2012

U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation with the National Park Service, the U.S. Forest Service, the Navajo Nation, and 

the Hopi Tribe

Geologic Map of the Tuba City 30’ x 60’ Quadrangle, Coconino 

County, Northern Arizona

By George H. Billingsley, Philip W. Stoffer, and Susan S. Priest

Pamphlet to accompany

Scientific Investigations Map 3227
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i

Contents

Introduction ....................................................................................................................................................1

Geography .............................................................................................................................................1

Previous Work ...............................................................................................................................................1

Mapping Methods .........................................................................................................................................2

Geologic Setting ............................................................................................................................................2

Precambrian Rocks ......................................................................................................................................3

Paleoproterozoic ..................................................................................................................................3

Mesoproterozoic ..................................................................................................................................3

Neoproterozoic .....................................................................................................................................3

Paleozoic Rocks ............................................................................................................................................4

Cambrian ...............................................................................................................................................4

Devonian ................................................................................................................................................4

Mississippian ........................................................................................................................................4

Pennsylvanian ......................................................................................................................................4

Permian ..................................................................................................................................................4

Mesozoic Rocks ............................................................................................................................................5

Moenkopi Formation ............................................................................................................................5

Chinle Formation ..................................................................................................................................6

Moenave Formation .............................................................................................................................6

Kayenta Formation ...............................................................................................................................7

Kayenta Formation-Navajo Sandstone Transition Zone ................................................................7

Navajo Sandstone ................................................................................................................................7

Carmel Formation .................................................................................................................................7

Entrada Sandstone-Cow Springs Sandstone ..................................................................................7

Dakota Sandstone ................................................................................................................................8

Mancos Shale .......................................................................................................................................8

Cenozoic Volcanic Rocks ............................................................................................................................8

Pliocene-Pleistocene Gravel Deposits ............................................................................................8

Quaternary Surficial Deposits .....................................................................................................................8

Surficial Mapping Technique .............................................................................................................8

Local Surficial Deposits ......................................................................................................................9

Structural Geology ........................................................................................................................................9

Acknowledgments ......................................................................................................................................11

Description of Map Units ...........................................................................................................................11

Surficial Deposits ...............................................................................................................................11

Volcanic Rocks ...................................................................................................................................16

Sedimentary Rocks ............................................................................................................................16

Neoproterozoic Rocks ......................................................................................................................24

Mesoproterozoic Rocks ....................................................................................................................26

Paleoproterozoic Rocks ....................................................................................................................27

References Cited .........................................................................................................................................27
ii

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

mile, nautical (nmi) 1.852 kilometer (km)

yard (yd) 0.9144 meter (m)

Area

acre 4,047 square meter (m2)

acre 0.4047 hectare (ha)

acre 0.4047 square hectometer (hm2)

acre 0.004047 square kilometer (km2)

square foot (ft2) 929.0 square centimeter (cm2)

square inch (in2) 0.09290 square meter (m2)

square foot (ft2) 6.452 square centimeter (cm2)

section (640 acres or 1 square mile) 259.0 square hectometer (hm2)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2)
1

Introduction

This geologic map is a cooperative effort of the U.S. 

Geological Survey (USGS) in collaboration with the National 

Park Service, the U.S. Forest Service, the Navajo Nation, and 

the Hopi Tribe to provide regional geologic information for 

resource management officials and for visitor information 

services of the National Park Service, the U.S. Forest Service, 

the Navajo Nation, and the Hopi Tribe. Funding for the map 

was provided by the U.S. Geological Survey National Geologic 

Mapping Program, Reston, Virginia.

Field work on the Navajo Nation lands was conducted 

under a permit from the Navajo Nation Minerals Department. 

Anyone wishing to conduct geologic investigations on the 

Navajo Nation lands must first apply for, and receive, a permit 

from the Navajo Nation Minerals Department, P.O. Box 1910, 

Window Rock, Arizona 86515, (928) 871-6587. Permission to 

conduct field work on portions of the Hopi Moenkopi District 

at the south-central edge of the map was granted by the Department of Natural Resources of the Hopi Tribe. Any person wishing to conduct geological investigations within Hopi lands must 

obtain permission from the Department of Natural Resources, 

The Hopi Tribe, P.O. Box 123, Kykotsmovi, Arizona 86039, 

(928) 734-3601.

