the difference in thickness of the Carmel at places not far apart. In Dry Wash only discontinuous patches of the Carmel remain, and in places 

the Entrada rests directly on the eroded surface of the 

Navajo. (See sees. 18, 20, and 21, pp. 74-75.)

SUMMERVIL1E (?) FORMATION

As mapped by Gilluly and Reeside 32 the Summerville 

at its type locality, the San Rafael Swell, comprises 

"thin-bedded chocolate-colored sandstone, earthy redbrown sandstone and shale, some gypsum, and a little 

limestone" that conformably overlie the fossiliferous 

Curtis formation and unconformably underlie strata 

referred to the Morrison. In the Kaiparowits region 

Gregory and Moore 33 found few outcrops that could 

definitely be correlated with the Curtis and experienced 

difficulty in fixing the stratigraphic limits of a series of

M Gilluly, James, and Reeside, J. B., Jr., op. cit. (Prof. Paper 150), table facing p. 62. 

»' Gregory, H. E., and Moore, R. C., op. cit. (Prof. Paper 164), pp. 78-89.

red and variegated sandstones and shales comparable in 

position and mass composition with the Summerville. 

Many measured sections were therefore classed as "San 

Rafael group and Morrison formation undifferentiated."

In his studies of the Moab region Baker 34 found the 

Curtis formation absent and not represented by an 

unconformity, recognized the Summerville (25 to 65 

feet thick) and correlated it with "the thick and distinct 

Summerville formation in the San Rafael Swell", and 

placed the top of the Summerville "at the base of the 

first ledge of white sandstone in the Morrison", where 

an "apparent unconformity" was observed. In the 

San Juan country strata in the position of beds reasonably assigned to the Summerville are little like those 

at the type locality, and the contact of the Summerville 

and Morrison is somewhat arbitrarily drawn. In cliffs 

bordering the San Juan River, in Butler Wash and 

northward, the formation includes red, brown, white, 

and yellow sandstones and mudstones; red and variegated shale; some conglomerate of quartz, lime pellets, 

and mud balls; and a few thin lenses of limestone, 

gypsum, and large chert concretions. The sandstones 

are foliated or cross-bedded, lenticular, and weakly or 

firmly cemented with lime and iron. Most of the shale 

is gypsiferous and flaky; some of it is wrinkled or cut 

by tiny faults. All the beds tested are very calcareous. 

The evidence is insufficient to determine the conditions 

under which the Summerville was deposited. The 

relatively large quantities of chert suggest marine origin, 

but the lenticular bedding and the capricious changes in 

texture are more characteristic of stream deposits 

(pl. 14,4). -

An unconformity at the base of the Summerville that 

might represent the absent Curtis formation was not 

demonstrated. In Alien Canyon and in upper Butler 

Wash lenses of coarse white sandstone fill shallow 

channels in the Entrada, but at Tank Mesa and on the 

back of the Comb monocline east of Arch Canyon the 

Entrada seems to grade regularly upward into interbedded white sandstone and red shale. Baker 35 reports 

"that the Curtis formation grades laterally into the 

Summerville formation near Dellenbaugh Butte, on the 

Green River." The upper limit of the Summerville (?) 

along the San Juan is more clearly marked. The contact of the brightly colored calcareous and gypsiferous 

sandstones and shales assigned to the Summerville (?) 

with the overlying massive, cliff-making buff and white 

sandstone classed as basal Morrison (Bluff sandstone 

member) is characterized by an abrupt change in lithology and in most places by an unconformity in bedding 

that suggest regional erosion before the upper beds 

were laid down. The significance of this relation is 

uncertain in view of the fact that somewhat similar 

breaks in continuity of sedimentation appear above and

84 Baker, A. A., Geology and oil possibilities of the Moab district, Grand and San 

Juan Counties, Utah: TJ. S. Geol. Survey Bull. 841, p. 51.1933. 

ss Baker, A. A., op. cit. (Bull. 841), p. 51.
58 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

below the contact. The division plane may prove to lie 

at one of several horizons within 500 feet of Summerville (?) or of Morrison sediments. The strata here 

called Summerville (?) are the "crinkled beds" of Lee 36 

and his coworkers, who correlated them with the Carmel 

formation. (See sees. 18 to 21, pp. 74-75.)

MORRISON FORMATION (UPPER JURASSIC)

GENERA! FEATURES

Strata assigned to the Morrison formation in the 

San Juan country rise as cliffs on both sides of the 

San Juan River from Butler Wash eastward to the 

Colorado State line. Across Sage Plain they are exposed beneath the Dakota (?) rim rock in all canyons 

tributary to the San Juan and terminate westward in 

attractive cliffed slopes along upper Butler Wash and 

middle Cottonwood :Wash and in Piute Park. Characteristic sections are readily accessible on the BluffBlanding road and in Big Canyon and Brushy Basin 

on the Blanding-Kigalia road.

In'general appearance, style of bedding, mass composition, and age the outcrops at all these places resemble those defined as Morrison or fMcElmo in 

western Colorado, New Mexico, and Arizona and as a 

whole are correlated with them. Here, as elsewhere, 

the upper limit of the formation is the base of the 

Dakota (?) sandstone, and the lower limit an unconformity that has not been everywhere definitely placed 

in the stratigraphic column. However, the study of 

widely separated sections leaves the impression that 

fuller knowledge of unconformities and conditions of 

sedimentation will result in the recognition of two or 

more formations within the Morrison, perhaps even of 

different ages. The coarse thick-bedded lenticular 

sandstones, the thick massive sandstones, and the 

interbedded red shales and white sandstones in the 

Morrison of the San Juan drainage basin would seem 

out of place in the Morrison section of eastern Colorado.

In most sections the Morrison in eastern Utah includes two strongly contrasted parts a lower part 

comprising thin-bedded and massive red sandstone, 

sandy shale, gray cross-bedded lenticular conglomerate, together with subordinate limestone, clay, and 

gypsum; and an upper part consisting of "variegated 

shales." In the San Juan country the Morrison formation comprises four rather distinctive lithologic groups 

or members, which are described below. (See sees. 

23 to 26, pp. 76-78.)

BLUFF SANDSTONE MEMBER

The Bluff sandstone member is white, brown-stained 

commonly cross-bedded, and made up of medium to 

coarse quartz grains. Typically it is one massive bed 

200 to 350 feet thick that here and there includes aggregates of large quartz grains, clay balls, and short thin

'8Lee, W. T., Continuity of formations in western Colorado and eastern Uta 

(U. S. Oeol. Survey manuscript on file, 1925).

lenses of red mudstone. In some places it is arranged 

as long overlapping sandstone wedges bordered by a 

little red shale, and in other places as poorly defined 

beds 20 to 40 feet thick. Traced eastward, the Bluff 

sandstone that forms the top of Tank Mesa is less persistently massive. Near the mouth of Montezuma 

Canyon 10 to 20 feet of bedded white sandstone are 

incorporated in red sandy shale that thins, thickens, 

bunches up, or flattens out along the strike. Traced 

northward along Butler Wash and Cottonwood Canyon 

the Bluff sandstone is represented in places by three or 

more beds. (See pi. 3, C.) Vertical joints outline 

square columns and long slabs that weather in place 

as monuments and furnish huge blocks to the talus. 

Weathering on cliff faces produces elongated niches, 

pockets, and "owl holes" suitable for nests of birds and 

bats, and at the base of the sandstone deeply recessed 

grooves with flat floors and overhanging roofs, chosen 

by Cliff Dwellers as building sites. The Bluff sandstone 

derives its name from the town of Bluff, where, on both 

sides of the San Juan River, it is the outstanding topographic feature.

RECAPTURE SHALE MEMBER

The interval between the Bluff sandstone member 

and the lowermost bed characteristic of the Westwater 

Canyon sandstone member is occupied by a series of 

strongly colored shales and sandstones 100 to 300 feet 

thick. They appear in many places as sloping platforms at the base of cliffs and are particularly well 

displayed near the mouth of Recapture Creek, from 

which the name is derived. The shales are prevailingly 

dark red, but some are variegated pink, ash, brown, 

and gray. Many of them include firm, strongly calcareous beds that break into slabs and friable, imbricated gypsiferous beds that weather as tiny cliffs. The 

sandstones are white beds of glistening quartz cemented 

by lime, few of them more than a foot thick or continuous for more than 1,000 feet. Some are gypsiferous 

and friable, but most are more resistant than those in 

the Bluff or the Westwater Canyon member and are 

represented in the talus as angular blocks. The shales 

and sandstones combine to form slopes, low mesas, 

and platforms, and the edges of sandstone beds appear 

as shelves and small benches. The outcrops are attractively color-banded, but as the shale and sandstone 

feather out and replace each other along the strike the 

arrangement of sections 1,000 feet apart is quite different. The amount of sandstone in the Recapture 

shale member is generally about 15 percent; at the 

base of Turners Bluff it constitutes so small a part that 

the shales weather like marls. In gross lithology the 

strata of the member resemble those observed in the 

Morrison about 8 miles south of Woodside, Utah, which 

Gilluiy and Reeside 37 place at the base of the Salt 

Wash sandstone member.

u Oilluly, James, and Reeside, J. B., Jr., op. cit. (Prof. Paper 150), pp. 102-103, 

1928.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 188 PLATE 11

A. VIEW IN JOHNS CANYON AK.Ul ITS .11 iNCTIO.N WITH SAN JLAN CANYON. 

Hermosa and Rico in canyon wall; Halgaito and Cedar Mesa in distance.

B. WALL OF ROAD CANYON. 

Halgaito strata (lower part.) and shaly phase of Cedar Mesa (upper part).

(.'. WALL OF ARCH CANYON NEAR ITS HFAD. 

Composed of Cedar Mesa sandstone overlain by Organ Rock, De Chelly, and Moenkopi beds.
GEOLOGICAL SURVEY PROFESSIO

1. (.IJFF NEAR STAR SPRINGS, WHITE <: \Mu.V

Stands on Cedar Mesa sandstone. Slope and vertical wall composed of Organ Hock shales and sandstone. Top thin bed of De Chelly sandstone.

/(. EAST li.NTRAINCL To CLAY III1.LS PA

Moenkopi formation overlying strata at the top of the Organ Rock mem

C. VIEW ON RASP TRAIL. 

De Chelly sandstone (at the base) and Moenkopi.

D. VARIEGATED MARLS AT CLAY HIL

Chinle formation.
GEOLOGICAL SURVEY PROFESSION

A. DIVIDE BETWEEN WHITE CANYON AND HED CANYON. 

Chinle, Wingate, and Kayenta strata.

B. WALL OF CASTLE WASH. 

Kayenta and Navajo formations.

C. DRY CREEK, ALLEN CANYON COUNTRY. 

Entrada formation unconformably overlying Navajo sandstone (lower left).

D. WEST FACE OF BLACK MESA. 

Upper part of Morrison formation (Brushy Basin shale member) capp
GEOLOGICAL SUKVEY PROFESSIO

A. VIEW NEAR MOUTH OF COTTON WOOD WASH. B. GOBLET OF VENUS.

^^B^rl|^(HP

Summerville (?) formation capped by Bluff sandstone member of ', Erosion remnant in Enlrada sandstone on Blanding-Kigalia road. 

Morrison formation. .-/

C. BRUSHY 

Brushy Basin 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 188 PLATE 15

1

Generalized section of Circle Cliffs,

Waterpocket Fold, and Henry

Mountains

By H. E. Gregory and R. C. Moore,

U. S. Geological Surrey Prof.

Paper 164, 1951

Morrison formation £62 feet

Summerville form. 90 feet

Entrada. sandstone 1,070 feet

Carmel formation 

450± feet(?)

Navajo sandstone 

1,350 feet

Todilto(?) formation 175 feet

Wingate sandstone 300 feet

San Juan country 

This report

Brushy Basin shale member 

400 feet

Westwater Canyon sandstone member 250 feet

Recapture shale member 

200 feet

Bluff sandstone member 

300 feet

Summerville(?) form. 100 feet

Entrada sandstone 50 feet

Carmel (?) formation 100 feet

Navajo sandstone 650 feet

Kayenta formation 150 feet

Wingate sandstone 300 feet

Generalized section of rocks, exposed 

at the surface in the Moab district

By A. A. Baker,

U. S. Geological Survey Bull. 841, 

1953

Morrison formation 

Salt Wash sandstone member 

540-565 feet

Summerville form. 25-65 feet

(Moab tongue)

Entrada sandstone 

360-405 feet

Garmel formation 20-70 feet

Navajo sandstone 

325-470 feet

Kayenta formation 

230-270 feet

Wingate sandstone 

275-340 feet

Generalized section of rocks exposedin Monument Valley-Navajo

Mountain region

By A. A. Baker,

[}. S. Geological Survey Bull. 865, 

1956

6

Generalized section of rocks of the 

Navajo country

By H. E. Gregory,

U. S. Geological Survey Prof.

Paper 95, 1917

6

Generalized section of sedimentary 

rocks of the La Plata quadrangle

By Whitman Cross,

U. S. Geologic Atlas., Folio 60,

1899

Morrison formation 480 feet

Entrada sandstone 440 feet

Carmel formation 130 feet

Navajo sandstone 1,100 feet

Kayenta formation 

140-225 feet

Wingate sandstone 

290-337 feet

McElmo formation 400-700 feet

Navajo sandstone 

400-1,000 feet

Todilto formation 3-200 feet

Wingate sandstone 

30-450 feet

McElmo formation 400-500 feet

La Plata sandstone 

300-400 feet

CORRELATION CHART SHOWING RELATIONS OF THE JURASSIC FORMATIONS OF THE SAN JUAN COUNTRY TO THOSE IN ADJOINING REGIONS.

Thicknesses are averages of measured sections recorded to the nearest 100 feet.
JURASSIC FORMATIONS 59

WESTWATER CANYON SANDSTONE MEMBER

In reports on the geology of the region north of Moab 

and other places in east-central Utah Lupton 38 described a coarse-grained "gray conglomeratic sandstone", in places lenticular and cross-bedded, that 

forms cliffs about 350 feet from the top of the Morrison strata sufficiently uniform and persistent to serve 

as a datum plane for mapping. For this sandstone he 

proposed the name "Salt Wash member of the McElmo 

formation." As classified by Gilluly and Reeside 37 

the Salt Wash sandstone member lies at the base of 

the Morrison and includes not only gray conglomeratic 

sandstones but also clay, limestone, and gypsum. 

Baker 39 defines this member as "white conglomeratic 

sandstones interbedded with red sandy mudstones and 

red shale" that occupy the'lower half of the Morrison 

south of Moab.

In the San Juan country a sandstone that appears 

to lie in the position of the Salt Wash member as 

defined by Lupton plays a large part in developing the 

topography. It stands as cliffs and forms the base of 

many canyon walls that continue upward through 

variegated shale to a rim rock of Dakota (?) sandstone. Along the San Juan River north and northwest of Bluff, between Brushy Basin and middle Cottonwood Canyon, and in other places where the 

variegated shales have been removed, this sandstone 

appears as mesas, ridges, and the tops of broad platforms. Tentatively the local name "Westwater Canyon 

sandstone member", derived from West Water Canyon, 

is here given to this sandstone, because its exact 

equivalency to the typical Salt Wash sandstone has 

not been satisfactorily established.

This member is essentially a series of white sandstones 

composed of rounded medium to coarse grains of quartz, 

cemented by calcium carbonate and arranged in lenticular, irregular beds 1 to 30 feet thick. They include 

conglomeratic bands and stringers composed of quartz 

aggregates, colored chert, concretionary masses of 

compact green-white clay, and rare fragments of petrified wood and dinosaur bones. Interbedded with the 

sandstones are red earthy soft fine-grained sandy 

shales perhaps better called "mudstones" that thin, 

thicken, or disappear in short distances. With them 

are associated a few thin short lenses of gray limestone 

conglomerate. These mudstones, which make up 8 to 

20 percent of measured sections, are extremely irregular. A bed in Big Canyon 14 feet thick disappears in a 

distance of 120 feet, and one less than 2 feet thick in 

Montezuma Canyon was traced for half a mile. Few 

beds of shale or of sandstone retain their individuality

« Gilluly, James, and Reeside, J. B., Jr., op. cit. (Prof. Paper 150), pp. 102-103, 

1928.

38 Lupton, C. T., Oil and gas near Green River, Utah: U. S. Geol. Survey Bull. 

541, pp. 125-127,1914; Geology and coal resources of Castle Valley in Carbon, Emery, 

and Sevier Counties, Utah: U. S. Geol. Survey, Bull. 628, pp. 23-26.1916.

» Baker, A. A., Geology and oi! possibilities of the Moab district, Grand and San 

Juan Counties, Utah: U. S. Geol. Survey Bull. 841, pp. 52-53,1933. 

145824 38 5

for as much as a mile. Unconformable contacts at the 

base of the Westwater Canyon member were observed at 

several places. Features that indicate exposure of the 

top beds before the Brushy Basin shale was laid down 

were noted in McElmo Canyon, but generally the sandstone grades upward through a series of gray sandy 

shales arid merges into the variegated shales at different 

horizons. The relation is somewhat like that between 

the Shinarump and the Chinle, and the Westwater 

Canyon sandstone may prove to mark the beginning of a 

cycle of sedimentation that continued until interrupted 

by pre-Dakota (?) erosion. The thickness of eight 

measured sections of the Westwater Canyon sandstone 

member ranges from 222 to 295 feet.

BRUSHY BASIN SHALE MEMBER

The upper part of the Morrison of the San Juan country consists of the well-known variegated shales (Morrison shales, fMcElmo shales) that generally in Utah 

and western Colorado lie immediately below the 

Dakota (?) sandstone. In fact, they owe their preservation to the resistant Dakota cover. Directly beneath 

cliffs of Dakota (?) sandstone they stand in almost 

vertical walls; where the sandstone has been stripped 

back they form slopes that continue outward into 

mounds and ridges spread over a platform of Westwater Canyon sandstone. Their appearance is everywhere the same brightly variegated masses that are 

exceeded in beauty of coloring only by the Chinle 

"marls." The dominant beds are white, gray, green, 

purple, and red sandy shales and sandstones. (See 

pis. 13, D; 14, (7.) Subordinate beds are gray, pink, 

blue, and gray limestones; conglomerates of red, green, 

and white cherts; and buff hard sandstones. The buff 

sandstone is more abundant near the base and seems to 

increase in amount eastward toward the Colorado line. 

South of the San Juan River much of the bedded shale is 

replaced by massive white or green-white sandstone. 

At the "Jump-off" on the highway between Blanding 

and Bluff some of the shale is evenly stratified, but 

generally all beds are lenticular. In Brushy Basin, 

where the variegated shales are admirably displayed 

for study, the thickness is 450 feet. (See sec. 25, p. 77.) 

Other sections measure 350 to 470 feet. Dinosaur bones 

from the lower part of the Brushy Basin shale in 

McElmo and other canyons of Sage Plain are included 

in local collections of curios. Parts of a skeleton 

gathered from the talus in Montezuma Canyon by the 

late Willis T. Lee were described by C. W. Gilmore as

the greater portion of a coracoid, two anterior caudal centra, one 

medium caudal centrum, and portion of a distal caudal vertebra, 

all apparently of one individual, a sauropod dinosaur of the 

Brontosaurus-Apatosaurus group. Associated with this material 

is the upper articular end of a tibia pertaining to a carnivorous 

dinosaur. Its size would indicate that it might be tentatively 

identified as Anlrodemus (Allosauru?), the largest carnivorous 

dinosaur to be found in this country associated with sauropod 

remains.
60 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

MORRISON-DAKOTA (?) CONTACT

In the San Juan country the strata assigned to the 

Dakota (?) formation are everywhere accompanied by 

those classed as Morrison, and everywhere the contact 

between the two formations is a zone of unconformity. 

But Morrisonlike sedimentary beds lie above what 

appears to be the major unconformity, and unconformities are present at horizons not far below. At most 

places a siliceous conglomerate lies with well-expressed 

unconformity immediately above beds accepted generally as Morrison (fMcElmo of Cross and others). 

In a few places this conglomerate with some sandy shale 

and thin-bedded sandstone constitutes most of the section between the Morrison and the Mancos, but in 

many places a basal conglomerate or its equivalent in 

sandstones is overlain by or interbedded with a series a 

few inches to 50 feet thick consisting of gray, red, green, 

or even variegated shales arranged as lenses or short 

regular beds. These beds seem out of place in the 

Dakota (?). They may represent reworked material 

brought in from Morrison or post-Morrison areas that 

were exposed to erosion while the lowest gravel of the 

Dakota (?) was being laid down in stream channels. 

It is possible, however, that these shales together with 

the underlying conglomerate are parts of an undefined 

formation of pre-Dakota (?) age. ~ In mapping the 

economic geology of southwestern Colorado Coffin 40 

used the terms "Dakota", "pre-Dakota", and postMcElmo" for subdivisions of the Cretaceous lying 

above clearly recognized tMcElmo (Morrison). His 

reasons for introducing new terms are given as follows:

Certainly the massive sandstone conglomerate and the unconformity used as the upper limit of the McElmo mark a definite 

change of conditions of sedimentation. Above this massive 

stratum are beds of more or less pure limestone, massive beds of 

chert, and much green shale strata the like of which have never 

been included in the Dakota. As there are no fossils to aid in the 

proper placing of these beds, lithologic character and stratigraphic position alone remain as usable evidence of their age. 

* * * The character of these beds would not admit of their 

inclusion'in the "Dakota" even with the qualified application of 

this term. Further, to place them in the McElmo formation 

would require the use of this term in a sense different from that in 

which it was first applied to strata in McElmo Canyon.

Properly to place the lower limit of the Dakota (?) is 

but part of the Dakota-Morrison problem. The exact 

age of these formations and the stratigraphic units 

that constitute them a're alike imperfectly known.

CRETACEOUS FORMATIONS

DISTRIBUTION AND TOPOGRAPHIC EXPRESSION

As noted by Newberry 41 and also by Holmes,42 

strata of Cretaceous age (Dakota (?) and lowermost

« Coffin, R. C., Radium, uranium, and vanadium deposits of southwestern 

Colorado: Colorado Geol. Survey Bull. 16, pp. 97-112,1921.

« Newberry, J. S., Geological report, in Report of the exploring expedition from 

Santa Fe, N. Mex., to the junction of the Grand and Green Rivers of the Great 

Colorado of the West, in 1859, pp. 10, 104-105, 1876.

« Holmes, W. H., Geological report on the San Juan district: U. S. Geol. and Geog. 

Survey Terr. 9th Ann. Rept., pp. 257-264, pis. 35, 36, 1875.

Mancos) flank the Abajo Mountains and floor Sage 

Plain; elsewhere in the San Juan country they have 

been removed by erosion. "Westward they terminate 

abruptly in cliffs bordering Dry Canyon, middle Cottonwood Canyon, and Butler Wash and next appear in the 

Henry Mountains and the Kaiparowits Plateau, 70 to 

90 miles distant. Southward the Cretaceous of Sage 

Plain ends in narrow interstream plateaus and detached 

mesas that above Aneth directly overlook the San 

Juan River but farther west recede 5 to 10 miles. The 

beds that terminate along Butler Wash and Cottonwood 

Canyon reappear in Black Mesa, in the Navajo country, 

50 miles south of the San Juan. The northern limit of 

the Cretaceous in the San Juan country is the crenulated escarpment at the heads of the streams that drain 

Dry Valley, north of Monticello. Eastward the strata 

continue with little change far beyond the Utah line; 

in fact, the Cretaceous strata in southeastern Utah 

are but short extensions of equivalent beds in the huge 

Cretaceous deposits of southwestern Colorado. Over 

most of the area in which Cretaceous strata are present 

the Dakota (?) sandstone forms the surface, in many 

places bare or thinly coated with patches of soil. But 

scattered over the Dakota (?) on Sage Plain are small 

mesas, buttes, and broad, flat mounds of Mancos shale, 

and near the Abajo Mountains the shale is sufficiently 

thick and continuous to conceal the Dakota (?) except 

in' canyons. The Mancos is readily distinguished from 

the Dakota (?), however, and these two formations 

from the Morrison beneath. On plateau faces and in 

canyons the exposures are everywhere alike brilliantly banded and variegated slopes (Morrison) 

capped by a gray and brown vertical cliff (Dakota?) 

over, which lie sprawling masses of blue-gray crumbling 

gullied shale (Mancos). In the absence of the protecting Mesaverde sandstone, the Mancos is openly 

exposed to the attack of erosive agents, to which it 

readily yields. Much of the mud dumped into Recapture, Montezuma, and McElmo Creeks comes directly 

from areas of 'this shale. In contrast with its function 

in the Mesa Verde Plateau, the Mancos in the San Juan 

country takes no part in forming great cliffs. The 

Dakota (?), however, is a maker of prominent cliffs. 

It is the most resistant of the sandstones in this region 

and is favorably placed with reference to the friable 

underlying Morrison shales. For this reason it forms 

the rims and box heads of main and tributary canyons 

and caps outlying mesas. The lofty Shay Mountain 

owes its preservation to a cap of Dakota (?) sandstone. 

The presence of impervious though friable shale immediately below porous sandstone makes the base of the 

Dakota (?) a zone of erosion by ground water. On 

many cliffs weathering at this horizon has produced 

recesses and wide-mouthed caves chosen by the Cliff 

Dwellers as building sites. Deepening of these recesses 

undermines the ledges until huge blocks are broken off. 

On slopes below the rim of West Water and Devil
CRETACEOUS FORMATIONS 61

Canyons slabs of Dakota (?) sandstone measuring as 

much as 30 by 15 by 10 feet were seen, and about the 

highest peaks of the Abajo Mountains talus blocks are 

much more abundant than outcrops of beds in place.

On Sage Plain the Cretaceous sediments are nearly 

horizontal, forming a floor broken only by canyons. 

Where upturned on the flanks of the Abajo Mountains 

they form hogback ridges, the steeper ones worn into 

pinnacles along their crests. Parts of beds carried 

upward by igneous intrusions lie in various positions.

DAKOTA (?) SANDSTONE

IITHOIOGIC FEATURES

As represented in the San Juan country, the Dakota (?) is a group of sedimentary rocks, rather than a 

bed or a mass of homogeneous material, traversed by 

bedding planes. Its persistent general features are 

predominance of sandstone, lenticular arrangement, 

cross-bedding, and wide range in composition, color, 

and thickness of the subordinate shale. Its outstanding local feature is coal. The sandstone is prevailingly 

coarse, much of it conglomeratic. Most of the material 

called "shale" is in reality thin-bedded sandstone, and 

even the coals and the layers of macerated plants are 

mingled with sand. The formation is everywhere 

lenticular: few beds of uniform thickness and texture 

are continuous for as much as 50 feet. Thick wedges, 

thin wedges, and curved lenses of conglomerate, coarse 

sandstone, fine sandstone, and shale overlap or end 

abruptly and are replaced along the strike by different 

materials. Some masses of coarse sandstone are completely surrounded by shale, and at a place on Alkali 

Creek conglomerate borders a coal bed. Most of the 

individual beds are likewise irregularly lenticular. The 

sandstones are commonly cross-bedded. In the coarser 

ones straight laminae meet each other at various angles; 

in the finer ones curved laminae also appear. In places 

the parting planes between laminae are so evenly 

spaced as to outline readily worked building blocks.

Plant impressions on sandstone were observed at 

several localities, also cobbles of petrified wood. Sun 

cracks, ripple marks, and worm tracks are common in 

the shales and in the finer-grained, even-bedded sandstone. Local lateral unconformities and features due 

to channeling are conspicuous.

In composition and texture the Dakota (?) varies 

widely. The coarser parts consist chiefly of subangular 

pebbles that average less than half an inch in diameter 

but include strings of pebbles 1 to 3 inches in diameter. 

The most abundant pebbles are white, gray, and brown 

quartzite and quartz, but black and white chert, 

feldspar, and dense black limestone are fairly common. 

The conglomeratic beds include also angular fragments 

of greenish-white mud shale 2 to 6 inches long, rounded 

shale balls and sand balls, short slabs of sandstone, 

ironstone and sand-lime concretions, and tiny chunks of 

carbonized wood. At a place on middle Recapture

Creek angular fragments of chert and chalcedony constitute as much as one-tenth of a bed 20 feet thick, and 

in specimens collected in upper Big Canyon the only 

large grains are kaolinized feldspar.

The cement of the Dakota (?) is calcareous, ferruginous, and siliceous. At outcrops where calcite forms 

the cement the rock readily crumbles, sand piles replace 

talus, and holes bored by bees appear in the soft finergrained beds. The much more abundant iron cement 

holds the pebbles firmly together, forms hard black 

concretionary masses, and gives dark-brown and yellow 

tones to exposed surfaces. The black color patches on 

many ledges and the glistening black coating (desert 

varnish) of boulders on Black Mesa and along the 

Blanding-Bluff road are doubtless derived from the 

iron cement. Where the cement is siliceous the rock 

is especially resistant. It breaks about as readily 

through the constituent pebbles as around them and 

forms the least-weathered cliffs in the region. At 

contacts with igneous rock on the Abajo Mountains all 

beds, regardless of texture, composition, and cement, 

have been metamorphosed to quartzite. The weathering of.the lime cement, the removal of mud pellets and 

sand balls, and the decomposition of the feldspar and 

vegetable remains have given the Dakota (?) a porosity 

which fits it for a ground-water reservoir. : ;

STRATIGRAPHY AND CORRELATION

The Dakota (?) of the San Juan country includes the 

sandstone and conglomerate beds, the shale, and the 

thin seams of coal that lie between the thick Morrison 

formation (Jurassic) and the remnant masses of fossiliferous shale (Mancos) of Benton age. The base of 

the formation in' many places is a bed of gray conglomerate that lies unconformably above brightly 

colored Morrison shales or sandstones, but in sections 

measured along Butler Wash and Montezuma Creek 

the lowest beds are white sandy shale. The top of 

the formation likewise is in some places a single bed 

of coarse sandstone, in other places thin-bedded brown 

sandy shale that grades conformably upward into 

gray-blue fossiliferous shale, so that the plane of contact of Dakota (?) with Mancos cannot be drawn 

with assurance. For the region as a whole the total 

thickness of beds assigned to the Dakota (?) is less 

than 200 feet. The thinnest section measured is 

92 feet..

In most sections measured three subdivisions are 

recognizable (1) a basal conglomerate with subordinate shale; (2) thin-bedded sandstones, shales, and 

coal; (3) sandstone, most of it coarse or conglomeratic. 

In color, thickness, composition, and continuity these 

subdivisions show great variation. Their constituent 

beds interfinger to such a degree that no two sections 

have the same sequence. The bottom subdivision 

in 14 sections measured ranges in thickness from 20 

to 65 feet. (Thorpe records 84 feet in a well hole
62 THE SAN JUAN COUNTRY. SOUTHEASTERN UTAH

iy2 miles east of Monticello.) In six of the sections 

this subdivision is essentially a massive cross-bedded 

stratum; in the others it consists of two or more lenticular conglomeratic or sandstone beds with thin 

sandstones beneath and shale, a little carbonaceous 

material, and impure limestone here and there on 

parting planes. (See sees. 27 and 28, p. 78.)

The middle subdivision ranges in thickness from 10 

to more than 60 feet. Along lower Recapture, Montezuma, and McElmo Creeks it constitutes 3 to 15 percent of the Dakota (?) present; on northern Sage 

Plain about 20 to 50 percent. Most of the beds are 

thin, platy sandstones, but this subdivision includes 

layers of red, brown, green, gray, and black shales, 

also coal. A little carbonaceous shale but no coal 

beds were observed in sections studied along Big 

Canyon, West Water Canyon, and lower Recapture 

and Montezuma Canyons, but earthy coal is common 

at Monticello, and farther east these beds become 

persistent and in places thick enough to mine. (See 

p. 110.)

The topmost subdivision, -where its surface has not 

been reduced by erosion, is 30 to 80 feet thick. The 

highest figures are for outcrops at the northeast base 

of the Abajo Mountains. Like the sandstone at the 

base of the formation, those at the top are displayed 

as massive beds or thick short lenses. In general 

they are less coarse but include conglomerates with 

pebbles an inch or more in diameter. In places the 

coarse, thick, strongly cross-bedded strata are replaced by thin, regular sandstone beds or even by 

shale.

Having La mind the lithologic differences on which 

subdivisions of strata classed as Dakota (?) are based 

and especially the significance of the coal-bearing 

shales between beds of coarse sandstone, Boyer and 

Lee 43 argued for the substitution of the term "Dakota 

formation", as applied by Cross,44 for the more widely 

used term "Dakota (?) sandstone."

The stratigraphic and textural features of the 

Dakota(?) imply topographic and climatic conditions 

favorable for the deposition of sand and gravel in 

streamways and on deltas and for the accumulation of 

silt in water bodies shallow enough to permit the growth 

of swamp vegetation. The formation rests on an erosion 

surface which in pre-Dakota(?) time approached baselevel throughout southern Utah and northern Arizona. 

The mud lumps, sand balls, and fragments of limestone 

and of highly colored shales in the basal Dakota (?) beds 

and colored shales higher in the section suggest reworking of sediments derived from the underlying Morrison

« Boyer, W. W., and Lee, W. T., Coal in the Dakota (?) formation in southwestern 

Colorado and eastern Utah (manuscript on file in U. S. Qeol. Survey). Lee, W. T., 

Continuity of formations in Colorado and Utah (manuscript on file in U. S. Oeol. 

Survey).

4 'Cross, Whitman, U. S. Qeol. Survey Qeol. Atlas, Telluride folio (no. 57), 1899.

or post-Morrison beds. The dominant pebbles of 

quartzite and quartz were derived from unknown, 

distant sources. The sequence and composition of beds 

and the local unconformities indicate progressive 

changes, but with many interruptions, from a forested 

landscape marked by streams and fresh-water ponds to 

one that included bodies of brackish water and to a final 

complete submergence by an advancing sea. As elsewhere in the plateau province, the clastic lignitic deposits 

that constitute the Dakota (?) of the San Juan country 

are believed to represent a basal phase of Colorado 

deformation an oscillating progression from near-shore 

to marine sedimentation.

For the San Jaun country the fragmentary invertebrate fossils in the shaly beds and the pieces of wood in 

the conglomerates are not sufficiently diagnostic to 

place the Dakota (?) accurately in the time scale. But 

fossils, lithologic features, stratigraphic position, and 

regional relations prove equivalence with beds previously mapped as Dakota(?) in western Colorado, 

northern Arizona, and northwestern New Mexico. It is 

significant that the beds in the Dakota(?) pass without 

known interruption into those marked by a marine 

fauna of unquestioned Upper Cretaceous age.

MANCOS SHALE

The fossiliferous marine shales that conformably 

overlie the Dakota (?) in the San Juan country are 

undoubtedly the stratigraphic and lithologic equivalents of the lowermost beds in the Mancos shale prominently displayed in the Mesa Verde Plateau south of 

Cortez, Colo. In that region the Mancos has a thickness of 2,000 feet and is overlain by great beds of 

Mesaverde sandstone. West of the Colorado line the 

Mancos is poorly represented and the Mesaverde is 

absent. Generally on Sage Plain the Mancos constitutes small mesas and ridges that rise 10 to 100 feet 

above the Dakota (?) sandstone. On the lower flanks 

of the Abajo Mountains, where, protected by piedmont 

gravel, sections show .thicknesses exceeding 200 feet, 

and near Baker ranger station, about 350 feet of Mancos 

sedimentary beds are preserved in a shallow syncline. 

Along the San Juan River below Aneth and west of 

Elk Ridge the formation is absent.

The Mancos is predominately steel-gray sandy shale 

but includes stringers of earthy coal, impure limestones, 

and many thin beds of fine-grained yellow and brown 

sandstone composed chiefly of subangular and angular 

quartz grains cemented by lime. Gypsum appears in 

some beds, and selenite crystals are common hi the 

talus. In some sections the sandstones are more 

numerous and closer together at a horizon 100 to 150 

feet from the base and form the caps of mesas. A 

generalized section of a butte 2 miles east of Blanding 

shows the following beds:
QUATERNARY FORMATIONS 63

Section of Mancos shale in butte 2 miles east of Blanding

Feet

3. Sandstone, impure, thin-bedded, lenticular, in part 

cross-bedded, some coal seams; the abundant fossils 

include shells of Ostrea, Exogyra, and Gryphaea newberryi......................................... 30

2. Shale, slate-colored, gypsiferous.._-__-__---_-----_. 40

1. Sandstone, gray and brown, fine-grained, in regular 

beds 3 inches to 4 feet thick, and sandy brown shales 

containing Inoceramus . fragments, Exogyra, and 

Baculiles. _____________________________________ 20

TERTIARY FORMATIONS

No sedimentary rocks of Tertiary age have been 

mapped in the San Juan country. Possibly the pebbles 

of calcareous sandstone and of concretionary limestone 

in the yellow, firmly cemented gravel that appears as 

small patches on the high mesas are fragments of 

Tertiary beds. Likewise some of the chunks of limestone, in the piedmont gravel of the Abajo Mountains 

may date from the Tertiary. That sediments and 

lavas of Tertiary age once covered all or part of this 

region is suggested by their presence in adjoining 

regions the Animas and Mancos Valleys of Colorado, 

the Chuska Mountains of New Mexico and Arizona, 

the Uinta Mountains and the High Plateaus of Utah.

It is probable that during Wasatch time deposition 

prevailed in southern Utah, southwestern Colorado, 

and northern Arizona but that the conditions of sedimentation in this vast area varied from place to place. 

The basal beds are not lithologic equivalents, the 

sequence is different, and in composition the beds are 

predominantly limestone, shale, or sandstone. The 

known parts indicate deposition in several basins, with 

here and there overlapping rims. It seems unnecessary 

to follow Button in assuming that all the Tertiary 

sediments of the Colorado Plateaus were laid down 

contemporaneously hi a single large depression.

QUATERNARY FORMATIONS

In the San Juan country sediments of Quaternary 

age include talus, wind-blown sand, gravel on rock-cut 

terraces, piedmont gravel, valley fill, and lacustrine 

deposits.

Talus in great quantity is piled about the spurs of 

the Abajo Mountains beneath the southern and eastern 

rims of Elk Ridge, along Red House Cliffs, and on the 

south wall of White Canyon. Small patches of talus 

cling to the walls of canyons of Red Rock Plateau, 

Grand Gulch Plateau, and Sage Plain. In general the 

talus is more abundant and more widespread than hi 

regions south of the San Juan River, but few slopes, 

are coated by it from top to bottom. The talus resulting from disintegration of the igneous masses of the 

Abajo Mountains, from the mounds of Mancos shale, 

and from the slopes formed on Organ Rock, Chinle, 

and Morrison shales consists of fragments of small size, 

but that from the Dakota(?) and Shinarump is made

up largely of huge blocks about which the climber must 

select his route with care.

The wind-blown sand is distributed as thin sheets or 

as small areas of dunes over plateau tops and along 

floors of washes; in no place is it a conspicuous topographic feature.

Gravel presumably of Quaternary age lies on the 

rock-cut benches along the Colorado, the San Juan, and 

other streams. On the bare rock surfaces of Bluff 

Bench, about 500 feet above the present San Juan, and 

on mesas west of Elk Ridge at much higher levels 

scattered pebbles and continuous sheets of well-worn 

quartzitic gravel occupy favorable positions. Gravel 

also coats terraces cut in canyon walls at several different levels above the present stream beds and partly 

covers the bottoms of high-level meanders no longer 

used by streams. Most of these deposits range in 

thickness from 1 to 5 feet, several measure 10 to 15 feet, 

and near the mouth of Recapture Creek and at a few 

other places they form huge piles as much as 50 feet 

thick. In composition and texture the gravel deposits 

differ in accordance with their source and the position 

of the streams which formed them. On Sage Plain the 

highest gravel represents rocks in the Abajo Mountains; 

that at lower levels is chiefly disintegrated Dakota (?) 

conglomerate. Along the San Juan, especially above 

Comb Wash, the gravel consists predominantly of 

quartzite in places as much as 80 percent with 

porphyries and other crystalline rocks of the kinds 

common in the San Juan, Ute, and Carrizo Mountains. 

The materials range in size from pebbles smaller than 

buckshot to cobbles a foot in diameter. Probably 75 

percent have diameters less than 2 inches. Below 

Comb Wash they include large amounts of Carboniferous limestone from the Goodridge region. All along 

the San Juan River sandstone fragments are also present, especially on the lower terraces, and at the mouths 

of some tributary streams they attain sizes exceeding 8 

feet in diameter. In Glen Canyon the "placer gravel" 

that covers the rock-cut terraces 5 to 60 feet thick 

consists of igneous, metamorphic, and sedimentary 

rocks in great variety and large range in size, much of it 

from distant sources. Gravel on the rock terraces 

along Red Canyon, White Canyon, and Dark Canyon 

is made up chiefly of sandstone and concretionary limestone from the bordering walls but includes many 

quartzite pebbles from disintegrating Shinarump conglomerate, which caps Elk Ridge and underlies mesas 

farther west. "'

Throughout the San Juan country the pebbles and 

cobbles that cover rock benches are well rounded, and 

many of them, especially those along the San Juan, are 

lens-shaped. In most places they are loosely piled 

without sorting, except that the large ones are near the 

bottom. In much of the gravel the spaces between the 

cobbles are devoid of filling, and a gravel bank quickly 

slumps down in excavations. In some deposits the
THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

cobbles at their points of contact are cemented by a 

mixture of fine sand and calcium carbonate. ID a few 

places, particularly where it rests in. channels, the gravel 

is firmly cemented, and on Wilson Mesa it forms the 

framework for a considerable mass of caliche.

The flanks of the Abajo Mountains are generally 

coated with coarse deposits of piedmont gravel. On 

the south, southeast, east, and northeast they form 

continuous bench lands between the mountain tributaries of Recapture and Montezuma Creeks and northwestward to Harts Draw. On the southwest, west, 

northwest, and north slopes of the mountains, about 

the headwater tributaries of Indian and Cottonwood 

Creeks, they are represented by isolated patches of 

coarse gravel that extend upward from the canyon rims. 

High on the mountain flank at altitudes of about 9,000 

feet the deposits are 10 to 50 feet thick; at the junction 

of mountain and plain, where regional slopes decrease 

from 20 feet in 100 to 7 feet in 100, Thorpe measured 

thicknesses as great as 150 feet. Outward from the 

mountain base the deposits gradually thin to a layer of 

loosely compacted soil spread over the country rock. 

As continuous exposures most of the gravel ends about 

7 miles from the mountains, but small thin patches lie 

on the Causeway, on mesas in the Alien Canyon country, and on Sage Plain east of Blanding. Isolated 

boulders of igneous rock and of metamorphosed sandstone that were once part of the piedmont gravel lie on 

the rock platforms along the San Juan. Narrow bands 

of piedmont gravel border parts of Elk Ridge; from its 

south edge they extend 3 to 4 miles. About the high 

mesas of Red Rock Plateau accumulations of piedmont 

materials are absent or inconspicuous; merged into the 

talus they form a collar of broken rocks between vertical 

rock walls and flat-lying sandstone surfaces. On the 

slopes of the Abajo Mountains the gravel consists essentially of angular and slightly rounded boulders of porphyry and sandstone identical in composition with the 

rocks exposed on the mountain peaks. Near the mountains fragments 5 to 8 inches in diameter are common, 

and with them are embedded blocks as much as 10 feet 

in diameter and also lenticular masses of coarse sand.

The once widespread, essentially continuous sheet of 

piedmont gravel is now much dissected. Its surface is 

trenched by many gullies and by a score of canyons that 

extend through the deposit and into the rock below. 

Over considerable areas it has been entirely removed. 

It seems obvious that the gravel was deposited in a 

previous physiographic cycle, probably in the late 

Pleistocene, when conditions were favorable for rapid 

aggradation.

Valley fill displayed as stretches of sand on the floor 

of the washes and in the terraces that border the 

streamways is a conspicuous feature in the San Juan 

country. In enormous amounts this valley fill, deposited, eroded, and transported with changing volume 

of streams, has been furnished to the canyons and broad,

shallow valleys by caving banks, landslides, wind-driven 

sand, and the debris swept from the surface by torrential 

rains. It is prevalently fine sand but includes also silt, 

gravel, boulders, and vegetable debris. (See p. .)

Lacustrine deposits are exposed here and there where 

swamps and lakes once stood. Most of them are mere 

patches on valley walls or thin beds exposed along 

streamways in recently drained swamps. In Lake 

Canyon at its junction with "East Branch", lacustrine 

sediments, about 80 feet thick, consist essentially of 

partly consolidated, extremely fine sand and silt 

arranged in strata less than one-tenth of an inch thick. 

They include near the top several layers of black peat 

2 to 4 feet thick, which contrast strongly with the 

otherwise nearly white beds. Minute fossil shells are 

abundant.

Glacial deposits are lacking on the Abajo Mountains, 

and if any part of the mountains was glaciated the 

traces have been obliterated. Thorpe reported "no 

cirques, no hanging valleys, no moraines of any kind 

not even indications of nivation except on the higher 

summits in certain limited localities." The absence of 

glaciation on the Abajo peaks (altitude about 11,000 

feet) is worthy of note, inasmuch as nivation is evident 

on Navajo Mountain (altitude 10,416 feet), and moraines 

appear on the High Plateaus at 10,000 to 12,000 feet, 

on the La Sal Mountains at 10,000 feet, and on the San 

Francisco Mountains at 9,700 feet. Some part of the 

piedmont gravel on the Abajo Mountains, especially 

that high on the mountain flanks, may be glacial drift 

in place, and doubtless streams of glacial tune carried 

much debris from the high lands; but the topography 

of the mountains is unfavorable for the retention of 

masses of snow sufficiently large and long-lived to permit the formation of actual glaciers. It seems probable that the gravel on the benches bordering the San 

Juan River in its course through Utah is, in part at 

least, the extension of outwash gravel from Pleistocene 

glaciers in the San Juan Mountains of Colorado.

STRATIGRAPHIC SECTIONS

1. Section of Hermosa and Rico formations at Honaker trail on 

San Juan River

[Measured as fQoodridge formation by H. D. Miser, U. S. Geol. Survey Bull. 751, 

pp. 127-129, 1924]

Rico formation: Feet

1. Gray hard fine-grained limestone; top bed of

formation. _ ______..__-____-_-_____-___-_ 2

2. Red earthy sandstone and sandy shale; gentle

slope.---------.----------------------- 31

3. Massive gray pitted cross-bedded sandstone

(Baby oil sand)__....._____..._.-__._._.. 2-12

4. Red earthy sandstone; forms gentle slope; 

layer of gray limestone 1 foot thick near 

top___-__-.--__------------------------ 15

5. Gray pitted soft friable sandstone; forms ledge

(Goodridge oil sand)___-----------__---__ 18

6. Gray coarse-grained fossiliferous limestone-..- 2

7. Red earthy sandstone and sandy shale; forms

slope._-_-----_------------------.----- 25
STRATIGRAPHIC SECTIONS 65

1. Section of Hermosa and Rico formations at Honaker trail on 

San Juan River Continued

Rico formation Continued. feet

8. Massive medium-grained fossiliferous limestone; sandy and cross-bedded; forms ledge 

at head of Honaker trail _-__---_-__._____ 20

9. Red and purple shales and sandstones; gentle

63

5

35

10. Gray pitted soft cross-bedded sandstone (Third 

oil sand) _______________________________

11. Red and purple shales and sandstones; gentle 

slope __-__---___---_-------------___--_

12. Gray pitted cross-bedded soft sandstone; ledge

(Mendenhall oil sand) ___________________ 30

13. Red shale and sandstone; slope. -__.-_-_____ 56

14. Gray thin-bedded medium-grained limestone; 

ledge; Woodruff's fossil lot 158 obtained 

from this bed. This is base of the upper 

Goodridge fauna__--_---_-----_-----__-_ 10

Total Rico----.--------.--------- 314-324

Hermosa formation:

15. Red and lavender sandy shales; slope-.-.--.- 27

16. Gray sandy limestone with black flint nodules. 12

17. Gray coarse-grained limestone with nodules 

of red flint; the base of this bed appears to 

be the horizon of the Little Loop oil sand. 

Woodruff reports a thickness of 3% feet of 

the sandstone on the Honaker trail. ____.- 8

18. Red, lavender, and gray sandy shales; slope.. 50

19. Red, lavender, and gray sandy shales containing coarse-grained fossiliferous limestone in 

upper half_____---___--_-----_--_-----_ 35

20. Compact dove-colored limestone; massive at 

top; grades downward into shaly limestone; 

contains nodules of jasper___.______.-__ 12}_

21. Massive compact dove-colored limestone with

nodules of variegated chert___________ _.__ 20

22. Gray and black shales with thin layers of limestone. --._---_---____-_----_-__----_-__ 10

23. Drab knotty limestone and some gray shale.. 18

24.. Cherty drab limestone and some gray shale.__ 25

25. Gray and lavender shales and some thin beds

of knotty limestone; slope._______--___._ 78

26. Massive gray coarse-grained limestone, free

from chert._-________------____________ 15

27. Limy gray shale.____.__-____--._----_____ 10

28. Cherty drab limestone.__________^_________ 6

29. Gray shale with thin layers of drab limestone

near top..._.___________-_-___-__-_-_._ 11

30. Massive compact dove-colored limestone;

breaks with conchoidal fracture_________ 8

31. Gray shale interbedded with equal amount of

gray fine-grained cross-bedded sandstone_ 11

32. Massive compact dove-colored limestone;

breaks with conchoidal fracture_--.-____ 8

33. Gray shale with beds of calcareous sandstone 

near top and base; cherty knotty limestone 

in lower half; slope____________________ ,49

34. Massive cherty fine-grained drab limestone. __ 3%

35. Gray shale and shaly limestone with a bed of 

knotty black chert in lower half; chert 

weathers brown______--_-_-__-_________ 33

1. Section of Hermosa and Rico formations at Honaker trail on 

San Juan River Continued

Hermosa formation Continued.

36. Cherty drab fine-grained massive limestone; 

forms top of point known as "The Horn", 

which overlooks canyon,________________

37. Brownish sandstdne-____-_--_-__-_--_---.-

38. Massive gray medium-grained limestone with 

chert nodules_--_-_--_--_-__-__-______

39. Knotty and cherty limestone in "upper part; 

grades upward into overlying bed and 

grades downward into gray shale in lower 

part._______-_--____--__---_-_-_-_--__

40. Cherty drab limestone.__-____-____--______

41. Limy gray shale.______-___-____-------___

42. Massive drab limestone..__________________

43. Concealed._______________________________

44. Massive drab fine-grained cherty limestone. __

45. Massive drab sandy limestone______________

46. Drab sandy shale, grading into overlying bed.

47. Gray shale containing knotty black chert.___

48. Black papery shale.________________________

49. Gray shale and drab limestone interbedded; 

crops out on bench along which trail runs 

to north for .half a mile or more. _________

50. Dove-colored fine-grained massive limestone; 

7 feet below top 1 foot of limestone contains sulphur in cavities as much as 1 inch 

in their longest dimension______________

51. Limy gray shale with a few nodules of black 

chert near base.________________________

52. Shaly limestone and sandy limestone with 

black chert nodules.____________________

53. Drab sandy fine-grained limestone._____-.__

54. Massive, compact drab limestone with black 

chert nodules in upper part-_______-!__-...

55. Sandy gray shale..._______________________

56. Drab limestone with black chert nodules.__-_

57. Drab limestone with nodules of black chert_

58. Limestone like that above but more massive __

59. Yellow cross-bedded fine-grained sandstone _.

60. Concealed._______________________________

61. Massive drab fine-grained limestone, grading 

into earthy sandy limestone below. _______

62. Sandy and limy gray shale_____.__-_._____

63. Thin-bedded drab limestone________ ________

64. Sandy and limy gray shale.____.___._-_-__-

65. Drab thin-bedded limestone________________

66. Sandy and limy gray shale.________________

67. Drab limestone.__________________________

68. Calcareous fine-grained gray sandstone.______

69. Drab cherty. limestone.__-________.-____-__

70. Calcareous sandstone._______----___-___-__

71. Massive drab cherty limestone._____________

72. Limy gray sandstone._____________________

73. Cherty drab sandy limestone.______________

74. Limy fine-grained gray sandstone.__________

75. Sandy gray shale..________________________

76. Massive drab limestone,___________________

77. Calcareous fine-grained gray sandstone. _____

78. Talus to river____________________________

Feet

11

5

30

16

4

4

25

5

10

30

25

15

5

Total Hermosa__--__---_-_--__-_-_. 985 

Total exposed thickness of f Goodridge

formation.___.._.____..____ 1, 299-1, 309
66

2. Section of top part of Rico (?) formation in Dark Canyon between 

Poison and Trail Canyons

Cedar Mesa sandstone member of Cutler formation. 

Unconformity.

Rico (?) formation: Feet 

10. Limestone and limestone conglomerate in short 

lenses separated by irregular masses of red and 

gray shale; includes fragments of brown sandstone and red chert; thins along strike; fossils 

of lot 3 (see below) probably from this horizon. 6

9. Sandstone, white, red-streaked, and red, whitestreaked, calcareous, thin, irregularly bedded, 

friable; upper part dense, platy, cross-bedded; 

weathers in round-edged beds _._____-___-.-_ 60

8. Sandstone, gray, calcareous.._______________ 11

7. Shales and thin sandstones, red.______________ 32

6. Sandstone, white, very calcareous; fossils of

lot 2__.______.__.__...__.___,_._..._.... 20

5. Shale, sandy, thin mudstones, or fine-grained

sandstones, red.__________________________ 6

4. Limestone, gray, sandy, lenticular, conglomeratic

in part; fossils of lot l____________-_-______ 15

3. Sandstone, red, white-streaked, calcareous; in 

part cross-bedded and lenticular; breaks into 

thin beds; includes aggregates of calcite 

crystals, iron-lime concretions, and some 

fossil wood________-________i______________ 70

2. Sandstone, white, dense, very calcareous; shale at 

base; mottled purple and green; a prominent 

ledge.___________________________________ 9

1. Limestone, gray, sandy in upper part (base not

exposed)_______________________________ 10

Total Rico (?) measured.____________ 239

The fossils from Dark Canyon, collected in association with Arthur A. Baker and E. T. McKnight, were 

determined by George H. Girty in connection with a 

study of specimens from the Indian Creek region. 

Girty reports:

All the collections appear to be of Permian age, though those 

from Dark Canyon show certain peculiarities in their pelecypod 

representation not shown in those from Indian Creek, Salt 

Creek, etc. The,Dark Canyon collections contain suggestions 

of the Manzano fauna; the other collections .contain suggestions 

rather of the Rico. Neither group of collections presents a 

facies at all comparable to the Kaibab fauna.

Lot 1:

Aviculipecten sp. 

Bellerophon sp.

Lot 2:

Fenestella sp. 

Spiriferina kentuckyensis. 

Composita subtilita. 

Nucula levatiformis. 

Schizodus curtiformis? 

Deltopecten occidentalis. 

Streblopteria? sp. 

Pseudomonotis? sp. 

Pteria sulcataPteria longa.

Patellostium? sp.

Pteria sp. 

Monopteria? sp. 

Myalina perattenuata? 

Pleurophorus sp. 

Astartella subquadrata. 

Cypricardinia? sp. 

Euphemus? sp. 

Bulimorpha? sp. 

Aclisina? sp. 

Griffithides sp.

Lot 3:

Composita subtilita. 

Edmondia gibbosa. 

Nucula levatiformis. 

Schizodus sp. 

Deltopecten occidentalis. 

Deltopecten sp. 

Pseudomonotis sp. 

Myalina aff. M. perattenuata. 

Pteria longa.

Point between Lavender (?) and Davis Canyons, at base of 

white sandstone (Shinarump):

Pteria sulcata. 

Plagioglypta canna? 

Bucanopsis bella? 

Euphemus carbonarius? 

Goniospira? sp. 

Euconospira? sp. 

Sphaerodoma fusiformis. 

Naticopsis aff. N. nana.

Spirorbis sp. 

Edmondia gibbosa? 

Nucula levatiformis. 

Deltopecten occidentalis.

Aviculipecten sp. 

Pteria sulcata. 

Pleurophorus sp.

Feel

0-5

3. Section of Permian rocks in Arch Canyon 

[Combination of tbree sections spaced about 1, 5, and 7 miles from mouth of canyon

Cedar Mesa sandstone member of Cutler formation. 

Unconformity: uneven surface overlain in places by conglomerate; in other places massive sandstone fills depressions eroded in lower beds.

Halgaito (?) member of Cutler formation and Rico (?) 

formation:

12. Limestone, blue gray, earthy, in part conglomeratic, irregularly interbedded with lumpy masses 

of red sandstone and gray and slate-colored 

mud shales; includes much red chert and fragmentary shells; in places absent; forms bench 

in front of white cliffs____________________

11. Sandstone, mudstone, or sandy shale, red, calcareous, very fine-grained; in places forms compact, seemingly massive ledges 1 to 8 feet thick 

but generally splits into thin curved or flat 

beds; includes lenses of brown conglomeratic 

limestone and of mottled gray shale. Near 

Angels Arch the sandstone is dominantly white 

(weathering buff) and strongly cross-bedded; 

at Cathedral Arch the lower half of the unit 

consists of alternating beds of red, brown, 

white, and purple shale and white sandstone; 

one carbonaceous bed_________________ 180-210

10. Limestone, gray, firm, in three to seven regular 

beds; in places conglomerate with tiny lime 

concretions; fossils determined by George H. 

Girty as Septopora sp., Orbiculoidea aff. 0. 

meekana, Composita subtilita, Deltopecten occidentalis, Pleurophorus sp., Bellerophon sp.; 

absent in places_________________________ 0-6

9. Sandstone or mudstone, light red, thin, irregularly bedded in places; a series of alternating 

red and white beds, some of them crumpled 

and otherwise distorted--... ___;._-_________ 8-35

8. Limestone and red and blue-gray shale; jumbled 

mass of shale fragments, knobs, stringers, and 

lenses of limestone and red chert in pancakes, 

balls, and elongated forms; in some places 

merges into no. 10, in others represented only 

by chert; rests on eroded surface of no. 7___ %-5 

Unconformity.
STRATIGRAPHIC SECTIONS 67

3. Section of Permian rocks in Arch Canyon Continued

Halgaito (?) member of Cutler formation and Rico (?) 

formation Continued. Feet

7. Sandstone; thinly foliated or sandy shales in uneven bands of red and white that along the 

strike range in thickness from 6 inches to 13 

feet; one section shows massive white-streaked 

cross-bedded sandstone 22 feet thick; includes 

thin short lenses of limestone and porous calcareous material like travertine; upper and 

lower parts discontinuously separated by plasters of white mud balls and slabs._________ 23-56

6. Limestone, blue-gray, fossiliferous, in places conglomeratic; not everywhere present________ 0-4

5. Shale, sandy, or mudstohe, red_____________ 3-8

4. Sandstone, white, highly calcareous, friable;

weathers as a slope_____________________ 6-14

3. Limestone, blue gray, friable; observed in one

section only_________--______-__-__-_--___ 0^3

2. Shale, red brown, sandy, flaky, in part imbricated, slightly gypsiferous, and sandstone, 

white, red-streaked; near Cathedral Arch includes a 2-foot bed of knobby, earthy, gray, 

sparingly fossiliferous limestone and a 6-inch 

bed of dense blue-gray limestone________ 42-56

1. Sandstone, red, blotched and streaked with 

white, very fine-grained; lowest stratum measured in Arch Canyon______________________ 204-

Total thickness of beds represented, approximately. _______________________ 350

4. Section on east flank of Raplee anticline west and southwest 

of Navajo Springs

[Beds dip 20°-50° E. Nos. 52-96 measured 2 miles north of nos. 1-51]

Floor of Comb Wash.

Moenkopi formation: peet

96. Sandstone, greenish white, gypsiferous; splits into 

shale-like beds that crumble readily to sand; 

base not exposed.________________________"_ 35

95-90. Shales and thin sandstones, brown; a few 

white bands; in part regular- and evenbedded, in part lenticular; some crossbedding; many weathered slabs show rill 

marks, mud cracks, and abundant ripple 

marks._.___--__---_-____._.____________. 82

89. Sandstone, brown, with streaks and beds a few 

inches thick of white sandstone; verjj irregularly bedded; at base lenticular beds of greenwhite mud shales-----------_---__-_-__-___ 24

Incomplete Moenkopi________________ 141

Unconformity: regional erosion surface not clearly shown

in this section.

De Chelly sandstone member of Cutler formation (Permian) :

88. Sandstone, light red to buff, massive, strongly 

cross-bedded; at the base includes lenses and 

thin beds of shaly sandstone; prominent horizon marker; thickness estimated ____________ 80

4. Section on east flank of Raplee anticline west and southwest 

of Navajo Springs Continued

Organ Rock member of Cutler formation: Feet 

87-73-. Shale and sandstone like nos. 71 and 72, red, 

somewhat darker color and more solidly 

bedded toward top; at a distance appears 

fairly even-bedded but in detail shows much 

irregularity; some cross-bedding; a few 

white bands___-------_-__-_-__--_-____-__ 404

72. Sandstone, fine-grained, calcareous; appears 

massive but splits on weathering into thin 

slabs____--______-____-___-__-____-__-__ 4

71. Shales, sandy, or thin mudstones, fine-grained;

weather to flat and curved cliffs.___--______. 55

Total Organ Rock member_____________ 463

Unconformity (?); suggested by abrupt change in color, 

texture, style of bedding, and topographic expression. 

Cedar Mesa sandstone member of Cutler formation, 

typically thick-bedded:

70. Limestone or highly calcareous sandstone, 

unevenly lenticular; many foliation surfaces; 

includes aggregates of calcite crystals and 

some chert; along strike becomes conglomeratic, with gray limestone concretions and 

fragments of brown sandstone. ------.--

69. Sandstone and shale, like nos. 62-67. __________

68. Shale, light red; weathers to thin chips like mica; 

includes two lenses of nodular limestone, 

each about 3 inches thick; persistent for long 

distances. _____-___-___---_-__---_-_-l----

67-62. Sandstones, white, calcareous in part, crossbedded, 2 to 5 feet thick, and red sandy mud 

shales, irregularly bedded-.---.. .__--______

6L Sandstone, white, very fine-grained, even-bedded; 

red-purple band at bottom and top __-___-_.

60-56. Shales or thin sandstones, light red, slightly 

gypsiferous, interbedded with white calcareous cross-bedded sandstones 6 inches to

2

37

12

26

3

45

55. Limestone, nearly black, lumpy, concretionary; 

joint cracks filled with gypsum; bed traced for 

half a mile..-. -_-_--------------_-----_--

54. Shale and thin sandstones in fairly regular beds, 

red and gray; much gypsum in seams, beds, 

and disseminated in rock; weathers to rounded, 

powdery knolls; largely concealed.. _ -_.__-_-

53. Gypsum, white, interbedded with dark sandstone; includes limestone concretions and 

chert; a lens about 400 feet long. ___________

52. Sandstone, light red and white, in thin irregular 

beds, gypsiferous; includes thin, short lenses 

of earthy limestone--...-------.---------.

51, Sandstone, buff, cross-bedded, massive, thickness 14 to 30 feet... ____ -------- __ ___.

50. Shales, red, white-banded___------_-_----__-_

49. Sandstone, buff to white, cross-bedded, in places 

stained red; thickness along strike increases 

to 18feet_-____________---_---___---_-_.-

48-41. Shales, red, sandy, gypsiferous; crumble to 

powder; interbedded wfth white to pink slabby 

sandstone in beds a few inches thick; includes 

a few thin short lenses of earthy limestone-.-

140

138

22

5

30

146824 3*
68 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

4. Section on east flank of Raplee anticline west and southwest 

of Navajo Springs Continued

Cedar Mesa sandstone member of Cutler formation 

Continued. ' Feet

40. Sandstone, white to1 buff, massive, cross-bedded 

on large and small scale; in places separated 

into lenticular beds by red clay shale._______ 35

39. Sandstone or arenaceous limestone, white and 

purple; extremely irregular in bedding and 

texture; includes red chert, gray mud lumps, 

and concretionary aggregates of hard blue 

limestone; top is porous; a prominent bed that 

along the strike is 3 to 15 feet thick_________ 7

38-35. Sandstone, white, in uneven lenticular beds 

2 to 15 feet thick, interbedded with variegated 

sandy gypsiferous shale; 1,000 feet to the 

north along the strike becomes cross-bedded 

white, red-stained sandstone; to the south 

becomes more than half shale; forms steep 

slope banded dark reddish white and grayish 

yellow_ _ ________-__-___---__--_------__ 64

34. Limestone, nearly black, composed of pellets and 

irregular forms; much white and red chert at 

the base._____-________..-.._..______-___,-__ %-l

33-30. Shale, light red to pink, gypsiferous,' increasingly arenaceous toward top; includes 

irregular lenses of white cross-bedded calcareous sandstone as much as 8 feet thick.__ 36

Total Cedar Mesa member_____.-_.__-- 610

Unconformity (?).

Halgaito member of Cutler formation:

29. Limestone, gray, black-spotted, conglomeratic, 

with pellets and lozenges of concretionary 

limestone, clay mud balls, and fragments of 

red shale; thickens, thins, or disappears as 

traced along the strike.-____-_-___________- 0-1

28-20. Shale and sandstone, red, like no. 1; at 42 

feet above the base includes a lens of 

greenish-white mud lumps_________________ 97

19. Sandstone, red, poorly bedded, slightly gypsiferous; in three divisions separated by brightred shales; some specked with mica; shows mud 

cracks, worm trails, and impressions of plants; 

forms prominent step___________________ 28

18-12. Shale, red, like no/ 1; slope of sandy unevenly 

bedded shale crossed by round-edged steps of 

sandstone 3 to 6 feet high; includes 3-inch 

lens of nodular limestone 6 feet above the base. 116 

11. Sandstone and shale, red, purple, and white; very 

irregular, lumpy; rests on wavy surfaces of 

no. 10_------_-----_-_-_---_--_--_-__--_- 2

10. Limestone, gray, sandy, resistant; forms cap of

local mesas_____________________________ 1

9. Shale, red, like no. 1_________________________ 6

8. Sandstone, gray, very calcareous,'firm, in evenly 

foliated beds about 2 inches thick; forms low 

escarpment for more than a mile.___________ 5

7. Shale, like no. 1; top 12 feet compact and forms

cliff _____________________________________ 35

6. Sandstone, grayish brown, red-stained along 

strike; represented by two beds separated 

by 4 feet of red shale_____________________ 8

5. Shale, red, like no. 1_________________________ 14

4. Limestone, gray, irregular lens; disappears along 

strike ___________________________________

4. Section on east flank of Raplee anticline west and southwest 

of Navajo Springs Continued

Halgaito member of Cutler formation Continued. Feet 

3. Shale, red like no. I--.----------------.---.- 12

2. Limestone, blue gray, nodular._______-___-__- 1

1. Shale, sandy, red; in places appears as sandstone 

in beds as much as 12 feet thick, which, 

however, split readily into thin sheets with 

glistening surfaces; some mica; at 12 feet from 

base thin band of slabby limestone __________ 76

Total Halgaito member._________________ 402 +

Unconformity?

Rico formation (Permian): Top bed is cherty limestone

2 feet thick; depressions in its upper surface filled with

intermingled red, yellow, and blue-gray shale.

In the foregoing section the thicknesses of units are 

approximate, and the boundaries of the members below 

the De Chelly sandstone are tentative. Local unconformities, abrupt changes in composition and texture 

along the strike, and marked differences in sequence 

of sections no more than 1,000 feet apart are features 

subject to more than one interpretation. Likewise 

variation in dips and the concealment of outcrops by 

disintegration of gypsiferous beds prohibit satisfactory 

measurements by clinometer-compass and pacing.

5. Section of Halgaito member of Cutler formation in Johns 

Canyon

Cedar Mesa sandstone member of Cutler formation.

Unconformity (?).

Halgaito member: Feet 

21. Sandstone, dark red, fairly coarse-grained, some 

mica and feldspar; most of it in regular beds 

about one-eighth inch thick that weather as 

slatelike slabs as much as 3 by 6 feet; at the 

top a bed of white sandstone 3 feet thick 

marks a horizon of springs and seeps..------ 16-30

20. Sandstone, nearly black, nodular, and dark-red, 

white-streaked shales intermingled as fragments and lenses that suggest reworking of 

material; zone of unconformity(?)----------- 3-8

19. Sandstone, light red, most of it even-bedded;

some ripple marks; forms cliff______________ 20

18. Shale, dark red, streaked with white, argillaceous, 

arranged in thin lenses; surface sun-baked and 

ripple-marked. _ __________________________ 2

17-16. Mudstone or shaly sandstone, red, with four 

lenses of limestone conglomerate; much like 

no. 14; at the top is a persistent band of white 

sandstone about 6 inches thick _____________ 54

15. Sandstone and shale, forming a cliff: (1, at bottom), gray massive calcareous muscovitic 

quartz silt, coarser in grain than red beds 

below, with vertical tubes like worm holes 

filled with yellow earthy limestone, 9 feet; (2) 

even-bedded blue-gray clay shales, 1 foot; (3) 

black massive, very fine-grained carbonaceous 

sandstone decorated with white circles and 

cylindrical areas that resemble worm holes or 

root tubes, 6 feet; (4) yellow and gray evenbedded clay shales, 2 feet. This series is absent from a section 2 miles distant; it seems 

to occupy a local depression._____.___-_-_-_ 18
STRATIGRAPHIC SECTIONS 69

5. Section of Halgaito member of Cutler formation in Johns 

Canyon Continued

Halgaito member Continued Feet 

14. Mudstone or shaly sandstone, red, like no. 1; 

some disseminated gypsum; a few thin, short 

lenses of limestone and of white sandstone; 

forms steep slope__.___----_-___---_____-_ 244

13. Limestone conglomerate; persistent as bed 6 

inches to 2 feet thick for nearly half a mile 

along strike. . ____________________________ 1

12. Mudstone, red, shaly, like no. l__--_-_---__--_ 25 

11. Limestone, dark purple, composed of angular 

fragments, aggregates, and concretions of 

limestone; capped by bed of white sandstone. _________-_______---------__-.__-_-_ 4

10. Mudstone or shaly sandstone, light red, in thin, 

flat, and curved beds; like no. 1, but includes 

two thin beds of limestone conglomerate, each 

capped by a layer of white sandstone; forms 

slope broken by benches. __------------_--_ 82

9-7. Limestone, blue gray, nodular, resistant, 5 feet 

thick, overlain in turn by 5 feet of white finegrained sandstone that contains lenses of 

limestone conglomerate and 2 feet of lumpy 

red shale; forms cliff. _____________________ 12

6. Mudstone, red, shaly, or thin-bedded lumpy sandstone; abundant brown iron concretions and 

aggregates of white quartz grains __ ________ 16

5. Sandstone, white, hard, glistening, very fine,

even-grained; traced 1,000 feet along strike __ 1 

4. Mudstone, shaly, red, like no. 1__ _____________ 5

3. Sandstone, white; weathers buff; appears massive but splits readily into fairly even slabs 

about 4 inches thick; abundant dark-blue 

and black concretionary masses that simulate 

plant stems __ ________---__-_--_-----_--- 6

2. Limestone, dense, gray, in lenticular beds; forms

Shale, sandy, thin sandstone or sandy mudstone, 

maroon to dark red-purple; composed essentially of poorly rounded grains of quartz invisible to the naked eye. some specks of iron, 

muscovite, and red feldspar cemented with 

lime-iron-clay mixture; beds regular but lack 

uniformity in details; tops and bottoms are 

lumpy and otherwise irregular; the most 

shalelike beds split into layers about oneeighth inch thick; most of the sandstonelike 

beds, 3 inches to 6 feet thick, have no division 

planes; some are cross-bedded and are represented in the talus by irregular blocks and by 

fiat and curved chips; includes a band of 

white sandstone; forms slope. _ _-__---__-._ 27

Total Halgaito^member. _________________ 459

Rico formation (Permian); top is bed of blue-gray firm 

limestone 2 feet thick.

6. Section of Cedar Mesa and Halgaito members of Cutler formation 

in "Dry Wash" branch of Fish Creek

[Measured as Supai and Coconino formations by R. W. Sherman (unpublished

data)]

Cedar Mesa sandstone member: peet 

19. Massive tan sandstone; weathers to brownish

red; forms rim at top of canyon..-_________ 47

18. Dark brownish-red shale._---------_------_-. 6

6. Section of Cedar Mesa and Halgaito members of Cutler formation 

in "Dry Wash" branch of Fish Creek Continued

Cedar Mesa sandstone member Continued. Feet 

17. Pinkish-brown and tan fine-grained cross-bedded

sandstone_________.___--____ ___________ 21

16. Alternating thin beds of brownish-red shale and

reddish-brown sandstone.._________________ 16

15. Massive reddish fine- and medium-grained sandstone with thin layer of red shale at base_ ... 21 

14. Cross-bedded reddish-brown and tan sandstone _. 47 

13. Massive reddish-brown and tan sandstone___.__ 68 

12. Alternating thin layers of brownish-red shale and

red and tan sandstone.__-_----_____-______ 19

11. Massive reddish-brown and tan sandstone_.__ 42 

10. Beds of reddish-tan sandstone with thin layers of

! red shale_______________________________ 24

9. Massive reddish-brown and tan sandstone with

thin layer of red shale at base.____'_________ 34

8. Same as no. 9-___------_---_--._.----------- 8

7. Massive tan, pink, and white sandstone; thin

shale layer at base...__..__-_-__________.._ 136

6. Cross-bedded and massive sandstone; thin shale

layer at base.____________________________ 136

5. Same as no. 6-___-___--__-_-----___-__--__._ 18

4. Massive reddish-brown and tan sandstone with 

thin layer of red shale at base; weathers in 

turretlike forms and mosques----------..-. 30

3. Reddish and dirty-white cross-bedded fine sandstone ____________________________________ 71

2. Chocolate-red sandy shale___-_--__-___-_-.___ 4 

1. Tan cross-bedded sandstone (base of Coconino of

Sherman)____-___---__^-_---__-__-__.____ 35

Total Cedar Mesa- 683

Unconformity (?). 

Halgaito member:

8. Shale, chocolate brown, sandy (top of Supai of

Sherman)________________________________ 9

7. Shale, alternating layers of tan and chocolate

brown, sandy.____________________________ 4

6. Shale, lavender gray, calcareous.______________ 8

5. Sandstone, massive, lavender, shaly; and sandy

shale.-._------________---______-_____. 37

4. Shale, alternating layers of lavender gray and

dark maroon, sandy. Nos. 6 to 4, inclusive,

form variegated talus slope.________________ 45

3. Shale, brownish red, sandy___--___-_-------_- 12

2. Shale, brownish red, sandy, with streaks of gray

calcareous sandstone about 1 foot thick______ 73

1. Shale, brownish red, sandy, with occasional

streaks of gray and blue limestone (base of

Supai of Sherman) _________________________ 15

Total Halgaito........._...._--....-.-.. 203

7. Section of Cedar Mesa sandstone member of Cutler formation in 

Grand Gulch near Collins

Feet

11. Sandstone, white, in three beds, separated by thin 

layers of red shale like no. 7; includes chert; 

forms top of canyon wall._____ '_'_'____-__..__ 30 

10. Shale, red purple, like no. 4; includes lenses of 

limestone and sandstone; weathers as a groove 

beneath a round-edged . projecting ledge of 

sandstone; at nearby places the site of Basket 

Maker storehouses._____.---________--_--. 6
70

7. Section of Cedar Mesa sandstone member of Cutler formation in

Grand Gulch near Collins Continued

Feet 

9. Sandstone like no. 1; even-bedded at base; massive, cross-bedded at top___________----:--- 38

8. Shale, sandy, or thin-bedded sandstone, red7. Sandstone like no. 1, in beds 8 to 20 feet thick; in 

part cross-bedded; interbedded with shales 

like nos. 2 and 4, 2 inches to 4 feet thick; includes thin limestones; forms cliff with horizontal grooves___-_____-----_-_-__-------- 130

6. Shale like no. 2; thickness along strike 6 inches to

3 feet........._..._..._....__-.__-. 2

5. Sandstone like no. 1; less cross-bedded; no limestone _____________________________________

4. Shale, red brown, sandy, calcareous, paper-thin; 

overlapping layers along strike include thin 

beds of sandstone__ ______________________

3. Sandstone like no. 1; includes two thin short 

lenses of gray limestone...________._-______

2. Shale, red, calcareous, in even beds, with lumpy

surfaces; thickness along strike 2 to 8 feet.___ 4

1. Sandstone, cream white, calcareous, fine-grained, 

cross-bedded, some curved laminae folded and 

otherwise distorted; weathers to powder; extends to bottom of canyon wall ______________ 22

56

42

Incomplete thickness of Cedar Mesa member. 340 

8. Section at head of Comb Wash

Feet

Shinarump conglomerate.

Unconformity.

Moenkopi formation (Lower Triassic):

15. Shale and sandstone, 1 to 3 feet thick, chocolate 

brown, in regular beds and lenses; some red 

and white bands; on talus large ripple-marked, 

slabs are common; partly concealed--------- 253

14. Sandstone, dark red, white at base and top; 

weathers into white-streaked rounded knobs; 

along strike appears as beds 1 to 4 feet thick, 

ripple-marked. ___________________________

13-11. Shale, red and brown, and thin sandstone, 

imbricated; weather as cliffs._______________

10. Sandstone, red brown, thin beds combined to 

form a ledge____________________________

9. Shale, chocolate-colored or red brown, fissile; 

breaks readily into thin .slabs; surfaces of top 

beds marked with mild cracks, worm borings, 

and ripples_______'l_____________________ 65

32

24

16

Total Moenkopi formation_______________ 390

Organ Rock member of Cutler formation (Permian):

8.1 Sandstone, light red, hard, very calcareous; 

appears as one massive bed with lines of holes 

to represent division planes; along the strike 

bedding and vertical joints developed by 

weathering into ''organ pipes"______________ 52

7. 1 Sandstone, white; fine conglomerate of black 

and white quartz, lime and iron grains, resting 

in pockets of no. 2..._____________________ 8

Unconformity.

i As nos. 7 and 8 lie above an unconformity, they should perhaps be included in 

the Moenkopi. *

8. Section at head of Comb Wash Continued

Organ Rock member of Cutler formation Continued. Feel 

5-1. Sandstone, red, calcareous, or sandy shale, in 

beds 4 to 6 feet thick, rounded by spalling at 

top and bottom; and shalelike beds; whiteblotched; includes three thin beds of white 

sandstone, one of them persistent for half a 

mile; some beds show plasters and inclusions 

of gray-blue limestone; a slope with steps____ 102

Total Organ Rock member...._..____.._ 

Unconformity; uneven surface coated with plasters of

limestone and nodular red clay. 

Cedar Mesa sandstone member of Cutler formation in

walls of canyon.

9. Section of clijffs 4 miles north of Clay Hills Pass

6. Shale, red, in general even-bedded but irregular in 

detail; includes bands of white sandstone 1 to 

6 inches thick; forms slope but in places 

weathers as grooved columns_______________

Shinarump conglomerate.

Unconformity.

Moenkopi formation (Lower Triassic):

10. Shales, brown, sandy, rippled and variegated, 

and earthy shales; upper part concealed by 

landslide; thickness estimated ______________

9. Shales and shaly sandstones, brown and dark red; 

produce a "slab talus" of large, very thin 

sheets with rill marks, ^yo^m trails, mud cracks, 

and ripples; resemble typical Moenkopi of the 

Little Colorado Valley________________

8. Shales, sandy, fissile, and thin sandstones, chocolate brown, traversed by greenish-white 

bands; gypsum in seams, in a 3-inch bed, and 

disseminated. _ --- T ____- -_-----___-_______

7. Shales, regularly bedded, brown, fissile, split into 

very thin sheets; include four bands of white 

ripple-marked sandstone 1 to 3 inches thick. _

360

Total Moenkopi formation.

206

Feet

140

25

34

59

258

Unconformity.

6. Sandstone, light red and gray, in places con- , 

glomeratic, with limestone pellets. In position of be Chelly sandstone.___-__-._______ 1

Organ Rock member of Cutler formation (Permian):

5. Sandstone like no. 4; weathers to steps and

slopes ________--_----__---_-._-__________ 60

4. Sandstone, red, in thick beds; composition and 

texture like no. 1 but more firmly cemented; 

weathers in part like shale; bedding and vertical jointing made prominent by weathering, 

combine to. produce fluted cylindrical columns 

like mass of organ pipes, the effect intensified 

by white bands; top is thin bed of limestone; 

forms an unscalable waU_:-_--___________ 110

3. Shale like no. 1; some beds mottled greenish 

 white; with nos. 1 and 2 forms slope broken by

steps.________-___-_-__--_-_-_______-_-__ 155

2. Conglomerate, gray; pellets, lozenges, short fat 

lenses, and irregular masses of limestone 

mingled with fragments of calcareous sand- 

' stone; a persistent ledge; forms bench--_.._. 4
71

9. Section of cliffs 4 miles north of Clay Hills Pass Continued 10. Section 3 miles southwest of Kachina Natural Bridge Con.

Organ Rock member of Cutler formation Continued. Feet

Shale, sandy, thin sandstone or muds'tone, very 

fine-grained, calcareous, red; parts:.'appear, as 

massive beds but weather into thin.slabs; base 

not exposed-_____________________ j_ ._ _--_ 92+

Total Organ Rock member. _____-_.-____ 421 + 

Cedar Mesa sandstone member of Cutler formation.

10. Section 3 miles southwest of Kachina Natural Bridge

Shinarump conglomerate (Triassic):

12. Grits arranged as lenticular wedges, lenses of 

conglomerate with pebbles as much as half an 

inch in diameter of brown, red, and white 

quartz and quartzite, gray chert, and fragments of sandstone; some petrified wood; and 

cliffed edge of a platform that extends backward for more than a mile, ________--_-__-_

Unconformity.

Moenkopi formation (Lower Triassic):

11. Shale, largely covered by landslides. Part exposed includes thin brown sandstone and 

sandy shale, variegated in blotches and bands, 

red, ash, brown, and greenish white; includes 

lenses of yellow limestone conglomerate, strips 

of mud balls, and a bed 8 inches thick of dense 

resistant green sandstone. Talus includes 

many large chunks of red chert. Forms a 

slope____. ____-________________ -_ _____..__

10. Sandstone like no. 4__- ----------------------

9. Shalelike no. 5__--_-------------_----------

8. Sandstone like no. 4_ ___----_-. ..___-__-______

7. Shalelike no. 5..----------------------:----

6. Sandstone like no. 4_____----_-__j-_---___---

5. Shale, brown, banded with white, slightly gypsiferous; weathers as broad, thin ripple-marked

Feet

48

4. Sandstone, brown and gray, in beds about 1 foot 

thick, with division planes of greenish shale; 

beds split readily into sheets an inch or less 

thick, most of them profusely rippled; a cliff 

3. Sandstone, thin-bedded, and sandy shales, chocolate brown, lime- and iron-cemented; ripple 

marks, sun cracks, worm borings; forms

Total Moenkopi formation.

180

16

20

28

12

11

45

16

28

356

Unconformity; erosion surface and abrupt changes in 

lithology.

Organ Rock member of Cutler formation (Permian): 

2. Division B: Mudstone, red; composition and 

texture essentially like that of division A but 

thicker-bedded and more firmly cemented. 

Weathering has produced horizontal curved 

fluting along beds and vertical fluting on 

unevenly placed joints. The base is marked 

by a bed of greenish-white sandstone about 

1 foot thick that may be traced for miles. 

An unscalable cliff that in 3 miles along the 

strike ranges in height from 60 to 120 feet__-_ 

Division A: Shales or mudstones, light red and 

dark red, in thin regular beds, extremely fine76

1.

Organ Rock member of Cutler formation Continued. feet 

grained, highly calcareous; some beds or lenses 

show no division planes in thicknesses of 10 "" 

feet or more and appear as steps; all beds 

weather as flat or disk-shaped chips' that 

partly cover the round-edged beds; forms a 

steep slope..__________________ .:_ .:_-,____ 275

Total Organ Rock member.______________ 351

Unconformity (?); wavy surface and accumulation of

concretions. 

Cedar Mesa sandstone member of Cutler formation.

11. Section of Permian and Triassic formations at Rock Springs, 

White Canyon

Wingate sandstone (Jurassic?).

Unconformity (?).

Chinle formation (Upper Triassic): . peet 

10. Sandstone, red, uniformly fine-grained, evenbedded, in part cross-bedded; strata 3 to 10 

feet thick separated by thin layers of red 

shale.--..-----_------_-------___-------_ 70

9. Shales, red, purple, ash gray, and greenish white; 

includes two beds of hard green sandstone, 

three beas of dense blue-gray limestone, and 

many lenses of limestone conglomerate; petrified wood common; most of it weathers into 

mounds with fluffy surf aces. _______________ 510

Total Chinle formation. 580

Shinarump (?) conglomerate (Triassic) :

8. Sandstone, greenish-gray, lenticular, coarse; 

includes conglomerate lenses of slabs of red 

sandstone clay balls, white chert, and a little 

quartz and quartzite. _____________________

Moenkopi formation (Lower Triassic) :

7.. Shales, sandy, gray, purple, and white, largely 

concealed by slides and talus ________---____

6. Sandstone like no. 4; weathers into ripple-marked

48

97

43

5. Shale, sandy, chocolate-colored, streaked with 

white, slightly gypsiferous, imbricated^ 

weathers into large thin slabs with smooth, 

hard, shining surfaces decorated with ripples, 

herring-bone patterns, and deeply filled sun 

cracks. ________--___^_________. ______..__

4. Sandstone, brown and buff, in four to six irregular 

beds parted by evenly foliated layers of ripplemarked chocolate-colored shale. __-_----___-

3. Shales and thin sandstones, chocolate-colored; 

foliation surfaces are sun-baked and show 

ripples, rill marks, and sun cracks 1 to 6 inches 

deep filled with consoldated yellow mud; at 

the base and in lenses just above are discontinuous conglomerate beds composed chiefly 

of lozenges, balls, and irregular fragments of 

clay shale, red sandstone, and iron and lime 

concretions _ __ . _________________________

34

38

90

Total Moenkopi formation _______________ 302
72 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

Feet

11. Section of Permian and Triassic formations at Rock Springs, 

White Canyon Continued

Unconformity; erosion surface and abrupt change in 

lithology; conglomerate.

Organ Rock member of Cutler formation (Permian):

2. Division B: Mudstones or sandstones, red, calcareous, extremely fine-grained; in places 

appear massive, but generally a series of very 

uneven beds; weathering has developed bedding planes and joints into grooves on unscalable cliff__..-_____---_-_-_---________-

Division A: Shales, sandy, and calcareous mudstones, red; beds very irregular in thickness 

and extent; eroded as round-edged benches 

combined to form slope; crumbles to flat and 

curved chips; top marked by band of white 

sandstone._______________________________ 184

86

1.

Total Organ Rock member..._.__.____._- 270

Unconformity (?).

Cedar Mesa sandstone member of Cutler formation.

12. Section of Permian and Triassic at Rasp trail, 5 miles above 

mouth of White Canyon

Wingate sandstone (Jurassic?), 300 feet thick. 

Chinle formation (Upper Triassic): peet 

15. Sandstone, red, in fairly even thin and thick beds 

separated by red and gray clay like shales; 

measured at point 1 mile distant__________ 78

14. Shale, banded red, gray, and white; weathers as a

slope like' 'marls''; thickness estimated _______ 100

13. Shale, chiefly pink and white, highly calcareous, 

and beds of blue, gray, pink, and mottled limestone; forms series of vertical cliffs; thickness 

estimated-_l_______-_____-__-_-__________ 160

12. Sandstone, white, coarse-grained quartz with

calcareous cement._______________________ 8

11. Shale, banded pink and white, highly calcareous; 

few lenses of limestone conglomerate and of 

white sandstone._______________________i_ 72

10. Sandstone, greenish white, lenticular, friable..-- 3 

9. Shale, variegated~--------_------------_-___ 6

8. Sandstone, brown, white-striped, in part crossbedded; contains concretionary limestone 

" pellets; lower third mostly limestone conglomerate in short irregularly overlapping lenses. _ _ 16 

7. Shale, variegated, chiefly green, yellow, and gray;

forms a slope with loose porous surf ace. _____ 105

6. Sandstone, greenish gray, coarse, calcareous, in

thin overlapping plates; forms a cliff._______ 12

5. Shale, banded yellow, ash gray, brown, and purple; 

fragments of fossil wood; on weathering forms 

"marls"; a slope------.------.--......____ 80

Total Chinle formation.._____'_._________ 640

Shinarump (?) conglomerate (Triassic):

4. Conglomerate and grits of chert, and clay pellets in 

patches distributed unevenly over top surface 

of no. 3_____________._-._______..__.. J..-1-

Moenkopi formation (Lower Triassic):

3. Shale, sandy, chocolate-colored, regularly bedded, 

and lenticular beds of brown sandstone; shaly 

beds and massive beds alike split readily into 

thin ripple-marked slabs.__________________ 182

12. Section of Permian and Triassic at Rasp trail, 5 miles above 

mouth of White Canyon Continued

Moenkopi formation Continued.

2. Conglomerate, gray; chiefly angular and partly 

rounded fragments of white chert and crystalline quartz as much as 3 inches in diameter, 

cemented by coarse grit; lenticular; in position 

of DeChelly sandstone: thickness along strike 

2 to 8 feet.______________________________

Feet

Total Moenko'pi_.-__-__.--------------- 186

Unconformity: jumbled mass of clay balls and lenses on

uneven surface of no. 1. 

Organ Rock member of Cutler formation (Permian):

1. Mudstone or sandstone and sandy shale, red, 

alternately massive thick beds and thin beds, 

all irregular; lower part (largely covered) a 

slope formed of thin beds, upper part a cliff 

fluted horizontally; base not exposed-------- 278 +

Cedar Mesa sandstone member of Cutler formation.

13. Section at head of Arch Canyon

Shinarump conglomerate (Upper (?) Triassic); forms top

of Elk Ridge. 

Unconformity.

Moenkopi (Lower Triassic): Feet 

20. Sandstone and shale, largely concealed by talus

and slides; not measured.

19-11. Shales, dark brown, sandy, imbricated, fissile; 

on talus sheets as thin as cardboard show 

ripples and mud cracks; a few thicker sandstone beds and a few very thin white beds _____ 105

10. Sandstone, red brown, cross-bedded; appears massive, but along strike breaks up into beds 1 to 6 

inches thick; forms cliff____________________ 22

9. Shale or thin sandstone, chocolate brown blotched 

with white; weathers to ripple-marked slabs; 

base is coarse-grained red, yellow, and white 

shale and lenses, strings, and individuals of 

greenish-white clay mud lumps that on weathering give rock a porous appearance.____---_ 46

Incomplete thickness of Moenkopi formation. 173

Unconformity (?).