The Tuba City 30' x 60' quadrangle encompasses approximately 5,018 km2 (1,920 mi2) within Coconino County, 

northern Arizona, and is bounded by lat 36° to 36°30' N., long 

111° to 112° W. The map area is within the southern Colorado 

Plateaus geologic province (herein Colorado Plateau). The map 

area encompasses the southwest portion of the Navajo Nation, 

part of the Hopi lands, and eastern Grand Canyon National 

Park, where new geologic mapping is needed for geologic connectivity to the regional geologic framework. The Tuba City 

30′ x 60′ quadrangle will benefit local, federal, state, Navajo, 

and Hopi resource managers who direct environmental and land 

management programs such as range management, biological 

studies, flood control, water resource investigations, and natural 

hazard assessments associated with sand dune mobility. Our 

geologic information will support ongoing and future geologic 

investigations and associated studies within the region.

The west half of the Tuba City quadrangle was mapped 

primarily by George Billingsley and the east half was mapped 

primarily by Phil Stoffer. Mapping was compiled at 1:24,000-

scale using a combination of aerial photography, digital orthophotos, and field checking. The mapped area is presented as two 

1:50,000-scale views, west half (sheet 1) and east half (sheet 2), 

with related information on a third sheet (sheet 3). This pamphlet contains a description of map units applicable to the entire 

Tuba City quadrangle.

Geography

The Tuba City quadrangle is locally subdivided into eight 

physiographic areas: the Grand Canyon (which includes the 

Little Colorado River Gorge and Marble Canyon), Walhalla 

Plateau, Kaibab Plateau, the southern part of House Rock 

Valley (west of Marble Canyon), Coconino Plateau, Moenkopi 

Plateau, Kaibito Plateau, and Marble Plateau (east of Marble 

Canyon) as defined by Billingsley and others, 1997 (fig. 1, 

sheet 3). Shinumo Altar, Blue Moon Bench, Limestone Ridge, 

Bodaway Mesa, Yon Dot Mountains, Red Point Hills, and the 

Painted Desert are collectively referred to as part of the Marble 

Plateau. Landmark features of the Kaibito Plateau east of the 

Echo Cliffs include Preston Mesa, Middle Mesa, a portion of 

White Mesa, Tuba Butte, and Wildcat Peak. The Moenkopi 

Plateau in the southeast corner of the map area includes Coal 

Mine Mesa. Coal Mine Canyon erodes into Coal Mine Mesa 

and is a tributary to Moenkopi Wash. Elevation ranges from 

about 2,480 ft (756 m) at the Colorado River in Grand Canyon, 

southwest corner of map, to about 8,860 ft (2,700 m) on the 

Kaibab Plateau, north rim of Grand Canyon near Point Imperial, 

west-central edge of map.

Settlements within the Tuba City quadrangle area include 

Tuba City, Moenkopi, Moenave, The Gap, and Cedar Ridge. 

Not shown are the small communities of Coal Mine Canyon 

about 1 mi (1.6 km) south of the southeast corner of the map 

and Tonalea about 1.6 km (1 mi) northeast of the northeast 

corner of the map.

U.S. Highway 160 and State Highway 264 provide access 

to the eastern half of the map area, U.S. Highway 89 to the central part, and State Highway 64 to the Grand Canyon and southwest corner. Roads and trails within the Kaibab National Forest 

are maintained by the National Forest Service, and roads in the 

Grand Canyon National Game Preserve of House Rock Valley 

area are maintained by the National Forest Service and the 

Grand Canyon Trust. Roads on Walhalla Plateau are maintained 

by Grand Canyon National Park. Unimproved dirt roads provide 

access to remote parts of the Navajo Nation Reservation. Some 

are maintained by the Navajo Nation Roads Department in 

Window Rock, Arizona, and others are maintained locally by 

chapter governments (Cameron, Coalmine Canyon, Tuba City, 

Bodaway/Gap, Kaibito, and Tonalea Chapters). Four-wheel 

drive vehicles are recommended for winter driving on dirt roads 

of the Navajo Nation areas north and west of Tuba City due 

to mud and snow. Four-wheel drive is also recommended for 

all unmaintained dirt roads north and east of Tuba City due to 

sandy conditions. Extra water and food is highly recommended 

for travel in this region.