Organ Rock member of Cutler formation (Permian):

8. Sandstone, white, coarse, in shalelike layers, with 

some lenses of fine conglomerate; position of 

De Chelly sandstone.________________.---_ 1

7. Sandstone, red, massive; forms strong cliff -_ 12 

6. Shale, sandy, red; weathers as flakes...-.----- 62

5. Sandstone or mudstone; composition and texture 

like no. 4; appears as compact beds 5 to 20 feet 

thick, separated by thin shales; weathers as 

rounded shoulders from which curved and 

straight chips peel off; in part blotched and 

striated with white; forms succession of cliffs 

and slopes.______-___-__._-_-_-_---_-_--- 98

4. Shale, sandy, or thin mudstones, red; appear 

evenly bedded but beds irregular in detail; 

form slope with steps.______-_--_--------- 248

3. Shale, white, fissile, sandy.....-.-.--.-------- 3

2. Sandstone, yellow and gray, fine-grained, calcareous, uneven-bedded__-_____--. .___-_- 5

Total Organ Rock member. -...-------- 431
STRATIGRAPHIC SECTIONS 73

13. Section at head of Arch Canyon Continued

Unconformity (?).

Cedar Mesa sandstone member of Cutler formation: Feet 

1. Sandstone, buff, highly calcareous, in beds 10 to 

40 feet thick separated by red shale; unevenly 

coated with gray nodular concretionary limestone; forms canyon walls; thickness estimated.. _____-___-_____---_------------_- 800+

14. Section of Moenkopi formation at Long Point, south end of 

Elk Ridge, head of Grand Gulch

Shinarump conglomerate (Upper ? Triassic).

Unconformity.

Moenkopi formation (Lower Triassic): Feet

5. Shale; from a lower part like nos. 2 and 3 changes 

gradually in color, texture, and bedding to an 

upper part that consists of a series of friable, 

sandy, slightly gypsiferous shales; variegated 

red, brown, gray, and purple.______________ 143

4.^ Sandstone, buff and brown; appears as a single 

massive bed, in part cross-bedded, but is easily 

separated into thin ripple-marked layers_.__. 10

3. Shale, sandy, brown, very thin-bedded, with some 

parting planes of greenish white; most beds 

. profusely ripple-marked, sun-cracked, and 

crossed by incipient channels; breaks readily 

into slabs and flat chips that show glistening 

specks of gypsum.________________________ 49

2. Sandstone, purple and brown; appears massive; 

bedding indicated by lenses of brown glistening 

shale and black streaks of manganese (?)_ 48

1. Shale, sandy, or thin-bedded sandstone, brown;

largely concealed by talus--------------_-._ 70

Total Moenkopi formation.______________ 320

Unconformity; conglomerate of clay balls and fragments of

sandstone and limestone. 

Organ Rock member of Cutler formation (Permian): Red

mudstones.

15. Section of Shinarump conglomerate at Elk Ridge, near head of 

Arch Canyon

11. Sandstone, white; grades upward into sandy shale 

mottled black, white, and yellow; pebbles 

abundant at the base___--_-___----._________ 6

10. Shales, black and grayish blue, carbonaceous, full of

iron concretions and scattered pebbles.__________ 8

9. Sandstone, gray, coarse, with strings and scattered

pebbles. _-__-.__.________._._.._,________._.__ %

8. Shale, gray, sandy, in overlapping beds._______^_._ 11

7. Sandstone, white, coarse, glistening,_______________ 3

6. Shale, yellowish brown, sandy, with layers of carbonaceous matter.________________________________ 8

5. Conglomerate; pebbles of white chert and quartzite,

well rounded, 1 to 3 inches in diameter._________ 6

4. Shale, brown, sandy_--___.____-_._______________ 4

3. Sandstone, gray, cross-bedded, porous; includes

strings of pebbles and impressions of plants ______ 18

2. Shale, yellowish brown, sandy.___________________ 13

1. Sandstone, grayish brown, glistening, coarse; includes conglomerate lenses of quartzite, quartz, 

chert, and petrified wood; top of Elk Ridge._____ 23

Total__--_---_____-.---.-.___.___....___ 100+

16. Condensed section of Chinle formation at the Bears Ears, Elk

Ridge

Wingate sandstone (Jurassic?).

Unconformity (?).

Chinle formation (Upper Triassic): Feet

33-22. Shales, red and yellow, sandy, and thin irregularly bedded red sandstone; abundant 

mud lumps and some limestone conglomerate 

associated with shales form steep slopes..-. 152

21. Limestone conglomerate, greenish white, in six

lenticular beds separated by red shale,______ 14

20. Shale, light yellow, sandy, friable; mud balls,

ripple marks, impressions of plants________ 20

19. Limestone, conglomerate, greenish white, and 

purple sandstone irregularly cross-bedded; includes clay balls, concretionary lime pellets, 

saurian bones, and fragments of sandstone 

and shale._____-------_-_-_--__-_--______ 77

18-11. Shale, light red and yellowish red, calcareous, 

friable, and red imbricated sandstone in alternating beds 3 to 12 feet thick. _____________ 193

10-2. Shales, variegated, friable, calcareous, and five 

beds of limestone conglomerate 1 to 3 feet 

thick; brightly colored "marl" slope on which 

limestone forms shelves..-.__--________-___ 66

1. Shale, purple, ash, blue, green, red, and brown, 

and gray thin-bedded sandstone. Flat slope 

largely concealed by talus and landslide. 

Thickness estimated----__--_--____._______ 400

Total Chinle formation _ _ _ 

Shinarump conglomerate (Upper? Triassic):

856

17. Condensed section of Chinle formation at Clay Hills Pass

Wingate sandstone (Jurassic?).

Unconformity.

Chinle formation (Upper Triassic): Feet

18. Sandstone, dark brown, slightly cross-bedded in 

six to ten lenticular beds; includes lenses and 

rounded aggregates of brown mud balls, lone 

pellets of greenish-white clay and lenses of 

coarse limestone conglomerate more abundant 

near the base___-___--__----___-________ 60

17. Limestone conglomerate with lenses of brown

sandstone.._ ___--_-----__-_--___i________ 6

16. Shale, yellow, sandy.________________________ 8

15-10. Sandstone, white, hard, alternating with pink 

limestone conglomerate in beds 2 to 4 feet 

thick___________________________ 13

9-7. Shale, yellowish red, sandy, indistinctly 

banded; includes four beds of compact finegrained white sandstone.__________________ 122

6-2. Shales, prevailingly red and pink, friable, with 

lenses of calcareous white sandstone and limestone conglomerate that weathers as shelves 

and pancakes on an otherwise even slope. A 

bed of pink limestone conglomerate at the top 

4 feet thick and another near the middle are 

continuous for at least a mile__-_--___--_._ 276 

1. Shales, brown, red, green, ash, and purple, with 

many balls and short lenses of limestone conglomerate and a few lenses of gray calcareous 

sandstone; some dinosaur (?) bones; weathers 

as a brightly variegated slope and marl-like 

material. __-_-_---------__-._____________ 330

Total Chinle formation _______

Shinarump conglomerate (Upper? Triassic).

815
74 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

18. Section of Morrison formation and San Rafael group on

south face of Tank Mesa

Feet.

Morrison formation (Bluff sandstone member): Persistent ledge, buff, white, greenish white, red-stained, 

lenticular on a huge scale_--___-_______.____^_____-_ 200+

Unconformity (?); abrupt change in color and lithology;

sinuous contact. 

San Rafael group:

Summerville (?) formation:

15. Sandstone, white, stained red, in beds 1 to 4 

feet thick, and thin red, white-blotched, 

highly calcareous shale; chert in large 

pancakes abundant in uppermost shale 

beds.-..___---------_,----..___--__ 24

14. Sandstone, white to brown, roughly bedded, 

cross-bedded, and thin discontinuous 

bands of imbricated shale. At a distance 

nos. 14 and 15 appear as color-banded 

portion of vertical cliff below Bluff sandstone -__---___-___-___-__--________ 7

13. Shale, yellow, tan near base, banded dark 

red, brown, ash, and gray above, all 

sandy and gypsiferous; includes thinly 

laminated brown ripple-marked sandstone and thin short lenses of limestone; 

forms steep slope over which are scattered 

thin chips of red shale, angular fragments 

of limestone, and red chert._____________ 8

Total Summerville (?) formation___. Ill

Entrada sandstone:

12. Sandstone, orange re'd, strongly crossbedded, calcareous; upper two-thirds one 

massive bed in nearly vertical cliffs 

streaked with white lines along joints and 

dotted with round white spots; weathers 

into bobbins, "hoodoos," and low domes; 

lower part appears as roughly defined 

beds 6 to 8 feet thick__..__________ 86

Carmel(?) formation:

11. Sandstone, light red, uneven, wavy, nodular 

beds 1 to 5 feet thick, in part cross-bedded; 

alternately bedded with dark-red shale 1 

to 4 feet thick; white streaks along joints, 

tiny faults, and some cross-bedding 

laminae__ __---_-_---_---_-_-_^____- 28

10. Sandstone, white, lumpy, lenticular; includes

flat slabs of clay_____________________ 2

9. Shale, light red, sandy; forms slope interrupted by little benches formed by lenses 

of more calcareous material. _-________.._ 21

8. Sandstone; lower 11 feet massive, dark red, 

nodular; upper 5 feet poorly bedded, light 

red and white; top dense white calcareous 

resistant bed; forms broad bench. _______ 16

7. Shale,red_._----.---_--_.-----_-_.___ 2

6. Sandstone, pure white, fine-grained quartz, 

some specks of garnet and iron, loosely 

cemented with lime; imbricated nodular 

beds break into irregular thin slabs_ _ _ _ _ 1

5. Shale, dark red, with white spots___________ 3

4. Sandstone, red, highly calcareous, or limestone; breaks into slabs about 1 inch thick; 

profusely ripple-marked-_-__----_______ 2

18. Section of Morrison formation and Sari Rafael group on south 

face of Tank Mesa Continued

San Rafael group Continued.

Carmel (?) formation Continued. Feet 

3. Shale, light red, in which are lenses of rt d, 

white, and spotted, very calcareous sandstone...- _____________________________ 10

2. Sandstone like no. 6-_-_-_--______________ 2

1. Shale, light red; fits into pockets and channels

of Navajo sandstone_________________ 10

Total Carmel (?) formation.__________ 107

Unconformity.

Navajo sandstone (of Glen Canyon group).

Traced along the strike, groups 13-15 of the Tank 

Mesa section show extraordinary range in color, bedding, and composition. Within half a mile 20 beds 

may be replaced by 1, and the color may change from 

brown and dark red to light red and pink; a group of 

shale layers is in one place even-bedded, in others 

nodular or wrinkled; gypsum, a constituent of most 

beds, ranges in amount from lenses to disseminated 

grains; chert appears in the upper 50 feet of the section 

as widely scattered pellets and as lenses almost continuous for more than 100 feet. All the beds assigned 

to the Summerville difter in color, composition, texture, 

and bedding from the overlying Bluff sandstone member 

of the Morrison.

19. Section at the village of Bluff

Feet

Morrison formation (Bluff sandstone member). 

Unconformity (?); uneven, slightly eroded surface. 

Summerville (?) formation:

6. Sandstone, white (tan-coated), progressively coarser and more cross^bedded from bottom to top.. 12

5. Sandstone, dark brown, separated unevenly into 

beds by lenses of extremely fine-grained darkred clay-mud shale with greenish-white spots; 

all calcareous and gypsiferous; weathers into 

recesses and breaks into shapeless slabs; top 

is a zone of seeps.______________--_--_---- 56

4. Sandstone, white,' relatively coarse; white quartz 

grains, some black and red grains and gypsum; 

decreases in thickness along strike __________ 14

3. Sandstone, white and red, in fine beds with intervening dark-red shale that ranges in amount 

from one-third to two-thirds of the section. 

No bed continues for more than 100 yards; 

in places a single ledge of white sandstone 

makes up one-third of the group. All seems 

gypsiferous__________-_-_-____--___---__ 21

2. Shale, red at base, banded dark brown and white 

above, calcareous and gypsiferous; most of it 

irregularly bedded and lumpy. In nearby 

places some of the gypsiferous shale beds at this 

and higher horizons are conspicuously wrinkled 

and are separated by angular unconformities. _ 58

Total Summerville (?) formation._-____-__ 161 

1. Sandstone, bright red, massive, cross-bedded, very 

fine-grained, streaked with white; may be top 

of Entrada sandstone___----------------- 4
STRATIGRAPHIC SECTIONS 75

20. Section of Morrison formation and San Rafael group at head 

of Butler Wash

Morrison formation: Sandstone, gray, coarse, lenticular, 

in part cross-bedded, and irregular beds of brown calcareous shale. 

San Rafael group:

Summerville (?) formation: feet 

13. Shale, red, earthy; breaks into flat slabs... 26 

12. Sandstone or mudstone, red, resistant; forms

surface of broad bench-._______-----_. 5

11. Shale, red, and white sandstone, in beds 

1 to 4 feet thick; forms brightly banded 

slope.___-_____--_____-___---__----__ 38

10. Shale, dark red, lumpy, friable; breaks into 

flakes like mica; includes three beds 8 to 

12 inches thick of gypsiferous ripplemarked white sandstone.______________ 15

9. Sandstone, white, thin, uneven beds, ripplemarked; includes black iron sand and 

concretions; weathers to knobby surface. 6 

8. Shale, dark red, earthy; breaks readily into

thin flakes.___--__-__---------------- 4

7. Sandstone, white, cross-bedded, gypsiferous;

crumbles to dust____-___--____-_--_- 6

6. Shale like no. 81 .________________... 9

5. Sandstone, white, in thin overlapping beds;

forms bench________________________ 3

4. Shale like no. 10; on uneven surface of no. 3_ 20

Total Summerville (?) formation____ 132

Entrada sandstone:

3. Sandstone, orange red or brick red, massive, 

cross-bedded, streaked with white; weathers into arched cavities, pedestals, and 

bobbins__ _ ____________________j_-_ 42

Unconformity (?); conglomeratic mass of shale, calcareous sandstone and lime mud balls; lies on 

uneven surface of no. 2.

Carmel (?) formation:

2. Shale, red, lenticular, very calcareous, 

crumbles readily.____.-__-_--___-_-___

1. Sandstone, dark red, calcareous, slabby, in 

beds 1 to 4 feet thick; weathers like shale; 

limestone concretions at the base. ______

12

52

Total Carmel (?) formation _____.___. 64

Unconformity.

Navajo sandstone (of Glen Canyon group), white, yellow, 

stained.

In a section about 6 miles south of the head of Butler 

Wash 315 feet of strata are classed as Carmel (?) a 

succession of alternating red and pink shales. 3 inches 

to 35 feet thick and white calcareous sandstone 8 

inches to 6 feet thick. The topmost thin beds of shale 

and sandstone are firmly cemented and form a platform 

at the base of the Entrada. In this section the Summerville seems to be absent; a grayish-white crossbedded lenticular sandstone 125 feet thick, considered 

the Bluff member of the Morrison, lies unconformably 

above the Entrada.

21. Section of Morrison formation and San Rafael group in Dry 

Wash, Alien Canyon country

Morrison formation: Sandstone, gray, coarse, with lenses 

of gray sandy shale and conglomerate of white chert, 

lime balls, clay balls, and quartz. 

Unconformity. 

San Rafael group:

Summerville (?) formation: Feet 

12. Shale, red, peaty, friable, calcareous; some

wrinkled beds________-________________ 14

11. Sandstone, greenish white, resistant.______ 1

10. Shale, red, like no. 12__________________ .. 16

9. Sandstone, white, firm, cross-bedded_______ 1

8. Shale, like no. 12______._________________ 8

7. Sandstone, like no. 9__________________ 1

6. Sandstone, yellow, coarse, coated on surface

with sand balls; weathers like travertine. 20 

5. Sandstone, yellow, fine-grained, in thin lenticular beds, including bands and blotches 

of dense pink sandstone.______________ 30

4. Shale, pink, friable, calcareous and gypsiferous; includes very thin lenses of resistant white sandstone._______________ 23

3. Sandstone, buff, very unevenly bedded, and

thin lenses of red calcareous shales._____ 5

2. Shales, red, sandy, friable, with three lenses

of white sandstone 1 to 4 inches thick___ 12

Total Summerville (?) formation___. 131 

Unconformity (?). 

-Entrada sandstone:

1. Sandstone, orange red, massive, crossbedded, fine-grained; weathers as roundedged ledge__-__-__---__-____________ 80

Unconformity; erosion surface represents absent Carmel

formation. 

Navajo sandstone (of Glen Canyon group).

In. the Alien Canyon country within a radius of 4 

miles the Carmel (?) formation ranges in thickness from 

a knife edge to 55 feet (?); the Entrada sandstone from 

45 to 205 feet, including interbedded red shale; and the 

Summerville formation from 127 to 283 feet. In 

several places the Entrada rests directly on the Navajo 

sandstone.

22. Section of Carmel (?) formation at west edge of Wilson Mesa

Carmel (?) formation: Feet 

10. Limestone, firm, knobby; weathers like caliche;

forms top of mesa_______________________ 2-8

9. Shale, light red, with discontinuous thin bands of

white sandstone.__________________.__ ____ 23

8. Sandstone, white, black, spotted, very finegrained, resistant; grades downward into no.

7.-_:-,-----------_--______._-__________ 2

7. Shale, red, sandy__________________________ 6

6. Sandstone, red, white, blotched, very calcareous _ 2 

5. Shale, red, sandy, very irregularly bedded and

nodular; forms slope._____________________ 15

4. Sandstone, gray, part stained black, irregular

beds; forms persistent ledge._______________ 2

3. Shale, red, sandy series of overlapping thin

lenses ___________________________________ 28
76 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

22. Section of Carmel (?) formation at west edge of Wilson Mesa 

Continued

Carmel (?) formation Continued. Feet 

2. Sandstone, red, lenticular.___________________ 5

1. Shale, red, lumpy, and some calcareous pellets;

rests in depression of underlying rock_ _______ 0-3

Total Carmel (?) formation. 

Unconformity. 

Navajo sandstone.

92-94

23. Section of Morrison formation along canyon of Recapture

Creek

[Combined from six partial sections. See pi. 16, A]

Dakota (?) sandstone. 

Unconformity. 

Morrison formation:

Division D (Brushy Basin shale member):

19. Shale, greenish yellow, and thin greenishwhite soft sandstone; at the base a 

6-inch bed of resistant sandstone. __ 

18. Sandstone, greenish white, massive, 

cross-bedded; along strike replaced 

by interbedded maroon shales and 

white sandstone, very lenticular. ___ 

17. Sandstone, soft, white; includes lenses 

. of conglomerate made up of red, black, 

and gray chert, quartz, and fragmentary bones; concretions of lime 

and Of mud shale at base__________

16. Shale, pink, maroon, yellow, ash, and

white; includes long, thin lenses of

greenish-white shaly sandstone, pink,

black, red, white, and mottled lime-

. stone, and chert conglomerate...... 210-228

15. Sandstone, greenish gray, hard, brittle; 

forms bench____________________

14. Shale, green and gray, irregularly 

bedded; in places nearly all green 

shale; includes conglomerate of concretions and white sandstone fragments at the base...______________

Feet

35-60

10-50

4-22

1-4

8-30

Estimated total, Brushy Basin 

member.._________ __________ 360-440

Division C (Westwater Canyon sandstone member):

13. Sandstone, white and yellowish white, 

soft, massive, in part cross-bedded; 

lenses of greenish-white mud shale;- 

, lens of conglomerate made up of concretionary pellets of limestone and 

fragments of shale and sandstone; top 

surface hardened; weathered surfaces 

show cavities and grooves; forms 

lower wall of Recapture Canyon.... 

Unconformity; fragments of shale and 

conglomerate of no. 13 on eroded surface of no. 12; relief as much as 20 

feet in 500 feet.

12. Shale, gray and greenish white, and lenticular beds of hard green sandstone^

11. Sandstone, white, some greenish white, 

in three to eight cross-bedded lenticular strata separated by thin lenses 

of ash-gray shale and greenish-white

20-30

8-23

23.' Section of Morrison formation along canyon of Recapture 

Creek Continued

Morrison formation Continued. 

Division C Continued.

clay pellets; strong vertical joints; at 

base lenses of chert and quartzite conglomerate; along strike includes gray 

shale______----___.______________ 32-80

10. Shale, gray, ash, yellowish green._____ 35-42

9. Sandstone, white and yellowish green, 

coarse, cross-bedded; lenses of conglomerate and gray shale; indefinitely 

parted into three or four beds; forms 

vertical cliffs.____________________

8. Shale, red and greenish white, with thin 

lenses of white sandstone __________

7. Sandstone, white, massive, cross-bedded, 

with a few shale lenses; appears porous on weathered surfaces__________

Feet

40-55

4-14

12-27

Total Westwater Canyon member.. 180-253

Division B (Recapture shale member):

6. Shales, predominantly maroon, some 

ash gray, in groups of strata 6 to 45 

feet thick, interbedded with white 

soft cross-bedded sandstone 3 inches 

to 3 feet thick, more abundant near 

the top; weathers as attractively 

banded slope in which thin sandstones 

project as steps; shale constitutes 

more than 85 percent of the beds.._ 111-230

5. Sandstone, white, flaky, in thin overlapping ledges. ___________________ 0-8

4. Shale, dark red and ash gray, flaky,

mottled, irregular beds_____-_-___. 2-16

3. Sandstone, tan, coarse, lenticular, soft,

porous on weathered surfaces_.___ 0-4 

Unconformity (?); uneven surface of 

no. 2 coated with jumbled fragments 

of green and red clay.

2. Sandstone, red, brown, and tan, in 

very uneven beds 6 inches to 10 feet 

thick; shale, dark red, flaky, irregularly bedded, 2 inches to 2 feet thick; 

all beds highly calcareous, some gypsiferous; thickness and structure 

change rapidly along strike; weathers 

as banded column and bosses.______ 40-55

Total Recapture member._______ 220-290

Division A (Bluff sandstone member):

1. Sandstone, white; weathers tan; firm, 

cross-bedded, massive; base not exposed____.______-________-_---__ 100+

Bed of San Juan River.

24. Section of Morrison formation on east side of Butler Wash, 

about 14 miles from its mouth

Division D (Brushy Basin shale member); not measured.

Division C (Westwater Canyon sandstone member): feet 

24. Sandstone, white; .weathers somewhat yellow; 

coarse-grained, cross-bedded; lime cement; 

lenses of conglomerate, chiefly chert pebbles; 

lenses of green shale 1 to 30 inches thick, 1 to 

50 feet long; generally soft but top surface casehardened; on weathered surface appears 

porous; forms nearly vertical cliff and platform._-.____--.._____-----_-..-.-_ 136
STRATIGRAPHIC SECTIONS 77

24. Section oj Morrison formation on east side of Butler Wash, 

about 14 miles from its mouth Continued

Division C Continued. Feet 

23-18. Sandstone, white, lenticular, unevenly deposited as beds 2 to 12 feet thick; greenishwhite shale in thin lumpy bands.___________ 58

17-16. Sandstone, white and gray, in beds 2 to 3

feet thick, alternating with red shale_ _______ 42

15. Shale, red, with greenish-white bands__--___-__ 5 

14. Sandstone, white, friable, lumpy, cross-bedded

i1i irregular lenses 6 inches to 2 feet thick_____ 23

13-11. Shales, red, interbedded with white coarse

friable sandstone.__-____-__-_-_____-____ 21

10. Sandstone, white, cross-bedded, lenticular, 

weakly cemented with lime; at base and along 

cross-bedding laminae strings and aggregates 

of greenish-white mud lumps; suggest unconformity __---_-__-_----------------------- 12

Total Westwater Canyon member. _ ______ 297

Division B (Recapture shale member):

9. Shales, red, streaked with white; top surface

eroded--...------------------------------ 15

8-5. Shale, red, sandy, irregularly bedded; includes 

several thin bands and two thick short lenses 

of white sandstone._______________________ 90

4. Sandstone, white; weathers yellow and light red; 

unevenly bedded; includes lenses consisting 

chiefly of hardened clay balls__-_---_---_--_ 16 

3. Shale, red, made of short overlapping flakes. .... 11

2. Sandstone like no. 4_--------_----_--_------- 18

1. Shale, red, calcareous, argillaceous; near the 

base are lenses of green mud and fragments 

of red shale.___-___------_-_-__--___-__-- 27

Total Recapture member.--------------- 177

Division A (Bluff sandstone member)________'_______L._ 125

25. Section of Morrison formation in Brushy Basin

Dakota (?) sandstone. 

Unconformity. 

Morrison formation:

Brushy Basin shale member: feet

28-24. Shale, red and white, sandy, and white 

lenticular coarse-grained porous sandstone, in alternating beds; forms stepped 

slope.---------_---_---_------_--_--- 61

23. Sandstone, white and greenish yellow, 

coarse, very lenticular, in part crossbedded; lenses of conglomerate consist 

chiefly of red and black chert, fragments 

of green sandstone, and clay balls; includes round white aggregates of quartz 

and elongated brown concretions of iron 

and sand; forms cliff._________________ 27

22-20. Shale, red, ash gray, yellow, and green, 

sandy, and lenses of white sandstone; 

forms color-banded slope_____________ 59

19. Sandstone, dark green, hard, very finegrained, persistent ledge.______________ -2

18. Shale, red, yellow, green, purple, and white; 

color distributed in regular bands and in 

blotches to form variegated slope; beds 

include lenses of pink, purple, and white 

limestone, white and brown sandstone, 

and limestone conglomerate consisting of

25. Section of Morrison formation in Brushy Basin Continued

Morrison formation Continued.

Brushy Basin shale member Continued. Feet 

concretionary balls, chert, and bone 

fragments; weathers to form loose, fluffy, 

marl-like material, partly concealed by 

landslides.-.--------.-- ______________ 224

17. Sandstone, dark green, resistant, like no. 6_- 1

16. Sandstone, brown; appears as massive ledge

but weathers readily to shalelike beds. _ _ _ 12

15. Shale, dark red, unevenly bedded; thin 

band of white powder-fine sandstone at 

top and base_--_---_----____--__-_--_ 15

14. Shale, red and slate-colored _!_____________ 29

Total Brushy Basin member._________ 450

Westwater Canyon sandstone member:

13. Sandstone, white and greenish yellow, with 

lenticular partings of greenish shale; top 

surface hardened and uneven -.___._____- 24

12. Shale, banded red and greenish white, flaky, 

and thin white sandstone, in overlapping 

lenticular beds._______________________ 30

11. Sandstone, white, thin-bedded, and red 

shale, irregularly interfoliated; forms 

broad platform. _ __ ___________________ 16

10. Sandstone like no. 1 but coarser-grained;

forms strong ledge_ ___-___-___-_____._ 20

' 9. Shale, red, streaked greenish white. -------- 3

8. Sandstone like no. l__--___---__.-_-.-_-_ - 22 

7. Shale,red;formsbench______-.--__-_-_--_ 8

6. Sandstone like no. 1; base firmly cemented 

mass of fragments of sandstone, red shale, 

and white mud shale; rests in hollows and 

about ridges at top of no. 5_____-__--__ 25

5. Sandstone, greenish-white, and lumpy mud 

shale; contains lime concretions and fragments of carbonaceous material __. _____ 5

4. Shale, red; forms platform. ___-__--__-_-_- 3 

3. Sandstone like no. 1___._--_--_______-.__- 23

2. Shale, red, unevenly bedded, imbricated;

weathers to leaf-like chips ______________ 30

1. Sandstone, white; weathers yellowish white, 

most of it cross-bedded and lenticular; 

lenses of conglomerate made up chiefly of 

lozenges and scales of greenish-white clay, 

chert, and fragments of shale; a few very 

thin short lenses of red shale; weakly 

cemented with lime; round holes and slots 

give weathered cliff face a spongy appearance. ___.__-__-______-_-___---_-__-- 46

Total Westwater Canyon member

exposed. ___ ______________________ 255

26. Section of Morrison formation at Decker ranch, 10 miles above 

mouth of Cottonwood Canyon

Westwater Canyon sandstone member: Feet 

17. Sandstone, yellow, buff, and white, coarse-grained, in lenticular beds 6 to 30 feet thick, separated by yellow and gray sandy shales; includes 

lenses of conglomerate composed of white chert; 

lenses of blue and green clay mud balls and 

lozenge-shaped masses of yellow carnotite (?); 

forms cliff; thickness exposed.______________ 222
78 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

26. Section of Morrison formation at Decker ranch, 10 miles 

above mouth of Cottonwood Canyon Continued

Unconformity by erosion.

Recapture shale member: Feet

16-9. Sandstone and shale in alternate layers. 

Sandstone white, brown, and green, calcareous, in beds about 1 foot thick, much of it 

porous and friable; shale red, white, and gray, 

lenticular; breaks into tiny chips___________ 27

8. Shale, white, yellow, and light red; forms banded

slope _-____________-___-_-_--____-_--____ 36

7. Sandstone, olive green, dense, very resistant;

forms cliff________________-_______________ 3

6-1. Shale, light, red and purple, white-streaked, 

sandy, and white sandstone in beds about 1

 foot thick. Sandstone irregularly bedded, 

some cross-bedded, porous where greenishwhite mud fragments have weathered out. _ _ _ _ 63

Total Recapture member_______________ 154

Bluff sandstone member._____________________________ 120+

27. Section of Dakota (?) sandstone in Bulldog Canyon opposite 

Grayson ranger station

[Measured by M. R. Thorpe]

Ft. in.

26. 

25.

24.

23. 

22.

21. 

20.

19.

18. 

17.

16. 

15.

14.

13;

12.

11. 

10.

Sandstone, soft, brownish, thin layers____________ 4

Sandstone, hard, massive, cross-bedded; ledge 

maker___________________________________ 2

Sandstone, soft, thin-bedded, cross-bedded, finegrained, with local lenses of conglomerate _______ 12

Conglomerate, coarse._______________________ __ 1

Sandstone, very strongly cross-bedded, thin-layered, 

soft; some conglomerate in thin bands-_________ 7

Sandstone, massive, cross-bedded, fine-grained; 

ledge maker._______________________________ 2

Sandstone, cross-bedded, thin-bedded; local layers 

of fine conglomerate; lower half fine-grained sandstone, upper half more conglomerate ___________ 13

Shale, greenish, with thin layers of fine conglomerate___--_---_--_--_____________________ 2

Sandstone, with conglomerate in wedges, lenses, 

and irregular shapes; fine to medium coarseness. _ 4

Sandstone, fine-grained, coarsely cross-bedded, 

bluish gray, with small reddish and brownish 

spots and blotches, also purplish streaks about 

a quarter of an inch in width._________________ 8

Sandstone, even-bedded, thin layers, fine-grained. _ 7

Sandstone, thick-bedded, fine-grained, with narrow 

bands of cross-bedded laminae; conglomerate 

wedges and lenses between cross-bedded laminae_______________________________________ 5

Sandstone, soft, white, with yellow blotches, slightly 

cross-bedded.______________________________ 5

Conglomerate in sandstone matrix; pebbles of 

quartz and chert.__________________________ 2

Sandstone, thick-bedded, and small streaks of conglomerate; not very resistant-__---_____------ 5

Conglomerate, fine, cross-bedded__--_____--_--__ 2

Sandstone, massive, thick-bedded; weathers almost 

black; cross-bedded to some extent______---_- 6

Conglomerate in layers with coarse calcareous 

cement _-__-______-.___L___________________ 2

Sandstone, coarse-grained, cross-bedded, reddish 

brown; contains bands'of fine conglomerate with 

a few large pebbles_'_______________________ 4

Sandstone, gray, fine-grained, even-bedded, with 

thin streaks of'fine quartz pebbles___________ 8

m. 

6 

6

27. Section of .Dakota (?) sandstone in Bulldog Canyon opposite 

Grayson ranger station Continued

Ft. 

6. Conglomerate, gray__________________________

5. Sandstone, fine-grained, gray, not cross-bedded____ 1 

4. Conglomerate_._____---_--_-_--_____________ 1

3. Sandstone, smooth, gray, with minute quartz pebbles, not cross-bedded_____---_______________

2. Conglomerate cemented by sandstone matrix; pebbles angular to subangular, a few rounded; large 

percentage of quartz; some pebbles an inch in 

diameter, most less than a quarter of an inch; 

cross-bedded with finest pebbles at the top_ __ 8

1. Dakota (?) talus; huge blocks of strongly crossbedded sandstone-___---__----____-__-__-___ 80

Total...________--___---_-_____._______ 197 3

28. Section of Cretaceous beds on west side of Recapture Canyon

[Dakota (?) sandstone measured about 13 miles south, and Mancos shale 2 miles 

east of B landing]

Mancos shale: Feet 

12. Sandstone, impure, thin-bedded, lenticular, in 

part cross-bedded; some coal seams; the abundant fossils include shells of Ostrea, Exogyra, 

and Gryphaea newberryi_____-_--_-_________ 30

11. Shale, slate-colored, gypsiferous.__-__-_____._._ 40

10. Sandstone, gray and brown, fine-grained, regular 

beds 3 inches to 4 feet thick, and sandy brown 

shales containing Inoceramus fragments, Exogyra, and Baculites... ____________________ 20

Dakota (?) sandstone:

9. Sandstone, yellowish gray, coarse, cross-bedded, 

composed of clean glistening grains of quartz 

and lenses of conglomerate 6 inches to 6 feet 

thick and 10 to 60 feet long, consisting chiefly 

of pebbles of quartz and quartzite with some 

chert and hard limestone; forms rim of canyon 

for many miles_________-___---__ _________

8. Sandstone, fine-grained, white, with long, thin 

lenses of greenish-gray sandy shale __ ______

7. Sandstone, gray, coarse-grained, thin, even6. Shale, dark red, short overlapping lenses and regular beds. _____-______-_-____-__--__-____

5. Sandstone, yellowish gray, thin, irregular beds;

eroded into slabs __ ______________________

4. Shale, reddish brown, sandy; disappears in 30 feet.

along strike. __________----_______--____._

3. Sandstone, grayish green, with red blotches, finegrained. _________________________________

2. Sandstone, buff yellow, medium-grained, lenticular beds 1 to 4 inches thick, and yellowish-gray 

sandy shale in beds that thicken, thin, and 

disappear along strike; form with nos. 3 to 8 a 

steep terraced slope. _ _____-_--___--__-.___

1. Sandstone, brownish gray, coarse, and conglomerate consisting of well-worn round and flat pebbles of quartz, quartzite, chert, and compact 

clay one-eighth to 1% inches In diameter; mud 

lumps, sand balls, and fragments of limestone 

at the base; strongly cross-bedded; a single 

resistant ledge. _ _----_____-___._---_-____

Total Dakota (?) sandstone._____________

Unconformity.

Morrison formation: Variegated shales, white sandstone, 

pink limestone.

36

14

28

33

149
CHAPTER 3. IGNEOUS ROCKS

REGIONAL RELATIONS

Though widely distributed in adjoining regions, 

igneous rocks are rare in the San Juan country. No 

extrusives have been mapped within the belt, some 170 

miles long and 100 miles wide, that extends from the 

Aquarius Plateau eastward across Utah and well into 

Colorado: the lavas and tuffs that may have spread 

over parts of this great region during Tertiary time 

are now represented only in the escarpments of the 

High Plateaus and the cliffs at Telluride. Intrusives 

likewise are poorly represented. They are exposed in 

the Henry Mountains and Abajo Mountains, but for 

many miles north of the San Juan River and lower 

Glen Canyon only one dike has been observed.

In the San Juan country deep-seated granite and 

granitic gneiss have been penetrated in oil wells at 

Soda Basin and in Dark Canyon. On the surface and 

in stream channels east of Comb Wash, also along the 

San Juan and Colorado Rivers, pebbles of igneous rock, 

chiefly from the Abajo and Carrizo Mountains and 

from mountains in Colorado, are widespread. So far 

as observed, the black rocks on mesa tops and flats 

adjoining Cottonwood Wash, known locally as "lava" 

or "malpais", are fragments of quartzite and sandstone 

coated with desert varnish. Outcrops of igneous rock 

have been mapped only in the Abajo Mountains and 

Lime Creek Valley. (See pi. 17.)

The igneous rock characteristic of the Abajo Mountains is similar in appearance and composition to that 

which constitutes the bulk of the laccoliths in Carrizo 

Mountain, Ariz., the Henry and La Sal Mountains, 

Utah, and Ute Mountain, Colo., and doubtless has the 

same general source and history.

In the Abajo Mountains the dominant rock is porphyritic hornblende latite, and the subordinate masses 

range from trachyte to andesite. (See p. 80.) In 

Carrizo Mountain Emery 45 found' a central mass of 

porphyritic diorite and small dikes of shonkinite, 

minette, and dacite. The laccolithic mass in the 

Henry Mountains as described by Gilbert 46 consists 

essentially of "porphyritic trachyte", perhaps better 

described as porphyritic hornblende diorite. For the 

La Sal Mountains, rocks analyzed by W. F. Hillebrand 47 

show a large igneous mass of porphyritic monzonite 

cut by dikes of monzonite, syenite, pulaskite, and

« Emery, W. B., The igneous geology of Carrizo Mountain, Ariz.: Am. Jour. Sci., 

4th ser., vol. 42, pp. 354-359, 1916.

« Gilbert, O. K., Report on the geology of the Henry Mountains, pp. 60-66, U. S. 

Qeog. and Geol. Survey Rocky Mtn. Region, 1877.

« Clarke, F. W., Analyses of rocks and minerals from the laboratory of the United 

States Geological Survey, 1880 to 1914: U. S. Geol. Survey Bull. 591, p. 145,1915.

noselite-syenite. The core of Ute (El Late) Mountain 

as described by Holmes 48 and by Coffin 49 consists of 

andesitic or dioritic porphyry, composed chiefly of 

plagioclase and hornblende phenocrysts in a microcrystalline groundnmss of feldspar, hornblende, and 

magnesite.

Unlike those in the laccolithic Abajo, Carrizo, Henry, 

La Sal, and Ute Mountains, the dikes and volcanic 

necks along the San Juan River in the Navajo country 

are basaltic. Augite is present in all specimens examined and is the predominant mineral in most of them. 

With the augite are the potassic minerals biotite, 

sanidine, and leucite. This association of minerals 

places the rocks in such classes as leucite basalt, 

melilite basalt, trachydolerite, monchiquite, limburgite, 

augite minette, and augitite. They represent high 

differentiation toward the mafic end of- a strongly 

alkalic series.

BELL BUTTE DIKE

Near Bell Butte, about 5 miles north of Goodridge, 

the continuity of the limestone surface is interrupted 

by a low dike about a mile long and 2 to 8 feet wide, 

trending N. 10° W. Like Alhambra Rock and other 

intrusives south of the San Juan River, this dike is not 

massive or uniform in texture. It appears as a series 

of vertically overlapping schistlike laminae of ferromagnesian rock with which are mingled angular fragments of granite gneiss, schist, limestone, and sandstone, derived from the rocks through which the plastic 

magma ascended. The dike has not appreciably 

metamorphosed its bordering sediments and seems to 

have no relation to the accumulation of oil in the beds 

that it traverses. As seen in a hand specimen, the 

igneous part of the dike; of greenish-brown color, 

consists of much brown biotite and green augite and 

some feldspar and calcite. The prominent hexagonal 

plates of brown biotite. are so arranged as to give the 

rock a platy fracture, suggesting an original fluidal 

arrangement. In thin section ;a porphyritic texture is 

revealed: abundant phenocrysts of biotite (phlogopite?) 

and augite and a few of orthoclase and plagioclase are 

set hi a groundmass composed of lath-shaped orthoclase 

crystals intermingled with some diopside, biotite, and 

unidentified material. Bright-green, strongly pleochroic aegirite-augite forms borders of many large 

augite crystals and completely replaces some of the

« Holmes, W. H., U. S. Geol. and Geog. Survey Terr. 9th Ann. Rept., for 1875 

pp. 272-273, 1877.

«. Coffin^ R. C., Radium, uranium, and vanadium deposits of southwestern Colorado: Colorado GOD!. Survey Bull 16, p. 121,1921..

79
80 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

smaller ones. Calcite, analcite, and zeolite are also 

present as minerals of secondary origin. The rock 

differs little from a typical augite minette.

PETROGRAPHY OF THE ABAJO MOUNTAINS

By MALCOLM E. THORPE

Typical rock. The whole laccolithic mass of the 

Abajo Mountains is homogeneous, and the igneous 

material must have all come from the same reservoir, 

notwithstanding the fact that intrusion took place at 

three or more different horizons in the sedimentarystrata. Rock specimens collected at many localities, 

when studied under the microscope, show similarity of 

composition. There is no evidence pointing to differentiation products except in a few places near the contacts 

between the igneous and sedimentary rocks.

The typical igneous rock is a bluish-gray porphyritic 

rock with large crystals of feldspar embedded in a finegrained groundmass. Microscopic study of 42 thin 

sections of the igneous rock from different laccolithic 

bodies shows 27 to range from trachyte to andesite, but 

as a group they are best classed as hornblende latites. 

Gilbert has called this group of rocks, showing no mica, 

hornblende trachytes, and Cross has called them 

porphyrites.

These rocks contain both feldspar and hornblende 

phenocrysts. The feldspar crystals range from 1 to 4 

millimeters in length and are about twice the diameter 

of the hornblende crystals. The hornblende ranges 

from light yellowish brown to green. Augite is rare 

and occurs only as small residual areas in hornblende. 

The only mica observed is a little fibrous secondary 

material. In 13 specimens quartz was found as muchcorroded phenocrysts, but it is abundant only in the 

groundmass.

Orthoclase was identified in a specimen from the 

lowest tunnel of the Gold Queen .mine, although in 

many specimens the faintness of twinning in some 

oligoclase phenocrysts and the alteration of the rocks 

make the distinction between the two feldspars difficult. A fresh orthoclase rock from South Peak contains phenocrysts with a graphic intergrowth of quartz 

and untwinned feldspar, but most phenocrysts are the 

usual twinned plagioclase. A dozen other rocks show 

a few phenocrysts that lack the albite twinning and 

may be partly orthoclase. These rocks resemble, those 

of neighboring regions, in which orthoclase is rarely 

identified but is certainly present, as shown by the 

analyses, and probably forms a considerable part of 

the groundmass. Of the phenocrysts, which make up 

30 to 75 percent of the rock, plagioclase is much more 

abundant than hornblende and is in general the bestpreserved mineral of the rock. The plagioclase ranges 

from sodic oligoclase to andesine; it shows zonal structure in about half of the thin sections and is probably 

obscured by weathering in others. These plagioclase 

crystals range in size from less than 1 millimeter to 4

milUmeters. The plagioclase of the groundmass is 

usually needlelike in form and sodic in character. 

Hornblende is second in abundance to plagioclase. 

Titanite forms characteristic wedges as small phenocrysts in about half of the rocks. Magnetite or ilmenite is present in nearly all the specimens, occurring as 

small phenocrysts and resorption residues around the 

hornblende and as dust in the groundmass. Apatite 

can be fourd as needles in the groundmass and as 

larger crystals in nearly all the rocks. Zircon is visible as very -small grains in only two specimens, one 

from the eastern peak of Twin Peaks and the other 

from the igneous sheet in the Johnson Creek Basin. 

AUanite, which has been reported in rocks from nearby 

regions, was not identified, but it may be present in 

small amounts. Nephelite was not observed and probably is not to be expected in rocks that are so siliceous.

Alteration of the common propylitic type has affected 

the whole series more or less. Pyrite is abundant in 

only one specimen, which came from the Dream mine. 

Sericite, epidote, chlorite, carbonates, and quartz are 

present in many specimens and brownish uralitic aggregates in a few. There has been but little dynamic 

action in this area. A few veins are filled with epidote 

and quartz. In most of the rocks examined alteration 

has affected the hornblende before the feldspar. The 

hydro thermally altered rocks are especially subject to 

weathering.

The groundmass ranges in average grain from 0.1 to 

less than 0.01 millimeter. Five of the rocks differ from 

this fine granular texture in that they show an obscure 

poikilitic intergrowth, ghostlike grains about 0.1 millimeter in size enclosing several smaller grains.

The rocks of the Abajo Mountains fall into two 

classes laccolithic rocks and fragmental contact dike 

rocks and ores. Descriptions of typical specimens are 

given below.

Hornblende andesite from Twin Peaks. The rock 

forming the eastern peak of Twin Peaks is dark brownish gray in the hand specimen, has an even granular 

texture, and weathers into small reddish-brown fragments. It is characterized by white to gray phenocrysts of plagioclase and less abundant ones of hornblende, which together form about 60 percent of the 

rock. A microscopic study shows that the hornblende 

forms slender needles 0.1 to 0.2 millimeter in length, 

which are more highly weathered than the plagioclase. 

The plagioclase has zonal structure and is partly altered 

to sericite. Next in abundance is uralitic hornblende, 

which is for the most part brown but shows gradations 

to the more ordinary green type. Secondary magnetite is found as an alteration product. Apatite occurs 

in unaltered needles and irregular masses. The groundmass is poikilitic, with the host grains as much as 0.1 

millimeter in diameter and the inclusions less than 0.01 

millimeter. Plagioclase, secondary biotite or uralitic 

hornblende, minute grains of magnetite, a small
PETROGRAPHY OF THE ABAJO MOUNTAINS 81

amount of apatite, and probably orthociase are the 

chief recognizable constituents, but probably quartz 

and orthociase make up much of the groundmass.

Dacite from North Peak. A hand specimen of the 

typical porphyritic dacite of North Peak shows feldspar 

and hornblende enclosed in a fine-grained groundmass. 

The color of a fresh surface is dark blue, with gray feldspar and black hornblende crystals. Weathering turns 

the color to a brown and causes the rock to break up 

into angular, more or less oblong fragments a few inches 

thick and 2 or 3 feet in maximum length. The rock is 

massive, heavy, hard, and very resistant to weathering. 

The plagioclase grains are both large and small, some 

oblong and some spherical. The hornblende crystals 

occur as grains and as long, slender laths 6.0 millimeters 

in maximum length. A microscopic study shows that 

the phenocrysts make up 50 percent of the rock. They 

are somewhat irregular in shape, show carlsbad twinning, 

and are embedded in a fine-grained groundmass. The 

feldspar phenocrysts, which appear to be plagioclase, 

are much altered to sericite. Quartz occurs in small 

rounded grains and also as large irregular-shaped forms. 

Primary magnetite is characterized by sharp edges; 

secondary magnetite occurs in small grains that are an 

alteration product of hornblende and probably of biotite. The groundmass is composed of grains about 0.02 

millimeter in diameter. Quartz, orthociase, and plagioclase are the chief components; minute grains of zircon 

and irregular grains of magnetite are also present.

Dacite from Abajo Peak. The rock at the summit of 

Abajo Peak is a typical porphyritic dacite much like 

that found elsewhere in the mountains, a greenish-gray 

rock in which the feldspar and hornblende stand out 

prominently. As seen hi the hand specimen, a grayishwhite feldspar is very abundant in oblong or irregularshaped crystals. A small quantity of quartz is present 

as rounded grains, some of considerable size. Hornblende is not abundant and occurs both as rounded 

grains and as laths. A microscopic study shows that 

this rock contains about 60 percent of phenocrysts that 

are somewhat ragged in outline (perhaps from alteration), embedded in a medium-grained groundmass. 

Among the phenocrysts, plagioclase, with twinned 

crystals, is the most abundant, but there may be some 

orthociase. Hornblende occurs in greenish irregular 

grains, and a considerable amount of quartz is present 

as irregular grains of medium size. The magnetite 

forms irregular-shaped grains that are for the most part 

a secondary alteration product, but a few clear-cut 

crystals are primary. The groundmass is mediumgrained, and its crystals, which average about 0.1 millimeter in diameter, include quartz, plagioclase, probably 

orthociase, sericite, carbonates, brown biotite as an 

alteration product, and grains of magnetite.

Dacite from Horsehead Peak. The rock at the summit of Horsehead Peak is porphyritic with a grayishgreen groundmass, which weathers to a deeper brown.

On weathering it breaks up into angular fragments 

that reach a maximum length of 6 or 8 inches. Phenocrysts of plagioclase, quartz, and hornblende form 

about 40 percent of the rock. The feldspar crystals 

are gray to white and reach a maximum length of 10 

millimeters. A small amount of orthociase may also 

be present. Quartz forms rounded grains. Hornblende Is present as small green rounded grains and as 

slender crystals that reach 5 millimeters in length. 

Magnetite and titanite complete the list of phenocrysts. 

The groundmass is very fine, with grains averaging 

0.03 millimeter, and is composed of quartz, feldspar 

(probably both plagioclase and orthociase), and grains 

of magnetite.

Andesite from Mount Linnaeus. The rock at the 

summit of Mount Linnaeus'is a porphyritic andesite 

in which phenocrysts make up about 50 percent. The 

primary essential minerals are zoned plagioclase, horn- 

" blende, quartz, and possibly some orthociase. The 

primary accessory minerals are apatite, magnetite, and 

titanite. The secondary alteration products are calcite, chlorite, and sericite. The groundmass is poikilitic, composed of quartz (?) and feldspar, darkened by 

a good deal of opaque iron oxide dust. The poikilitic 

areas are a little more than 0.1 millimeter in diameter, 

but some granular areas, as well as inclusions, are much 

smaller.

Dacite from Johnson Creek Basin. The rock forming 

the igneous sheet that covers several acres in the foothills of the Abajo Mountains on both sides of Johnson 

Creek is a brown, very much weathered dacite. It has 

a porphyritic texture, and the irregular and corroded 

phenocrysts make up about 60 percent of the rock. 

The primary essential minerals are medium sodic 

plagioclase, orthociase (?), rounded quartz, and ferromagnesian minerals, which are now wholly altered. 

The primary accessory minerals are magnetite, apatite, 

and zircon (?). The secondary alteration products are 

limonite, kaolin, sericite, and brownish uralite. The 

quartz crystals are rounded and resorbed. The limonite stain permeates nearly the whole rock, and a brownish radial fibrous mineral, resembling biotite, is very 

abundant. Few grains have any resemblance to the 

original ferromagnesian minerals, and many are now 

very fine mineral aggregates. There are also dusty areas 

of feldspar that have been altered to sericite and kaolinitic material, which may have been ortboclase. Zircon is 

abundant. The fine grains of the groundmass are less 

than 0.01 millimeter in diameter.

Andesite from South Peak. The main mass.of South 

Peak is composed of andesite, gray where fresh and 

very light brown on a weathered surface. The texture 

is porphyritic, with medium to small phenocrysts of 

feldspar and hornblende, which form about 50 percent 

of the rock. The primary essential minerals are sodic 

plagioclase, orthociase, corroded quartz, and hornblende that has been wholly altered. The primary
82 THE SAN JUAN .COUNTRY, SOUTHEASTERN UTAH

accessory minerals are magnetite, titanite, and apatite. 

The secondary alteration products are sericite and 

uralite. Some phenocrysts show a graphic intergrowth of quartz and orthoclase. The groundmass is 

a very fine granular aggregate much dusted with brown 

grains that reach 0.05 millimeter in diameter and are 

probably the same as the larger brown uralite.

Contact rock from North Creek. The rock at the contact between the laccolith and the Mancos shale at the 

head of North Creek is gray, with large inclusions of 

black irregular-shaped masses of shale and small 

rounded quartz pebbles. It is hard and does not 

weather readily, although some specimens are much 

altered. One of the thin sections shows an extremely 

fine-grained rock, whose grains are about 0.1 millimeter 

in size. The structure is fragmental, and the specimen 

is composed of quartz, small irregular grams of magnetite, small rounded grams of apatite, minute shreds 

of sericite, much secondary calcite, and a small amount 

of feldspar. Another thin section, of a much-altered 

rock, shows fine-grained groundmass and phenocrysts 

of feldspar, altering to sericite, irregular masses and 

grains of magnetite, a small amount of quartz as aggregations and rounded grains, biotite, and much-altered 

hornblende. Other fragments seem to be quartzite 

and such substances as devitrified rhyolite. The 

groundmass shows an aggregate structure and consists 

of magnetite, quartz, feldspar, sericite, and biotite.

Rhyolite from Horsehead Peak. About 50 yards 

south of the crest of Horsehead Peak is a circular 

igneous plug with a diameter of about 20 feet. It 

consists of slabs about 2 inches thick standing in a 

vertical position. The rock is even-grained and is 

composed of feldspar, hornblende, and quartz. The 

color is grayish green on the fresh surface, but on 

weathering it turns brownish green or dark green. 

Though the minerals are igneous, the hand specimen 

shows some angular dark fragments, and the section as 

a whole shows few good phenocrysts, for all are angular 

and look fragmental. The feldspar is chiefly orthoclase, but some plagioclase is present in the form of 

laths and angular or rounded grains and has undergone 

sericitization and replacement by carbonates. Grains 

of magnetite are probably primary. Green hornblende, 

a few small grains of quartz, brown biotite, a very small 

amount of apatite, sericite, and secondary epidote make 

up the remainder of the mineral constituents. The 

groundmass consists of quartz, ferromagnesian minerals, 

and titanite. ...

Volcanic breccia at Gold Queen mine. Angular slabs 

of volcanic breccia a few inches thick and a few inches 

to 2 feet in length cover an area of about 2 acres on the 

ridge about a quarter of a mile southeast of the Gold 

Queen mine. The slabs represent an outcrop broken 

up by weathering. This rock is a typical volcanic 

.breccia or agglomerate, composed of large crystals of 

gray feldspar and included fragments of shale. Quartz

and fine particles of magnetite, which can be seen 

megascopically, make up the remainder of the rock. 

Some of the feldspar crystals are more than an inch in 

length, and none of these have clear-cut outlines. The 

rock on a fresh surface is grayish brown to grayish blue; 

on a weathered surface it is light brown and has a 

pitted appearance. It is of about medium weight and 

easily fractured. This rock contains a very large 

amount of feldspar, which has been so extensively 

altered to kaolinitic material that its original character 

is obscured. The feldspar is mostly plagioclase, in 

grains of irregular shape. There is a considerable 

amount of magnetite, both primary and secondary, as 

square and irregular grains.. Brown biotite, much 

altered and decomposed, occurs in irregular patches, 

and there is also some sericite as an alteration product of the feldspar, All the fragments are angular, 

and the predominant constituent is altered feldspar.

Andesite (?) from dike in North Canyon. An igneous 

mass, about 100 yards long and 15 feet wide, known 

as Black Dike, appears on the west wall of North 

Canyon, below the Innis sawmill. It trends northwest. 

On a fresh surface the rock is dark gray, but weathering 

turns it to a light brown with a pitted appearance. The 

general appearance of the rock is sandy, with cleavage 

faces of some mineral apparently enclosing many grains 

of sand size. The secondary alteration products are 

carbonates, kaolinitic material, limonite, and quartz, 

and garnet occurs as a product of metamorphic recrystallization. The most striking feature of this rock 

is the appearance of a granular fragmental texture by 

reflected light under the microscope. This appearance, 

however, is deceptive, to judge from the mineral composition, which is that of a contact-metamorphic zone. 

Dusty and apparently weathered carbonate material 

is intergrown with quartz that is almost equally dusty. 

The garnet crystals, being cracked and full of inclusions, do not stand out so distinctly as in most other 

rocks. *

Trachyte from dike in North Canyon. White Dike 

is a band of trachyte just below Black Dike on the west 

wall in North Canyon. It trends northwestward, is 

about 10 feet wide and crops out intermittently for a 

distance of about 600 feet. This rock is composed 

chiefly of feldspar with some calcite. The color on a 

fresh surface is dirty white to gray, from the feldspar, 

which is probably a soda-lime variety. The rock is 

even-textured, light, and easily broken. The feldspar 

is in irregular-shaped grains and is not clearly defined. 

This rock, whose original texture was massive, contains 

about 45 percent of phenocrysts. The primary essential 

minerals are orthoclase (?), a little sodic plagioclase, and 

possibly some perthite; the accessory minerals are titanite, hornblende, and apatite. Secondary alteration 

products are carbonates, quartz, and leucoxene. The 

small amount of ferromagnesian minerals is the most 

striking characteristic of the rocks, but there are
PETROGRAPHY OF THE ABAJO MOUNTAINS 83

indications of their former presence in greater abundance. Some areas of feldspar are still fresh, but other 

areas are dusted over with leucoxene arid in polarized 

light show an aggregate of carbonates and feldspar, 

which are evidently secondary. The groundmass, 

though mostly very light colored feldspar, is peppered 

with leucoxene and carbonates as well as apatite. 

Probably there is some quartz in the rock. 

. Rhyolite from dike in North Canyon. A dike of 

rhyolite on the west wall of North Canyon, near its 

head, trends northeast. It is several feet wide and 

extends for more than half a mile down the canyon.

This is a light-gray, fine-grained porphyritic rock 

of fragmental appearance, with large dark inclusions, 

tt has medium sandlike grains, and the variation in 

size makes it impossible to draw a line between phenocrysts and groundmass. The primary essential minerals are medium-sized plagioclase, orthoclase, hornblende, and quartz, with titanite, magnetite, and 

apatite as accessory minerals. The alteration products 

are magnetite, quartz, and uralite. In a rock of 

megascopic porphyritic appearance it is surprising to 

find the mineral grains angular and prbbably fragmental. The grains range from 0.2 millimeter down 

to submicroscopic size. The hornblende is twinned 

and zoned and has partly altered to a fine-grained 

mineral aggregate. The cement or groundmass is 

very fine and siliceous, resembling the groundmass of 

an ordinary porphyritic rock, but is unusually variable 

in size of grain.

Hornstone in North Canyon. On the west wall of 

North Canyon, just above Innis sawmill, an outcrop of 

banded hornstone is easily traceable for more than half 

a mile along the canyon wall. Its trend is northeast. 

The original rock was sedimentary with well-defined 

bedding, but it is now fragmental and very fine-grained, 

with grains averaging 0.04 millimeter in diameter. 

The bands range in color from light to dark green and 

in thickness from microscopic streaks to bands about 6 

millimeters thick. The rock is hard and resistant to 

weathering. The only primary essential mineral is 

quartz, which makes up about 50 percent of the rock. 

The metamorphic recrystallvzation minerals are epidote, 

15 percent; chalcedony, 20 percent; and hornblende and 

garnet in minor amounts. Epidote and quartz have 

also been introduced into the rock. This rock has 

undergone some recfystallization, but apparently the 

quartz retains an original fragmental condition, and the 

sedimentary bedding planes are clear. The thin 

section shows that epidote forms some distinct veins in 

addition to the grains intergrown with quartz. A 

definitely later quartz vein crosses all these minerals. 

The materials identified as garnet are minute colorless 

isotropic grains, well scattered apparently along certain 

beds.

Dacite dike on Abajo Peak. Near the summit of 

Abajo Peak is a dike of light-gray, even-grained dacite

5 feet wide. Feldspar, quartz, and a ferromagnesian 

mineral, probably hornblende, are the chief constituents. Light-gray feldspar, probably soda-lime plagioclase, forms the main body of the rock, but it is 

impossible to make out the size or shape of the crystals. 

The quartz occurs as small rounded grains and is not 

abundant. The hornblende is lathlike in shape and is 

likewise not very plentiful. This rock is soft and of 

medium weight. Weathering penetrates far below the 

surface, producing irregular cavities that have a very 

dark-brown lining. Weathering reduces the rock by 

fairly rapid stages until it becomes almost as fine as 

powder. Many corroded phenocrysts, making up 

about 40 percent of the rock, lie in a fine-grained groundmass. These phenocrysts comprise large rounded and, 

irregular-shaped quartz crystals with wavy extinction, 

very much altered feldspar, which is largely plagioclase, 

irregular masses and grains of magnetite, pyrite, and 

sericitic alteration masses after hornblende. The 

groundmass is made up of quartz, iron ore, sericite, 

orthoclase, and plagioclase in grains averaging about 

0.02 millimeter in size.

Andesite dike on Abajo Peak. Near the summit of 

Abajo Peak is a dike of andesite (locally known as 

"Black Dike"), 10 feet wide, that trends southeast. 

No traces of it could be found on either side of the ridge. 

It is a massive dark-colored rock that is extremely 

hard, is coarsely jointed, and resists weathering. The 

rock is composed of phenocrysts of feldspar in a dense 

fine-grained groundmass. The feldspar phenocrysts 

are nearly all of uniformly small size and nearly all 

oriented the same way. They are very prominent in 

contrast to the dark groundmass, which is made up of 

feldspar and a ferromagnesian mineral. About 50 

percent of the rock is composed of fairly well formed 

phenocrysts, most of which are feldspar, chiefly plagioclase. The crystals are very large, and many of them 

show zonal structure. Other phenocrysts are quartz 

in rounded masses that are largely secondary, hornblende, magnetite, sparse grams of apatite, sericite in 

large amounts, and small grains of titanite. Secondary 

epidote, chlorite, and carbonates after hornblende are 

also present. The groundmass' is very fine-grained, 

has a brownish color, and shows ghostlike poikilitic 

texture. It is composed of innumerable microscopic 

grains of magnetite, sericite, carbonate, quartz, and 

feldspar, averaging 0.01 millimeter in size.

Gold ore from Recapture Creek. On the Log Cabin 

claim, at the head of Recapture Canyon, a specimen 

of gold ore was taken from the contact between the 

porphyry and the Dakota (?) sandstone. It is composed chiefly of brecciated rhyolite and porphyry. The 

rock is fragmental and has been much altered by hot 

solutions. The porphyry is very soft, brown, and 

traversed by minute fractures that have been filled 

with iron pyrites. The rock contains feldspar; nearly 

all of which has been largely altered to kaolinitic
84 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

material and sericite and whose original character has 

been largely destroyed, though it was mostly plagioclase. A large amount of secondary magnetite is 

.present, with carbonates. Quartz is found in medium 

amount in small interlocking pieces and in large angular 

or rounded fragments. Sericite (?) has filled the cracks 

in the feldspar.

Andesite from Innis mine. The rock near the end 

of the long tunnel at the Innis mine, North Canyon, is 

a fine-grained medium- to light-gray andesitic porphyry 

with small well-formed phenocrysts that make up 

about 40 percent of the rock. The primary essential 

minerals are orthoclase (?), sodic plagioclase, and 

almost wholly altered hornblende; the accessory 

minerals are titanite, apatite, and quartz (?). Calcite, 

epidote, chlorite, and iron ores are the alteration 

products. The groundmass is probably made up of 

orthoclase and quartz and is very fine-grained but with 

ghostlike areas about 0.05 millimeter in size, poikilitically enclosing smaller ones.

Another specimen from the Innis mine was collected 

at the extreme end of the long tunnel, where it penetrates not more than 2 feet into the andesite. This 

rock is composed of feldspar, hornblende, and some 

quartz. The feldspar is plentiful in phenocrysts of 

various sizes; the hornblende is chiefly in minute 

rounded grains or slender lathlike crystals. Quartz 

is very rare. The texture is porphyritic, the phenocrysts being enclosed in a fine dark-gray groundmass 

of the same composition. The phenocrysts make up 

about 45 percent of the rock and are rather irregular 

in form. The primary essential minerals are sodic 

plagioclase, hornblende, and quartz (?); the only 

accessory mineral is granular iron ore. Iron ore occurs, 

also as an alteration product. The rock has an altered 

appearance on the whole but is very fresh. The 

groundmass is largely feldspathic, in grains mostly 

0.01 millimeter in diameter but with some larger ones 

scattered through the rock.

A third specimen from the Innis mine was found in 

contact with the black andesite at the extreme end of 

the long tunnel. This rock is a white porphyritic andesite with phenocrysts of quartz and a little hornblende 

that constitute about 50 percent of the whole.. As the 

rock is light gray, the feldspar is not prominent. The 

primary essential minerals are sodic plagioclase, some 

orthoclase(?), and hornblende, which has been wholly 

altered. Iron oxide is the only, accessory mineral. 

The alteration products are magnetite, kaolinitic material, quartz, and hematite. The groundmass has a 

fine texture and is mostly feldspar dusted with dark 

minerals and perhaps a little quartz in grains about 0.01 

millimeter in diameter.

Metamorphic rock jrom Duckett mine. At John 

Duckett's mine on Jackson Ridge, just east of Mount 

Linnaeus, a metamorphic rock covers an area of not 

more than an acre.

In general appearance this rock is fine-grained and 

black. Its texture is granular, and the original structure was probably fragmental. Under the microscope 

this metamorphic rock shows the recrystallization minerals garnet, quartz, calcite, amphibole, epidote, chlorite, 

and graphite or iron ore. The rock has a spotted appearance, and the coarse calcite and finer-grained quartz in 

smaller amount is peppered with garnet of a very dustlike granular habit. The garnet grains are so filled 

with birefracting inclusions and the calcite and quartz 

so full of inclusions of high relief that the distinctions 

are not everywhere clear.

Greenstone from Dream mine. The east crosscut of 

the long tunnel of the Dream mine, near the head of 

Johnson Creek, has penetrated a few feet into greenstone. The hand specimen appears as an impure 

greenish sandstone, with a fragmental texture of angular 

grains in a fine matrix. There is an indication of bedding showing the original- structure. The primary 

essential minerals are quartz, microcline, plagioclase, 

and orthoclase, with tourmaline as an accessory mineral. 

The secondary alteration product is leucoxene. Pyrite 

and hematite are introduced substances. The angular 

grains make up probably 85 percent of the rock, and 

the matrix 15 percent. Subangular to angular quartz 

constitutes about 90 percent of the grains. The cement 

is mostly chalcedonic or opaline silica, with some 

sericite.

Low-grade ore Jrom Dream mine. At the end of the 

Dream mine, near the head of Johnson Creek, a specimen of low-grade ore was collected in the tunnel that 

runs along a brecciated zone for about 10 feet. This 

rock is brecciated mineralized vein material, with some 

of the porphyritic wall rock. The original structure 

was porphyritic. The primary essential minerals are 

calcite, quartz, pyrite, and a black opaque mineral. 

Leucoxene occurs as an alteration product, and a quartz 

veinlet has been introduced. The thin section shows 

a coarse breccia, not readily interpreted. In one area 

the intergrowth is very fine-grained, mostly quartz, 

pyrite, and a black opaque mineral. This possibly 

represents a fragment of some sedimentary rock, now 

graphitic and mineralized. Another area is more like 

a mineralized porphyritic rock that includes large calcite and pyrite crystals in a silicified groundmass, but 

no indications of original minerals now remain unless 

the leucoxene is to be so taken. There are no clear 

signs of texture, but some calcite aggregates may be 

pseudomorphs after phenocrysts.
CHAPTER 4. STRUCTURE

REGIONAL RELATIONS

The large-scale structural features that characterize 

the Colorado Plateau province are represented in the 

San Juan country by an up warp like the Kaibab and 

the De Chelly, a downwarp like the Kaiparowits and 

the Tusayan, monoclinal folds like Echo Cliffs and the 

Waterpocket Fold, and a laccolithic mass like the 

Navajo, Henry, Carrizo, Ute, and La Sal Mountains. 

The synclines and anticlines present are but modifications of larger features, and the faults are short and 

of small displacement. There are no deep, sharply 

bounded synclines comparable to that which has preserved the coal beds at Gallup, N. Mex., and no master 

faults such as outline the Paunsaugunt and Markagunt 

Plateaus of Utah. The cones and lava f elds of the 

Grand Canyon region and the volcanic necks of the 

Navajo country are likewise not represented.

Here as elsewhere in the plateau region the prominent folds have a general north-south trend and dip 

steeply eastward. They affect all the rocks exposed 

Upper Cretaceous down to Pennsylvanian and so far 

as known date from a pre-Tertiary period of regional 

crustal movement. All the larger folds and many of 

the, smaller ones cross the San Juan River, and published descriptions by "Woodruff,50 Gregory,51 Miser,62 

and Baker 53 of structural features along and south of 

the river apply equally well to those north of it. In 

fact, the walls of the San Juan canyons present an 

excellent cross section of the warps and folds that have 

distorted the sedimentary rocks of southeastern Utah.

As no adeauate base map was available, structural 

features were determined in the field by measurements 

of dips and by study of drainage patterns. The position, length, and height of anticlines and the depth and 

boundaries of synclines and downwarps shown in 

sections (pi. 1) are therefore only approximate. Detailed 

mapping undoubtedly will reveal many small anticlines, 

synclines, and^ faults not recognized in reconnaissance 

traverses.

SAGE PLAIN DOWNWARP

In a broad view the surface of Sage Plain seems to be 

almost fiat in an east-west direction and to slope gently 

southward to the San Juan River, but measurements of

M Woodruff, E. G., Geology of the San Juan oil field, Utah: U. S. Geol. Survey Bull. 

471, pp. 92-93, 1912.

81 Gregory, H. E., Geology of the Navajo country, a reconnaissance of parts of 

Arizona, New Mexico, and Utah: U. S. Geol. Survey Prof. Paper 93, pp. 109-116,1917.

" Miser, H. D., Geologic structure of San Juan Canyon and adjacent country, 

Utah: Geol. Survey Bull. 751, pp. 131-140,1924.

»> Baker, A. A. Preliminary map showing geologic structure of the Monument 

Valley-Navajo Mountain region, San Juan country, Utah, U. S. Geol. Survey, 1933; 

Geology of the Monument Valley-Navajo Mountain region, San Juan County, 

Utah: U. S. Geol. Survey Bull. 865, pp. 63-75, 1936.

dips on the Dakota (?) sandstone, which generally 

floors the plain, indicate a shallow regional depression 

with a broad troughlike bottom about 10 miles northeast of Bluff, from which the strata slope upward 

toward the north, east, south, and west. Northward 

dips of 1° to 2° measure the inclination except where 

the strata are steeply upturned on the flanks of the 

Abajo Mountains; eastward dips that average less than 

1° extend beyond the Utah-Colorado border and at Ute 

Mountain steepen to more than 20°; southward dips 

of 1° to 2° increase to about 4° beyond the San Juan 

River; westward dips of generally less than 2° continue 

to Butler Wash and upper Cotton wood Wash, beyond 

which the strata bend steeply upward in Comb Ridge. 

Only the western border of this basin has been defined.

The regional slopes of the down warp are interrupted 

by minor folds at Ucolo, on Boulder Creek, near the 

mouth of Recapture Creek, about 8 miles above the 

mouth of Montezuma Creek, and at the head of Brushy 

Basin. Local steepening of dips was observed at several 

places. The axis of most of these folds is parallel with 

the north-south strike of the rocks on which'they are 

superposed, and the upbowing is insufficient to bring 

to view rocks below those in the canyon walls. But 

just below the mouth of Verdure Creek a fold that trends 

approximately northwest reveals Jurassic beds of a 

type not exposed in nearby canyons.

In the Sage Plain downwarp are preserved the 

Jurassic and Cretaceous strata which elsewhere in 

southeastern Utah have been stripped from the 

Navajo sandstone. The southern extension of the 

downwarp is the structural basin in the Navajo country 

mapped by Gregory as the Gothic Mesa syncline.

MONUMENT UPWARP

Among the structural features of the San Juan 

country the Monument upwarp ranks first in size and 

as a control in the development of topography. In 

the plateau province as a whole it is equaled in length, 

breadth, and height only by the Kaibab upwarp, and 

it resembles that great fold in that its surface features are plainly exposed and its interior is revealed 

by a canyon sunk deep into its southern slope. Beginning 30 miles south of the San Juan River with dips of 

8° to 20°, the axis of the Monument upwarp slopes 

gently upward to the top of Elk Ridge, 30 miles north 

of the river, then descends with steepened dips into 

Beef Basin and the valleys tributary to Indian Creek. 

Throughout its length the crest of the upwarp is poorly 

marked; over large areas the cap rocks lie nearly flat. 

The eastern flank is clearly marked by Comb Ridge, a

85
86 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

monocline with dips exceeding 50°. The western flank 

is a region of plateaus and cliffs in which the strata, 

with dips of /2° to 2°, extend 30 to 50 miles to the 

Colorado River and continue beyond the river as 

features of the downwarp in which rest the sediments 

of the Kaiparowits Plateau. Erosion of the up warp 

has brought into view strata of Pennsylvanian age 

(Hermosa formation) and succeeding beds up to the 

Dakota (?) sandstone. The youngest formation exposed on the western flank is the Carmel (?); on the 

crest, the Wingate sandstone; on the eastern flank, 

the Navajo sandstone in Comb Ridge and the Morrison 

in Butler Wash. The Wingate sandstone at the Bears 

Ears stands at an altitude of 9,040 feet, in Glen Canyon 

at 3,200 to 3,500 feet, and in Comb Wash at 4,200 to 

4,400 feet. As thus outlined the Monument upwarp 

is about 110 miles long and 40 to 60 miles broad and 

represents a displacement of about 5,500 feet. However, its northern and western edges have not been 

defined, and the few measurements recorded are subject to revision.

Though in general the Monument upwarp is characterized by a broad, nearly flat top, gentle westward 

slope, steep eastward slope, and moderate slopes at its 

north and south ends, none of its slopes have a consistently uniform attitude. Locally on Grand Gulch 

Plateau .dips of 1° to 3° flatten within short distances to 

horizontality or increase to as much as 5°, and on steeper 

slopes local changes in dip of as much as 10° appear. 

Short low synclines and anticlines and elongated domelike uplifts appear at several places. Furthermore, toward the northeast and the southwest the regional inchnation of slopes has been greatly modified by the intrusion 

of igneous rocks at the Abajo and Navajo Mountains. 

On the crest of the upwarp two low anticlines are present 

at Elk Ridge (fig. 2), and two strong anticlines in the 

Goodridge oil field. The broad west flank of the upwarp 

is irregularly corrugated by unevenly spaced synclinal, 

anticlinal, and monoclinal flexures, with axes roughly 

parallel to that of the main uplift. Most of them are 

gentle bowings revealed in the walls of White, Red, 

Moki, Castle, and San Juan Canyons, and though their 

extent and their relation to each other and to structural 

features outside the San Juan country are not known, 

they are thought of as local features. Two of the flex- 

_ures the Step, at the head of Lake Canyon, and the 

Rincon, on the Colorado River are prominent features 

of the present topography. In lower White Canyon 

the regional westward dip of about 2° changes gradually to 8°; the Moenkopi beds high on the canyon walls 

above Duckett form the base of the walls in Glen 

Canyon.

The following description of folds that modify the 

Monument upwarp is supplementary to those previously given in published reports by Woodruff, Gregory, 

and Miser.

Comb monocline. The Comb monocline the steeply 

downfolded eastern edge of the Monument upwarp 

extends from Marsh Pass northward to the northeast 

base of Elk Ridge, a distance of more than 100 miles. 

(See pi. 16r B, <7.) Near the San Juan River dips of 

35° to 60° were measured; at the head of Comb Wash 

of 30°. Along upper Cottonwood Canyon, over the 

Causeway, and down Mormon Pasture Creek the dips 

decrease gradually from about 25° to 12°. Everywhere 

the steep eastern dips change to dips of 1° to 2° within 

a distance of a mile; near the head of Butler Wash and 

at Notch Canyon sharply upfolded beds become nearly 

horizontal within 1,000 feet. For a distance of about 

35 miles north of the San Juan River erosion has carved 

the monocline into the narrow cuestalike Comb Ridge, 

a barrier difficult to pass. Comb Wash has isolated the 

ridge from the main part of the Monument upwarp by 

carving a subsequent valley bordered on the west by 

regional dip slopes of the Cedar Mesa sandstone and on 

the east by precipitous cliffs as much as 1,000 feet high 

cut in the edges of Chinle, Wingate, and Navajo strata. 

A parallel subsequent stream, Butler Wash, that flows 

at the east base of the monocline has stripped away the 

higher beds and revealed the massive Navajo sandstone 

as a core rock that forms the crest and the eastern flank 

of the structure. North of Whiskers Creek the eastern 

slope of the monocline is generally exposed, but its top 

is not well defined. Cross sections of its structure are 

revealed in Hammond, Notch, and other canyons 

tributary to Cottonwood Canyon.

Raplee anticline. The fold defined in published reports as the Raplee anticline is an elongated dome 

sharply bounded on the east and west by monoclines. 

Beginning near the mouth of Comb Wash, the beds of 

Rico limestone that form the cap rock of the anticline 

rise abruptly westward from beneath higher beds with 

dips of 15° to 40°, flatten to less than 3° across the 

crest, then bend sharply downward and disappear 

beneath beds of the Cutler formation in the Mexican 

Hat syncline. As a structural and topographic unit 

the anticline is 15 miles long and 4 to 6 miles wide and 

at Soda Basin stands 1,000 feet above its eastern and 

western edges. As mapped by Woodruff, its top is not 

a continuous structural ridge. Instrumental surveys 

show low anticlines with ends that overlap. In the 

intervening shallow synclines Sugar Loaf and other 

buttes, composed of strata younger than the Rico, have 

been preserved (pi. 16, Z>).

Mexican Hat syncline. Parallel with the western 

base of the Raplee anticline and extending across the 

Mexican Hat loop of the San Juan River, strata of Rico 

and Cutler age lie in a shallow trough, with sides that 

slope upward at angles of about 4°. This trough, 

which has appropriately been named by Miser the 

Mexican Hat syncline, has been traced for about 18 

miles. South of the San Juan River the syncline is 

occupied by the valley of Gypsum Creek; north of it 

by Lime Creek.

Mitten Butte anticline. The Rico and younger beds 

that make up the western lim'b of the Mexican Hat
STRUCTURE 87

R.I7.E R.I9 E. R.2O E.

/ .'' .<? /

1 --:__

Contours on top of Coconino sandstone; interval 

100 feet,datum approximately sea level

FIGURE 2. Struccure map of Elk Ridge. By Warren 0. Thompson; courtesy of Midwest Oil Co.
88 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

syncline continue their upward inclination but with 

decreasing dip until in the vicinity of Cedar Point they 

form the cap of an uplift in which beds dip about %° 

both east and west. This is the crest of the broad, high 

Mitten Butte anticline, in which the San Juan River 

has sunk itself 1,300 feet at the Honaker trail. South 

of the San Juan the anticline lies between Gypsum and 

Oljeto Creeks, and north of the river it extends beyond 

Grand Gulch. A few miles west of the summit the 

long western slope of the anticline has a regional dip 

of 2° to 4°, then decreases to about 1°. Along the San 

Juan River the Mitten Butte anticline is essentially the 

summit of the Monument upwarp, but toward the 

north it seems to merge into other features and may be 

genetically related to the anticlines on Elk Ridge.

The Raplee ("East") and Mitten Butte ("West") 

anticlines and the Mexican Hat ("Lime Creek") 

syncline are the "oil structures" on which wells of the 

San Juan oil field have been located. The producing 

wells are in the Mexican Hat syncline west of its axis.

Oljeto syncline. The Oljeto syncline, which in the 

Navajo country underlies the floor of Oljeto Valley, 

crosses the San Juan River and extends an unknown 

distance northward. The beds of sandstone that 

constitute its broad eastern flank and its narrow western 

flank slope upward at angles of 1° to 4° to the bordering 

Mitten Butte and Organ Rock anticlines, to which the 

syncline is roughly parallel.

Organ Rock anticline. Miser describes the Organ 

Rock anticline as "a terracelike fold" that "trends N. 

10° E. from Organ Rock, crossing the San Juan River 

and apparently fading out in the vicinity of Clay Hill 

Pass." "Where trenched by the San Juan Canyon the 

Cedar Mesa sandstone displayed in the fold lies flat 

on the crest, dips eastward to the floor of the Oljeto 

syncline at an angle of 3° and westward for about 5 

miles at angles of 1° to 3/2°. North of the San Juan 

River the fold flattens but continues as a structural 

and topographic unit for about 3 miles, beyond which 

its features are not clearly recognizable. Along the 

western edge of Grand Gulch Plateau, on Grand Flat, 

also at Red House, Clay Hills, and other places in the 

wall of Red Rock Plateau the regional dip of strata 

involved in the Monument upwarp is interrupted by 

slight upbo wings, some of which may prove to be closely 

related to flexures in the San Juan Canyon. The Organ 

Rock anticline is probably the northward continuation 

of the prominent structural feature mapped by Gregory 54 as the Hoskinnini monocline.

Balanced Rock anticline. From, the head of Clay 

Hills Pass, where it stands at 6,000 feet, the Navajo 

sandstone slopes generally westward across Red Rock 

Plateau to the rim of Glen Canyon, at an altitude of 

4,000 feet. Along upper Castle Wash, also near the 

Colorado River, the regional dip is modified by minor

M Gregory, H. E., o p. cit. (Prof. Paper 93), p. 114.

folding and at the head of Lake Canyon is sharply 

interrupted by a huge monocline in which the Navajo 

and underlying beds are bent steeply upward to a height 

of perhaps 800 feet. This fold, the Balanced Rock anticline, indicated by dip symbols on the map of the Navajo country and later.described by Miser,55 is represented in the topography along Nokai Creek and northward 

across the San Juan nearly to the Colorado River. In 

the wall of San Juan Canyon at Zahns Camp the 

fold has revealed a remarkable section of Permian, 

Triassic, and Jurassic rocks. As revealed in lower 

Castle Wash (Spring Gulch), Johnny Hole, and Lake 

Canyon, where the Navajo and Wingate sandstones 

have been deeply trenched and exposed here and there, 

the Chinle, the eastern flank of the fold, dips eastward 

20° to 25° near the San Juan River; 30° at the head of 

Johnny Hole Canyon, where the fold is highest and 

broadest; and 6° at Hermit Lake, north of which dips 

as low as 2° were measured. From a flat summit the 

western flank of the anticline, measured on strata of 

Carinel (?) age, at the top of Wilson Mesa dips 1° to 2°. 

Near the San Juan River Miser recorded dips "ranging 

from 5° to less than 10°." (See pi. 18, (7.)

Paralleling the Balanced Rock anticline on the east 

a synclinal trough appears near the junction of Johnny 

Hole and Castle Wash and as an inconspicuous feature 

may be traced for several miles northward. Southeastward it extends across the San Juan River as the Spring 

syncline, described by Miser.

OTHER FOLDS

Numerous folds that stand as wrinkles on the broad 

west flank of the Monument upwarp are revealed in 

canyon walls and in cliffs that border mesas. In 

regularly bedded strata such folds are easy of recognition, but in the wide expanses of cross-bedded Navajo 

sandstone the determination of the position, extent, and 

curvature of small folds proved impracticable.

About 5 miles below the mouth of Piute Creek a 

symmetrical fold with dips of 8° to 10° on the east slope 

and 2° to 5° on the west slope crosses the San Juan 

Canyon and may be traced a few miles north. Parallel 

with it on the east is a syncline with dips of 1° to 2°. 

The anticline was named by Miser the "Navajo 

Mountain anticline" and later by Baker the "Beaver 

anticline." The syncline was named by Miser the 

"Rapid syncline".

Wilson Mesa doubtless has a general synclinal 

structure. The strata upturned in the Balanced Rock 

anticline dip toward it from the east, those near the 

Great Bend of the San Juan dip slightly from the 

southeast, and those in the Rincon from the west 

and northwest. As most of the mesa is floored by 

the strongly cross-bedded, intricately dissected Na-

«» Miser, H. D., op. cit. (Bull. 751), pp. 134-135.
STRUCTURE 89

vajo sandstone, the axis, dimensions, and amount of 

displacement of the structure can be established only 

by instrumental surveys. If .the structure of the mesa 

is of the regional type, the Beaver and Rincon anticlines 

may be genetically related and a syncline with northsouth axis lie east of the Rincon.

The Waterpocket Fold, an outstanding topographic 

and structural feature in the Kaiparowits region, 

crosses the Colorado and appears in the San Juan 

country as the Rincon. This canoelike end of the fold 

is recognizable for some 5 miles south of the river. Its 

maximum eastward dip is 6°; its western and southern 

dips, 1° to 2°. Streams developed along the strike of 

the curved ends have cut a horseshoelike trough in 

Chinle beds surrounding an island of Navajo sandstone.

Mold Canyon is crossed by three low folds that trend 

approximately north-south, and near the trail into the 

canyon at Red Cone Spring the strata form a dome 

trending northeast with dips as high as 8°.

On Fish Creek a dome about 4 miles wide and 10 

miles long consists of two low anticlines that trend 

about N. 40° W. and dip l°-3° W. and 2°-3° E. An 

intervening shallow syncline has determined in part the 

position of drainage channels. The dome has been 

mapped as an "oil structure."

The floor of Arch Canyon is slightly upwarped in 

several places. One fold that brings into view fossiliferous limestone may be the northern continuation of 

the Fish Creek fold.

The crest of the Monument upwarp on Elk Ridge 

consists of two anticlinal flexures that as topographic 

features correspond to West Elk Ridge and East Elk 

Ridge. (See fig. 2.) The East Elk anticline is low 

and short and merges into the Comb monocline. The 

West Elk anticline, likewise low and inconspicuous, is 

an independent fold, the highest part of the Monument 

upwarp. From a high point near Reservoir Canyon its 

southward-sloping axis passes through the Bears Ears 

and probably could be traced some distance out onto 

Grand Gulch Plateau.

In White Canyon west of Duckett the Cedar Mesa 

sandstone is arched up in a broad, low fold through 

which the stream has cut a narrow, deep trench. 

About 6 miles above the mouth of White Canyon the 

regional westward dips of 1° to 3° change to 8° and 

bring the Moenkopi beds down to the river's edge.

Along the south border of Beef Basin the Monument 

upwarp appears to terminate as a flattened dome with 

dips east, west, and north of about 2°. The north side 

of the basin is a low anticlinal fold with an axis trending 

northwest through Home Spring. Near the junction 

of Beef Basin and Fable Creeks a fold of unknown 

extent shows southwest dips as high as 20°. These 

folds have brought into view a large expanse of white 

sandstone, below which red beds and limestones are 

exposed in canyon walls and above which stand buttes 

capped by Shinarump conglomerate.

FAULTS

Small-scale fractures and faults are common in the 

San Juan country, but except in the Abajo Mountains 

faults with displacement sufficient to exert topographic 

control were not observed. Most of the faults lie along 

folds where changes in dip are greatest. Near the 

mouth of Verdure Creek a fault with a downthrow of 

70 feet on the south trends N. 70° W. across Montezuma Canyon, and 20 miles to the south another fault 

crosses the canyon. In the walls of San Juan Canyon 

several faults were mapped by Miser, one of them with 

a throw of 60 feet. Short faults with displacements of 

1 to 3 feet break the strata in canyons on Red Rock and 

Grand Gulch Plateaus, in the Comb monocline, and at 

the head of Beef Basin. Along White Canyon below 

Duckett faults are associated with; wide joint cracks 

now filled with yellow sandstone. The three parallel 

faults at the Hole in the Rock, one of wnich crosses Glen 

Canyon, are discussed by Miser.66

STRUCTURE OF THE ABAJO MOUNTAINS

By MALCOLM R. THORPE 

GENERAL FEATURES

Newberry 57 recognized the core of the Abajo Mountains as an intrusive mass which made its way upward, 

perhaps to the surface, through Mesozoic and probably 

also Paleozoic strata, and said that the Cretaceous 

strata on the mountain flanks are "apparently the 

remnants of a plateau corresponding to, and once 

connected with, the Mesa Verde."

Holmes 58 clearly expressed the view that the Abajo 

Mountain system was formed by intrusion and that 

Cretaceous beds formerly covered the igneous rock.

As part of a comprehensive geologic study of the 

Abajo Mountains the writer recorded and discussed 

the structural features in detail.59 From a manuscript 

that served as a source for this published paper most 

of the following descriptions have been compiled. 

(See also pi. 17.)

The Abajo Mountains owe their existence to intrusions of magma into sedimentary beds of Jurassic and 

Cretaceous age in such manner as to produce a group 

of laccoliths. The main features of laccolithic bodies 

are well represented: the ground plan is roughly circular; 

the superincumbent strata have been lifted by doming 

instead of by faulting; the rock is porphyritic in texture, 

and regardless of locality shows remarkable uniformity 

in composition; features of extrusives are absent; dikes, 

sills, and sheets associated with the large igneous masses

"Miser, H. D., Geologic structure of San Juan Canyon, Utah: U. S. Oeol. Survey Bull. 751, pp. 139-140, 1924.

« Newberry, J. S., Geological report, in Report of the exploring expedition from 

Santa. Fe, N. Mex., to the junction of the Grand and Green Rivers of the great Colorado of the West in 1859, p. 100, Washington, 1876.

«s Holmes, W. H., Report on the geology of the Sierra Abajo: U. S. Geol. and Geog. 

Survey Terr. 10th Ann. Rept., for 1876, pp. 191-192, 1878.

»» Thorpe, M. R., Structural features of the Abajo Mountains, Utah: Am. Jour. 

Sci., 4th ser., vol. 48, pp. 379-389, 1919.
90 THE SAN JUAN COUNTEY, SOUTHEASTERN UTAH

are in crosscutting relations with the sediments; at 

both the lower and the upper contacts with the igneous 

rock the sediments are metamorphosed. The structure, 

however, is not simple. The laccoliths composing the 

mountains differ in both horizontal and vertical position. 

Part of the floor of a laccolith is the uneven roof of the 

one next below. The original cover of the individual 

laccoliths has been unequally removed.

The cover of Shay Mountain remains intact except 

for a small dike or plug that rises from the igneous mass 

beneath. At North Peak more than half of the cover 

has been removed; at the other laccoliths one-third to 

one-half. The remnants of the former roof consist of 

Morrison, Dakota (?), and Mancos strata. Mesaverde, 

now absent, probably was once present. Measured 

from the top of the Mancos .the depth of original cover 

over Shay Mountain is about 2,750 feet; over Mount 

Linnaeus, Abajo Peak, and South Peak, 1,500 feet; 

and over. Horsehead, Twin, and North Peaks, 1,200 

feet.

In the roofs of the laccoliths metamorphism has 

affected the sediments for distances of 10 to 200 feet 

from the contact. Sandstones have been changed to 

quartzites and shales to argillites, without, however, 

changing their structure or content except for slight 

mineralization. (See p. 91.) The metamorphosed 

sediments resist erosion, and their edges stand as 

ridges and revetment crags. The igneous mass is 

little changed by contact with the sediments.

No evidences of stoping or assimilation were observed 

in the Abajo Mountains, and it seems almost certain 

that the mountains owe their existence to injection in 

which the magma was aggressive and forced up the 

overlying strata in order to form a chamber for itself.

IOCAI FEATUEES

Shay Mountain is essentially a dome of sedimentary 

rock. Dakota (?) sandstone forms the top of the 

mountain; Morrison and Glen Canyon strata are exposed in canyons on its flanks. The dip on the east 

side of the dome is 12°, on the south 5°, on the west 9°, 

and on the north 15°, with a gradual flattening out to 

5°. At the crest of the mountain is a plug or dike of 

blue porphyry about 110 square yards in area which 

has broken through the roof of the laccolithic chamber. 