The Kaibab National Forest and Grand Canyon National 

Park manage lands in the western third of the quadrangle. The 

Navajo Nation and local Navajo chapter governments manage 

lands in the eastern two-thirds of the area. The Hopi Tribe and 

Moenkopi Village manage the Hopi Moenkopi District in the 

south-central map area.

Previous Work

An early reconnaissance photogeologic map that includes 

the eastern two-thirds of the Tuba City quadrangle was compiled by Cooley and others (1969, map 1 of 9) for the Navajo 

and Hopi Reservations of Arizona, New Mexico, and Utah. 

These maps were not registered to a base because a topographic 

base larger than 1:250,000-scale did not exist. Wilson and 
2

others (1969) compiled an early reconnaissance geologic map 

of Coconino County and the State of Arizona (1:500,000-scale) 

using the work of Cooley and others (1969). A geologic map 

of the Marble Canyon 1° x 2° quadrangle (1:250,000-scale) 

covers the Tuba City quadrangle (Haynes and Hackman, 1978). 

Huntoon and others (1996) produced a geologic map of the 

eastern part of Grand Canyon National Park and vicinity, and 

Timmons and others (2007) most recently produced a geologic 

map of the Butte Fault/East Kaibab Monocline area in eastern 

Grand Canyon. The Precambrian bedrock geology of Timmons 

and others (2007) in Grand Canyon is reproduced on this map. 

The Quaternary geology of all previous maps has been modified 

and significantly updated to match adjoining 30′ x 60′ quadrangle maps, which include Valle (Billingsley and others, 2006), 

Cameron (Billingsley and others, 2007), and Fredonia (Billingsley and others, 2008). The Grand Canyon 30' x 60' quadrangle 

(Billingsley, 2000) adjoins the west edge of the Tuba City 

quadrangle and reflects the bedrock geology of Huntoon and 

others (1996), but the Quaternary geology was not mapped in 

detail on that map.

Mapping Methods

Geologic mapping of the Tuba City quadrangle was produced by stereoscopic analysis of aerial photographs augmented 

by digital orthophotos and extensive field checking. Primary 

resources include 1:54,000-scale black and white aerial photographs from 1958 and 1968 and 1:24,000-scale and 1:40,000-

scale color aerial photographs from 2005. Geologic features 

were compiled onto 1:24,000-scale topographic maps. Geologic 

map units were extensively field checked to verify bedrock and 

surficial units and descriptions. Mapping of the eastern half of 

the quadrangle was enhanced by using 1:40,000-scale digital 

color orthophotos. The orthophoto mapping is not quite aligned 

with the 1:24,000-scale base in some areas.

Many of the Quaternary alluvial and eolian deposits have 

similar lithology and geomorphic characteristics and were 

mapped almost entirely by photogeologic methods. Pliocene, 

Pleistocene, and Holocene surficial deposits are differentiated 

chiefly on the basis of morphologic character and physiographic 

position. Older alluvial and eolian deposits generally exhibit 

extensive erosion whereas younger deposits are actively accumulating material and are slightly eroded. Eolian deposits are 

stabilized by vegetation in most areas but are partially reactivated during severe drought or storm conditions.

In the eastern half of the quadrangle, small eolian and bedrock outcrops were not individually mapped. Instead, they were 

lumped into a dominant classification. All surficial contacts 

adjacent to alluvial, eolian, and bedrock map units are approximate.

Surficial deposits within the Grand Canyon area were not 

investigated in the field and are largely photo interpretations 

based on previous field reconnaissance mapping (Huntoon and 

others, 1996). For a detailed description of surficial deposits and 

Precambrian rocks within the Grand Canyon area, see Timmons 

and others (2007).