As all the strata from Glen Canyon to Dakota (?) have 

been involved in the doming of the uplift, it is reasonable to suppose that the igneous material spread out 

in the Chinle formation. A synclinal ridge, whose axis 

trends east-west and pitches west, joins Shay Mountain 

and Mount Linnaeus. The Dakota (?) sandstone that 

caps the ridge forms dip slopes on the south side of 

Shay Mountain and on the north slope of Mount 

Linnaeus.

Mount Linnaeus is a partly uncovered laccolith. 

Dakota (?) sandstone overlaps its northeast side; Morrison sandstones and shales the other sides. These

strata, if projected in accordance with their dips, would 

form the cover of the laccolith. The horizon of intrusion of the magma is most probably the middle Morrison 

except dn the northeast, where the magma broke 

through to the base of the Dakota (?) sandstone. 

Patches of the roof rock are present in several places 

and at different altitudes on the mountain. On Duckett 

Ridge three isolated patches of Dakota (?) sandstone, 

metamorphosed to quartzite, have been floated up to 

an altitude of more than 10,250 feet, and at the south 

end of this ridge, above 10,000 feet, is a large patch of 

red Morrison shales that dip 20° N. A small unmetamorphosed patch of Mancos shale overlies Dakota (?) 

sandstone on the west side of Dry "Wash at an altitude 

of 9,500 feet. The north side of the ridge that forms 

the west end of Jackson Divide is formed of Dakota (?) 

sandstone with a dip of 15° N.; the south side is almost 

entirely made of fine porphyry talus with no indications 

of sedimentary strata.

The area including Abajo Peak, South Peak, and the 

east end of Jackson Divide is structurally like the south 

and west sides of Mount Linnaeus. Dakota (?) and 

upper Morrison beds so thoroughly flank the mountain 

sides that igneous rock is well exposed only near the 

summits. On the south and east sides the Dakota (?) 

slopes up with a gentle but constantly increasing dip 

until it reaches well up the flanks. In this area the 

Dakota (?) and Morrison shales unquestionably formed 

the cover at the time of intrusion. Southwest of 

South Peak the intrusive rock is exposed between strata 

of the Morrison formation. On the east side of Abajo 

Peak at an altitude of more than 11,000 feet the 

Dakota (?) sandstone is changed to a quartzite that 

contains numerous vugs filled with a fine mesh of quartz 

crystals of all sizes. Beneath the Dakota (?) lie the 

metamorphosed Morrison strata. At the base of the 

principal eastern spur, where Holmes' party encamped 

in the fall of 1876, there is a double row of revetment 

crags, formed of Dakota (?) and Morrison strata that 

dip as much as 45°.

In the area that includes Horsehead Peak, North 

Peak, and Twin Peaks the magma was intruded at or 

near the base of the Mancos shale a higher horizon' 

than elsewhere in the Abajo Mountains. Only on the 

east slope of Horsehead Peak does the Dakota (?) overlap the igneous body. A large mass of highly metamorphosed Mancos shale forms the divide between the 

head of Indian Creek and North Creek. Isolated 

patches of the same material appear on top of North 

Peak and in other places at altitudes of more than 

11,000 feet. Fossils in these argillites were identified 

by T. W. Stanton as middle Mancos an indication 

that the igneous mass was intruded at or near the base 

of the Mancos, as local contact metamorphism would 

hardly extend through several hundred feet of strata. 

On the summit of North. Peak these strata forming 

blocks of tilted and folded argillite dip southwest and
GEOLOGICAL SURVEY PROFES

A. VIEW ON RECAPTURE CREEK. 

Undiffercntiated Morrison formation.

B. COMB WASH AT MOUTH OF ARCH 

View looking north up the wash. Down-curved beds of Monument u

escarpment of Comb monocline at right; spur of Elk R

 **>*fcl-«

 * > * 

C. EASTERN FLANK OF MONUMENT UPWARP ON BLANDING-KIGALIA ROAD.

View looking south. Chinle capped by Wingate at center and left and in center distance. Forestcovered Shinarump sloping upward to Elk Ridge at right.

D. WEST FLANK OF RAI'LEE ANTICLINE AT 

View looking north across Lime Creek Valley toward Cedar Mesa. 

gaito in middle distance. Photograph by E. G
U. S. GEOLOGICAL SURVEY 109°30' PROFESSIONAL PAPER 188 PLATE 17

\ i ^ c^ > ^

Base from U.S.Geological 

and Ha.yden Surveys

109°3O' Geology by Malcolm R.Thorpe

P lain

EXPLANATION

SEDIMENTARY ROCKS 

MAP SECTION

Dakota (?) sandstone 

(Indurated quartzose sandstone with carbmiaceom shale, locally amtnmmg 

coal: small areas of Afancos shale inchided in places.)

Jms i~

Morrison formation arid

San Kafael group 

(Alternating sandstones and shales.)

Glen Canyon group 

(Two massive sandstone layers separated by thin, red calcareous shale.)

Chmle formation 

(Brilliant red shale.)

IGNEOUS ROCKS

Ti

Intrusive rooks

Mine or prospect

GEOLOGIC AND TOPOGRAPHIC MAP AND SECTIONS OF THE ABAJO AREA, SAN JUAN COUNTY, UTAH

Horizontal scale

4-Miles

Vertical scale 

o 10,000 Feet
GEOLOGICAL SURVEY PROFESSIO

A. VALLEY OF BUTLER CREEK.

View looking north. Subsequent valley developed on the back slope of Comb monocline. Stream 

occupies narrow canyon cut into the floor. Navajo sandstone overlain by formations of the San 

Rafael group. Bluff sandstone member of Morrison formation in right distance.

B. TALUS SLOPE ON IGNEOUS ROCK IN ABAJ

Photograph by M. R. Thorpe.

C. BALANCED ROCK ANTICLINE.

View looking north across the San Juan River, here deeply entrenched. Castle Wash at foot of dip slope. Organ Rock member (OR) in canyon wall and above it, in turn, D

Mosnkopi (M), Shinarump (S), Chinle (Ch), and Wingate (W) strata. Photograph by J. B. Reeside, Jr.
STKUCTURE 91

northeast at an angle of 5°. On the east side of the 

saddle between Harts Draw and the head of Indian 

Creek (altitude 10,350 feet) the shale dips S. 27° W. 

At the head of Indian Creek (altitude 10,600 feet) the 

dip is S. 24° W. At the head of North Canyon the dip 

is N. 30° W. In North Canyon, where the shale is in 

contact with blue porphyry, the igneous rock encloses 

fragments of argillite. At the head of Harts Draw 

the Mancos shale is in contact with a dike of igneous 

rock that extends northeast from the eastern peak 

of Twin Peaks and ends at an altitude of 9,800 feet. 

In the dugway that leads up to InmV sawmill about 

10 feet of highly metamorphosed shale is enclosed in 

the blue porphyry. In a butte near the dugway, where 

the contact between the roof and the intrusion is 

displayed, the Dakota (?) within a few feet of the 

contact dips at an angle of 80° away from the igneous 

body. At a distance of about 200 feet it flattens out 

to 16° and then gradually decreases still more. In the 

Twin Peak-Horsehead Peak region the Dakota (?) sandstone is apparently the floor of the laccolith except on 

the east side, where the magma, instead of breaking 

through the sandstone, arched it up.

Between Recapture Creek and Johnson- Creek, 

south of Jackson Divide, is a large sheet of dacite, an 

offshoot of the major intrusions. Its roof is represented by many isolated patches of Dakota (?) sandstone 

and some beds of Morrison shale (not shown on the 

map). The upper surface of this sheet was originally 

somewhat uneven, and, now that the roof is removed, 

shallow water-filled depressions are left. On the eastern edge of this sheet Dakota (?) sandstone dips 16° S. 

and strikes east. The east half of the floor of the sheet 

is within the Morrison formation, but the west half

lies at a deeper horizon. Intrusion has produced 

faulting along the western margin.

Few faults are associated with the laccoliths in the 

Abajo area. None of them are shown on the map 

(pi. 17). The most conspicuous fault, that at the base 

of South Peak, trends nearly north and has a throw of 

about 500 feet. Its steep western escarpment is the 

eastern wall of Recapture Canyon. This fault is 

crossed at right angles by another fault with a southward-facing escarpment that attains its greatest height 

at its west end. The two faults combined form a block 

whose surface dips 12° E. until it merges with the 

regional dip of 3° E. At many places on the mountains 

marginal faulting has broken off strata and carried 

them to the mountain summits or high on their flanks. 

In Pole Creek faulting has left about 500 feet of Morrison and Dakota (?) strata far above their normal 

horizon. On the west side of North Canyon, above 

Innis' sawmill, many slickensides were observed, and 

at the Copper Queen mine large blocks of slickensided 

Dakota (?) sandstone have been blasted out. The 

sheet of dacite between Johnson and Recapture 

Canyons is bounded on the west side by an intrusion 

fault which has brought the Dakota (?) and the Morrison in touch with the igneous rock along a well-defined 

contact. On the eastern border of this dacite sheet 

upturned strata of Navajo, Morrison, and Dakota (?) 

formations dip 38° to 75° E. Faulting and the tilting 

of strata about the igneous iritrusives have determined 

the location of the headwater tributaries of Montezuma, 

Recapture, and other streams draining the east and 

south sides of the Abajo Mountains. Indian Creek 

between Shay Mountain and North Peak follows a line 

of structural weakness.

145824 3S
CHAPTER 5. PHYSIOGRAPHY

REGIONAL RELATIONS

The physiography of the Sari Juan country is closely 

related to that of the adjoining Navajo country, the 

Kaiparowits region, and the wide belt of plateau lands 

north and south of the Grand Canyon. The stratigraphic series in which the topographic features are 

developed, the kind and date of diastrophic movements, 

and the time of igneous intrusion correspond in general 

with those for the Colorado Plateaus as a whole. Likewise the topographic features are similar in form and 

have in general the same history. Outstanding differences are the absence of faults of large displacement; 

the absence of Tertiary sedimentary rocks, which 

probably once extended across southern Utah; and the 

fact that beds of Jurassic age occupy the highest altitudes, and the Cretaceous strata, which beyond Glen 

Canyon and the San Juan form lofty mesas, lie at 

relatively low altitudes.

The physiographic history of the Colorado Plateaus 

is essentially one of post-Eocene erosion, conditioned 

by climate, altitude, and tectonic deformations. The 

present topography measures the progress of adjustment of drainage to structure and to rock hardness.

As it appears today the plateau country is a region of 

plateaus, mesas, cliffs, and canyons. Except for such 

laccolithic masses as the Abajo, Carrizo, Navajo, and 

Henry Mountains and the volcanic San Francisco and 

Uinkaret Mountains, the highlands are flat or slightly 

inclined tables, benches, and steps bordered by precipitous cliffs; and the streamways are high-walled, 

flat-bottomed trenches. In distant views the plateau 

surfaces are conspicuous. Long stretches of sky line 

seem nearly horizontal, and platforms at different levels 

seem interrupted only by scattered buttes and mesas 

that rise above their surfaces. The canyons are lost 

in the general levelness. Unlike the graceful outlines 

of mountains and valleys in humid climates, the landscape is bold and rugged; curves are replaced by angles. 

In further contrast the protecting cover of vegetation 

is largely lacking; the dominant grays and greens of 

humid regions give way to whites, reds, and browns 

the colors of the rocks themselves.

In the development of the characteristic topography 

the stripping and recession of cliffs are major processes. 

The dominant stripping of weak formations from resistant formations has produced many surfaces that are 

essentially residuals of widespread postmature erosion 

surfaces. But unlike old-age surfaces developed under 

humid conditions, those produced by stripping tend to 

be flats in soft rocks and slopes that conform in steep92

ness with the dip of the strata in hard rocks. Cliffs, 

as they weather back, maintain steep profiles; they are 

not transformed into slopes that decrease hi declivity 

with age. The mural aspect of much of the plateau 

scenery is due to the fact that cliffs once formed retain 

the. appearance of topographic youth until the canyons 

and mesas which they bound are entirely destroyed.

The topography of the plateau province is obviously 

not the work of a single cycle. Superimposed drainage, 

discordant profiles, and the juxtaposition of old-age and 

youthful surfaces indicate periods in physiographic 

history when dominant aggradation Was replaced by 

degradation, uplifts by still-stands, and humid by arid 

climates. To reconstruct the successive events involves 

the interpretation of such outstanding features as postmature topography of plateau tops, truncated folds in 

Cretaceous and older beds, graded platforms adjoining 

deep canyons, entrenched meanders, incipient peneplains, gravel-floored rock terraces, canyon fill, and 

alluvial terraces. As discussed more fully elsewhere,60 

these heterogeneous elements in the present topography 

serve to outline a series of long and short erosion cycles 

during each of which distinctive landscapes were 

developed. The oldest cycle of which there is clear 

evidence the pre-canyon cycle began with a postEocene uplift, which raised widespread, low-lying 

Tertiary limestones nearly to the height of the present 

plateaus. The slopes and inequalities of this newly 

made high-level surface are believed to have determined the position and gradients of the ancestral 

Colorado, the San Juan, and their oldest tributaries. 

The Paunsaugunt, Kaiparowits, and Chuska Plateaus 

and other scattered remnants of this broad expanse of 

early Tertiary sedimentary beds in Utah and Arizona 

show the maturely dissected slopes that characterize 

an advanced stage of denudation.

During the long pre-canyon cycle of erosion all the 

Tertiary sedimentary rocks, most of the Cretaceous, 

large parts of the Jurassic and Triassic, and some of 

the Permian of southeastern Utah were stripped away. 

As the gradients of the ancient Colorado and its tributaries were reduced to a gentle slope, meanders developed and topographic inequalities were subdued.

«° Button, C. E.( Tertiary history of the Grand Canyon district: U. S. Qeol. Survey 

Mon. 2, pp. 206-229,1882. Davis, W. M., An excursion to the Grand Canyon of the 

Colorado: Harvard Coll. Mus. Comp. Zoology Bull., vol. 38, pp. 118-121, 167-169, 

1901. Gregory, H. E., Geology of the Navajo country: U. S. Geol. Survey Prof. 

Paper 93, pp. 122-123,130-132,1917. Gregory, H. E., and Moore, R. C., The Kaiparowits region: U. S. Geol. Survey Prof. Paper 164, pp. 138,139,143-144,1931. Gregory, 

H. E., Colorado plateau region: 16th Internal. Geol. Cong. Guidebook 18, 1932. 

Robinson, H. H., The Tertiary peneplain in the plateau district and adjacent country 

in Arizona and New Mexico: Am. Jour. Sci., 4th ser., vol. 24, pp. 115-118, 1907.
93

Much of the country, in particular the strips along the 

main drainage channels, was reduced to a plain where 

the valleys were shallow and the hills conspicuous. 

That parts of this old surface stood on a level so uniform that the streams lacked the power to entrench 

themselves deeply is shown by erosion surfaces that 

extend without significant inequalities across hard and 

soft rocks and across faults and folds. At such widely 

spaced areas as Hopi Buttes, in the Navajo country; 

Black Point, in Little Colorado Valley; Echo Cliffs, 

east of the Marble Gorge; and Mount Trumbull. and 

Hurricane Cliffs, in northwestern Arizona, fragmentary 

peneplains are preserved beneath lavas. Similar flat 

lands, likewise developed with little regard to rock 

composition or structure, are characteristic of interstream areas along Glen Canyon, in Paria Valley, and 

generally about the base of the High Plateaus. In 

sharp contrast with the present youthful topography, 

these representatives of a former surface retain the 

features of a mature or even postmature landscape on 

which drainage was fully developed. A study of these 

remnant landscapes leads to the belief that they are 

essentially local features; no amount of reasonable 

interpretation can regard them as parts of a regional 

peneplain on which drainage had reached baselevel. 

Throughout the pre-canyon cycle the old-age surfaces 

along the larger streams terminated at the base of cliffs 

whose tops also had reached old age. There is thus 

presented an unusual topographic complex two immediately adjoining regions, one 2,000 to 5,000 feet 

higher than the other and both characterized by an 

advanced stage of denudation.

The extension and full development of the erosion 

surfaces produced during the pre-canyon cycle were 

inhibited by a regional uplift that initiated the canyon 

cycle (the present major cycle) of erosion. The physiographic evidence for this uplift is the readjustment of drainage by shifting of divides, the stripping of 

talus and accumulated alluvium from cliff faces and 

lowlands, and the cutting of deep, narrow, verticalwalled canyons with ungraded floors. It seems evident 

that the position and habit of the streams, now so completely out of accord with the structure, were established 

at a time when the structure had not been revealed by 

erosion, and that the enclosed meanders of the Colorado, 

the Virgin, the San Juan, the Kanab, and many smaller 

streams mark courses inherited from the pre-canyon 

cycle.

The evidence for the uplift that introduced the canyon cycle is conclusive. The erosion surfaces produced 

during the pre-canyon cycle have been deeply and 

intricately dissected. Steepened gradients have enabled the streams'to convert their former shallow valleys into profound gorges and to dig hundreds of new 

trenches, thus substantially remodeling the topography, 

The present meandering streamways are trenches cut 

in a former graded surface from which to a large degree

their alinement and pattern have been inherited. 

Widely distributed peneplain" remnants afford supplementary evidence. In fact, most of the features that 

make the Colorado canyons an outstanding illustration 

of stream work belong to the canyon cycle.

The pre-canyon and canyon cycles of erosion as outlined mark undefined stretches of time during which 

conditions were generally favorable for the destruction 

of high-lying land. The tectonic movements and the 

climatic conditions that initiated the cycles and prevailed throughout their courses are imperfectly known. 

Likewise the dates of uplift, of still-stands, and of 

changes in conditions of sedimentation and erosion can 

be assigned with only rough approximation. It seems 

improbable that the stages of topographic development 

were contemporaneous -or uniform over the entire 

plateau province.

For the pre-canyon cycle no subdivisions have been 

recognized. Existing maps are inadequate for the 

correlation of small-scale topographic features. Even 

with much fuller knowledge of form and position, differences in altitude of the remnant erosion surfaces and 

in the extent to which inequalities of hard and soft 

rocks were in different places obliterated would greatly 

hinder if not prevent satisfactory definition. However, 

there is no reason to believe that the first uplift was 

accomplished all at one time, that once started it continued at a uniform rate, or that the same climate 

prevailed throughout.

For the canyon cycle the subdivisions are more 

readily established. Throughout this cycle erosion, 

though dominant, has not been continuous/ The 

intermittency. of down-cutting is clearly in evidence. 

The ungraded floors of all the canyons and the discordance in longitudinal profile between the side 

canyons and the master canyons indicate rather recent 

rejuvenation. On the other hand, rock-cut, gravelfloored terraces at different levels on the canyon walls 

mark periods when normal vigorous erosion changed to 

deposition. The relative lengths of the pauses in 

downward erosion are indicated roughly by the extent 

and evenness of the eroded surfaces and the thickness 

and texture of the covering gravel, also by the .depth 

and distribution of canyon fill. The canyon cycle 

includes at leasts two epicycles the inner-canyon epicycle, during which a pause in dominant down-cutting 

provided conditions favorable for aggradation, and the 

terrace epicycle, marked, by a renewal of vigorous 

erosion and consequent development of alluvial terraces. During the inner-canyon epicycle many canyons were so completely filled with alluvium-thai .their, 

uneven rock bottoms were cpjiverted : :inttD/relatively 

smooth gravel floors at a higi(er; level, o,<!3?he.easting 

remnants of these floors along the large streamways are 

at grade with those in side canyons and thus represent 

a surface of wide extent. In contrast with the body of 

the gravel deposits, their tops are much weathered, and
94 THE SAN JUAN COUNTKY, SOUTHEASTERN UTAH

here and there silt-filled channels and lacustrine sediments mark the course of slow-moving winding streams 

that flowed in and out of ponds. This evidence that 

the gravel floor, once completed, remained intact for a 

considerable period is reinforced by the appearance of 

the canyon walls weathered rock above the gravel 

surface and fresh rock below. The inner-canyon epicycle was followed by the terrace epicycle. Aggradation gave place to erosion, which is still in vigorous 

progress. The inner-canyon gravel floors have been 

generally dissected into terraces that border the present 

streams; in places the canyon fill has been entirely 

removed, and the streams are once more running on 

rock., (See pp. 101-102.)

AGE OF THE TOPOGRAPHIC FEATURES

The topographic features in the plateau province 

have been developed in post-Eocene time, but the 

length of the cycles and epicycles of erosion has been 

determined only with wide approximation. Dutton 

dated the pre-canyon cycle as Miocene and Pliocene. 

In his view the "great erosion" 61 of the plateau was 

most probably accomplished in Miocene time but continued with diminished rapidity throughout the Pliocene; the erosive work of the Pliocene ended with the 

production of the "outer" rim of the Grand Canyon 

and corresponding features along other streams. In 

the light of present knowledge it seems reasonable to 

assign most of the work of the canyon cycle to late 

Quaternary time.

Blackwelder 62 has recently expressed the extreme 

view that no intergraded drainage system existed in 

the plateau province in Miocene or Pliocene time and 

that the Colorado "may actually be a young river that 

did not exist until about the beginning of the Pleistocene 

period."

The inner-canyon and terrace epochs of the canyon 

cycle are assigned to late Pleistocene and Recent tune, 

with the possibility that the formation and partial 

destruction of some gravel terraces mark stages of 

waning glaciation. .

The events of the inner-canyon and terrace epicycles 

may be ascribed to changes.of climate that for long 

periods profoundly affected the rate and manner of 

weathering and corrasion. In the absence of contradictory evidence it seems equally reasonable to explain 

the periods of alternating degradation and aggradation 

as evidence of tectonic movements and to class them as 

the latest in the series of uplifts and still-stands which, 

since the beginning of the pre-canyon cycle, have controlled the development of, plateau topography.

°i Dutton, C. £., Report on the geology of the High Plateaus, p. 21, U. S. Qeog. and 

Geol. Survey Rocky Mtn. Region, 1880.

6J Blackwelder, Eliot, Origin of the Colorado River: Qeol. Soc. America Bull., 

vol. 45, pp. 551-565.1934.

FACTORS THAT INFLUENCE EROSION

CLIMATE AND RUN-OFF

The climate of the San Juan country is "spotted." 

Though the region as a whole is arid, rainfall and temperature vary widely in time and with respect to topographic position. The mean annual rainfall at three 

valley stations is 7.37 inches, including years with less 

than 4 inches. The average for two plateau stations 

is 16.15 inches, for the driest year 8.90 inches, for the 

wettest year 23.44 inches. The Abajo Mountains and 

Elk Ridge probably receive in most years as much as 

20 inches of combined rain and snow. At all stations 

the range in amount received each month is extreme. 

The intermittent supply of rain is insufficient to keep 

the streams going throughout their courses. Even if 

the rainfall were evenly distributed the average flow 

would be small and might be largely counterbalanced 

by evaporation during the dry, hot days of summer. 

As regards erosion the most significant feature of the 

rainfall is the violence of showers. Most rains are 

short-lived, widely spaced, torrential downpours. The 

precipitation for a month or even two months may be 

the result of a single storm that lasts only half an hour 

and covers only a few square miles. (See p. 15.)

In this region, where bare rock is more widespread 

than soil and vegetation, most of the precipitation is 

represented in the run-off. The falling rain gathers at 

once into gullies and flows swiftly to larger drainage 

channels. "Where gullies are lacking it flows as a sheet 

of water that temporarily comes to rest in some local 

depression or continues to a canyon rim, over which 

it plunges as a sheet waterfall. During their short, 

vigorous lives these ephemeral streams sweep from the 

surface wind-blown sand, disintegrated rock, and stray 

bits of vegetation and carry them to nearby canyons. 

In the canyons themselves streams of muddy water 

quickly form and, as more and more side gullies make 

contributions, increase to turbulent floods. In narrow 

canyons, dry for a month or more, the water of a newly 

made, swift-flowing stream may reach a height of 10 

feet or more within an hour and disappear in another 

hour. Some of these flood streams, particularly those 

flowing on bedrocks, eventually join their master 

streams, but many of them lose their water within a few 

miles by sinking into the porous gravel of the canyon 

floor.

In the generally dry air of the San Juan country, 

supplemented in spring and summer by high temperature, the run-off and consequently the transportation 

of sediment are affected by evaporation. In night time 

and on cloudy days streams from springs of uniform 

supply lengthen, and streams appear on canyon floors 

that at other tunes are dry. During the passage of
PHYSIOGRAPHY 95

the hot winds that occasionally sweep along canyons 

and across lowlands, water in such shallow streams as 

Comb Wash markedly diminishes in volume or even 

disappears.

Frost is an active agent. Temperatures below the 

freezing point are recorded for 7 months of the year in 

Glen Canyon, 9 months in the San Juan Valley, and 10 

months on the plateau at Blanding. During most of 

these months periods of freezing and thawing alternate. 

Blocks quarried by frost are strewn thickly about the 

peaks of the Abajo Mountains, the rims of Elk Ridge 

and Wilson Mesa, and the cliffs between Red and White 

Canyons. Though most of the fragments that are 

pried from canyon walls, from cliffs of thick-bedded 

sandstone, and from steep slopes in thinly stratified 

rock are removed about as fast as they are formed, 

talus of large and small blocks borders many streamways and forms patches on the face of plateaus. (See 

pi. 18, B.) Some of it is incorporated in landslides. 

(See pp. 102-103.)

STREAM GRADIENTS

 The longer streams in the San Juan country rise in 

the Abajo Mountains and Elk Ridge at altitudes of 

8,000 to 10,000 feet and join the San Juan or the 

Colorado at points 3,500 to 4,500 feet above sea level. 

All of them have steep gradients. Below their headwaters, which above 7,000 feet descend as rapidly as 

500 feet in a mile, Montezuma, Recapture, and Cottonwood Creeks flow on an average slope of about 50 feet 

a mile. The gradient of Grand Gulch is about 90 feet 

a mile, of WThite Canyon about 80 feet a mile. Typical 

of streams that cross Red Rock Plateau, Mold Canyon, 

some 25 miles long, has a gradient of about 100 feet to 

the mile. Streams 3 to 8 miles long that drain the 

west end of the plateau have average falls of more than 

200 feet to the mile. In contrast with these steep 

gradients the San Juan River below the mouth of Comb 

Wash has a total fall of 950 feet in about 132 miles, an 

average of 7.17 feet to the mile, and the Colorado in 

Glen Canyon has a gradient of only about 2 feet to 

the mile.

The gradient of the streams is far from regular. 

Instead of a curve, steep at the headwaters and flattened lower down, the valley profile is a succession of 

steep and gentle gradients. Waterfalls, rapids, and 

stretches of relatively smooth water are distributed at 

irregular intervals. In some places the stream flows 

over bare rock, in others over thin sheets of gravel and 

sand, and in still others over deep valley fill. No 

stream is graded throughout its course. Flood waters 

carry great quantities of fine rock waste across steep 

and gentle slopes alike and push forward along their 

bottoms coarse gravel, boulders, and angular blocks 

torn from adjoining cliffs. In flat stretches the smaller 

streams and even the great Colorado are barely able to 

carry the load of waste supplied by their tributaries.

Little energy is available for deepening their, beds. In 

steep stretches the transportation of huge loads is but 

part of the general work of down-cutting.

VEGETATION

In parts of the San Juan country the effect of vegetation in regard to run-off and checking erosion is 

obvious; elsewhere it is inconspicuous. On Elk Ridge 

and adjoining flat lands at altitudes above 8,000 feet 

forests of pine, aspen, and oak, together with the 

undergrowth of shrubs, grasses, and annuals, provide 

forest litter that prevents rapid formation of gullies. 

Much of the precipitation soaks into the ground or 

remains here and there as swamps and ponds. On 

these plateaus the flatness of the surface and deep 

layers of snow seem as effective as vegetation in retard-° 

ing run-off. Thus on the flat but unforested Wilson 

Mesa the drainage system is poorly developed; on the 

steep-sided forested Abajo Mountains it is clearly defined. On Sage Plain, Grand Gulch Plateau, and other 

surfaces 5,000 to 6,000 feet above sea level stands of 

pifion and juniper with a density of 2 to 100 trees to the 

acre interfere somewhat with the run-off, particularly 

in places where sage and other hardy plants occupy 

spaces between the trees. Over many square miles 

plants serve as centers for the accumulation of windblown sand, which temporarily blocks the tiny channels, thus forcing the rain-born rivulets to delay long 

enough to remove the obstruction or to establish a 

new roundabout course. Throughout large areas the 

vegetation is too scanty to exert an appreciable influence. In general the potential effectiveness of the 

plant cover is greatly diminished by its habit of growth. 

Trees, shrubs, grass stalks, flowering annuals, and 

weeds rise as individuals from a floor of rock or alluvium ; areas of closely spaced trees, matted grasses, and 

sod are rare. Between the plants the drainage channels are little interrupted.

In loosening joint blocks and prying them from cliffs 

and canyon rims, plants are effective agents. As the 

depth of soil is in few places sufficient for the development of roots, cracks and bedding planes are utilized 

to an extent unknown in humid regions. Most of the 

trees and larger shrubs, outside of the highland forests 

and the alluvial washes, appear to be anchored in cracks. 

Their roots extend along the cracks, descend deeply into 

them, or pass from one crack to another around rightangled turns. In removing tree stumps large joint 

blocks come with them, and uprooted shrubs show a 

basketlike mesh of root fibers enclosing a block that 

fits nicely into the general ledge. At the top of canyon 

walls many cubes of unweathered rock 3 to 8 feet in 

diameter have been separated from their ledges by 

growing roots, aided, no doubt, by freezing water for 

which roots have provided a channel. In interstream 

spaces roots have aided in breaking the surface beds 

into a pavement of loosened blocks outlined by joints.
96 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

GROUND WATER o

As a factor in erosion in arid regions ground water 

holds a prominent place. Working alone or in cooperation with other agencies, it is the chief agent in producing 

rock shelters and other recesses along bedding planes 

at the top of impervious strata and innumerable alcoves, 

"caves", pits, elongated niches, arches, and bridges in 

the thick cross-bedded sandstones. Even more effective is the water that seeps through the body of the 

sandstones, removing or weakening the cement and 

leaving on the surface loosened grains that are removed 

by the first shower. In landslides the work of ground 

water is further shown. (See pp. 102-103.)

RELATION OF TOPOGRAPHY TO GEOLOGY

In the San Juan country, as in the adjoining Navajo 

and Kaiparowits regions, the topography reflects the 

control exercised by the composition, texture, and 

attitude of the rocks. The drainage and sculpture 

may be almost completely described in terms of rocks 

(hard and soft), upwarps, and monoclinal folds. Features produced by faulting and by interruption in 

cycles of erosion are few and inconspicuous. As elsewhere stated,63 it is readily observed that the surface 

of each broad bench or mesa is upheld by a rock mass 

that is resistant to erosion. From most benches the 

overlying weak rocks have been stripped away so that 

the present surface coincides closely with the top of the 

hard beds. The cliffed borders of plateaus and of 

canyons are likewise determined by hard rocks. In 

fact, the dominance of cliffs in the landscape is a 

reflection of the topographic influence of rock composition. Hard beds determine the broadly level plateau 

surfaces; where they are gently inclined the surface is 

similarly inclined; and where they dip steeply the 

topography is mainly controlled by the sloping surface 

of the beds. Monoclines are represented in the topography by hogback ridges or by prominent lines of cliffs 

that are developed on the harder rocks. The surface 

exposures of weak beds are in general characterized by 

slopes or by gently undulating topography. Where the 

weak formations are disintegrated by weathering and 

by the corrosion of streams they strongly affect the 

configuration of valleys and the position of drainage 

lines.

In the .present stage of physiographic development 

erosion, guided by rock texture and composition, has 

made of the San Juan country a region of cliffs. High 

cliffs outline the major topographic features, and low 

cliffs combine to make the prevailing steep slopes. 

Gentle slopes are elements in the late mature topography on Sage Plain, Elk Ridge, and smaller areas 

where the cap rock is a continuous stratum in essentially 

horizontal position, but such slopes are quite out of

63 Gregory, H. E., and Moore, R. C., The Kaiparowits region, a geographic and 

geologic reconnaissance of parts of Utah and Arizona: U. S. Geol. Survey Prof. 

Paper 164, p. 127. 1931.

harmony with the mural escarpments, the platforms, 

steps, and horizontal moldings that characterize the 

region as a whole.

Weathered surfaces show that the sandstone beds, 

which constitute fully 80 percent of the strata exposed, 

terminate in cliffs at the edges of plateaus and mesas and 

in canyon walls; that the limestones, even in beds less 

than 1 foot thick, everywhere present cliff faces; and 

that because of differences in such structural features as 

jointing, . stratification, and cross-bedding the cliffs 

developed in each stratigraphic unit are distinctive. 

For example, the limestones in the Rico formation are 

so uniformly dense and so resistant to erosion in this 

dry climate that the cliffs are chiefly vertical joint 

planes; in the conglomeratic, lenticular Dakota (?) 

and Shinarump sandstones the cliffs, though generally 

vertical, are indented by pits and long oblique gashes 

.and extend as crooked walls broken down at places 

where undermining by ground water is effective; in the 

friable, thick-bedded Cedar Mesa sandstone and to a 

much greater degree in the massive, strongly crossbedded Navajo sandstone, cliff profiles are straight or 

undercut at the base and rounded at the top, and surfaces between canyons weather into domes, haystacks, 

rounded ridges, and tepees; in the Wingate sandstone 

the dominant vertical jointing tends to produce a 

palisade-like wall; in the Halgaito member of the 

Cutler formation and the Moenkopi formation the long 

low cliffs that interrupt the general slopes are the 

edges of strata of limestone or of sandstone more firmly 

cemented than adjacent beds; in the predominating 

shaly Morrison formation the thin sandstones and limestone conglomerates weather as low steps, the massive 

Bluff sandstone member as a crenulated wall, and the 

Westwater Canyon sandstone member as pronounced 

cliffs of highly irregular vertical and horizontal profile.

The dominance of cliffs is the result not only of 

lithologic and stratigraphic controls but also of climate 

and physiographic age*. In consequence of rapid runoff incident to infrequent torrential rain, products of 

disintegration are promptly carried away. Successive 

layers of weathered rock are removed from cliff faces 

and from surfaces beyond their tops, and blocks are 

broken from the cliff wall without destroying the 

profile. The streams are young and, though intermittently powerful, have so far been unable to grade 

their floors. In cutting their immediate runways 

deeper and wider they increase the height and maintain 

the steepness of the bordering walls. Under these unfavorable conditions the reduction of cliffs and canyon 

walls .to slopes with mature profiles seems almost 

impossible.

Many streams in the San Juan country are obviously 

adjusted to structure. Johnson Creek, North Creek, 

and other headwater tributaries of. Recapture and
PHYSIOGEAPHY 97

Montezuma Creeks occupy synclinal troughs tilted 

downward in harmony with the slopes of the Abajo 

Mountains, and below the junctions their master 

streams continue down the dip slope of northern Sage 

Plain. McElmo Creek and the eastern tributaries to 

Montezuma Creek slope toward the axis of the Sage 

Plain do wnwarp. Butler Wash and the upper part of 

Cottonwood Creek follow the base of the Comb monocline, and in weak beds of the monocline Comb Wash 

has developed as a subsequent stream that affords a 

runway for Arch, Mule, Fish, and other consequent 

streams established on the east flank of the Monument 

upwarp (pis. 18, A; 19, A). Upper Castle Wash 

and the streams in White, Ked, and Mold Canyons are 

roughly in accord with the westward-sloping limb of 

the Monument upwarp. Lower Castle Wash (Spring 

Gulch), continued northward as Johnny Hole, and upper 

Lake Canyon are in synclines at the base of the. Balanced Rock anticline. But although many drainage 

channels are thus wholly or in -part well adjusted to 

structure, some disregard it in part, and others entirely. 

Grand Gulch follows the crest, crosses the crest, and 

passes obliquely down the west flank of the Monument 

upwarp. The Colorado River crosses the Waterpocket 

Fold without evident deviation from its course, and the 

meandering San Juan River cuts squarely across downwarps, upwarps, anticlines, synclines, and flat-lying 

beds. Among the existing structural features no more 

unsuitable routes for these streams could have been 

chosen. It is evident that in their present courses these 

streams are superposed on structural features that have 

been revealed by erosion. Once established, they 

maintained their courses across folds, with only such 

shiftings in position and changes in grade as were required for adjustment to-new-found conditions.

In developing their runways the small, weak streams 

of the San Juan country have been guided by structure, 

rock hardness, and local slopes; the strong streams are 

deepening channels inherited from previous physiographic cycles. (See p. 92.)

FORM OF VALLEYS

The typical valley in the San Juan country is a 

flat-bottomed, steep-sided gorge with a longitudinal 

profile made up of steps separated by stretches of steep 

or gentle gradients. The influence of rock composition 

and texture is obvious. Where hard rocks are exposed 

the valley walls are near together and precipitous and 

the stream gradient steep; where soft rocks underlie 

and border the streamway the valley is more open and 

the gradient less steep. But because the outcrops of 

soft rocks are small and down-cutting by streams is 

vigorous, valleys with V-shaped sections are rare: 

even in alluvial deposits the canyon form prevails? 

Valleys with flaring sides are conspicuous only on Elk 

Ridge, Wilson Mesa, and Sage Plain. So persistent is 

the causal relation between rock hardness and valley

form that with a general knowledge of regional stratigraphy the type of canyon may be predicted. The 

explorer soon learns that areas of the Mancos, Chinle, 

and Morrison formations present no serious obstacles 

to travel, and that by following gullies and taking 

advantage of talus and landslides, routes for pack 

trains may be found across slopes built of Halgaito, 

Organ Rock, Moenkopi, and San Rafael strata, but 

that feasible routes across the Cedar Mesa, Wingate, 

and Navajo sandstones, and in places the Dakota (?), 

are few. The walls of Cedar Mesa sandstone in White 

Canyon and its tributaries, Armstrong, Long, and 

Gravel Canyons, can . be descended on horseback at 

Soldiers Crossing and Duckett, but those that border 

Grand Gulch form an impassable barrier for about 30 

miles. The one practicable crossing of Moki Canyon, 

lined from its source to its mouth with Navajo sandstone, is made possible by sand dunes on the south wall 

and faulted rocks on the north. The San Juan below 

Bluff and the high dividing mesa between WMte Canyon and Red Canyon can be crossed where along folds 

the cliffs of Navajo sandstone give way to Chinle and 

Moenkopi beds and numerous joints are present in the 

Wingates. To reach the opposite side of a canyon in 

these resistant formations may require a day of travel. 

Climbing with the aid of ropes is a common experience.

Valleys such as Comb Wash and Butler Wash, which 

are developed in soft beds upturned in a monoclinal 

fold, are fairly straight for long distances; they follow 

the trend of the structure. But nearly all the canyons 

are sinuous to a remarkable degree; their tortuously 

winding courses include open curves, horseshoes, and 

almost right-angled turns, so close-set that in many 

places the parallel canyon walls are visible for less than 

half a mile. Though held between towering walls, 

the streams are as crooked as those on wide flood 

plains. The San Juan River through the "Goose 

Necks" travels 23 miles to cover an air-line distance 

of 7 miles, and in the Great Bend it wanders 8% miles 

where the direct-line distance is about 1 mile. From 

Comb Ridge to the Colorado River the San Juan 

Canyon is 135 miles long; the overland distance is 63 

miles. By eliminating the meanders in Glen Canyon 

its course could be shortened 62 miles. The course of 

the streams in Grand Gulch, Dark Canyon, Moki 

Canyon, and other deep trenches is likewise tortuous. 

In White Canyon the loops and angular turns leave 

little room for tangent stretches; the alinement of the 

lowest 5 miles is remarkably complex.

Many or perhaps most of the meanders in stream 

channels of the San Juan country are the result of 

normal vertical and lateral corrasion during the life 

of the drainage system, but as discussed in detail, elsewhere 64 the magnificent series of entrenched meanders 

in Glen Canyon, San Juan Canyon, and similar high64 Gregory, H. E., and Moore, R. C., The Kaiparowits region: U.S. Oeol. Survey 

Prof. Paper 164, pp. 124,135-138,1931.
98 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

walled gorges in the plateau province are believed to 

have been inherited from ancestral streams. Field 

evidence indicates that these streams developed their 

meandering habit while flowing on a graded surface 

which once stood above the present canyon rims, and 

that -a regional uplift enabled them to sink their beds 

deeply without greatly altering their .courses.

In longitudinal profile the floors of valleys in the San 

Juan country are very uneven. The floor of many a 

canyon is a series of steps, some of them bare ledges, 

over which the stream progresses by rapids and waterfalls separated by stretches of steep or flat gradient. 

In general the steps in tributary streams are more 

numerous and higher near the headwaters and near 

their mouths, thus making the generalized stream 

profile a curve steep at both ends. These interruptions 

in the general gradient of individual valley floors are 

but a feature of the regional discordance of drainage 

channels.. Of streams tributary to the San Juan, 

McElmo, Cottonwood, and Comb Creeks meet their 

master stream at grade, and in stages of high water 

their mouths are flooded; Recapture Creek, Johns 

Canyon, Grand Gulch, and some smaller tributaries 

terminate as ephemeral waterfalls 30 to 80 feet high 

over relatively resistant thick strata. Likewise the 

mouths of the streams in Red Canyon and White 

Canyon are accordant with the level of water in Glen 

Canyon, but the smaller streams from Red Rock 

Plateau join the Colorado by passing over ledges of 

descending steep slots cut in thick-bedded sandstone. 

Many tributaries of the second and third order occupy 

hanging valleys in hard rocks and soft rocks alike, and 

where valleys are poorly defined ephemeral sheet 

streams drop water directly into box-headed canyons.

The walls of most canyons in the San Juan country 

rise from the floor as a single series of steps or of steps 

and slopes determined by the position and relative 

hardness of the stratigraphic units. White Canyon 

has two sets of walls. The outer walls enclose a flat 

floor of rock 1 to 3 miles broad and some 30 miles long, 

into which the present stream has cut a deep, narrow 

meandering trench an inner canyon within an outer 

canyon. From Elk Ridge, Deer Flat, and the tops of 

mesas at the head of Red Canyon, the position of White 

Canyon is shown by a broad roadway of white rock 

bordered by lofty cliffs. The canyon itself is invisible, 

for, though it is several hundred feet deep, it is in most 

places less than 200 feet wide and meanders so intricately that no long stretches can be seen. Only at a 

few places is it practicable to enter the canyon, and 

within it only the steep white walls of a crooked defile 

are in sight. To form the broad esplanade at the top 

of the inner canyon the upper red beds of the Cutler 

formation have been stripped from the white Cedar 

Mesa sandstone. Along Cedar Creek an esplanade 

has been formed on flat-lying Kayenta beds and is 

bordered by cliffs of Navajo sandstone. Along the

San Juan River west of Comb Wash the undulating 

floor of a platform abruptly terminated by cliffs has 

been developed on Rico limestones.

On the poorly marked drainage divides between 

the Colorado and the San Juan some stream channels 

are being lengthened and others correspondingly shortened by shifting of divides, accompanied in some places 

by stream capture. At the northern edge of Sage 

Plain, east of Monticello, streams flowing north to 

the Colorado are cutting back into the region now 

occupied by tributaries of the southward-flowing 

Montezuma Creek. Farther east tributaries to Montezuma Creek rise almost on the rim of Dolores Canyon; 

a trench about 200 feet deep would permit the Dolores 

River to join the San Juan. At the Causeway the 

southward-flowing Cottonwood Creek is successfully 

competing with tributaries of Indian Creek, and along 

the east face of the Balanced Rock anticline the stream 

in Johnny Hole has invaded the territory previously 

drained by Lake Canyon.

RATE OF DENUDATION

The present base-level of erosion for streams in the San 

Juan country is at the head of Marble Gorge, where the 

Kaibab limestone greatly retards the down-cutting of 

the Colorado. Back of this barrier the streams in 

Glen Canyon and in the lower canyons of the San Juan 

are no longer actively deepening their channels. They 

flow on alluvial fill, which they seem unable to move, 

and are barely able to transport the rock waste contributed each season from bordering lands. Until the 

load of waste is much decreased or Marble Gorge is 

deepened these streams are likely to maintain their 

present positions and thus constitute a temporary baselevel to which hundreds of tributary streams are seeking 

adjustment. Unlike these master streams, their many 

branches are not only carrying all the waste supplied in 

the present cycle but are removing sediments deposited 

in previous cycles and cutting into rock beneath. They 

are obviously quarrying and transporting enormous 

quantities of material. That down-cutting of canyons 

is rapid is shown by the freshness of rock and alluvial 

walls and by the fact that meander belts have shifted 

little. In open curves and sharp angular bends alike 

the opposite walls of a canyon are equally steep; 

slip-off slopes are generally absent. On the nearly flat 

lands that lie between gullies and canyons on Elk 

Ridge, Sage Plain, Gray Mesa, and Dark Canyon 

Plateau streams are doing little work, and because of 

the arid climate the limestones that form the surface of 

the Raplee and Mitten Butte anticlines are remarkably 

resistant to weathering. On the sloping surfaces of 

sandstone the prevailing type of rock disintegration 

is facilitated by weak cement, lack of soil cover, and 

sharp fluctuations in temperature and rainfall. The 

regional fate of erosion is indicated by the amount of
PHYSIOGEAPHY 99

rock waste carried by the master streams. The Bureau 

of Reclamation 68 estimated the silt carried by the San 

Juan River each year as 24,000 acre-feet, or about 1 

acre-foot from each square mile of the drainage basin. 