Mapping was compiled by hand on 1:24,000-scale paper 

topographic maps. The base maps were then scanned and 

brought into ArcMap for georeferencing. Geologic features 

were digitized, symbolized, and cross-checked against the original field sheets in an ArcGIS personal geodatabase. Thirty-two 

detailed 1:24,000-scale maps were compiled to produce this 

publication. This map is the eighth in a series of digital 30′ x 60′ 

geologic maps of the Grand Canyon region.

Geologic Setting

The Tuba City quadrangle is characterized by nearly flatlying to gently dipping sequences of Paleozoic and Mesozoic 

strata that overly tilted Precambrian strata or metasedimentary 

and igneous rocks that are exposed at the bottom of Grand 

Canyon. The Paleozoic rock sequences from Cambrian to 

Permian age are exposed in the walls of Grand Canyon, Marble 

Canyon, and Little Colorado River Gorge, herein collectively 

referred to as the Grand Canyon. Mesozoic sedimentary rocks 

are exposed in the eastern half of the quadrangle where resistant sandstone units form cliffs, escarpments, mesas, and local 

plateaus. A few Miocene volcanic dikes intrude Mesozoic rocks 

southwest, northwest, and northeast of Tuba City, and Pleistocene volcanic rocks representing the northernmost extent of the 

San Francisco Volcanic Field are present at the south-central 

edge of the quadrangle (Ulrich and Bailey, 1987; Billingsley 

and others, 2007). Quaternary deposits mantle much of the 

Mesozoic rocks in the eastern half of the quadrangle and are 

sparsely scattered in the western half. A brief discussion of the 

surficial deposits is presented later in the text.

Principal folds are the north-south-trending, east-dipping 

Echo Cliffs Monocline and the East Kaibab Monocline. The 

East Kaibab Monocline elevates the Kaibab, Walhalla, and 

Coconino Plateaus and parts of Grand Canyon. Grand Canyon 

erosion has exposed the Butte Fault beneath the east Kaibab 

Monocline, providing a window into the structural complexity 

of monoclines in this part of the Colorado Plateau. Rocks of 

Permian and Triassic age form the surface bedrock of Marble 

Plateau and House Rock Valley between the East Kaibab and 

Echo Cliffs Monoclines (fig. 1, sheet 3).

The Echo Cliffs Monocline forms a structural boundary 

between the Marble Plateau to the west and the Kaibito and 

Moenkopi Plateaus to the east. Jurassic rocks of the Kaibito and 

Moenkopi Plateaus are largely mantled by extensive eolian sand 

deposits. A small part of the northeast-dipping Red Lake Monocline is present in the northeast corner of the quadrangle.

A broad and gentle elongated anticline, the Limestone 

Ridge Anticline, forms the crest of Marble Plateau. Here, 

Paleozoic and Mesozoic strata generally dip less than 1° to 2°

in all directions from a central high area along Limestone Ridge 

north of Bodaway Mesa and east of Cedar Ridge and The Gap 

(fig. 1, sheet 3). The Limestone Ridge Anticline plunges gently 

southeast toward the Painted Desert at the south edge of the 

quadrangle and northward toward Lees Ferry, Arizona, at the 

north-central edge of the quadrangle. The Tuba City Syncline is 

a very broad northwest-southeast-oriented synclinal downwarp 
3

that parallels the Echo Cliffs Monocline north of Tuba City. 

The Preston Mesa Anticline is a small fold present on Kaibito 

Plateau north of Tuba City (fig. 1, sheet 3; Cooley and others, 

1969; Haynes and Hackman, 1978).

Precambrian Rocks

At the bottom of Grand Canyon in the western third of the 

quadrangle, the Colorado River has exposed the oldest rocks of 

late Precambrian age. Proterozoic rocks of the Grand Canyon 

form three main packages that record distinct depositional and 

tectonic episodes in the Paleoproterozoic, Mesoproterozoic, and 

Neoproterozoic. These rocks, from oldest to youngest, include 

the Granite Gorge Metamorphic Suite and Zoroaster Complex 

(Paleoproterozoic), the Unkar Group (Mesoproterozoic), and 

the Chuar Group (Neoproterozoic).

Paleoproterozoic

The Paleoproterozoic rocks form the basement rocks 

for the map area and underlie all younger rocks in the region. 

These metamorphic and igneous rocks are commonly called 

the Granite Gorge Metamorphic Suite and Zoroaster Complex 

(Ilg and others, 1996: Karlstrom and others, 2003). Within the 

quadrangle, these rocks span ages between 1,680 and 1,750±2 

Ma (Hawkins and others, 1996); however, some of the oldest 

rocks are dated at 1,842 Ma southwest of the quadrangle (Ilg 

and others, 1996). These lithologic units represent a complexly 

deformed package of metasedimentary and metavolcanic rocks 

intruded by numerous granitic dikes and plutons. These rocks 

record the assembly and stabilization of a juvenile continental 

crust in the southwest during a southward (present coordinates) 

growth of the Laurentian continent by the accretion of volcanic 

arc terrains (Hoffman, 1988; Karlstrom and Bowring, 1988). Following continental assembly, the Paleoproterozoic rocks stabilized and remained at middle crustal depths from 1.65 to 1.45 Ga 

as suggested by the 1.375 Ga age of granite near Quartermaster 

Canyon in western Grand Canyon (Karlstrom and others, 2003). 

Mesoproterozoic 

The 1.4 Ga thermal/tectonic events are hypothesized 

to have been regionally important in driving the uplift and 

exhumation of middle crustal rocks prior to the deposition of 

the Mesoproterozoic sediments of the Grand Canyon Supergroup. The beveling of the basement metamorphic and igneous 

rocks prior to deposition of the Grand Canyon Supergroup is 

recognized as the Greatest Angular Unconformity (Powell, 

1875) marked between basement Paleoproterozoic rocks and 

the overlying Mesoproterozoic rocks of the Unkar Group. The 

Great Unconformity separates all Precambrian rocks from the 

overlying Paleozoic rocks in the Grand Canyon region.

The 1,250 to 1,100 Ma Unkar Group is approximately 

6,900 ft (2,100 m) thick and is divided into five formations, in 

ascending order: the Bass Formation, Hakatai Shale, Shinumo 

Sandstone, Dox Formation, and Cardenas Basalt as defined 

by Timmons and others (2007). These five formations reflect 

nomenclature usage published by Timmons and others (2007) 

and do not reflect the USGS style as defined by Elston (1979) 

and Hendricks and Stevenson (2003). The succession contains 

both fluvial and shallow-marine deposits with one main disconformity below the Shinumo Sandstone. In general, the rocks of 

the Unkar Group dip northeast (10°–30°) toward normal faults 

and the normal faults dip 60° southwest (Sears, 1973). 

The combined sedimentologic and deformational history 

of the Unkar Group highlights an important period of geologic 

history in the U.S. Southwest. Plate tectonic forces at the plate 

margin (currently west Texas) created massive alpine-scale 

mountain ranges along the eastern margin of Laurentia (Grenville orogeny). The far field forces related to that collision manifested as deformational features and depositional systems in 

Grand Canyon (Timmons and others, 2007). Rocks of the lower 

Unkar Group are involved in northeast-striking monoclines that 

record northwest-directed crustal shortening (see Red Canyon 

on map; Timmons and others, 2005, 2007). These monoclines 

are intimately related to deposition of the lower Unkar Group. 

The lower Unkar Group and its associated deformation are 

buried by the upper Unkar Group that records dominantly 

northeast-directed extension along northwest-striking faults 

(Timmons and others, 2005).

Neoproterozoic

Deformation of the Unkar Group continued into Nankoweap Formation time as indicated by an unconformity 

within that formation and an angular unconformity between the 

Nankoweap and overlying Chuar Group rocks. Rocks of the 

Chuar Group include, in ascending order, the Galeros Formation and the Kwagunt Formation that are in turn subdivided into 

four and three members, respectively (Karlstrom and others, 

2000). Deposition of the mudstone-dominated Chuar Group 

began approximately 300 m.y. after the eruption of the Cardenas 

Basalt and marks a new depositional and deformational episode 

in the Grand Canyon and adjacent areas. By 800 to 742 Ma, 

deposition of approximately 5,250 ft (1,600 m) of the Chuar 

Group of sediments had ended, and deposition of the overlying 

Sixtymile Formation occurred soon after.