Even this large figure is much too small, for, as pointed 

out by Miser,66 it "does not take into account the bed 

load of sand, pebbles, cobbles, and boulders which 

slide, roll, and make short hops and skips" materials 

that because of the frequent floods constitute a large 

part of the total load. The San Juan is always muddy, 

at times carrying nearly as much silt as water, and is 

also a settling basin in which at intervals part of the 

sediment is stirred up and carried forward into Glen 

Canyon.

Though estimates of the rate of erosion based on 

measurements of suspended silt are unsatisfactory, 

those based on rate of disintegration of rocks on 

plateaus, cliffs, and canyon walls are even more so. The 

rate is different for each type of rock and each topographic position. At the bottoms of canyons, especially 

those filled with alluvium, and on rounded bare surfaces 

of weak sandstones it is remarkably fast; near the top 

of canyon walls, on cliff faces, and on exposed flat 

surfaces of limestone and siliceous conglomerate it is 

much slower; on small erosion remnants it is inappreciable. The pedestals, hoodoos, and rock babies 

carved in massive sandstones seem almost invulnerable. In the San Juan Valley hammer marks made beneath the cap of erosion remnants in 1909 showed no 

appreciable weathering in 1929, and in the Alien Canyon 

country, on Whiskers Creek, and on the rim of Moki 

Canyon areas 1 foot square coated in 1925 with chalk 

had retained most of this superficial covering after an 

exposure of 4 years. In protected places steps cut in 

rock perhaps 400 years ago may still be used as approaches to cliff houses. It is therefore not surprising 

that Bryan and La Rue 67 found substantially identical 

details in photographs of "The Twins" at Bluff taken 

in 1875, 1909, and 1925. Even if the rate of erosion at 

Bluff were as fast as the estimated average for the 

Colorado drainage system (1 inch in 440 years), the 

vertical cliff that includes The Twins would have 

retreated only about one-eighth of an inch in 50 years.

Though no quantitative measure for regional denudiation seems practicable, the impression gained from 

field work is that erosion in the San Juan country is as 

rapid as in other parts of the plateau province and more 

rapid than in most humid regions; also that the present 

rate is as fast or even faster than at any other time since 

the dissection of the Tertiary highlands began.

« U. S. Reel. Service 18th Ann. Kept., p. 404,1919.

M Miser, H. D., Erosion in San Juan Canyon, Utah: Qeol. Soc. America Bull., vol. 

36, p. 375. 1925.

w Bryan, Kirk, and La Rue, E. C., Persistence of features in an arid landscape: 

Qeog. Rev., vol. 17, pp. 251-257,1927.

145824 38 8

PHYSIOGRAPHIC FEATURES

GENERAL RELATIONS

For the San Juan country as a whole the flat or 

slightly inclined beds, the warped beds, and the intrusive igneous masses have guided the development of 

topography. In a broad sense they have organized 

the agents of erosion; but when viewed close at hand, 

the development of the landscape seems little influenced 

by regional controls.

Innumerable canyons, cliffs, and mesas and a few 

sharp-crested ridges have been carved in sedimentary 

beds that vary widely in hardness and thickness. The 

edge of each plateau block and mesa cap is a cliff cut 

from a single stratum, a single formation, or several 

formations combined. The San Juan River from Butler 

Wash to the town of Bluff and parts of White Canyon, 

Comb Wash, and Cottonwood Canyon are bordered by 

walls of different material and unequal height; but most 

canyons are rimmed on both sides by the same stratum, 

at the general level of the plateau top. So completely 

do the surfaces on one side of the canyon seem to merge 

into those on the other that the canyon itself appears 

only on close approach. Within a mile of their rims 

the presence of even such profound gorges as Dark 

Canyon, San Juan Canyon at Polly Mesa, and Glen 

Canyon at Trail Cliff are not clearly revealed by the 

topography. Likewise the surfaces that at a distance 

seem broad and smooth are intricately dissected or 

broken into long platforms by canyons, some of them 

hundreds of feet deep.

As seen from Abajo Peak an apparently even surface, 

broken only by the Ute and Carrizo Mountains, extends 

far into Colorado and across the San Juan River into 

Arizona and New Mexico the position of some 20 

canyons sunk deeply into Sage Plain cannot be determined. From the cliffs above Clay Hills Pass the Red 

Rock Plateau appears as an area of overlapping low 

mounds unbroken by definite drainage channels. No 

features suggest the presence of such gorges as Moki, 

Cedar, and Lake Canyons. A traverse of the plateau 

surface involves climbing in and out of straight-walled 

canyons, ascending and descending cliffs at places 

where sand dunes or talus slopes provide a practicable 

route.

As major elements in the landscape, irregularities produced by igneous activity and by tectonic movements 

are little less conspicuous than the subhorizontal 

plateaus. The laccolithic Abajo Mountains, which 

culminate in Abajo Peak at an altitude of 11,445 feet, 

rise 5,000 feet- above the surrounding country, and 

toward them all beds bend upward. This mountain 

group is the collecting ground for the waters that have 

carved the canyons of western Sage Plain and the 

Indian Creek country. The lofty Comb monocline,
100 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

which extends almost without break for more than 100 

miles, separates two areas of plateau lands and has 

locally controlled the development of drainage. Likewise the Balanced Rock anticline is the common border 

of two platforms at different levels. It has produced an 

alinement of streams that does not conform to the 

regional pattern. . ;

EROSION SURFACES

The San Juan country is a region of vigorous youthful 

erosion. Areas, in which the topography presents 

features of maturity or old age are not prominent. 

Evidences of widespread peneplanation that might 

serve to correlate stages in Tertiary erosion in Colorado,

not consequents of tectonic movements. Local erosion 

surfaces of late Pleistocene and Recent time are represented by remnants at many places. Along the San 

Juan, the Colorado, and some smaller streams they 

have been preserved by sheets of gravel, and where 

developed on tilted strata they are conspicuous. The 

surface of the Causeway, now much dissected, is 

believed to represent a surface of considerable extent 

produced by benching the edges of strata upturned in 

the Comb monocline and the Abajo Mountains. Along 

lower Comb Wash and southward across the San Juan 

River, remnants of old erosion surfaces at approximately 

accordant grades extend for nearly 5 miles as old-age 

surfaces developed on tilted Permian and Triassic

w.

3/4 Mile

FIGURES. Erosion surfaces on tilted beds. A, Near mouth of Comb Wash; B, AJong the Causeway between Elk Ridge and the Abajo Mountains. JK, Dakota (?) 

and Morrison formations and San Rafael group; Jgc, Glen Canyon group; "5, Triassic rocks; "B and Cp, Triassic and Permian rocks; Cph, Herinosa formation 

(Pennsylvanian)'.

Arizona, Utah, and Nevada call for too much interpolation to justify acceptance. The larger areas that 

reveal old-age features are floored with resistant flatlying rocks that even in a single cycle would show 

features older than those in adjoining areas, and they 

stand at different altitudes. Thus the surface of Elk 

Ridge (in reality a plateau), developed on Shinarump 

conglomerate; of Wilson Mesa, on calcareous sandstone 

and shales of the. Carmel (?) formation; of the intercanyon flats of Sage Plain, on Dakota (?) sandstone; 

and of parts of Grand Gulch Plateau, on Cedar Mesa 

sandstone, are ah1 characterized by low relief wide, 

shallow valleys, swales, and rounded low divides. In 

altitude these old-age surfaces range from about 4,000 

to 8,000 feet, and so far as known their positions are

beds (fig. 3). Likewise the strata upturned in the 

Balanced Rock anticline have been worn down to 

conform with horizontal beds farther west. (See

pi. 2, 0.)

GRAVEL-FLOORED TERRACES

Sheets of gravel made of rounded and flattened pebbles a fraction of an inch in diameter and cobbles 1 to 

4 inches in diameter rest on rock terraces along the San 

Juan and within some of its tributary canyons. They 

appear also on the floors of high-level abandoned 

meanders. In some places the sheets are narrow bands, 

parallel with the present stream and a quarter to half a 

mile long. In other places they are distributed as 

irregular-outlined patches that range from an acre to a 

few square yards. Most of the remnant sheets are 1
PHYSIOGRAPHY 101

to 10 feet thick, several exceed 50 feet, and at a few 

places Miser 68 recorded measured thicknesses as much 

as 100 feet.

In most places where the gravel terraces are present 

cross sections of the canyon show two or more terraces-; 

in vertical sequence on one or both sides of the present 

channel. Along the San Juan River above Goodridge, 

the approximate positions of the terraces above high 

water are 30, 75, 200, and 400 (?) feet near Aneth; 

30 and 210 feet near the mouth of Recapture Canyon; 

20 (?), 130, and 450 feet at Bluff; 135 and 275 feet at 

Butler Wash and Comb Ridge; 125 feet at the mouths 

of Comb Wash and Chinle Creek; 20, 50, 125, and 275 

feet between Soda Basin and Goodridge Bridge. 

Below Goodridge the heights of gravel terraces along 

the San Juan are given by Miser 69 as 600 ± feet at the 

mouth of Oljeto Creek; 50, 165, 245, and ''several terraces up to 300 feet" at Clay Hill Crossing; 50, 160, 

and 240 feet at Zahns Camp; 400 feet at Spencer Camp 

(east end of Great Bend); and 400 feet on the floor of 

an abandoned canyon near the junction of the San 

Juan and the Colorado. In Glen Canyon thick deposits 

of gravel appear in patches 20 to 40 feet above high 

water, and pebbles of material foreign to the San Juan 

country lie in protected places about 220 feet above the 

river at the Rincon and near the mouth of Knowles 

Canyon.

In the canyons tributary to the San Juan and the 

Colorado gravel terraces are less readily recognized. 

The resistant, distinctive quartzites are generally lacking, and the erosion of alternating hard and soft beds 

has produced innumerable terraces that serve as temporary resting places for fresh products of local disintegration. In a few places gravel older than that of the 

present cycle lies on-truncated spurs and where the walls 

are low extends some distance from the stream. Such 

terraces were observed in McElmo Canyon at a height 

of 50 feet; in Montezuma Canyon at 20, 50, and 130 

feet; in Cottonwood Canyon at 40 and 180 feet; in 

Comb Wash at 20 and 100 feet; in Grand Gulch at 60 

and 200 feet; and in tributaries to White 'Canyon at 30 

and 175 feet. Gravel in small pockets on southern Sage 

Plain and at the top of walls of canyons tributary to 

Comb Wash which now lie 200 to 400 feet above the 

nearest stream bed may also represent terraces.

The distribution of these gravel deposits, their texture and composition, and the leveled rock surfaces on 

which they lie constitute evidence of pauses in the 

down-cutting of canyons. The gravels are not the 

deposits of flood plains; they are thick and coarse and 

rest on benches on steep, high walls. The floors on 

which they lie are local peneplains developed indifferently in flat and tilted strata, the end products of 

several cycles or epicycles of erosion. The number of 

cycles represented and their duration are alike unknown;

88 Miser, H. D. ( Erosion in San Juan Canyon, Utah: Geol. Soc. America Bull., 

vol. 36, p. 369. 1925. 

" Miser, H. D., unpublished notes.

satisfactory correlation of widely spaced deposits at different levels must await the preparation of detailed topographic maps. Likewise the age of the terraces can be 

determined only relatively! Their development occupied part of the time consumed in excavating Glen 

Canyon, Grand Canyon, and their major tributaries. 

As tributaries of the San Juan in Colorado once derived 

their water and sediments from glaciers, it seems probable that the San Juan terraces are extensions of the 

morainal and interglacial gravel deposits of Pleistocene 

age in the Mancos and Animas Valleys.

CANYON FILL

The canyons in the San Juan country were deeply 

sunk into rock and then filled with sediments 5 to at 

least 100 feet deep and thus bear evidences of a cyclical 

change from dominant erosion to dominant deposition. 

The fill consists of interbedded sand, gravel, and silt 

that varies widely in extent, thickness, and coarseness 

and shows the lacustrine beds and the lateral unconformities common to fluviatile deposits. Erosional unconformities mark temporary pauses in deposition. In 

places where the fill has been removed the bottom of 

the old canyon is revealed as a floor cut by sheer-walled 

trenches or by grooves and crossed here and there by 

ledges over which the streams pass as waterfalls. The 

length of time represented by the filling is unknown. 

If the average rate of deposition is assumed as 1 inch 

a year and the average thickness 30 feet, 360 years 

would have been required. Some such period is suggested by decayed corncobs and ash heaps about 15 

feet above the base of the deposit in Grand Gulch and 

Montezuma Canyon and fragments of pottery higher 

up material left by the Basket Makers and Cliff 

Dwellers, who are thought to have occupied this region 

intermittently during the period 1300 (?) to 1700 A. D. 

Trunks of still living cottonwood trees 100 to 200 years 

old are buried-10 to 30 feet by the fill. On the other 

hand, greater antiquity is suggested by zones of decomposed material along erosional unconformities and by 

top layers that have weathered into soil suitable for 

agriculture. Hermit Lake, a feature of the aggradation 

cycle, lasted long enough to permit the accumulation of 

about 85 feet of silt, peat, and marl. The aggradation 

may have been contemporaneous with the development 

of the erosion surfaces in Comb Wash and elsewhere 

and of the lowest gravel terraces in the San Juan 

Valley.

ALLUVIAL TERRACES

The typical tributary to the San Juan and the Colorado flows between alluvial terraces within rock-walled 

canyons. The canyon fill of a previous cycle has been 

cut into flat-topped, steep-faced segments by streams 

of the present cycle (pi. 20, -A).

In making terraces the streams have been effective 

in accordance with their size, their gradient, the width 

of their floors, and the number of violent showers that
102 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

fall within their drainage basins. In general the terraces are increasing in length by headward erosion and 

in height by down-cutting, but all stages of development are represented. In some places the two terraces 

that border a stream are separated by a narrow vertical 

trench; in other places they are far apart and may 

even appear as flat-topped embankments pressed close 

against opposing canyon walls. In places the terraces 

are absent and the original canyon fill remains intact 

or has been so completely removed that the position 

of the terrace is indicated only by patches of sand that 

cling to the canyon wall, and its height by a band that 

separates zones of unequally weathered rock. In parts 

of their courses some streams have cut entirely through 

the alluvium and into the rock below. As downcutting and undermining are more rapid than surface 

weathering, the fronts of most terraces are vertical. 

To climb these walls of crumbling sand is no easy task.. 

To find a place where their tops can be reached, pack 

trains may have to travel many miles. The construction 

of these terraces involves erosion on a large scale. For 

example, the amount of fill removed in a typical 1-mile 

stretch is estimated as 1,000,000 cubic yards for Grand 

Gulch, 800,000 cubic yards for Cottonwood Canyon, 

and J650,000 for Butler Wash. North of Wilson Mesa 

a canyon 6 miles long, 160 to 200 feet wide, and once 

filled to a depth of nearly 80 feet has been entirely 

stripped of alluvium.

It seems reasonable to assume that the time consumed in tearing up and transporting such great quantities of sand, gravel, and silt from hundreds of canyon 

floors would be measured at least by centuries, but 

nearly all the terraces have been formed during the last 

50 years, many during the last 10 years, and each year 

adds to their number. In place of the present wide 

washes floored with sand moved about by ephemeral 

streams and bordered by flat-topped banks of alluvium, 

the pioneers of 1880 found "broad fields", "meadows", 

."clear streams flowing through willows and alders", 

"cane swamps", "little ponds", "canyons floored from 

wall to wall with level, fertile fields." The Piutes say 

that the trouble began with the coming of the white 

man.

The date and the extent of terracing in the San Juan 

country are duplicated in canyons south of the San 

Juan, west of Glen Canyon, and generally through 

Arizona, New Mexico, and southwestern Colorado. 

The channeling that produced the terraces may be the 

result of climatic changes, of uplift, or of these two 

agencies combined. The immediate cause of much of 

it is overgrazing. With the destruction of the protective vegetation the run-off became spasmodic, and the 

streams were intermittently given power to remove 

canyon fill. As discussed more fully elsewhere,70 the 

balance between aggradation and degradation in the

70 Gregory, H. E., Geology of the Navajo country: U. 8. Geol. Survey Prof. Papei 

93, pp. 130-132, 1917. Gregory, H. E., and Moore, R. C., The Kaiparowits region: 

U. S. Geol. Survey Prof. Paper 164, pp. 30-31, 143-144, 1931.

plateau province is so closely adjusted that slight 

changes in rainfall, amount and kind of plant cover, or 

gradient of streams are sufficient to change stream 

habit. "The construction of a dam or an irrigation 

ditch, the killing off of beavers, the building of roads, 

and the plowing of fields may begin far-reaching 

changes."

The enormous amount of material supplied by tributary streams during the present cycle of degradation 

has almost choked the San Juan canyons. Though 

its gradient below Comb Ridge is steep and its volume 

in flood times great, the San Juan River flows on 

unconsolidated material piled thickly on the canyon 

floor. Near Bluff a well shows 32 feet of river sediment 

above bedrock, a figure believed to represent the 

approximate thickness of fill between Comb Ridge and 

Aneth. Miser 71 gives estimated depths of less than 

10 feet at the "narrows" hi Soda Basin and above and 

below Goodridge, an average between 30 and 40 feet 

for the lowermost 100 miles of river, and a maximum of 

105 feet at the mouth of Piute Creek. These figures 

are in harmony with measurements at Lees Ferry, 

where borings reveal 78 feet of fill. The overloaded 

river is unable to remove the debris dumped into its 

channel by tributary streams; at the mouths of side 

canyons the river is pushed toward the opposite wall or 

crosses the gravel deposits as rapids. At low-water 

stages islands of sand, gravel, and boulders are conspicuous. That the river is incompetent to transport 

the material provided is shown by widely swinging 

braided channels on the alluvial flats at and above 

Bluff, at Clay Hill Crossing, Piute Farms, and Zahns 

Camp. As remarked by Miser,72

long stretches of the San Juan present most of the time the 

peculiar example of an alluvial or aggrading stream flowing 

between close towering walls of solid rock. Yet on the assumption that mtich or all of the canyon fill is moved at times of high 

flood the river is in reality not an alluvial or aggrading stream 

but a degrading stream. To determine whether any of the 

present canyon fill is or is not a permanent deposit can be 

settled only by observations over a period of at least a few 

decades.

LANDSLIDES

In the San Juan country many slopes are bare or 

coated with ribbons and scattered patches of debris: 

they are too steep to permit the accumulation of much 

talus. On the nearly vertical walls developed in thickbedded sandstones, on the steep slopes in the mudstone 

of the Permian red beds, and on the gentle slopes of 

limestone caps of anticlines the products of disintegration are removed about as fast as they are formed. 

The water that the slopes receive from rains and ephemeral sheet floods disappears before the surface rocks 

are saturated, and the little talus that accumulates 

rests directly on dry rock. The conditions favorable

" Miser, H. D.. The San Juan Canyon, southeastern Utah: U. S. Qeol. Survey 

Water-Supply Paper 538, pp. 67-71, 1924. 

»Idem, p. 59.
PHYSIOGRAPHY 103

for landslides are lacking. On the other hand, many 

slopes developed in the Moenkopi, Chinle, and Morrison 

shales are heavily coated with talus, which from time 

to time moves downward in a mass.

About the rim of Elk Ridge the weak Moenkopi shales 

that lie just below a zone of ground-water seepage 

provide a sliding plane for fragments of Shinarump conglomerate weathered from the cliffs just above. Down 

this plane jumbled masses of pebbles, angular boulders, 

joint blocks, and slices of the cliff have slid several 

hundred feet. In canyons on Sage Plain similar conditions account for the presence of fragments of Dakota (?) 

sandstone and Mancos shale on slopes of Morrison 

shale. In the Chinle formation the conditions for producing slides are exceptionally favorable. The thin 

sandstone beds readily break into talus fragments, and 

the "marl" beds when saturated seem to move by 

their own weight. Talus from the formation itself and 

from the Wingate, Kayenta, and Navajo above rests 

on a surface that when wet is slippery. Along the 

south side of White Canyon landslides in the Chinle 

appear as a band about a mile wide so continuous that 

the bedded rocks beneath are concealed except in 

gullies. In general their downward movement is arrested at the top of the Shinarump conglomerate, but 

at several places it continues across the Moenkopi and 

Organ Rock strata and even to the Cedar Mesa 

sandstone that floors the canyon, thus forming feasible 

routes of travel up otherwise unscalable cliffs. The 

material is a heterogeneous mass, 5 to 200 feet thick, 

composed of angular fragments of limestone, shale, 

and sandstone a few inches to as much as 20 feet in 

diameter. Its surface is exceedingly rough. In' the 

cliffs south of Clay Hills Pass sections of the Chinle 

have slid from their .original position and now stand 

as tilted ridges on Shinarump and Moenkopi beds.

That the slides are not all ot one age is shown by the 

differences in position, shape, and degree of weathering 

of the fallen masses. Part of the material is decomposed and is trenched by gullies that seem as old as the 

present cliffs. Considerable age is indicated also by 

weathered boulders that lie 1,000 to 2,000 feet in front 

of slides the remnants of accumulations destroyed by 

erosion. In contrast with these evidences of age the 

slide rock in places consists of slabs, blocks, and pebbles 

unmodified by weathering, includes upturned living 

trees, and shows no defined drainage system. It is 

reported that trails have been blocked by slides within 

the last 20 years. Instability is further shown by mud 

flows that after heavy rainfall issue from the base of 

slides. In places recurrent movement is indicated by 

the arrangement of material in parallel ridges on Chinle 

slopes and by unconformities in the piles of debris 

successively pushed over cliffs. The evidence that 

talus has been largely stripped from many slopes, that 

old slide material has been deeply eroded, and that 

some of the existing slides are active finds a place in

the discussion of physiographic cycles and the rates of 

regional denudation. (See p. 98.)

WHITE CANYON BRIDGES

The walls of White Canyon and its principal headwater tributaries are wonderfully carved with bays, 

alcoves, niches, and rounded overhanging ledges, many 

of them the sites for cliff dwellings. The most spectacular features are three natural bridges Kachina 

and Sipapu, in White Canyon, and Owachomo, in 

the adjoining Armstrong Canyon. (See pis. 19, B; 

20, B; 21; 22, A, B; 23, B.) In this region the streams 

are readjusting their roundabout courses, and the 

conditions are favorable for eliminating meanders by 

undercutting. The canyon walls consist of layers of 

porous sandstone lenticularly interbedded with relatively impervious shales, forming suitable conditions 

for the seepage of ground water from the upstream to 

the downstream sides of meander necks; the meanders 

are close pressed, the necks of some of them less than 

100 feet wide; the streams have steep gradients and in 

time of flood vigorously attack the concave meander 

walls. The process of bridge formation is clearly 

showa at the Kachina arch, which is still in a youthful 

stage of development. Here a bed of porous, coarsegrained sandstone 100 feet wide and 170 feet thick, 

underlain by dense thin-bedded sandstone, constitutes 

the wall between two meander bends. Water seeping 

through the wall at the contact of the massive and 

shaly beds has established underground runways and 

progressively enlarged them into a slit through which 

the entire White River passes. Since the river assumed 

this new course it has deepened the opening by cutting 

through the shales and into an underlying sandstone. 

The opening has been further enlarged by spalling of 

slabs from the top and sides, developing a rough-hewn 

arch with a span of 203 feet and a height between 

girder and stream bed of 108 feet. The abandoned 

channel of the White River, with its bed on shale, 

passes around the east end of the bridge between high 

curved walls of sandstone. (See pis. 21, 22, B.)

The conditions that permitted the formation of the 

Sipapu Bridge duplicate those at the Kachina, but the 

bridge is older. The stream has cut deeper, spalling 

and decomposing of the sandstone top have proceeded 

much further, and curves and rounded edges have 

replaced angular profiles. The bridge spans the stream 

as a graceful flat arch, 53 feet thick, 268 feet long 

between abutments, and 167 feet above the canyon 

floor. The top sandstone that once constituted the 

rim of the meander neck has been reduced to a roadway 

30 to 50 feet wide. (See pis. 20, B; 22, A; 23, B.) 

Of known natural bridges Sipapu is exceeded in size 

only by the Wonderfully symmetrical Nonnezoshie 

arch (Rainbow Bridge) at Navajo Mountain, which 

rises 309 feet above the stream and has a span of 278 

feet.
104 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

The Owachomo Bridge, like the Kachina and the 

Sipapu, is the remnant of a neck that once separated 

the concave walls of two meanders, but unlike the 

other bridges it extends across a passage between two 

roughly parallel streams that flow on different levels. 

Seepage through the walls of the higher unnamed 

canyon into the more deeply cut Armstrong Canyon 

disintegrated the sandstone above the impervious 

shale in a zone that later became an opening. The 

bridge thus outlines a huge perforation near the top of 

a canyon wall. (See pi. 19, J5.) The Owachomo arch 

is old. The short ephemeral stream that flows beneath 

it has cut a channel some 50 feet below its abandoned 

bed, and the wall that once separated the two streams 

has been reduced to a slab 27 feet wide and less than 10 

feet thick at its middle point. Slow weathering has 

widened the original slit to a span of 180 feet and 

increased its height nearly 100 feet.

The region that includes the White Canyon bridges 

was the home of the Basket Makers and a hunting 

ground for Navajos, Utes, and Piutes. It is not unlikely that prospectors and trappers from Colorado saw 

the bridges as early as 1870, but the first recorded visit 

of a white man was that of Cass Hite, who in 1880 

established a mining camp at Dandy Crossing (Hite), 

the head of Glen Canyon. In the fall of 1883, under 

the guidance of Piute Indian Joe, this adventurous 

prospector spent -several days among the interlaced 

upper tributaries of White Canyon, during which he 

located "copper streaks", "Moqui houses", and three 

large bridges, two "over the river" and one "on the canyon wall." Kite's picturesque reports attracted the 

attention" of placer miners on the Colorado River and 

of cattle men at Elk Ridge and led to visits by the 

pioneer settlers at Bluff, Moab, and Hanksville. To 

the outside world the three big arches became known 

chiefly through an illustrated article by Dyar,73 who 

described an excursion by a mining engineer, Horace 

J. Long, in 1903, under the guidance of James Scorup, 

of Bluff. In 1905 an expedition under the auspices of 

the Salt Lake Commercial Club 74 procured measurements and sketches of the bridges, on which the widely 

known paintings by H. L. A. Culver are based. In 

1907 additional information, including good photographs, was obtained by the University of Utah expedition under the leadership of Prof. Byron Cummings.75 

By a Presidential proclamation dated April 16, 1908, 

a tract of unsurveyed land immediately surrounding 

the three bridges was set aside as a national monument. 

After surveys in 1908 by W. B. Douglass, of the Gen^ 

eral^Land Office, the limits of the monument were 

established. As defined in the Presidential proclamaHeight of bridge above lowest 

floor of wash. 

Depth of arch (thickness of 

girder.

Length of span __ _______.__..

Width at narrowest point (top 

of girder).

. girder).

Owachomo

105^ 

9

180

27%

802

Kachina

210 

93

f 203^ 

J (north side)

] 350 

[(south side) 

44

103^

Sipapu

220 

53

i 268

31

858

 7 * Dyar, W. W., The colossal bridges of Utah; a recent discovery of natural wonders: 

Century Mag., August.1904; [abstract], Nat. Geog..Mag., vol. 15, pp. 367-368, September 1904. 

74 Holmes, E. F., The great natural bridges of Utah: Nat. Geog. Mag., vol. 18, 

pp. 199^204, 1907; articles in the Salt Lake' Tribune and Deseret News, April and 

May 1905.

" Cummings, Byron, The great natural bridges of Utah: Utah Univ. Bull., vol. 3, 

no. 3, pt. 1, pp. 1-24,1910.

tion of September 1909, the Natural Bridges National 

Monument includes not only the three bridges but also 

Snow Flat Cave Spring, on a tributary to Fish Creek 

and Cigarette Spring, near Road Canyon.

The dimensions of the bridges as measured by 

Douglass are as follows:

Dimensions, in feet, of natural bridges in San Juan country

In descriptions of the bridges several sets of names 

have been used. Cass Hite called them the President, 

the Senator, and the Congressman. Horace Long 

named the larger bridge in White Canyon, Augusta, 

after his wife, the smaller one Carolyn, after the mother 

of James Scorup, and the huge structure in Armstrong 

Canyon Little Bridge. The Commercial Club accepted 

Augusta and Carolyn as satisfactory names but rechristened Little Bridge as Edwin Bridge, after Col. 

Edwin F. Holmes, of Salt Lake City. Cummings 

adopted this terminology. In the Presidential proclamation more appropriate terms are used. For the 

massive flat arch that spans the main fork of White 

Canyon in a region of cliff houses and ancient granaries, 

the Hopi name Sipapu ("the gateway through which 

the souls of men come from the underworld and .finally 

return to it") replaces President and Augusta; for the 

unfinished archway over White Canyon near the mouth 

of Armstrong Canyon, Kachina ("the sacred dance" 

an interpretation of the symbols carved on the bridge) 

replaces Senator and Carolyn; and the elevated roadway 

spanning a dry tributary of Armstrong Canyon locally 

known as the Congressman or Edwin Bridge has been 

rechristened Owachomo ("flat-rock mound"), from a 

nearby lookout point, mentioned in Indian tradition.

These three magnificent bridges represent stages in 

the process of eliminating meanders a process now hi 

operation. Along many tributaries of White Canyon 

and in other canyons walls of Cedar Mesa sandstone 

enclose winding channels. At several places water is 

seeping through meander necks, and here and there 

cavelike slits extend far into the rock walls from the 

downstream sides. There are many abandoned meander curves at different levels above present streams, 

and in some trenchlike cut-offs the worn buttresses of 

ancient bridges still cling to the canyon walls. Pack 76 

speaks of a broken arch, the "Fallen Monarch", that

?« Pack, F. J., Natural bridging in the High Plateaus: Pan-Am. Geologist, vol. 37, 

p. 223,1922.
PHYSIOGRAPHY 105

once spanned the White River 2 miles above the Sipapu 

Bridge, and states that the abutments of the arch 

"are still standing, one of them in excellent state of 

preservation."

In Grand Gulch the elimination of meanders has left 

several abandoned horseshoe bends at different levels 

above the floor. In some places water is seeping 

through meander necks, and in others the stream passes 

through high-walled chutes that have not been long in 

use. Prospectors report that about 2 miles below 

Collins the buttress of a ruined bridge stands like a 

tower on the canyon floor between the present channel 

and the abandoned channel, and farther downstream 

the stub end of a broken bridge girder projects almost 

horizontally from the wall. Bridges in process of formation and others in ruins seem to be characteristic of 

intricately meandering, swift streams deeply entrenched

in canyons.

ARCHES AND WINDOWS

As agents involved in the erosion of walls of massive 

sandstone, decomposition and disintegration seem subordinate to quarrying. Weathering is effective in 

producing films of loosened grains that are continuously 

stripped from the ledge by rain storms, but the walls 

retreat mainly in consequence of the removal of whole 

sheets and blocks outlined by structure planes. The 

scars left on the wall reflect the number, spacing, and 

inclination of joints, the regularity of stratification, and 

the type of cross-bedding.

In rocks that are evenly bedded or angularly crossbedded blocks pried loose by frost or by undermining 

commonly have angular outlines. In rocks with«curved 

cross-bedding the detailed sculpture is characterized by 

curved surfaces in both vertical and horizontal directions. Thus on many bare exposures of Navajo sandstone, also in places on the Cedar Mesa, Entrada, 

Wingate, and Bluff sandstones, cross-bedding outlines 

arches. (See pis. 14, B; 23, A.} Some of these 

arches appear as if drawn on the smooth rock face; 

others form the borders of panels and blind windows 

recessed in the cliff faces; still others serve as the roofs 

of niches and rock shelters. As erosion continues most 

of the arched structures are detached from the walls 

and, lacking adequate support, collapse in response to 

gravity, exposing new curves and arches behind them. 

Some arches retain their individuality for long periods, 

and as the surrounding rock is worn away they stand 

like hoops with ends firmly attached to the ledge high 

above present stream beds. Thus in Dark Canyon an 

arch with a space of about 100 feet clings to the sandstone wall, and arches in various stages of development 

stand here and there on Grand Gulch and Red Rock 

Plateaus. Miser 77 describes two picturesque arches 

developed in the Navajo sandstone, one 2 miles below 

the mouth of Piute Creek and the other near the junction of the San Juan and the Colorado. As explained

" Mlsei, H. D., The San Juan Canyon, southeastern Utah: U. 8. Qeol. Survey 

Water-Supply Paper 538, p. 15,1924.

elsewhere 78 the free-swinging arches develop most 

readily at the heads of short box canyons, where erosion 

is most vigorous and continuous.

As alcoves are recessed deeper and deeper into canyon walls 

there is a tendency for surface water to make its way through 

the arched roof along vertical joint planes, a process which if 

continued under favorable conditions results in a crack open to 

the sky. Enlargement of this long, narrow skylight permits the 

outer part of the alcove roof to stand alone as an arch separated 

from the canyon wall by the width of the opening. Further 

erosion gives the arch the form of a hoop rising above the general 

rock surface or detaches it completely from the wall, making a 

bridge which spans the original alcove.

In the walls separating closely spaced canyons, in 

narro.w meander necks, in projecting buttresses, and hi 

detached dikelike ridges erosion from opposite sides may 

be so directed as to produce perforations the wellknown "natural" windows. In size these windows 

range from mere peek holes to openings many feet in 

diameter, and in shape from oblong to rectangular. 

Many of the windows are but the spaces left by the removal of joint blocks, and their square or rectangular 

frames are flush with the adjoining walls. Many 

rounded ones are the result of slow disintegration? and 

spalling guided by cross-bedding and are deeply recessed. The frames of many windows are broken.

The three beautiful windows in Arch Canyon (Cathedral Arch, Angel Arch, and Keystone Arch) are 

perforations in detached walls of interbedded shale and 

sandstone. (See pi. 24, A, B.) The top and the bottom of Cathedral Arch (pi. 23, (7) and Angel Arch and 

the bottom of Keystone Arch are flat bedding planes; 

the windows have been developed in the intervening 

sandstone by the falling of successive blocks, producing 

openings 60 to 100 feet wide and 50 to 140 feet,high. 

As the thick bed of sandstone is cross-bedded and also 

vertically jointed, removal of the blocks and sheets has 

left a frame made of both curved and plane surfaces.

Arches and windows seem to have the same physiographic history as rock shelters, bridges, and the multiform cavities in walls of porous sandstone. In early life 

they express the work of ground water; with their later 

development all agencies of erosion are concerned; at all 

stages rock structure is an influential control.

ROCK SHELTERS

In the San Juan country the canyon walls, especially 

those made of the thick-bedded sandstones, are sculptured in a remarkable way. As elsewhere in the plateau 

province the characteristic large-scale features sheer 

walls, overhanging walls, box heads, rincons, buttresses, 

and alcoves are decorated by carvings in relief and 

intaglio. Rounded bosses, capped columns, bobbins, 

"goblets", miniature pilasters, moldings, and frames 

of blind windows project from many rock surfaces, 

into which have been carved also innumerable niches, 

decorative grooves, and lines. The round, oblong,

78 Gregory, H. E., and Moore, R. C., The Kaiparowlts region: U. S. Qeol. Survey 

Prof. Paper 164, p. 144, 1931.
106 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

curved, and angular cavities in the walls range in size 

from tiny "eyes" and "toe holes" to caves as much as 

50 feet high and 100 feet wide and sunk 10 to 40 feet 

into the rock. Many of the large cavities protected 

from rain, from the heat of the sun, and from wind and 

sandstorms were utilized by the ancient inhabitants 

as sites for dwellings and storehouses "rock shelters" 

or "cliff caves" as termed by archeologists. Access 

to the sites is generally effected by steps cut into the 

steep rock wall.

These rock shelters are of two types flat-roofed 

recesses, eroded from shaly beds beneath a cap of 

resistant sandstone, conglomerate, or limestone, and 

arch-roofed structures, developed within strata of 

cross-bedded sandstone. In Montezuma Canyon and 

elsewhere on Sage Plain the grooves cut in Morrison 

shales at the base of the Dakota (?) sandstone provided 

ample space for houses. On the San Juan River the 

overhanging ledge of Bluff sandstone determined the 

site of Casa del Eco and many smaller structures. 

In Arch Canyon, Grand Gulch, and the tributaries to 

White Canyon the longitudinal recesses at the contact 

of sandstone and shale in the Cedar Mesa sandstone 

were utilized for building sites. Niches hi the Navajo 

sandstone in the Alien Canyon country and in the Cedar 

Mesa sandstone of Beef Basin, Fable Valley, and White 

Canyon are occupied by small isolated buildings, some 

of them mere caches for grain and seeds. The houses 

and villages that occupy cavities in the Navajo and 

De Chelly sandstones of the Navajo country are not 

duplicated north of the San Juan. On Red Rock 

Plateau, where many suitable building sites are available, the known ruins are few and small. (See pis. 25,26; 

fig. 4.)

Both the flat-roofed and arch-roofed rock shelters of 

all sizes and shapes are essentially the work of ground 

water. In regularly stratified rocks water seeping from 

the contact of porous and impervious beds has developed recesses by undermining the Dakota (?) sandstone, 

the Bluff sandstone, and in less degree the sandstone 

beds in the Cedar Mesa member. In the thick, massive sandstone beds the first stage in the development 

of cavities is the seepage of water along the surface of 

some locally impervious lens, with consequent removal 

of the cement, then the grams from the base of porous, 

saturated rock. This slight undermining permits 

grains and thin laminae, to fall in. response to gravity. 

As the process continues, shell after shell is detached 

from the roof and, because the cement has been largely 

removed by percolating water, reaches the floor as a 

disintegrated mass that is borne to the mouth of the 

cave by intermittent run-off. The back walls of many 

rock shelters are moist and thinly coated with waterloving plants. Some give rise to springs; others are 

coated with alkali or salt "bloom"; still others, especially those above the local water table, are dry. No 

field evidence supports the popular notion that the

cavities in the walls of canyons have been produced by 

sand blasts. On the contrary, little wind enters- them. 

Most of the small ones contain leaves, wings of insects, 

and dust that even a slight breeze would remove. 

Birds, bats, and rodents live in them, and during severe 

windstorms the large ones serve as refuges for beasts 

and men.

Q to in

/±ErJiLi' ,"rrT'1TT Limestone:^

10 Feet

<D 

JO

E

4J

cE 

OQJ 

-M c

t8 O

(0 

t) 

0)

O

60 Feet

FIGURE 4. Bock shelters: A, At contact of Dakota (?) and Morrison in Cottonwood 

Canyon; B, in thin-bedded Cedar Mesa strata at Cigarette Spring.

SAND DUNES

No large dunes or large areas of persistent small 

dunes were seen in the San Juan country. Here and 

there on the generally bare rock surface of Red Rock 

and Grand Gulch Plateaus sand dunes form and migrate, and on the floors of washes they are common. 

During the infrequent but severe wind storms great 

quantities of dust are swept from the ground and 

carried high into the air, but most of the wind-blown 

sand accumulates about the base of shrubs and trees 

or in the sheltered places on canyon walls. The topography is unfavorable for large-scale wind erosion or 

deposition.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 188 PLATE 19

A. COMB WASH.

View looking norlh. Subsequent valley developed on inclined Permian and Triassic beds along east flank of Monument upwarp. West face of Comb Ridge

at right. Photograph by W. H. Hopkins.

B. OWACHOMO NATURAL BRIDGE IN WALL OF ARMSTRONG CANYON. 

Cedar Mesa sandstone. Photograph by W. T. Lee.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 188 PLATE 28

A. VALLEY FILL OF SAND AND CLAY EXPOSED BY RECENT EROSION IN COMB WASH.

B. SIPAPU NATURAL BRIDGE, WHITE CANYON. 

Cedar Mesa sandstone. Photograph by W. H. Hopkins.
GEOLOGICAL SURVEY PROFESSIONAL PAPE

KACHINA NATURAL BRIDGE, WHITE CANYON. 

Cedar Mesa sandstone. Photograph by W. T. Lee.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 188 PLATE 22

A. SIPAPU NATURAL BRIDGE.

B. KACHINA NATURAL BRIDGE.

DIAGRAMS SHOWING FORMATION OF NATURAL BRIDGES.
GEOLOGICAL SURVEY PROFESSIONA

. 1. 1-TSHMOUTH CA\J,. 

Kroded in Nava.jo sandstone on hack slope of Comb Ridge.

B. VIEW ACROSS WHITE CANYON AT SIPAPU NATURAL BRIDGE.

The canyon at this place is cut 600 feet in Cedar Mesa sandstone. In foreground, neck of abandoned meander through which stream now flows.

C. CATHEDRAL ARCH, ARCH 

-, Cedar Mesa sandstone
GEOLOGICAL SURVEY PKOFESSIONAL PAPER 188 PLATE 24

i* »,t..

"' "I

. CATHEDRAL ARCH.

B. KEVSTONE ARCH.

NATURAL ARCHES IN ARCH CANYON
GEOLOGICAL SURVEY PROFESSIONAL PAPER 188 PLATE 25

kiife:

ROCK SHELTERS. 

A, B.C. In Cedar Mesa strata in White Canyon. D. In Bluff sandstone member of the Morrison on Ihe north side of San Juan River near Bluff.
GEOLOGICAL SUKVEY PROFESSIONAL PAPER 188 PLATE 20

ROCK SHELTERS.

A. At contact of Bluff sandstone and San Rafael strata on the south side of San Juan River near Bluff. (After Jackson, W. H., U. S. Geol. and Geog. Survey

Terr. 10th Ann. Rept. for 1876, pi. 49, 1878.) R. In Cedar Mesa sandstone, Fable Valley.
CHAPTER 6. ECONOMIC GEOLOGY

The San Juan country is poorly supplied with 

minerals of economic interest. Gold is a constituent 

of the gravel in the San Juan and Colorado Canyons 

and of the contact rocks of the Abajo Mountains; 

copper sufficient for mill tests is iucluded in the "green 

spots" of several sedimentary formations; vanadiumuranium minerals, largely carnotite, appear here and 

there in Morrison sandstone; and concretionary masses 

of manganese and iron are common. None of these 

minerals have been found in quantities that justify 

commercial exploitation. Likewise the coal seams in 

the Dakota (?) shales are too thin and too discontinuous 

to repay the cost of mining, and the petroleum obtained 

after expending "more than $2,000,000" in development is valued at "a few thousand dollars." Stone 

suitable for the construction of buildings is abundant, 

and lime could . be manufactured from beds in the 

Hermosa and Rico formations of Lime Creek Valley. 

The one economic resource of high value is the water 

available in the streams about the Abajo Mountains 

and Elk Ridge, in the San Juan River, in springs, and 

in artesian wells.

COPPER

DISTRIBUTION AND ORIGIN

Malachite, azurite, chalcocite, and other copper minerals are widely distributed in the San Juan country. In 

small quantities they are constituents of the Triassic, 

Jurassic, and Cretaceous beds, particularly of the Chinle, 

the Shinarump, and the Navajo formations, where they 

appear along joints, bedding planes, and cross-bedded 

laminae, in spherical and lenticular areas of copperimpregnated sandstone, and as widely scattered grains 

in the calcareous cement that surrounds quartz grains. 

The copper ore is restricted to the sedimentary beds, 

and the largest accumulations are on folds and minor 

wrinkles in regions where the continuity of the strata 

has been interrupted by closely spaced jointing, fissuring, and incipient faulting. No ore has been found 

within intrusive rocks or in such relations to them as to 

suggest igneous origin.

All the copper deposits in the San Juan country are 

"red beds" ores of the type found in sandstones at 

many other places in the plateau province and in 

Colorado and Texas as well.

The deposits are small and difficult of access. Mines 

in the Abajo Mountains and in White Canyon have 

proved to be unprofitable.

COPPER QUEEN MINE

In the Abajo Mountains the Dakota (?) and Navajo 

sandstones show areas impregnated with copper 

green spots on otherwise red or gray rock. Samples 

from such spots contain copper in considerable quantity. The Copper Queen mine, in North Canyon, has 

been developed by the construction of two tunnels, 

three shafts, and an open cut. From one of tho 

shafts a lenticular mass of malachite 2 feet wide is 

said to have yielded $14 a ton. The ore is in Dakota (?) 

sandstone, here quartzitic, and is concentrated in a 

zone of fractures.

DOLLY VARDEN AND BLUE DIKE MINES

In White Canyon many prospect holes record the 

hope that blue-stained sandstones in the Shinarump 

and Chinle formations might mark the position of 

workable deposits of copper ore. Prospecting began 

as early as 1880 (?) and was especially active in 1906 

and 1907, when the price of copper attained high levels. 

As late as 1916 ore was sent to the mill for testing. 

The mining claims considered most promising are the 

Dolly Varden, Blue Dike, and Frey Cabin. At Dolly 

Varden, about 10 miles from the mouth of White 

Canyon, a mineralized zone of white sandstone is 

about 500 feet long, 200 feet wide, and 1 to 20 feet 

thick. A tunnel driven about 180 feet into the deposit 

at the base of the Shinarump shows considerable copper 

irregularly distributed along the bedding and tiny 

fissure planes, in amounts decreasing with depth, with 

distance from fracture zones, and with scarcity of 

fossil plants. As shown by laboratory tests, the ore is 

chiefly bornite, replaced in part by chalcocite, and the 

black minerals cementing the grains are cobalt oxides.