Rocks of the Chuar Group record an important episode of 

sedimentation and deformation related to the incipient rifting 

of Laurentia in the Neoproterozoic. Faulting and folding of the 

Chuar Group and the Sixtymile Mile Formation record eastwest extensions along north-striking normal faults (Dehler and 

others, 2001). The timing of deformation and the marine depositional setting are consistent with an early phase of continental 

rifting and basin formation as rifting begins along the present 

day western cordillera.

The Precambrian bedrock presented in this map is that 

of Timmons and others (2007). Surficial deposits in the Precambrian area have been slightly modified from Timmons and 

others (2007) to better match and correlate with adjacent 30′ 

x 60′ maps of the Grand Canyon area (Billingsley and others, 

2006, 2007, 2008).
4

Paleozoic Rocks

The erosion of Grand Canyon by the Colorado River 

has exposed about 3,300 ft (1,006 m) of Paleozoic strata. 

These Paleozoic rocks are likely present in the subsurface 

of Coconino, Marble, Kaibito, and Moenkopi Plateaus with 

variable facies and thickness changes and an overall gradual 

thinning of most units toward the east. Paleozoic rocks from 

oldest to youngest are the Tapeats Sandstone (Lower(?) to 

Middle Cambrian), the Bright Angel Shale (Middle Cambrian), the Muav Limestone (Middle Cambrian), the Temple 

Butte Formation (Middle and Upper Devonian), the Redwall 

Limestone (Lower, Middle, and Upper Mississippian), the 

Surprise Canyon Formation (Upper Mississippian), the lower 

part of the Supai Group, undivided (Lower, Middle, and Upper 

Pennsylvanian and Upper Mississippian), and the Esplanade 

Sandstone, the Hermit Formation, the Coconino Sandstone, 

the Toroweap Formation, and the Kaibab Formation (Permian, 

Cisuralian).

Cambrian

Based on exposures in Grand Canyon and in the Verde 

Valley 40 mi (65 km) south of the map area, the Tapeats Sandstone and Bright Angel Shale gradually thin south and east of 

the map area and gradually thicken west and north. Both units 

locally pinch out on elevated Precambrian monadnocks west of 

the map area and likely do the same under the plateaus surrounding the Grand Canyon. The Muav Limestone gradually 

thins east and southeast and thickens west and north of the map 

area and may locally pinch out onto Precambrian rocks as it 

does just west of the map area in eastern Grand Canyon (Huntoon and others, 1996; Billingsley, 2000).

Devonian

The Temple Butte Formation includes a purple-red dolomite, siltstone, and conglomerate that fill channels as deep as 

120 ft (35 m) in the Marble Canyon area. The unit is locally 

discontinuous between channels in Marble Canyon and likely 

east of the Marble Canyon area. The Temple Butte Formation is 

a continuous unit in the southwest quarter of the map area and 

gradually thickens to the south and west.

Mississippian

The Redwall Limestone gradually thins eastward and 

thickens westward as seen in Grand Canyon exposures and 

unconformably overlies either the Temple Butte Formation or 

the Muav Limestone where the Temple Butte is locally missing. 

The Redwall Limestone forms a thick 500 to 550 ft (152 to 168 

m) reddish-gray cliff in eastern Grand Canyon. The overlying 

Surprise Canyon Formation is a discontinuous unit that locally 

fills shallow channels or caves eroded into the top part of the 

Redwall Limestone.

Pennsylvanian

The lower Supai Group, undivided, unconformably overlies the Redwall Limestone or the Surprise Canyon Formation 

(where present) and gradually thins eastward in the subsurface 

of the map area. The lower Supai Group maintains a general 

thickness of about 800 ft (244 m) north of the map area and 

gradually thickens westward.

Permian

The Esplanade Sandstone is the upper part of the Supai 

Group and forms a prominent sandstone cliff that gradually 

thins east and south and thickens north of the map area. The 

Hermit Formation unconformably overlies the Esplanade Sandstone where channels have eroded into the Esplanade as deep as 

30 ft (9 m).