At Blue Dike, about 15 miles from the mouth of 

White Canyon, copper minerals associated with plant 

remains are exposed in a lens of sandstone about 200 feet 

long and 1 to 10 feet thick. The outcrop and the walls 

of an old tunnel are coated with efflorescent salts. As 

determined by Butler,79 the blue and green salts are 

sulphates of copper, the yellow salts are sulphates of 

uranium, and the pink salts give tests for cobalt. The 

ores studied contain chalcopyrite, covellite, and chalcocite. Butler states: "There seems little doubt that 

the iron, cobalt, and uranium were all present in the 

sulphide ore."

78 Butler, B. S., Loughlin, O. F., Heikes, V. C., and others: The ore deposits ot 

Utah: U. S. Geol. Survey Prof. Paper, 111, p. 622,1920.

107
108 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

Near the mouth of Frey Canyon copper ore is revealed in several prospect holes, the so-called Harshberger claims.

GOLD

In the San Juan country gold has been recovered 

from placers in the San Juan Valley, in Glen Canyon, 

and in Johnson Creek and from mines developed in the 

mineralized zone near the roof of the Abajo Mountain 

laccolith. In pioneer history the search for gold in the 

unexplored canyons far from sources of supply is a 

chapter of absorbing interest, but as a commercial 

enterprise it has led only to disappointment. Wjth pan 

and sluice box many prospectors have made day wages, 

but mining companies whose operations call for the 

installation of machinery have failed. The value of the 

gold recovered is an insignificant fraction of the cost.

RIVER PLACERS

The discovery of gold in gravel along the upper tributaries of the San Juan River led to a search for the 

metal throughout its course. Starting from Animas 

City, Colo., hi 1879, E.^L. Goodridge worked his way 

by boat to the mouth of the San Juan the first known 

traverse of the river. He discovered flake gold at 

several places but gave discouraging reports regarding 

quantity and cost of recovery. After the settlement of 

Bluff (1880) some gold was panned by a Mr. Moss and 

others in sand bars above the mouth of Recapture 

Creek. Intermittent prospecting by local residents continued until 1891, when from unknown sources chiefly, 

it seems, from the notorious Indian trader, Bill Williams rumors spread that the gravel bars and terraces 

in the San Juan Canyon were rich in gold, particularly 

in the stretch below Clay Hill Crossing. Thus originated the "Bluff excitement" of 1892-93. A. L. 

Raplee reports that during these years some 1,200 men 

were working along the river between the mouth of 

Montezuma Creek and Glen Canyon. "Every sand 

bank and gravel bar was prospected and mud dipped 

out of the river's bed." To reach claims in the deepest 

part of the canyon the famous Honaker trail was built. 

Most of the prospectors returned empty-handed, a few 

obtained some gold, and it is reported that the Nephi 

claim yielded the equivalent of $3,000. Since 1893 the 

unprofitable search for gold along the San Juan has 

been continued at Zahns Camp, at Spencer Camp, near 

the mouths of Montezuma and Copper Canyons, and 

at other places thought favorable.

In Glen Canyon placer gold was discovered near the 

mouth of Trachyte Creek by Cass Hite in 1883, and 

during the period 1886-89 mining was vigorously in 

progress at claims on 21 bars distributed along the 

river from the mouth of White Canyon nearly to Lees 

Ferry. Since that tune the most promising claims 

have been worked intermittently. In 1927 the only 

man on the Colorado River in the San Juan country 

was a prospector at the mouth of Red Canyon.

In Glen Canyon all the gold obtained has the form 

of flour or microscopic flakes and when concentrated in 

the rockers and sluice boxes is accompanied by black 

sands mostly magnetite and hematite but also garnet, 

zircon, rutile, and other resistant minerals. The tiny 

particles of gold are thoroughly disseminated within 

the bars exposed at high water and in those perched 

higher on the canyon walls. It seems equally abundant 

"at the grass roots", within the gravel, and just above 

bedrock but is most concentrated in thin short streaks 

of "blue marl" and "red marl" impalpable sticky 

mud, readily disintegrated in water. Samples from 

this material showed as much as 0.06 ounce of gold to 

the ton.

The gold in the placers of the San Juan and Colorado 

Rivers is believed to have two sources. Some of it, 

doubtless, has been derived from areas of disintegrated 

auriferous rock in Colorado, transported and deposited 

by the present streams during their long life. The 

shape and size of the particles that make up the flour 

gold in Glen Canyon render them suitable for long 

transportation by streams of moderate volume and for 

deposition without marked sorting. Likewise the 

largest of the tiny flakes in the San Juan Canyon are 

like those mined along the Animas and other tributaries that rise in the gold-bearing San Juan Mountains. Probably most of the gold is derived from erosion of the Jurassic and Triassic rocks into which Glen 

Canyon, San Juan Canyon, and their many tributaries 

have been cut. These rocks, particuarly the Chinle, 

Wingate, and Navajo formations, are known to contain 

gold in amounts that average something like 5 cents a 

cubic yard. Some dunes made of disintegrated sandstone are as rich in gold as some of the river silts and 

gravel. Placer mining in San Juan and Glen-Canyons 

is further discussed in reports previously published by 

the Geological Survey.80

GOLD IN THE ABAJO MOUNTAINS

Systematic search for gold in the.Abajo Mountains 

began about 1892, at the time of the "gold rush" on 

the San Juan. In fact, many of the early prospectors 

were men whose experiences in mining on the river 

below Bluff had proved disappointing. After the discovery of placer gold in the bed of Johnson Creek and 

of ore at the head of that stream in 1893, the mountains 

were thoroughly explored, some 300 claims were staked, 

and many thousand dollars was expended in the construction of shafts, tunnels, and mills. The ruins of 

workings appear at many places, and the mountains 

are pitted with prospect holes from which samples of 

ore wore taken. On some claims assessment work is

80 Gregory, H. E., Geology of the Navajo country, a reconnaissance of parts o» 

Arizona, New Mexico, and Utah: U. S. Geol. Survey Prof. Paper 93, pp. 139-140, 

1917. Butler, B. S., Loughlin, G. F., Heikes, V. C., and others: The ore deposits of 

Utah: U. S. Geol. Survey Prof. Paper 111, pp. 152-158,1920. Miser, H. D., The 

San Juan Canyon of southwestern Utah: U.- S. Geol. Survey Water-Supply Paper 

538, pp. 21-22,1924. Gregory, H. E., and Moore, R. O., The Kaiparowits region, a 

geographic and geologic reconnaissance of parts of Utah and Arizona: U. S. Geol. 

Survey Prof. Paper 164, pp. 147-148, 1931.
ECONOMIC GEOLOGY 109

kept up, and prospecting intermittently continues in 

places that are still considered promising; but in the 

opinion of experienced miners the unfruitfulness of the 

Abajo Mountains as a gold country has been demonstrated. The results of mineral exploitation bear out 

the prediction of Gilbert 81 that, as in the Henry 

Mountains, "gold and silver will not be found in paying quantity in Navajo Mountain, the Sierra La Sal, 

the Sierra Abajo, the Sierra Carisso [Carrizo], or the 

Sierra La Plata [Ute Mountain?]." It seems that the 

quantity of metalliferous material in the original 

igneous masses of these laccoliths was too small and the 

changes incident to cooling at the contacts too slight 

to develop large ore bodies.

From a manuscript descriptive of gold mining in the 

Abajo Mountains prepared by Malcolm R. Thorpe in 

1915, the folio wing information has been abstracted:

Sometime previous to 1892 Frank Dixon, the pioneer 

prospector in the Abajo Mountains, located several 

gold claims at the head of Dixon Gulch, between South 

Peak and Gold Queen Gulch, on a mineralized belt about 

500 feet wide at the contact of Dakota (?) sandstone 

and blue porphyry. No gold was found on the surface 

or in the many tunnels driven into the mountain. The 

last work on this property was done about 1900.

In the cement of stream and terrace gravel along 

Johnson Creek at the base of the Abajo Mountains two 

prospectors, Parker and Owens, discovered placer gold 

in 1893. Within a few months the deposit was exhausted, and, the "Johnson Creek placer boom" 

collapsed.

In an effort to relocate the old "Spanish mine", said 

to have been worked "300 years ago before it was buried 

in a landslide", Andrew Straus located the Alma mine, 

at the south base of South Peak, in 1900 and, taking 

into partnership William Straus and S. J. Houser, 

worked the property for some years. Several tunnels 

driven into a mineralized zone in the porphyry yielded 

no valuable minerals, but a small amount of free gold 

was found nearby on Recapture Creek. That some 

gold-bearing ore was shipped from this vicinity is sho'wn 

by records at Santa Fe.

The Gold Queen mine, at the head of Gold Queen 

Gulch, southeast of Abajo Peak, was once the scene of 

considerable activity. .The discovery of a small vein of 

rich ore led to the construction of two tunnels, three 

shafts, cabins for miners, and a mill, at a reported cost of 

about $80,000. The mine is located on a mineralized 

zone about 600 feet wide that crosses the crest of a 

ridge. The igneous rock in this contact zone is filled 

with minute veins of iron ore, a little copper ore, and 

calcite. Extensive exploration by Carlson, Olsen, and 

Innis proved that the ore-bearing veins were tiny and 

the gold'in them superficial. Operations were suspended 

about 1903.

» Gilbert, G. K., Geology of the Henry Mountains, 2d ed., p. 146, U. S. Geol. and 

Qeog. Survey Rocky Mtn. Region, 1880.

The Viking mine, located by James Hewett and 

Henry Rose on the ridge northeast of the Dream mine, 

was developed by sinking two shafts and driving a 

tunnel 400 feet long into the mountain at the contact 

between porphyry and. Dakota (?) sandstone. No 

valuable ore was found. Just east of the Viking mine 

the owners of that property staked out the Log Cabin 

claim and sunk a shaft and a tunnel into the decomposed 

igneous rock near its upper contact. Small fissures in 

this rock are filled with iron ore and calcite associated 

with gold in amounts too small for profitable mining.

At the Duckett mine, on Duckett Ridge east of Mount 

Linnaeus, a shaft 35 feet deep has been sunk by the 

owners, J. A. and J. B. Duckett. A little ore taken 

from a narrow bank at the contact between porphyry 

and a metamorphosed calcareous bed in the Morrison 

formation showed "a few dollars per ton."

The Enterprise mine, on the first ridge west of the 

Viking mine, has been developed by a shaft and tunnel 

at the contact of porphyry with Dakota (?) sandstone 

and Mancos shale. Seams in the Dakota (?) are filled 

with a fine mesh of quartz crystals. The Mancos includes vugs and seams that contain minute crystals of 

quartz and calcite. It is reported that before the 

property was abandoned ore containing silver and gold 

was mined.

The Dream mine, a group of seven claims at the head 

of Johnson Creek, was located by C. A. Cooley and 

S. J. Houser in 1893.. After working the mine intermittently for 6 or 8 years, Cooley leased his interest to 

C. W. Houser, who is said to have taken out and sent 

to the mill $3,000 in gold. While the Housers controlled the property, Capt. Calvin Jackson, of Colorado, 

leased the Dream mine from them and founded Camp 

Jackson, where he built the first stamp mill in the 

mountains. His violent death soon after the mill was 

constructed ended the "Camp Jackson boom." Then 

the Housers failed, and the Dream mine changed hands 

several times until it came into the charge of A. P. 

Adams, who built roads and a stamp mill at a cost of 

about $35,000. After this Hansen and Young expended 

about $20,000, only to fail after extracting a small 

amount of gold. The Alamo Mining Co. next came into 

possession of the property, spent several thousand 

dollars in working it, then failed, and sold out to the 

present owners, S. J. and C. W. Houser. The mine 

workings consist of more than 2,000 feet of tunnels and 

crosscuts on three levels, two shafts, and a stamp mill. 

The tunnels are designed to penetrate the mineralized 

zone at the contact of the laccolith and its roof. The 

most valuable ore is near the surface. The gold is 

confined to the bedding planes of the metamorphosed 

sedimentary rocks and to a thin zone of igneous rock. 

All the ore is free-milling. Most of it has the form of 

fine flakes, but nuggets as large as nail heads have 

been found. A small amount of copper is present 

but not enough to prevent the use of cyanide. At the
110 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

end of the largest tunnel the gold ore is a conglomerate 

of fragments of porphyry and argillite with much iron 

pyrite that has a reported value of $1 to $27 a ton. 

En one of the crosscut tunnels gold has been found in a 

breccia composed of fragments of Dakota (?) sandstone, 

Morrison shale, and blue porphyry. In another tunnel 

a band of sulphide ore was encountered. According to 

the owners 50 tons of rich ore is stored in the mine, 

3,000 tons is on the dump, and 6,000 tons is in sight 

in the underground workings. S. J. Houser, who as 

owner or operator has been connected with the property 

since its discovery in 1893, states that the large sums 

spent on the development of the Dream mine and the 

nearby Goodhope and Puzzle workings have yielded 

returns.

The Illinois mine, on the west side of North Canyon 

between Innis' sawmill and the Copper Queen mine, 

was discovered some 35 years ago by Martin Hobbs. 

The workings consist of a shaft, three tunnels, and an 

open cut, and the property includes a stamp mill and 

crusher. The most extensive work was done on a tunnel 

500 feet long that penetrates in turn 106 feet of Dakota 

(?) quartzite, 26 feet of porphyry, 62 feet of quartz, 

10% feet of Morrison shale, 7 feet of porphyry, and 14 

feet of decomposed oxidized rock and terminates in 

mineralized porphyry. Mr. Innis, one of the present 

owners of the mine, states that a band of oxidized rock 

260 feet from the entrance of the tunnel yielded $8 to 

$40 a ton in gold and that a streak of black rock less 

than 1 inch wide was even richer. The bulk of the ore

is of low grade.

COAL

Coal appears at many places in eastern San Juan 

County as beds in the Dakota (?) formation. Its usual 

expression is a series of short, thin carbonaceous lenses 

that include bituminous shale, carbonaceous shale, and 

layers of macerated plants as well as true coal. Tracing 

of coal lenses along outcrops shows a wide range in 

thickness and purity within distances of a few hundred 

feet. No thick beds and no continuous beds of uniform 

quality were seen; the region contains no deposits of 

large commercial value. However, a detailed study 

by Boyer 82 of exposures in the region about Blanding 

and Monticello and eastward to the Colorado line 

shows that coal for local domestic use may be found at 

several localities.

Along Recapture and Johnson Creeks outcrops examined show only thin streaks of carbonaceous and 

bituminous shale. Near Monticello several openings 

reveal coal stringers 2 to 10 inches thick, and at a place 

4 miles north of the village a short bed 2 feet 9 inches 

thick is reported, but most of the coal produces much 

ash and clinker, and its mining involves the removal of

M Boyer, W. W., Coal in the Dakota (?) formation in southwestern Colorado and 

eastern Utah (manuscript on file, U. S. Geol. Survey).

large amounts of "bone" and country rock. It is 

unlikely to be much used until the abundant supply of 

wood fuel is exhausted. About 2 miles northeast of 

Lockerby post office coal exposed in a shallow wash 

tributary to Coal Bed Canyon yields fuel sufficient for 

local use. The characteristics of the beds in four 

prospect holes are illustrated by the following section 

of the Crepo mine measured by Boyer:

Section in Crepo mine

Ft. in.

Sandstone, gray to buff, medium-grained, cross-bedded. 17 

Shale, carbonaceous.______________________________ 6

Shale, gray, sandy._______________________________ 9

Coal, streaked with shale.__________________________ 10

Shale, gray______.._-------_---_-------_---_.-____. 7

Coal, bony_____________________________________ 1

Shale, carbonaceous, and streaks of poor coal_______ 9

Shale, gray, floor.________________________________ 5

In Piute Draw near Ucolo, where several small mines 

are intermittently worked, the thin coal beds are of fair 

quality. The beds are remarkably discontinuous. In 

no two of the six mines and prospect holes is the same 

bed visible. The arrangement of beds is illustrated by 

the following two sections measured by Boyer:

Section in Rassmussen mine, at Ucolo, 80 feet from the mouth of

Piute Draw

Sandstone roof. .Ft. in. 

Shale, gray_____________________________________ 11

Coal, dirty, and streaks of bituminous shale____._____ 6

Coal, bony streaks._______________________________ 1

Coal, dirty, and streaks of bituminous shale________ 11

Bone______--_--_-----__-_--__-______--_______-__ 2

Coal_____.__,__________________________ 6

Shale floor.

Section in Pendergraff mine, Piute Draw, 1 mile east of UtahColorado boundary

Ft. in. 

Sandstone, gray, quartzitic on top surface._________ 10

Clay, gray and blue_____-.____.________.._________ 1

Shale, carbonaceous_____----_--____-____--___-___ 3

Shale, carbonaceous, and bony coal intermixed. _____ 2 4^

Shale, red and yellow; appears burned(?)_!______-- 2-3

Shale, bituminous, and streaks of coal._____________ 11

Shale, blue, sandy, with carbonaceous layers._______ 1

Coal and carbonaceous shale intermixed___.---___-- 1 

Bone, dense, hard, sandy_______._________________ 1-1)4

Coal, good__----_____-___-______.__-_______-____ 1 10

Shale, blue, floor.

As shown by the analyses given below, the coal mined 

at Ucolo is of better quality than the coal from Cortez 

and inferior to that from Nucla, Colo. As the heating 

value of the coals from these three adjoining localities, 

calculated on moisture- and ash-free content, is essentially the same, the difference in quality is the result of 

impurities. The table of analyses shows also the quality of coal from the Book Cliffs a region that would be 

a competitor if the coal from San Juan County were 

to be commercially exploited.
ECONOMIC GEOLOGY

Analyses of coal from the San Juan country and the Book Cliffs

Ill

Source

Oberding mine, Nucla...

Rassrnussen mine, 

° Ucolo bone and bituminous - shale layers.

Rassmussen mine, 

Ucolo coal.

Mowry mine, near 

Cortez, Colo.

No. 1 mine, American 

Fuel Co., Book Cliffs, 

Utah middle bed.

Location

Sec.

13

36 

35

35 

35 

27

T.

46 N.

47 N. 

33 S.

33 S.

36 N. 

20 S.

R.

16 W.

16 W. 

26 E.

26 E. 

16 W. 

20 E.

Laboratory 

no.

A. 14442

A. 14444 

86825

86825 

12586 

17577

Airdrying 

loss

1. 1

4. 2 

1.7

3. 3 

3. 1 

2.0

|Form of 

analysis 1

A..._ 

B____

C____

'A....

B_.._

C-__

A__._ 

B_.._

C _

A____

B..._

C.._.

A_..__ 

B._._

C .

A.._. 

B____

c__:_

Proximate analysis

Moisture

2.5

6. 5

2. 7

4. 3

4. 84

7. 13

Volatile 

matter

32.5 

33. 3 

38.0

33.0 

35. 2 

39. 4

24. 1 

24. 7 

36.2

32. 3 

33.8 

38. 2

34. 56 

36. 32 

44.97

37.03 

39.87 

44. 92

Fixed 

carbon

52.9 

54. 3 

62.0

50. 7 

54.3 

60.6

42.3 

43. 6 

63.8

52.3 

54. 6 

61.8

42. 30 

44. 45 

55.03

45.40 

48.89 

55.08

Ash

12. 1 

12. 4

9.8 

10. 5

30.9

31. 7

11. 1 

11.6

18. 30 

19. 23

10. 44 

11. 24

Sulphur

.8 

.9 

1.01

1. 1 

1. 1 

1. 3

2.0

2. 9

3.8 

3.9

4.5

7. 56 

7.94 

9.83

.66 

. 71 

.80

Heatine; value

Calories

6,933 

7, 111 

8, 122

6,861 

7,339 

8,200

5,167 

5, 311

7,774

6,933

7,244 

8; 194

6,147 

6,460 

7,998

6,509 

7,009 

7,896

British 

thermal 

units

12, 480 

12, 800 

14, 620

12, 350 

13, 210 

14, 760

9,300 

9,560 

14, 000

12, 480 

13, 040 

14, 750

11, 065 

11, 625 

14, 396

11, 716 

12, 616 

14, 213

 A, As received; B, moisture-free; C, moisture-and ash-free.

OIL 

DISTRIBUTION

After his discovery of "little streams of oil coming 

from loose boulders on the bottom of the [San 

Juan] canyon" above the mouth of Slickhorn Gulch, 

in 1879, E. L. Goodridge located an oil claim near the 

present Goodridge bridge on the San Juan (1882), where 

"rock beds like those at the oil seeps are bent down into 

a basin." After discouraging efforts, funds necessary 

to develop the claim were obtained in 1907, and on 

March 4, 1908, oil was struck at a depth of 225 feet 

"a gusher, throwing oil to a height of 70 feet above the 

floor of the derrick." The success of this pioneer well 

(Crossing No. 1) led to the drilling of more than 50 

wells in the Goodridge field and adjoining regions and 

to the study of oil possibilities in all southeastern Utah. 

Most of the geologic investigation and most of the 

development has been along the San Juan River, but 

potential oil-bearing anticlines have been mapped at 

Fish Creek, Elk Ridge, and Beef Basin, and some 

hundreds of claims have been staked on northern Sage 

Plain, Grand Gulch Plateau, and westward to Glen 

Canyon. A deep well has been drilled in Reservoir 

Canyon, Elk Ridge (1926-27), and another at Boulder 

Knoll, east of Monticello (1926-28). The log of the 

Reservoir Canyon well ("Gerald Hughes No. 1 Elk 

Ridge well"), made available by the Midwest Refining 

Co., shows that the drill penetrated 4,422 feet of strata, 

chiefly limestone, in the Rico and older formations and 

terminated in "granite schist." Fresh water was encountered at 3,000 feet, and salt water at 2,595 and

4,090 feet, but no oil at any horizon. This well may 

reasonably be cited as proof of the nonproductiveness 

of the anticlines on the crest of the Monument up warp. 

The well at Boulder Knoll, in sec. 17, T. 34 S., R. 

25 E., about 6 miles southeast of Monticello, was drilled 

to a depth of 2,640 feet. Unlike the other wells in the 

San Juan country it penetrates Cretaceous, Jurassic, 

and Triassic strata. The well log, furnished by Albert 

Galloway, of the Boulder Knoll Oil & Gas Co., shows 

that water was encountered in Dakota (?) and Morrison 

beds and "heavy gas" and a "showing of oil" in the 

Chinle (?). It is reported that gas bubbling through 

salt water flowed continuously during the winter of

1928-29.

SAN JUAN OIL FIELD

By H. D. MISEK

OIL SEEPS

Several oil seeps deriving their oil from the Hermosa 

and Rico formations occur in the bottom of San Juan 

Canyon between Goodridge (Mexican Hat) and the 

mouth of Slickhorn Gulch. The largest of these is a 

rather continuous series of seeps extending for a distance 

of 1 % miles up the canyon from the mouth of the gulch. 

The seoeps were observed on the right bank of the river; 

the left bank was not visited. The oil comes up as 

bubbles in the water and as minute streams through 

sand and also through boulders of sandstone and limestone at the edge of the water. The boulders, which 

have fallen from the adjacent cliffs, are cut by cracks 

through which the oil passes. The drops of oil break 

on reaching the surface of the river and spread as thin
112 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

iridescent films. The oil is a brown liquid that flows 

easily, and although its odor is strong the odor of 

gasoline is not noticeable. A black asphaltic residue 

cements rather large patches of sand and rock fragments. At one seep a film of oil covering several 

square feet of a sand bar is used by flies as a breeding 

place, and hundreds of larvae live in the oily substance 

on the bare surface of the sand bar, in spite of the 

intensely hot rays of a summer's sun which beat down 

on them during the day. Westward-dipping beds of 

the Hermosa formation, which form the lower canyon 

walls near the seeps, are cut by a normal fault with a 

northeastward trend and a downthrow of 4 feet on the 

east side. The presence of this fault suggests that the 

oil ascends along the fault plane to the alluvial material, 

through which it passes to the surface.

Seeps are reported in Johns Canyon about 2 miles 

above its mouth.

About 1 yz miles southeast of the head of the Honaker 

trail minute trickles of oil and pas issue from a sand 

bar in the edge of the river. A chip saturated with the 

oil was set on fire. Gasoline, as indicated by its 

strong odor in this part of the canyon, forms a considerable part of the crude petroleum.

About 4 miles farther upstream a seep is reported 

on the right bank of the river in or near the Second 

Narrows.

The Goodridge oil sand, which forms a gorge and a 

superjacent bench at the Goodridge Bridge, contains 

small dark areas of oil in its joints and cracks for a 

distance of 200 feet along the river east of the bridge. 

The sandstone, which is here 27 feet thick, dips 2° E.

The Goodridge oil sand also contains showings of oil 

on the right bank of the San Juan half a mile northeast 

of the store at Mexican Hat.

Of the early development in the San Juan region 

Woodruff 83 says:

Though oil springs must have been seen by prospectors and 

traders who operated along San Juan River, they seem to have 

received only casual notice until 1882, when E. L. Goodridge 

made the first location of a claim. No drilling was done, however, until the fall of 1907, when the first well, Crossing No. 1, 

was begun. This well encountered oil March 4, 1908, at a depth 

of 225 feet. It was a gusher, throwing oil to a height of 70 feet 

above the floor of the derrick, and led to considerable excitement. 

Other wells followed in rapid succession in 1908 and 1909, but 

most of them were only prospect holes put down to validate the 

titles to claims and not with serious intention of determining the 

oil resources of the field. By the summer of 1910 considerable 

capital had been enlisted to exploit the field. One standard rig 

was in operation, and others were reported to have been ordered. 

There were 10 portable deep-well rigs in the area and several 

more on the way to it. During midsummer active development 

was somewhat retarded on account of the heat, but in the later 

part of August preparations were made to renew operations with 

greater vigor than before. Reports received from reliable sources

83 Woodruff, E. G., Geology of the San Juan oil field, Utah; U. S. Geol. Survey Bull. 

471, pp. 98-99,1912.

during the winter of 1910-11 indicate that the expection of 

activity has been fully realized. On February 1, 1911, according 

to a report by A. L. Raplee, there were 27 drilling rigs in the 

field and equipment for more on the way. Two oil wells were 

brought in during the winter, and there was considerable improvement at old wells. A small town had been established near 

Mexican Hat, and the roads and general facilities much improved.

Between 1911 and 1920 there was comparatively 

little drilling in the region, but since that time several 

wells have been drilled in the field and in the surrounding region. Most of these wells were deeper tests than 

the earlier wells.

The Mexican Hat Co. drilled a well in 1922 in the 

San Juan oil field, 1% miles southwest of the Mexican 

Hat town site. The well was drilled to a depth of 

362 feet and yielded a daily production of 50 barrels 

of oil said to have a gravity of 47° Baume".

A well at Halgaito (formerly spelled Hulkito) Spring, 

in sec. 35, T. 42 S., R. 17 E., south of the San Juan 

River, was drilled by -the Monumental Oil Co. about 

1920 to a depth of 1,300 feet or more. As far as the 

writer knows, no showings of oil or gas were obtained. 

A second well was drilled with a diamond drill by this 

company in 1923, in sec. 23, T. 42 S., R. 17 E., also 

south of the San Juan River. It was abandoned at a 

depth of 756 feet. No showings of oil or gas were 

reported. Another well near the same location was 

bored by the company with a diamond drill to a depth 

of 1,622 feet in 1923 and 1924. No production was 

obtained. In 1926 this company drilled a fourth well 

to a depth of 1,140 feet in sec. 19, T. 42 S., R. 18 E. 

(unsurveyed), south of the San Juan River. This well 

obtained small showings of oil and gas at depths of 

800 to 812 and 890 to 900 feet.

The London-San Juan Oil Co. drilled a well 213 

feet deep in sec. 13, T. 41 S., R. 18 E., in 1923. No 

showings of oil or gas were reported.

Between 1924 and 1928 the Utah Southern Oil Co. 

drilled a well in the" canyon of the San Juan River in 

sec. 27, T. 41 S., R. 19 E. Several small showings of 

oil and gas were found. The well was abandoned at 

a depth of 1,850 feet after drilling into mica schist.

The Utah Petroleum Corporation drilled a well in 

1926 in sec. 36, T. 41 S., R. 17 E., south of the San 

Juan River, to a depth of 1,707 feet. No showings of 

oil or gas were found.

In 1926 the Utah Southern Oil Co. started a well in 

sec. 28, T. 40 S., R. 18 E. The well was abandoned 

at a depth of 3,633 feet after drilling into mica schist.

In 1930 a new well was started by the Arcola Oil Co. 

in sec. 6, T. 42 S., T. 19 E., near the wells that had 

formerly produced oil in the San Juan oil field. The 

well, 263 feet in depth, obtained a small production of 

oil.

The only notable production has been obtained from 

a few wells of small individual capacity, near Mexican 

Hat and Goodridge. These wells, which are named
ECONOMIC GEOLOGY 113

below, are all in T. 42 S., R. 19 E., within a radius of 

miles of the common corner of sees. 5, 6, 7, and 8:

Hudson well, sec. 5. 

Bryce No. 1 well, sec. 6. 

Bryce No. 2 well, sec. 6. 

Mexican Hat well, sec. 6. 

Arcola well, sec. 6. 

Crossing No. 1 well, sec. 7. 

Monticello well, sec. 7.

Other wells within the same radius have bailed small 

quantities of oil or furnished showings of oil, and north 

of that locality showings of oil have been reported at 

various depths from scattered wells in T. 40 S., R. 19 E., 

T. 41 S., Rs. 18 and 19 E., and T. 42 S., R. 18 E. 

Showings of oil are also reported from wells as far west 

as Johns Canyon and the mouth of Slickhorn Gulch.

The production of the field has all been» consumed 

locally. No reliable estimate of the output of the field 

in the period of activity is available, though records of 

sales from the Bryce No. 2 well show that some 5,000 

barrels of oil was disposed of for field use in 1910 and 

1911, in addition to many barrels of oil either wasted 

or consumed in drilling by the owners of the well.

DIFFICULTIES OF EXPLORATION

The difficulties of exploration in this rough arid 

region, 150 to 200 miles from a railroad, are many. 

There are few inhabitants, and most laborers must be 

imported. All so-called roads west of Bluff and north 

of Kayenta are poor indeed and at times are impassable 

for wagons and automobiles. Most parts of the canyon 

country are not traversed by roads. The rainfall does 

not exceed about 6 inches a year, so that water for 

drilling as well as for drinking is scarce and generally 

has to be hauled or carried long distances. No timber 

is available for fuel except driftwood along the San Juan 

and scrub cedar and pinon on Cedar Mesa and other 

mesas of similar height farther west. The principal fuel 

for drilling has been oil from wells in the San Juan oil field. 

The cost of hauling coal into the region from the vicinity 

of Monticello or from other places is prohibitive.

GEOLOGIC OCCURRENCE OF OIL

The small producing, wells enumerated above are 

1 to 2 miles west of the northward-trending axis of the 

moderately depressed Mexican Hat syncline and penetrate beds that dip 2°-4° E., toward the trough of that 

fold. The oil showings to the northeast were found In 

strata of low dip on both flanks of the syncline. The 

oil showings in Johns Canyon were apparently found 

on the crest of the Mitten Butte anticline. The 

showings in the well at the mouth of Slickhorn Gulch, 

where there are numerous oil seeps, are in strata that 

dip 2° W. on the west flank of the anticline. The fault 

that cuts the strata at the mouth of the gulch may have 

influenced the accumulation of the oil by providing a 

channel for it.

The oil in the San Juan country occurs in the Hermosa and Rico formations, which contain many oilbearing sands. All the wells in the field, including those 

mentioned above, were drilled in these formations, and 

two of them those of the Utah Southern Oil Co. in sec. 

28, T. 40 S., R. 18 E., and sec. 27, T. 41 S., R. 19 E. 

passed entirely through the Hermosa and possibly older 

limestone and entered mica schist of pre-Cambrian age.

The sands vary in thickness from place to place, and 

some of them are as much as 50 feet thick. At some 

places the oil saturates the unbroken rock, indicating 

that such rock is uniformly porous, but at others, as at 

the seep in the Goodridg°e sand at the Goodridge Bridge, 

the oil stains are irregularly distributed along joints 

and other cracks, indicating that the sandstone is not 

uniformly porous.

The fact that only a few of the rather large number of 

wells drilled in the vicinity of Goodridge and Mexican 

Hat have produced more than meager quantities of oil 

suggests that the oil in the sands is pockety and that its 

discovery with the drill is more or less accidental. This 

suggestion seems to be borne out by the character of one 

of the principal sands the Goodridge as revealed at 

the Goodridge Bridge, where oil is not uniformly disseminated through the sandstone but is confined to 

joints and other cracks.

The original source of petroleum in the San Juan oil 

field is undetermined. It may have come from the animals now represented by fossils in the Hermosa and 

Rico formations, in which the oil is found. There is 

also the remote possibility that the oil is of inorganic 

origin and was produced by the igneous rocks intruded 

in the sedimentary beds. Whatever its origin, the accumulation of oil along the San Juan has been controlled by local structure, climate, and geomorphic features. A series of north-south anticlines and synclines 

are favorable for accumulation, but the aridity of the 

region and deep trenching by canyons are unfavorable. 

As oil remains above water underground as well as 

above ground, it will be forced up under the arches of 

anticlines in regions where the rocks are saturated with 

water and will rest on the limbs of anticlines or in the 

troughs of synclines where ground water is deficient.

In the San Juan field throughout long periods of 

aridity the strata are drained of water nearly down to 

the bottoms of the major canyons, and rainfall is insufficient to compensate for the loss. The height to which 

oil may rise depends somewhat on the composition of 

the oil-bearing rock, but chiefly on the amount of water 

and oil available to fill its pores. Ground water and 

oil seeps emerge into the bottom of San Juan Canyon. 

Above that level the rocks have been drained of 

liquids.

The history of drilling in the San Juan field bears out 

the predictions of Gregory and Woodruff that the 

geologic conditions are unfavorable for large yields.

SURFACE WATER

In the San Juan country the surface water is utilized 

for household purposes, for livestock, and for irrigation.
114

The development of power on the San Juan, particularly 

at the sharp meanders ("Goose Necks") below Goodridge and at the Great Bend, is feasible but at present 

not economical. Furthermore, as a control for flood 

waters on the lower Colorado, dams on the San Juan 

below the mouth of Comb Wash ("Bluff dam site") 

and in Glen Canyon just above the mouth of Lake 

Canyon ("Bedrock dam site") would have no purpose 

not equally well served by the proposed dam in Glen 

Canyon, above Lees Ferry. 84

The flow of the San Juan River has been observed at 

a gaging station in the vicinity of Goodridge during 

the periods October 1914 to September 1917 and March 

1927 to September 1933. During these periods the 

maximum discharge was about 70,000 second-feet on 

September 10, 1927, and the minimum discharge 26 

second-feet on December 30, 1932.

WATER FOR STOCK

Surface water for sheep and cattle that range on the 

public domain is available in water pockets, ponds, and 

streams.

The water pockets ("rock holes", "rock tanks") are 

depressions hi rock that fill with water after rains. 

They range in size from irregularly oval saucers a few 

inches deep and some tens of feet in diameter to round 

pits a few feet in diameter and as much as 6 feet deep; 

some of them are true potholes. They appear on bare 

surfaces at places where intersecting joints, abrupt 

change in direction of cross-bedding laminae, or weakly 

cemented rock facilitate local decomposition or local 

scour conditions best provided by the Navajo and 

Cedar Mesa sandstones. The deepest ones are just 

above and just below dry waterfalls. In the shallow 

depressions the water disappears within a few days after 

the shower or the sheet flood that supplies it. In the 

narrow deep ones it may last for months or even 

throughout the year, and at times when the streams in 

the washes and canyons have ceased to flow it may be 

the only supply within a large area. As much of the 

best forage is on plateau tops and distant from established drainage channels, these water pockets, even 

though ephemeral, have obvious value.

Most of the "ponds", "lakes", and "dry lakes" are 

little more than very shallow water pockets in bare rock 

enlarged to diameters of 50 to 100 feet, or swamps about 

springs. Those on Elk Ridge and at the head of Johnson, Montezuma, and other creeks on the Abajo 

Mountains, where rainfall is relatively abundant, are 

nearly or quite perennial; those on Sage Plain and 

Grand Gulch, Red Rock, and Dark Canyon Plateaus 

are quickly emptied by evaporation but last long enough 

to supplement supplies from other sources.

In the San Juan country, as elsewhere in the plateau 

province, streams are the most abundant and the most

'* La Rue, E. C., Water power and flood control of Colorado River below Green 

River, Utah: CJ. S. Geol. Survey Water-Supply Paper 556, pp. 20-24. 51-52,1925.

generally reliable sources of surface water. Their 

utilization, however, is seriously hampered by extreme 

fluctuation in volume and by inaccessibility. Of the 

master streams the San Juan is essentially perennial, but 

in its canyoned stretch of 135 miles below Comb Ridge 

it is accessible to stock at only three places. The water 

in the Colorado likewise is held within outer walls of 

rock and inner walls of alluvium and is readily reached 

only at the mouths of White Canyon and Red Canyon. 

On Sage Plain the construction of stock trails from the 

canyon rims to water in the intermittent and ephemeral 

streams presents no particular difficulties, but on the 

plateaus west of Comb Ridge the chief free grazing 

districts stream beds easy of access are usually dry, 

and cattle find water by descending tortuous trails along 

precipitous walls 600 to 1,200 feet high. Once on the 

canyon floor, even in tune of drought, water can usually 

be found in potholes or in "sand pools" where bedrock 

emerges from the alluvial fill. In most of the deep 

canyons during dry months these supplies are spaced at 

distances of a mile or less, but in some the intervening 

distances are 3 to 5 miles, and in lower White Canyon 

nearly 20 miles. The persistently reliable streams are 

the headwater tributaries within the national forests 

about the Abajo Mountains and Elk Ridge and tne rills 

that flow for short distances from such springs as those 

in Johns Canyon, Spring Gulch, Woodenshoe Canyon, 

and Fable Canyon.

Much more surface water could be made available 

for stock by the excavation of small reservoirs and the 

construction of short, low dams along the washes and 

on the plateau tops at some of the many places where 

the topography and rock texture are favorable. The 

usefulness to the stockman of such inexpensive development has been amply demonstrated on the nearby 

Navajo Reservation, where the rainfall, washes, canyons, and exposed rock surfaces are closely similar.85

IRRIGATION

The pioneers in southeastern Utah placed their hopes 

of prosperity on the probability that the waters of the 

San Juan and its tributaries could be used for the irrigation of the extensive terraces and flood plains adjoining those streams. For some years after settlement, 

ditches at Bluff, at the mouths of Cottonwood, Recapture, Montezuma, and McElmo Creeks, and at intermediate sites along the San Juan River supplied cheap 

water for successful crops. But the river proved 

unreliable. With the conversion of brushland and reed 

swamps into agricultural land and the extension of 

grazing on river bluffs, the San Juan, which once maintained a well-defined course, became a destructive 

agent, cutting deeply into its banks, changing its 

channel, and spreading its mud-laden waters over 

farms and pasture lands. The cost and effort of 

maintaining head gates, disposing of silt, and protecting

88 Gregory, H. E., The Navajo country: U. S. Geol. Survey Water-Supply Paper 

380, pp. 102-122, 1916.
ECONOMIC GEOLOGY 115

fields from floods and erosion are proving too great for 

the decreasing population. Fortunately at Bluff the 

water from the intermittently filled ditch is supplemented by that from artesian wells, and at Aneth water 

for irrigating some 40 acres of river flat can be taken 

from McElmo Creek. Irrigation at other places along 

the San Juan has been abandoned.

Irrigation practice at Blanding rests on a solider 

basis. After the great drought of 1896, when no water 

flowed in the San Juan during the irrigation season, and 

the still drier year of 1898-99, attention was given to 

the small but perennial streams flowing from the Abajo 

Mountains. Along the southeast base of the mountains the construction of a few short ditches for individual farms was followed by the development on "White 

Mesa" of an irrigation district that gave rise to the village of Grayson (Blanding). Here the main channels 

and many branches reach about 7,000 acres of irrigable 

land, 3,000 acres of which is partly irrigated and the 

remaining 4,000 acres used for dry farming. The upper 

canal, from Johnson Creek, and the lower canal, from 

Recapture Creek, take all the water from those streams 

during the irrigation season. This is insufficient to 

irrigate all the land available and in many seasons is 

inadequate for the fields under cultivation. To increase 

the supply and especially to insure regularity of flow in 

the ditches now in use, it is proposed to divert the surplus waters of Indian Creek by constructing a tunnel 

through the Abajo Mountains and a trench leading to 

Johnson Creek. By this method it is thought possible 

to obtain 1,600 to 1,800 acre-feet of water at an 

estimated initial cost of about $45 an acre.

At Monticello water for irrigation and part of the 

water for domestic use is obtained from canals heading 

in North Creek and South Creek (Pole Creek), branches 

of Montezuma Creek. About Carlisle the farms and 

ranches are irrigated from Vega Creek. At Verdure 

Verdure Creek supplies water for farms within the 

bordering walls of its valley. For the total area under 

irrigation, listed as 4,500 acres, the water from the 

ditches is usually sufficient during the critical months 

April, May, and June.

Irrigation farming is practiced on a small scale on 

the Indian reservation at Alien Canyon, in the northern 

Alien Canyon country, in lower Cottonwood Canyon, at 

the mouth of Red Canyon, and in some years at a few 

places along Montezuma Creek and other streams on 

Sage Plain. The irrigated ranch at the mouth of Arch 

Canyon is an oasis on the otherwise inhospitable floor 

of Comb Wash.

An ambitious prospect for using the waters of the 

Dolores River to reclaim some 50,000 acres along the 

Utah-Colorado line calls for the construction of a dam 

270 feet high, several miles of ditches, and a tunnel 

4,800 feet long through the low divide separating the 

Dolores and San Juan drainage basins. The estimated 

cost, about $175 an acre, seems prohibitive for this

land of moderate fertility without access to profitable 

markets.

In the San Juan country the conditions for utilization 

of water by irrigation are unfavorable. Most of the 

alluvial flats are narrow, the canyons are deep, the soil 

on the plateau tops is thin, and the supply of water 

.obtainable without prohibitive expense is inadequate. 

With the fullest development of surface water the 

cultivated fields about the Abajo Mountains would be 

green patches in a broad expanse of brush lands. 

Elsewhere they would be dots in many square miles of 

bare-rock surface and canyon floor.

GROUND WATER

In the San Juan country most of the rain water comes 

from short-lived showers and hurries away through 

thousands of ready-made channels, with the result that 

little is imbibed by the rocks. Except on talus slopes 

and highly porous flood plains only a small part (probably less than 5 percent) of the annual precipitation is 

absorbed by soil and rocks, and of this amount much or 

even all may be brought back to the surface by evaporation. A series of field tests showed that heavy showers 

during June, July, and August barely wet the surface 

of the Permian and Triassic shales, soaked into the 

Navajo and Cedar Mesa sandstones about a quarter of 

an inch, and soaked into the gravel and sand of washes 

and canyon floors 2 to 8 inches. At most of the places 

tested this wet zone was dried by evaporation before the 

next shower renewed the supply. It seems that in the 

dry, hot months some rain water becomes ground water 

by descending through open cracks and joints and that 

during periods of melting snow percolation into the rocks 

is general. Nearly all the ground water in the alluvium 

of the flood plains and canyon floors comes directly 

from lateral or vertical percolation of ephemeral and 

intermittent streams.

In this region the terms "ground-water reservoir" and 

"water table", as usually defined, are applicable only to 

the high talus deposits of the Abajo Mountains and the 

rim of Elk Ridge, and less definitely to the gravel 

deposits of the piedmont slopes and the sands of the 

narrow flood plains. In rocks of other kinds the 

saturated areas are discontinuous. For distances of 

miles horizontally and hundreds of feet vertically, 

deep-seated wet rocks are separated by dry rocks, and 

in many areas the ground water remains but a short 

time: it is on the way to the wall of some canyon that is 

cut below its horizon. Most of the water revealed in 

springs and wells occupies relatively thin zones of 

saturated rock between strata that are substantially dry.

SPRINGS

In cutting their deep trenches the hundreds of intermittent and ephemeral streams of the San Juan country have revealed water-bearing beds that in sequence 

and texture favor the emergence of springs. The
116 THE SAN JUAN COUNTRY, SOUTHEASTERN UTAH

Dakota(?), Westwater Canyon, Bluff, Navajo, Wingate, 

Shinarump, and De Chelly sandstones have estimated 

porosities of 6 to 15 percent, and the unconsolidated 

sand and gravel 10 to 40 percent. The water they may 

contain is prevented from passing upward or downward 

by relatively impervious shales, limestones, and mudstones but is free to escape where the edges of the strata 

are exposed in cliffs and canyon walls.

The position of springs is determined by.topography 

and the stratigraphic sequence of beds; their number, 

permanency, and size by the amount of rainfall received 

by the aquifer at nearby or distant places and by the 

effectiveness of evaporation. Thus the most numerous 

permanent springs are at the base of the Shinarump 

cliffs on Elk Eidge, where favorable conditions are provided by heavy snowfall, retarded run-off, a fractured, 

relatively porous aquifer, underlying beds of dense 

sandstone and shale, and a cover of talus that lessens 

evaporation. Similar conditions prevail on the slopes 

of the Abajo Mountains, where water from rain and 

snow accumulates in the thick talus at its contact with 

impervious igneous rock. On Sage Plain the spring 

zone is the contact of the porous Dakota (?) sandstone 

and the watertight Morrison shales. On Red Rock 

Plateau most of the springs emerge at the base of the 

loose-textured Navajo sandstone, where downward 

percolation is arrested by the shales and limestone of the 

Kayenta formation, and at the base of the muchjointed Wingate, which rests on compact Chinle shales. 

On canyon floors and along washes most of the springs 

are at the contact of alluvium and bedrock. For the 

region as a whole these division planes between relatively porous and relatively impervious formations are 

the spring zones, but some springs emerge directly from 

formations that as a whole are watertight: their position is determined by thin beds or lenses of limestone 

or dense sandstone that lie below layers of porous sandstone. Controlled by this arrangement of subordinate 

beds, springs issue from the Hermosa formation along 

the San Juan at the Narrows, at Soda Basin, and 

above the mouth of Slickhorn Gulch; from the Halgaito 

member in Johns Canyon; from the Cedar Mesa 

sandstone at the head of Fish Creek, in Arch Canyon, 

in Fable Canyon, and in Beef Basin; from the Organ 

Rock member at Red House and below the mouth of 

Frey Canyon (Rock Spring); from the Chinle at the 

Clay Hills and at the head of Comb Wash; from the 

Moenkopi at places about Elk Ridge; and from the 

Kayenta in Cedar Canyon, Castle Wash, Moki Canyon, 

and along the Red House Cliffs. Many of the springs 

that issue from these generally impervious formations 

are connected by joint cracks with water-bearing beds 

from which their supply is derived.

In the formations that are generally saturated water 

may find its way to the surface before reaching the impervious layer below. Springs of this sort are numerous in the massive sandstones. In the Navajo and the

Wingate they emerge between cross-bedding laminae 

or at the top of limestone lenses; in the Dakota(?) at 

the contact of conglomerate with green shale or coal. 

Some of these springs yield small perennial supplies, 

but most of them are tiny seeps tucked away in alcoves 

and tunnels high on canyon walls and flow only during 

the night or during cold months. On hot days evaporation removes the water at a surprising rate. A spot 

on a bare wall marked in the daytime only by efflorescence and patches of vegetation may yield at night 

water sufficient for camp needs.

Springs in the San Juan country supply much of the 

water used in homes and part of that needed for stock. 

Monticello derives its domestic supply from strong 

springs in the Abajo Mountains, and Blanding from 

spring-fed streams. Several ranches near Ucolo use 

the water from a spring in Piute Draw, and elsewhere 

on Sage Plain small springs supply the scattered farm 

houses. As a source of water for stock, springs in the 

forested area about the Abajo Mountains and Elk Ridge 

are adequate and conveniently placed, but those in the 

large grazing districts west and south of Elk Ridge are 

widely spaced. Many of them yield small supplies, and 

others are inaccessible. Green Water and Irish Green 

Springs, in upper Castle Wash, and Home Spring, in 

Beef Basin, are fortunately placed in broad expanses of 

unwatered country, and the strong springs in Johns 

Canyon and lower Castle Wash may be reached by 

roundabout trails cut hi canyon walls. It has been 

found impracticable to make use of the water that 

emerges in Clay Creek, Alcove Creek, and Wilson Creek 

and at the box heads of several other short, deep canyons tributary to the San Juan and the Colorado. Rock 

Spring, which makes possible the traverse of White 

Canyon in the dry season, provides enough water for 

about three horses. The other horses in the pack train 

must wait 20 to 30 minutes until the supply is renewed. 

In general the springs on the grazing lands merely serve 

to supplement the supply accessible in canyons and 

water pockets. When these surface supplies fail, the 

cattle drift to high lands where water is available. It 

is entirely possible to increase the yield of the springs 

in use and to develop new springs by methods adopted 

on the Navajo Reservation, where the controUing conditions are similar.

WELLS

In the San Juan country little attention has been 

given to the construction of wells; water for household 

use, for irrigation, and for livestock is derived almost 

entirely from surface water. The well at the Indian 

agency at Alien Canyon is representative of the few wells 

sunk in unconsolidated sediments that border the 

larger washes, and the shallow dug wells at Monticello 

and eastward on Sage Plain demonstrate the feasibility 

of obtaining small amounts of good water from the 

piedmont gravel deposits extending outward from the 

Abajo Mountains. Along the Monticello-Cortez road
ECONOMIC GEOLOGY 117

a few wells obtain water of good quality from the 

Dakota (?) sandstone.

The artesian wells at Bluff are the source of water 

much needed to replace that from shallow d,ug wells, 

weak springs, and the San Juan River. Drilling was 

recommended here because the region is structurally 

a basin (Sage Plain downwarp, Gothic Mesa syncline) 

toward which dip the water-bearing Navajo, Wingate, 

and Shinarump sandstones, each bordered above and 

below by relatively impervious strata. Two of the 

six flowing wells start in alluvium; the others in beds 

of the San Rafael group (Carmel (?) and Entrada 

formations). Four of them obtain most of their water 

from the Wingate or the base of the Navajo sandstone 

at depths of about 800 feet. The two other wells, 

reported as 1,085 and 1,165 feet deep (one informant 

gives 1,325 feet), probably tap water also in the Shinarump conglomerate. The flow of the first successful 

well tested in 1909 was 80 gallons a minute. Unfortunately the wells have been permitted to flow freely

even when the water was not needed, with the result 

that increasingly smaUer yields are recorded. At the 

present time the flowing wells at Bluff provide all the 

water for domestic use and for irrigating about 70 

acres of gardens, orchards, and hay fields. One well 

flowing about 30 gallons a minute has been left standing 

in the channel of the San Juan River by erosion of 

alluvial banks.

Between the San Juan River and Blanding and eastward across Sage Plain the conditions that permit the 

development of artesian wells are similar to those at 

Bluff, but the strata above the aquifers are thicker. 

At Boulder Knoll an oil well encountered water in the 

"Chinle" [probably Shinarump] at a depth of 2,640 

feet. At Blanding a well drilled to a depth of 1,100 

feet, most of it in Morrison shales and sandstones, 

found water at the base of the Dakota (?) sandstone 

at a depth of 800 feet. At the experiment station east 

of Monticello a well drilled in 1925 to a depth- of 405 

feet reached water at horizons between 215 and 230 feet.

INDEX

Page

Abajo Mountains, altitude of.. _._.. . 8 

geologic and topographic map of . pi. 17 

mineral deposits of......... . 107,108-110

petrography of . 79-84 

scenic interest of.. - -- 9 

springs on. 116 

streams flowing from..... > . 8

structure of.. ... .. 89-91,pi. 17 

vegetation of_ 8 

views of... . ...._ ._.... pis. 2, A, B, 18> JB

Abajo Peak, rocks of._____ ,. . 83,90 

Acknowledgments______ 3 

Aggradation cycle, evidences of 101 

Agriculture, climate in relation to.. . 19-20 

early-.. -- - - 7,21,30

land suitable for. .- ' 21,34-35

statistics of________ ...__... 35

water available for____ ..________ . 113-117

Alien Canyon country, description of 11

irrigation in.. ' 115

vegetation of__________________________ _.__ 11

view in___.___________ .___._____________ pi. 13, C

Alluvial terraces, origin and character of. 101-102

Alma mine __._____.____________ . __..... 109

Altitude of the area___________________ ___._.____ 6 

Andesite, occurrence of________________ ___.. 81-84 

Aneth, climatic conditions at_____________-----________.. 15-21

Irrigation at ......__.. . 115

Angel Arch, origin and features of ._______ ........ 105

Animal life of the area____ ._________ ___.. 26-27 

Arch Canyon, erosion features in .. 105, pis. 23, (7,24 

irrigation in ... . . . . ... 115 

sections along..._______._______.__ 66-67,72-73 

structure In____________.________ ___.____ 89 

views in...__..____............ .. .. pis. 11, C, 16, B, 23, C, 24

Arches, natural, formation of______________ - 105, pis. 23, A, C, 24 

Arcola Oil Co., well of__________________......___i___ 112

Armstrong Canyon, views in.. ...___ pis. 5, B, 9, D, 19, B 

Artesian wells.. __..._ ...___.. 117

B

Balanced Rock anticline, description of.______ ... __ 88

view of.____________.._____..__ ._________ pi. 18, C

Basket Makers, areas settled by_______________-_______-- 27-28

culture of. . 28

Bears Ears, section at_.___________________________ 73

view of. .. . . pi. 4, A

Bears Ears Plateau, use of name .... 10

Beaver anticline, location of.. . .... . 88

Beef Basin, general features of.... _.___ 15

oil possibilities in 111

structural relations of. . 89 

Bell Butte dike, rock forming.. . 79-80 

Birds of the area..______ . . 27 

Black Mesa, view of west face of....._......___ ___ pi. 13, D

Blanding, climatic conditions at. . ... 15-21 

establishment of settlement at . . .. 33 

Irrigation at.. . 115 

population of_ ..... . __ 34

Blue Dike mine.... . . .._ ..... 107

Bluff, climatic conditions at... __ __-_____ 15-21 

establishment of settlement at.. _-_ _________ 33 

Irrigation at.._______ . . .._.. _._______ 115 

placer mining near_____-___._______-__________ 33-34,108 

population of _________________________________. 34 

section at , 74 

Bluff sandstone, description of . 58 

rock shelters In . . . 106, pis. 25, D, 26, A 

section of _.______ _____ .. .......___ 76

topographic features of.__ __._______ ___.... 96

view of.___.________..__________....__ ..__.. pi. 3, C

Page 

Boulder Knoll, oil well at._.._______.__----- - _.__ 111

Bridges, natural, formation of__.___________ __ 103-104, pi. 22

natural, views of. . . ...- pis. 19, B, 20, B, 21

Brushy Basin, section in.... . . 77

view in_________________________ ~ pi. 14, C

Brushy Basin shale, description of . 59

sections of______________________ . .._.__ 76,77

views of......___.__________-___ .... pis. 13, D, 14, C

Bryce No. 1 well 113

Bryce No. 2 well.-.......--..-..-....-. - 113

Bulldog Canyon, section in___ ..___ _. 78

Butler Wash, cliff dwelling in...___... . . pi. 8, B

Navajo summer house near mouth of. pi. 9, A

sections along ..._._ ..-.. .. - . 75,76-77 

view of valley of . pi. 18, A

Canyons, down-cutting of...__ 98 

fill in..--.---.-. _ 101-102, pi. 20, A

general form of. ..__._ 97-98 

natural bridges In . .103-105, pis. 19, B, 20, B, 21, 22

sediments deposited in____._ . ...._.... 100-102, pi. 20, A

terraces in._ _ _____________.___ . 100-102 

Carboniferous formations, correlation of. :. . . . 37-40 

Carlisle, irrigation at ......... . .. . . ... 115

Carmel (?) formation, description of. 56-57

sections of.__________ . 74-76

Castle Wash, features of __ _. 14

view of wall of---.-..-.-. pi. 13, B

Cataract Canyon, view in __ i...... . : . .... pi. 5, A

Cathedral Arch, origin and features of_________.___ 105, pis. 23, C, 24, A

Cedar Mesa sandstone, cliff dwellings in_,____... 106, pis. 8, C, 25, A-C, 26, B

contact of Halgalto member and 42-43

contact of Organ Rock member and.._______ _________ 45-46

description of .... . 43-45

sections of..---..__.___ ._ 67-68,69-70

stratigraphic relations of 1 ..__. ..___. 44-46

topographic features of. . 96,97

views of . pis. 5, B, 6, A, 8, C, 9, C, D, 11, 20, B, 21, 23, B, C

Chimney Park, use of name_ _____... 11

Chinle formation, description of..-. __.___._ -...__ 49-50

oil showing in..__________________ . _______ 111

sections of.__..... . ....... .... . 71,72,73

views of.______________________ pis. 4, A, 6 B, D, 12, D, 13, A 

Church of Latter Day Saints, colonization by....__ ..__ 31-33

Clay Hills, views of.._____ ..___...__........... pis. 6, B, 12, B, D

Clay Hills Pass, section at.__.__ ....__.______._________ 73

section of cliffs north of ___ ______ __________. 70-71

view of entrance to_____ . _______ _.._____ pi. 12, B

Cliff caves, sites of.________________________________ 106

views of ................... . . .. . pis. 8, B, C, 25, 26

Cliff Dwellers, culture of..___.__.__.__...... . ..._______ 28-29

houses of._____________.__i___________ 28,106, pis. 8, 25, 26 

sites occupied by ..___..... __ . 27-29,106

Climate of the area_______ _________.__________ 15-21

erosion influenced by ____________________________ 94-95

Coal, analyses of_________________________________ 111

occurrence and quality of__ _._ ....______ 110-111

Coal Bed Canyon, coal in...___._._._____.____________ 110 

Cobalt, occurrence of. ______________________________ 107 

Coffin, R. C., quoted....__....__.............__...._______.___ 60

Collins, section in Grand Gulch near..____________________ 69-70

Colorado Plateaus province, previous surveys of._______________ 1-3 

Columnar sections____________________ ___________ pis. 10,15 

Comb monocline, description of....___..__________________ 86

views of.......__ ...... ...___..._____...__.. pis. 16, B, 19, A

Comb Ridge, structural relations of.______________________. 86

views of.______________________________ pis. W,B,19,A

Comb Wash, section at head of._______________________: 70

views of.... .... -- ..._.............. pis. 16, B, 19, A, 20, A

Copper, occurrence of.._________________._________ 107-108 

Copper Queen mine._____________________________,.. 107

119
120 INDEX

Page 

Correlation of formations, Carboniferous...._._..__._..______.. 37-40

Jurassic..____ __ __.__________________ 51-53,pi. 15

Cottonwood Canyon, features of.________________________ 11

irrigation in...______..____..____...___..._....____ 115

section in...-. ...________________________ 77-78 

Cottonwood Wash, view near mouth of......_______________ pi. 14, A

Crepo mine, section in_"..______..._____.......__...__.. 110

Cretaceous formations, description of.______________________ 60-63 

sections of.. __.__________._________________ 78 

Crops raised in the area________________ _____________ 21,35 

Crossing No. 1 well_____1________________________ ___ 111, 112 

Cutler formation, correlation of.-..'.....____..___ T ______.-.. .... 38-39

description of.___....-___.._ ___..______..._....._.. 41-47

sections of....____....____________________..._.. 64-73

terminology of._____________________________ 41-42

Cycles of erosion.... . ._..._________.___ ______ 92-94

Dacite, occurrence of..._._____________________________ 81,83 

Dakota (?) sandstone, coa! in.___________________.__.... 110-111

contact of Morrison formation and__________^_________ 60

lithologic features of.. ___-.________________________ 61 

sections of.. .......... ....___...-.-.-....___.63,78

stratigraphy and correlation of__..--..__.__.___....._.___ 61-62

topographic expression of... ' ..__ __... 60-61 

Dandy Crossing, location of...__...._____-.____________ 13

Dark Canyon, features of___...__________..________.... 10,12-13

fossils from.._.__.___...._._._._________________ 66

section in ........ . ..__...... .. .. 66

Dark Canyon Plateau, features of...______________________ 12-13 

De Chelly sandstone, occurrence and character of.______------ 46-47, pi. 12, C

section of...______---..-.________________....___ 68

Decker ranch, section at .. ________ .... 77-78

Denudation, rate of______.-.._____________________.___ 98-99 

Deposition, rate of, in canyons ...........__.___......___... 101

Dixon Gulch, prospecting along........_......_.......__.... _.___ 109

Dolly Varden mine___.__.._______._.__._ ..___..._...._...__ 107

JDolores River, proposed irrigation from___________....._.__.... 115

Drainage system of the area, general features of_____.___--..-..... 6

possible age of..____...---_______________._______ 94- 

Dream mine, development at_______._.._.-._..._---........ 109-110

rock at...___._:_____________.________________ 80-84

Drought of 1896 in the area_______...__________________ 19

Dry farming in the area..._____.________.____________ 21,34-35

Dry Wash (Alien Canyon country), features of____________.. 11, pi. 13, C

section in__________......_...._..._.___.......___ 75

Dry Wash (branch of Fish Creek), section in.__.._..._..._...___ 69 

Duckett mine, development at....-...-__........__..___.....__ 109

rock at...________.____............._..__..........____ 84

Duckett Ridge, rocks of..____._______________________ 90

E 

Eastwood, Alice, plants collected by_-----------------_.......----___ 25-26

Economic geology of the area. __..._...______________.___ 107-117

Elk Ridge, description of._.____________._____.______ 9-10

drilling for oil on__.___._______.._________. ______ ill

sections on____________..____._______________ 73

springs on.____......_._..._..._..._..._.........___ 116

structure of.__-----------------_.._------__..__.._...__ 87,89

vegetation of...__-----------_....__..__..__..__..____ 10,23-24

Enterprise mine.__--.-.....__.._____.__..._..._..____ 109

Entrada sandstone, description of.____________.__________ 57 

sections of.-..-.__.................................._________ 74,75

views of......................................................... pis. 13, C,14,B

Erosion, base-level of._______._______________________ 98 

by ground water___. ___. ______________. _________ 96,106 

cycles of___________.______________.____ 92-94,100-101 

factors influencing__....__.......____..__......._..__.. 94-96

forms produced by, general features of.._____------------_____ 92,99

"goblet," view of.-.-.. _____________________ pi. 14,1? 

natural bridges............................... 103-104, pis. 19, B, 20, B, 21,22

plateaus and mesas___. ________________________ 100 

rock shelters.___..:___________.__ 28-29,106, pis. 8,B, C, 25,26 

terraces_ ......................................................... 100-102

valleys....___-----------_..---.----....._..__..--------.--. 97-98

windows and arches...__._.____________-:.. 105, pis. 23, A, C, 24 

present conditions of...:______.____________'__...._____.. 6

rate of._____._____.__.-..........-.__.__ _-.- ...........

Escalante, Juan,- route followed by___..:..-.....:...';.....1.1..._____ 2

Exploration in southeastern Utah.___...j..-__. ---- .::.__:. .:...-__._ 1-2

F

Page

Fable Valley, cliff dwellings in.._________________._____ pi. 26, B 

Farming in the area, by early inhabitants of__________________ 7,21,30 

general features of..._______________________________ 34-35 

in Alien Canyon country_______.____________________ 11,115 

on Sage Plain________________________________ 7,8,115 

relation of climate to__-...-___------------__..___.......... 19-20

soil suitable for.._.._.__..-----.__.___..______......__ 21

water for....... .........................................__ 114-115,116-117

Faults in the area________ ______________ 89,91

Fauna of the area_________ -.-.-..-..__________________ 26-27

Fish Creek, oil possibilities near_____________.___________ ill

 section in Dry Wash branch of...---------- ..--____......____ 69

structure along... _..__ .. ..---....-.__________ 89

Fishmouth Cave, view of.....__________________________ pi. 23, A

Flora of the area____.__......_.___--..-...._________.... 22-26

Frey Cabin claim.......__ ....^.............................__....._.... 107

Frost, erosion effected by action of- ..._________ 95

G 

Geography of the area....____ ....__.______ 5-35

names used by early explorers.-------. ... ...--. 2

Geologic maps and sections.------ -- .------.-..-.... .. ------ pis. 1, 17

Gerald Hughes No. 1 Elk Ridge well....--.----.-.-.----.--....-....-..:'..... Ill

Gilmore, C. W., quoted_____________________________.._ 59 

Girty, G. H., fossils determined by_______________________ 66 

Glaeiation, lack of evidence of...... ....: ......___.._______.- 64

Glen Canyon, features of___----__-..-_v _..__..___.-.. 15, pi. 7, A-C

goldin................................................................^... 108

Glen Canyon group, correlation of. ...______ . .'51-5^, pi. 15

description of.___...__-..- ....___------_.- . 54-56

general features of...___ .__......__...__.....--_----- -------- 53

views of...... ...... .....-... . pis. 3, B, 4, A, 6, C, D, 7, A, C, 13, A, B

Goblet of Venus, view of...__-------___....____....__. pi. 14, B

Gold, in Abajo Mountains___.____________________.___ 108-110

in river placers..._______------__......._-..-__.-____ 108

Gold ore, character of._.......-..-----.-.-..-...-.-...........-..... 83,84,109-110

Gold Queen mine, operations at.... . ...... ------ 109

rock at...._....................-...-.-.---.--...--..----....._------- 80,82

Goodridge, E. L., exploration and prospecting by...__.-.-_ .. 2,108, 111 

Goodridge formation, name discarded __-------------__-__ . 39

section measured as_____..-.-...-..___......._.___....---- 64-65

Goodridge oil field, drilling in...-____.__.--_-.._.__..--_.._.___..____-_-_----. Ill

Goodridge sand, occurrence of oil in______..-.--__.._____.._. 112,113 

Grand Gulch, erosion features in. -------------- ... .. .. 105

sections along___________________________________69-70, 73 

Grand Gulch Plateau, description of...__--.-.-..... .... 11-12

oil claims on__________-......-_'.............;...____..... Ill

Grasses, lists of species______... _ -. . --...._ . .. 24-26

Gravel, occurrence and character of._._________________ 63-64,100-101 

Gravel terraces, relative height.of. ............L.......................... 100-101

Gray Mesa, use of name.____._.___..................___..__. 14

Grayson. See Blanding.

Ground water in the area.:____..--.--------.-..----._....____.- 115-117

erosion by.--_.......^.....^........................................... 96,106

Gundlock Creek, use of name..-.. -:.---:------ ....................... 11

Gunnison formation, use of namei.-.. .... ...... -------- 51

H

Halgaito member of Cutler formation, contact of Cedar Mesa sandstone"and.- 42-43 

description of___..._-. -'.--'------....... ^............__..__-.-. 42

sections of._________'...'..'...'............_________ 66-67,68-69

topographic features of...'.'..'.'.'................'......................'...... 96,97

views of_.__.__.--_--.-._-.._';;..___..-......-'..... pis. 4, B, C, 9, C, 11, A, B

Halgaito Spring, well at................-....-.......--.--..-...-..--.-..---.. 112

Hammond Canyon, features of..____'......................'............... 11

Harshberger claims.-____'.'.'.'.'.'_'..'_'..'.....___.1..'.................. 108

Hayden, F. V., map of Colorado issued by..._____1__________ 2 

Herbaceous plants, lists of species of._______'........................... 24-26

Hermosa formation, description of_'...'.'.'.....'..'....'.'........................ 40

oil in.......................-............:..-.;- .:....-... . 111,113

section of_______.___ __________ . .. 65 

views of..________.__.__-.___-.'-.--.....__ pis. 5, A, 11, A

Hite, Cass, discovery of gold by..........__._-------- .. 108

Hite, climatic conditions at_'.'..............______...... . ,15-21

location of._______.__.._______.. ........__.. 13

view across canyon at....._...'...."...'_'_____________.. pi. 7, B

Hole in the Rock Road, view along...'.. ."___.'...'_.....____...--- pi. 6, B

Holman, P., maps by_'.'.'.........:---. .. ...--..................... 2, 5
INDEX 121

Page 

Holmes, W. H., exploration by..__ .. 2.

Honaker trail, section at______..___ - 64-65

Hornblende andesite, occurrence of__.._ . .. --- 80-81 

Hornblende latite, occurrence of._.____ . . . 80 

Hornstone, occurrence of....._._____.- -.-.--.-.--...-.-.. .. 83

Horsehead Peak, rocks of_............................................... 81,82,90

Hoskinnini tongue of Cutler formation, occurrence of. . . 46 

Hovenweep National Monument, cliff house in.................-.--..... pi. 8, A

Hudson well_________________-.-_-------- .... 113

Hulkito. See Halgaito.

I

Igneous rocks, regional relations of 79

Illinois mine._____.__.__................-.-.........--.--. ....... 110

Indian Creek, proposed diversion from..-._--------------------------- -.. 115

Indians, number of, in the area__.._.... ----------------------.. 34

Industries of the area.....___....-_-..-.-.. .....-------------.--- 34-35

Inhabitants of the area, Basket Makers and Cliff Dwellers_____ 27-29

Piute, Ute, and Navajo Indians......... . ... ........ ... ... 29-31

white settlers.....-......................-------.--------------- . 31-35

Innis mine, rock at.._...._.................-.-.-.-....--.---..-. ..-. 84

Innis' sawmill, rocks near___.............-----.-.----------..- ......... 91

Iron, occurrence of.__...------------------.------------.------ ------- 107

Irrigation, general features of__- .- -- ------- --.---.------. 8,35

water for_____ 114-115.

Jackson, W. H., exploration by_.__._........-.------- 2

quoted- ______ - - - . _ 9

Jackson, Camp, goldminingat.. --..... 109

Jackson Divide, tocks of._..._._____ -... ..'. 84,90 

Johns Canyon, oil seeps in_.................--.--.-.- --------- .. 112,113

sectionin................................. - - -..--..... . 68-69

views in............................................... ........ pi. 9, C, l\,A

Johnson Croek, gold placers on.------- -.--.... .. 108,109

irrigation from.............._ _.--..----------..---.. 35,115

rock along....___.. ________........ . 81,84

Jurassic formations, correlation of___..__. . 51-53, pi. 15 

description of._______._____._... ... - 53-60 

general features of..... .... - 50-51

major divisions of.. _ _.......'. __.. 63-54

sections of._..______..__.___ - . 74-78

K

Kachina Bridge, origin and features of_____._________ 103,104, pis. 21,22, B 

section southwest of.....__.._.._.....---.-_-----------------__ 71

Kayenta formation, occurrence and character of_...... . 54-55

Keystone Arch, origin and features of.. 105,pl. 24, B

Laccoliths composing Abajo Mountains.______ ... .....__. 89-90

Lacustrine deposits, occurrence and character of.------------ ... 64

Lake Cany on, features of______________....__._».__ ___ 14

Landslides, conditions favorable for producing__..--.....- ........... 102-103

La Plata formation, use of name.---.-.--._.._..._....---.--__..__.. 51-53

LaRue,E.C.,surveyby.... ._..- --.-.--.. ........... 2-3

La Sal, population of_______________......___.__________ 34

Lava, nature of rocks locally known as______-_______:_______ 79 

Lime, resources of._.___ .__...___ _..__ 107

Lime Creek Valley, description of_._____________________ 12 

oil wells in............. 27,112-113

vegetation of.______________________._____.. 12, pi. 4, C 

views in_'. ____.._..........____..--...-__..._.. pis. 4, B, C

Lithology, influence of, on topography._.. . ..... 92,96,97-98

Location of the area______..___................................__.. 5

Log Cabin claim, gold ore from__________.___._____._.. 83-84,109 

London-San Juan Oil Co., drilling by...._. .-... ..-......---. .... 112

Long Point, section at_______________...__._.____.__... 73 

Loper, Bert, exploration by_______________.________.____ 2

M

Macomb, J. N., exploration by...___----.---------..-_ _-.._..__ 2

Malpais, nature of rock known as_____...-......... -_ .. _;. 79'

Mancos shale, occurrence and character of..__________________ 62-63 

sections of.__________________________________ 78 

topographic expression of._______..___............__..____ 60

Manganese, occurrence of_____________________________ 107 

Maps of the area, notes on_______. __ ___.. ____ _ __.. ___ 2,5-6 

Marl in Clay Hills, view of....____....__..................__..... pi. 12, D

McElmo Creek, irrigation from_________________________'...' 115 

McElmo formation, use of name____ *_________ - ______. __ 51-53 

Meanders, development of__________ ___........___..___.. 97-98

natural bridges formed by undercutting of _.._.......__..__ 103-105

Mendenhall, W. E., exploration by_______________________ 2 

Mexican Hat, view of........_..__.._..._._..___..____.. pi. 4, B

Mexican Hat Co.. well of.......... ....................................... 112,113

Mexican Hat syncline, features of. 

oil in... . 

Page

 86

 88,113

Minerals of the area... ________ , ________ . ___ . ____ .. 27, 107-117 

Miser, H. D., section on San Juan oil field by.-.-----------------------.. 111-113

Mitten Butte anticline, description of..... _ ...- . __ .. 86,88

oil in.. ........ ...................... 113

Moenkopi formation, description of _ .......-.....----------.-------- __ .. 47-48

sectionsof...-.....-......- .-----. --------- --- - -- 67,70-73

topographic features of. _ _ _______ _ ___ .. 96,97

views of _ . ____ . _ -........-.....-.......-.. ... ..-.-..-- pi. 12, B, C

Moki Canyon, features of __ -.-------.-................-----..-.---... 14, pi. 6, C

Montezuma Creek, irrigation from.... . . .... _ . 35,115

Monticello, climatic conditions at ___ .. _ ------ __ .. _ _____ __ . _ 15-21

drilling for oil near _ _ _ ........ __ ----------------- __ ____ __ 111

irrigation at. . - __ 115 

population of ... . __ . ____ .. 34

Monticellowell.. -.-- -- 113

Monument upwarp, description of . .. . ... ... . __________ 85-89

oil in.... - .. . . 88

section through... _. _ ....... .. ...... pi. 1

views of.... _ . _ ......................................... _ .... . pi. 16,5, C

Monumental Oil Co., drilling by. __ ______________________ . 112 

Mormon colonization in the area __ -.--.------. ................... __ .. 31-33

Morrison-Dakota (?) contact. ------- - .. ..- __ _.'__ __ .. 60

Morrison formation, description of. . . .:. 58-59 

general features of ... . . _ T ...._ 54,58

rock shelters in............ .-.-----.. .. .. ......... 106, pis. 25, D, 26, A

sections of.. _ . ------- _____ . _________ 74,76-78

topographic features of. ________ . ________ . _________ . 96,97 

views of..... ------ - ------ - --- pis. 3, C, 13, D, 14, C, 16, A

Mount Linnaeus, rocks of... _ .. ------- ... _ _ ___ .. 81,90

N

Names of geographic features used by early explorers --...- _ -.- 2

Natural bridges, formation of.. _____________ . _____ .. 103-104, pi. 22

views of. ___________________________ _ . pis. 19, B, 20, B, 21

Natural Bridges National Monument, establishment of. ____ ______ 104

Navajo Indians, areas occupied by __ __ __ -------------- __ .. __ .. 9,29-30

dwellings of.... . .. . .-... _ _ . 30, pi. 9, A

Navajo Mountain anticline, location of. _____ . _ . ____________ 88 

.Navajo sandstone, cliff dwellings in.. ___ .................... __ .... 106, pi. 8, B

description of _____________ . _ .......------- __ ... _______ 55-56

topographic features of __ ... ______ ..... 96,97

views of _____ ......... . ......... pis. 6, C, 7, A, C, 8, B, 13, B, 23, A

water from.. __ .. .... __________ __ .. 117

Navajo Springs, section on Raplee anticline near ________________ 67-68 

Nephi claim, gold reported from _________________________ 108 

Newberry, J. S., geologic reconnaissance by _ _ . _ .... ___ 2

quoted..... . ___ _________ ... _ ...--.----....... _ __ __ .. ' 7

North Canyon, mines and prospects in.. _ ....... _ ..... _ __ __ _ _ 107, 110

rocksin..... . - ... 82-83, 84-,'91

North Creek, rock at head of.. __________________________ 82 

North Peak, rocks of... _____________ .. _________________ 81,90

: O

Occupations in the area _ . _ ....... _ __ __ .. __ .. __ __ __ _____ 34-35

Oil, distribution of...... . .....................-.......... __ ..... 111-112

exploration for, difficulties of _ ..................... _ __ __ __ .. 113

geologic occurrence of __ .. __ .-.---.-. _ ................. _ ...... __ 113

wells drilled for... .. .............. _ .........-............... ..:. 111,112-113

Oljeto syncline, features of _ .:..... .... .. ... ... .... .......... ........ j. ...... 88

Olson, 0. F., plants collected by __ ............... -^ ... .... .... ... '. .... . ... 23-25

Organ Bock anticline, description of. _ _ __ . '. - _ .... __ 88

Organ Rock member of Cutler formation, contact of Cedar Mesa sandstone and. 45-46 

description of. ___________________________________ 46 

sections of. ___________________________________ 67,68,70-73 

views of.... _____ _______________ . ________ pi. 9, B, 12, A,B

Orthoclase, occurrence of.... _ . _ ._ ._ __ _ ....... ___ __ .. __ .. 80

Owachomo Bridge, origin and features of.. ________________ 104, pi. 19, B

Peat, occurrence of in Lake Canyon..____________.._._____ 64

Pendergraff mine, section in___________-.________.______ 110

Pennsylvanian formation, description of.._ . . ___._ .___..__ 40

section of____.._..__..___....__ -_- ___ 65

views of..____________________-.___________ pis. 3, A, 5, A

Permian formations, correlation of___________._...__________ 38-40

description of.___...-.________-..-.__._.____________ 40-47

sectionsof.____________________ ..-.-._____ __._.__ 64-73

Permian fossils.. ...__.______.__ ___-._...........________.' 66

Physiography of the area._________._________ '........ '_ ........ 92-106

Piute Basin, use of name..________.. ..__..._........_...._.. 11

Piute Draw, sections of coal beds at_.__..___._._____......_. 110

Piute Indians, culture of_____________..__.._____._...... 30

early history of.___..________......._.____._._.... 9,29-30

present status of________________........_................ 30-31
122 INDEX

Page

Piute Park, use of name ___ . ________ _________________ 11 

Plagioclase, occurrence of ____ . ________________________ 80 

Population of the area. ___ __ . ___ ., _ .. ___ ______ 34

Posada, Fray Alonzo de, exploration by....... __ __ . ___ .. _____ __ 2

Power, possibilities for development of _____________ '. ..... 114

Precipitation in the area, distribution of....... ______ . _________ 18-20

erosion in relation to _ . ___ . ___ __ __ __ ___ 94

rapid evaporation of. _ _ ---------- ___________ __ ...- __ __ 115

records of _ -..-.. . .. ________________ . 16-18

Q

Quaternary formations, occurrence and character of. _______________ 63-64

Radium, search for. ______ .. _______________________ 27 

Rainfall in the area, distribution of. __ _________________ 18-20 

erosion in relation to.^ .. .. __ ..-.-. ____ .- ____ 94 

records of .- .. 16-18 

Rapid syncline, location of _ .. .... ... ___ .. ____ __ ___ __ 88 

Raplee anticline, description of. .... __ .. _ 86 

oil in.......... ............... I.. ...........-.-..-..................... 88

section on east flank of ____ ... . ..... .'r _ .. __________ 67-68

views of. _____ . _____ .- __ .-- ____________ pis. 4, B, 16, D 

Rasmussen mine, section in __ .. .. . ... __ -. _ .... 110

Rasp trail, section at.... ____ ..... _ ..-. __ ___ ____ 72

view on. ________ _ .. __ ________ -. __ _ .- pi. 12, C

Recapture Canyon, fault forming wall of _ __ ... _ ..-. 91

Recapture Creek, gold on __ ______________ 83-84,109

irrigation from ________ - _ .. ... ________________ 35, 115

sections along.. . .. 76, 78

view on __ .. ... __ .... __ . pi. 16, A

Recapture shale, description of.-. ... _ ... ... __________ 58

sections of. ___________ - __ ... ___ _________ 76,77,78 

Red Canyon, view of divide between White Canyon and. ________ pi. 13, A 

Red Cone Spring, view at _ -... .............. .... ... ....... ____ __ .... pi. 6, C

Red House Cliffs, views of... .... .. ....... ...... ..... -. .. pi. 6, B, 9, B

Red Rock Plateau, description of. ....... _...._..---__ .... 13-14

views on ______ __ __ .. _ .. .... _______ ____ pi. 6, C, D

Reservoir Canyon, drilling for oil in .. ._ . 111

Rhyolite, occurrence of.. -.. ..-. 82,83

Rico formation, correlation of..r : _ . 39

description of ____ -.. ___ ... __ .... 40-41

oil in... ....... .....-.....-...... .. ... . ....... ......... .. 111,113

sections of ______ .......... .......... ___ - ... ______ . 64-65,66

topographic features of. .. . . 96

views of......... pis. 3, A, 11, A, 16, -D

Rivera, Don Juan Maria de, exploration by .. 2 

Road Canyon, view in.. .. pi; 11, B 

Roads in the area _ ..... . 3-5

Rock shelters.. .- 28-29, 106, pis. 8, B, C, 25, 26

Rock Spring, supply of water from. ........... __ ... _ __ . 118

Rock Springs, section at _____ - __ __ ___ ... _ 71-72 

Rock tanks, water supply from . 114 

Run-off, erosion influenced by i 1 94-95 

Rustlers Flat, use of name. . 14

Sage Plain, description of____ ...._..______.____ _ 7-8

irrigation on 7,115

oil claims on. __._.. . .. .. . Ill

vegetation of... . . - . - . 7-8, pi. 2, A

view of part of. __... _ ...__ pi. 2, A

Sage Plain downwarp, description of. _ . 85

Sand, in valley fill 64, 101-102, pi. 20, A

wind-blown....._..___.. -_-___._.._.__-______...... 63,106

San Juan oil field, development of . ___ .-.- 111-113 

San Juan River, canyons of. _... -----__ ... 97, 98-99, pi. 3, A, B

cliff dwellings along 28,106, pis. 8, B, 25, D, 26, A

flow of.______._.'......._.._ ._------__ . . 114

general features of.._ - 9 

gold placers on_.____ 108 

igneous rocks along______ . 79 

irrigation along. .. - ... 114-115

load carried by.....____.__..-.- .._ .... .. 99,102

oil field near..-- .. - . 111-113

power possibilities of_ . . 114 

previous surveys of.__ . 1-3

section at Honaker trail on. _. .. 64-65

springs along,. . . 116 

terraces along... .......... 100-102

vegetation along, list of species_ .. . 25-26 

views along pis. 2, C, 3, 7, A, 8, B, 25, D, 26, A

Page

San Rafael group, correlation of______________________ 51-53, pi. 15 

description of____________________________________ 56-58 

distribution of___________________________________ 56 

general features of..-.__..________________....__...... t>3-54

sections of.______.____________________________ 74-76 

Sedimentary rocks, columnar sections of__________________ pis. 10,15 

descriptions of________________________________ 37-64 

general stratigraphic relations of. ..._________ ______ 36-37 

sections of-----...... ... . .__.___.._.. 36-37,64-78, pis. 10,15

Settlement of the area, history of. _______________________.. 31-34

Shay Mountain, structure of___________________________ 90

Shinammp conglomerate, description of.._____________.'___»____ 48-49

sections of........._... ...... ..____.....___......_ 71,72,73

topographic features of .. ......___....._....__ 96

waterfrom._______.__________________________ 117 

Shrubs, lists of species of_____________________._______ 23-26 

Sipapu Bridge, origin and features of _________ 103,104, pis. 20, B, 22, A, 23, B 

Slickhorn Gulch, oil well at mouth of_________ _____________ 113 

Soil in the area._'........................................................... 21

South Peak, rocks of._. . ... .......... ...___..--.-... 80,81-82,90

Spanish mine, reports of-.___.._.____..__.__________--.. 109

Spring Gulch, location of._______...___________________ 14

Spring syncline, location of.._______.____.________._______ 88

Springs in the area_____________________. _________ 115-116

Star Springs, view of cliff near_________________._______ pi. 12, A

Stock raising in the area.__.._-.__.._..._______.._____.._ 35,114

Stratigraphy, descriptions of formations...____________..___-... 37-64

general relations of__...__________________________ 36-37

influence of, upon topography.... .. ___ 96,97

sections showing__ . .. .__... ____ 36-37,64-78, pis. 10,15 

Streams, courses of, in relation to structure..________._..______ 96-97 

debris transported by__. _____. ________: ___ 95,98-99,101-102 

from Abajo Mountains...-._.- ___.-______..____.. 8 

general features of... ... 6 

gradient of......._---....._.-.......,___......___.......-- . 95,98

meanders of...___._-------____________.__. _____ 97-98

run-off of. .. . .._---------_..----..__----- 94-95

valleys of, form of. _.__ 97-98

Structure in the area__________________________ 85-91, pis. 1,17 

streams in relation to.-..-________________------___.. 96-97

Summerville (?) formation, occurrence and character of,_____-. 57-58, pi. 14, A 

sections of.._______.._____.______________ _.. 74-75

T 

Tables of the Sun, location of______________,-.._ ___.... 13

Talus in the area, features of '........................................... 63

formation of-____ _____-_________.__ _ 95 

Tank Mesa, section on south face of..______________ ..__ 74 

Temperature in the area, records of______________.....___. 20-21

run-off influenced by...___..._____________. __ 94-95 

Terraces, origin and features of..._... _._ __ 100-102 

Tertiary formations, probable occurrence of, in San Juan country ... 63 

Thorpe, M. R., field-work by.._____..____._.__._ ..'........ 1

section on petrography of Abajo Mountains by. _______ __ 80-84 

section on structure of Abajo Mountains by...______ . 89-91 

Topography of the area, age of present features of.._.___.-.. 94 

controlling factors of_________-____-________ 92-97 

general features of...._._____________ _..-. -- 6,92

Trachyte, occurrence of..____-___________...__... .. 82-83 

Travel in the area..___ ~± ............................. 3-5

Trees, lists of species..._.. .._ ._..._.__......-.---- ... 23-26

Triassic formations, description of.._.-._......... ____. 47-50

regional relations of_ . _.. - - 47

sections of. ________.____..._____-. _ - - ' 71-73

Trimble, K. W., surveys by__________________.. '......... 2

Twin Peaks, rocks of.. ...............:..........^...................... 80-81,90

U 

Ucolo, section of coal beds at _____------- 110

Uranium, occurrence of... -. -- 107

Utah, southeastern, early exploration in.._____ ____ 1-2 

Utah Petroleum Corporation, drilling by______________----- 112

Utah Southern Oil Co., drilling by.- - - - - 112,113

Ute Indians, early history of...___... _ . . 11,29

present status of._.. .. ---------- .. ------ 30-31

V

Valleys, deposition and erosion in___. ____ ._ . ---- 100-106

form of.. .......... 97-98

Vanadium, occurrence of..-------- ------ ---------------- 107

Vega Creek, irrigation from..----------- --------- . ------------ 115
INDEX 123

Page 

Vegetation of the area, general features of.__............I................... 22-23

lists of species of____1_________.___.__..-_.______ 23-26 

of Abajo Mountains________________....__- 8-9, 23-24, pi. 2, A, B

of Alien Canyon Country____............................ t ........... 11

of Elk Ridge.....-...--.-....-..--.--.----.-------------------------.. 10,23-24

of Glen Canyon...___.....__......................._------------ is

of Lime Creek Valley.-....-......----.---..--------...---.-..-----.- 12, pi. 4, C

of Red Rock Plateau..._.........._.................................. 14

of Sage Plain...._................................................. 7-8, pi. 2, A

of White Canyon...___..................................... 13, pis. 5, B, 6, A

relation of, to run-off and erosion....__.___..__.------.-.-..__.. 95

types of, in the area_________ .___......_.-....-.-.__.... 23

Verdure, irrigation at..___-_______._..._.________-__..._-.--__._..____ 115

Viking mine___________________._.__...__.______.... 109

Volcanic breccia, occurrence of.______........___...___.__..... 82

W

Water supply, for irrigation__________...__.____...___. 114-115 

for stock___________________. _______________ 114 

ground water_____..____....._._-----------_-.-._ 115-117

meagerness of.___________.._---------.---------:_._-_ 4,114,115

sources of.________________________._.--_____.. 8,114 

springs..________________________.-.__________ 115-116 

surface water_....____.___ '................................... 113-115

wells.......,................-....... ................................ 116-117

Water table in the area. ___. 

Waterpocket Fold, features of.

115

Page

Wells in the area..._____'...I________.___.____.______ 116-117 

Westwater Canyon sandstone, description of..--------__._--------..... 59

sections of.._............._............_...-.-_-.---------.-.---.. 76-77

topographic features of__..._....................-...----.--.-.--..... 96

White Canyon, cliff dwellings in...............-°.-.--........ 13, pis. 8, C, 25, A, B, C

early history of....__.._.--._-----__-____-----_--.----.-.- 103

general features of--.-.-....__..._..._____-...._.......___ 13,98

landslides in----...__---------___-------.. ------------- . 103

natural bridges in.-.....-...-.--...---..---..--.--.... 103-104, pis. 20, B, 21, 22

prospecting in.........................._..._-----------_----------- 107

sections in.-......-.-....__._._._._--.-.--_-------------------.-----. 71-72

structure iu---___----------_........-.--.-------------.----.-'-------._ 89

vegetation of...._.._-..____....___..-.__......_ 13, pis. 5, B, 6, A

views in and near............... pis. 5, B, 6, A, 12, A, 13, A, 20, B, 21, 22, 23, B

White Cliffs sandstone, use of name-----..---..-.---.----------------------.- 51

White dike, features of....._.-..--..-.----_--------------- .----.-.....- 82

White Mesa, irrigation on..........._...._......^........................ 115

Wilson Mesa, features of.......___.............._........... ... 14-15

section at west edge of--------.--------..-----.---------------_...._.. 75-76

structure of............................................................... 88-89

Wjnd, direction of, in the area....._..--..--.--.--....--.-.'.-..--.--. 15,21

Windows, natural, formation of__---.---.---..--.----------.----------.---- 105

Wingate sandstone, occurrence and character of...... 54, pis. 3, B, 4, A, 6, D, 13, A

topographic features of.._.._.._---------------------- . 96,97

water from........-...-..------------_-.._............... --..-. 117

Woodruff, E. O., quoted.- .......;.....................-. ... ..... 112

O
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