The Hermit Formation thins eastward to less than 20 ft 

(6 m) in the Little Colorado River Gorge and likely pinches 

out before reaching the Tuba City area. The Hermit Formation 

thickens north and west of the Grand Canyon in the subsurface 

of the map area. A sharp planar erosional contact separates the 

Hermit Formation from the overlying Coconino Sandstone.

The Coconino Sandstone forms a shear buff-white cliff in 

the Grand Canyon and is about 600 ft (183 m) thick throughout 

the southwest half of the map area and thins to the north and 

west of the quadrangle. The basal part of the Coconino Sandstone includes a red sandstone in the Little Colorado Gorge that 

is likely the northern extent of the Schnebly Hill Formation 

exposed in the Verde Valley south of the quadrangle as defined 

by Blakey (1990; Ronald C. Blakey, oral commun., 2005). 

The Coconino Sandstone (not the Schnebly Hill Formation) 

is actually a tongue of the Seligman Member of the Toroweap 

Formation in the western and northern part of Grand Canyon 

(Fisher, 1961; Schleh, 1966; Rawson and Turner, 1974; Billingsley and others, 2000; Billingsley and Wellmeyer, 2003) but 

is a well-established unit in Grand Canyon nomenclature that 

forms a distinct mappable unit throughout the Grand Canyon 

region. The Coconino Sandstone and Schnebly Hill Formation 

gradually thicken south and southeast of the map area. Both the 

Schnebly Hill Formation and the Coconino Sandstone form an 

important groundwater bearing unit known as the “C” aquifer.

The Toroweap Formation overlies the Coconino Sandstone 

and undergoes a substantial west-to-east facies change in the 

Grand Canyon and in the subsurface of the map area. All three 

members of the Toroweap Formation, as defined by Sorauf and 

Billingsley (1991), are recognized in the south and west edges 

of the map as, in ascending order, the Seligman, Brady Canyon, 

and Woods Ranch Members. All three members become 

indistinguishable along the eastern rim of Grand Canyon, 

Marble Canyon, and the Little Colorado River Gorge owing to 

a facies change into cliff-forming sandstone and are mapped 

there as the Toroweap Formation, undivided. The west-to-east 

Toroweap facies change roughly parallels the Colorado River. 

The Toroweap Formation gradually thins east, north, and south 

of the Grand Canyon area and thickens west.
5

The Kaibab Formation forms the rim of the Grand 

Canyon and the surface bedrock for much of the Coconino, 

Walhalla, and Kaibab Plateaus, House Rock Valley, and the 

western half of Marble Plateau where not covered by remnants 

of the Moenkopi Formation or surficial deposits. The Kaibab 

Formation is divided into, in ascending order, the Fossil 

Mountain and Harrisburg Members as defined by Sorauf 

and Billingsley (1991). A gradational and arbitrary boundary separates the ledge- and cliff-forming Fossil Mountain 

Member from the overlying slope- and ledge-forming Harrisburg Member of the Kaibab Formation in the walls of Grand 

Canyon and its tributaries. The Fossil Mountain Member 

contains brachiopod, sponge, and trilobite fossils and abundant 

chert beds, lenses, and nodules. The Harrisburg Member is primarily a sandy limestone or calcareous sandstone that locally 

contains a few mollusk fossils. The Harrisburg Member of 

the Kaibab Formation forms a ledge-and-slope profile above 

the cliff-forming Fossil Mountain Member. The Harrisburg 

Formation is often weathered or stained dark gray or black by 

manganese oxide. The Fossil Mountain and Harrisburg Members undergo a west-to-east facies change within the map area, 

making it increasingly difficult to distinguish one member 

from the other east of the Grand Canyon. The Kaibab Formation gradually thins east of the map area and thickens toward 

the northwest and west.

Mesozoic Rocks

An unconformity with general relief of less than 10 ft (3 

m) separates the Permian Kaibab Formation from the overlying 

Triassic Moenkopi Formation. This unconformity is commonly 

recognized by a color change from the grayish-white sandy 

limestone beds of the Kaibab Formation to the light-red, thinbedded siltstone and sandstone beds of the Moenkopi Formation. Erosional depressions and channels form the lenticular 

basal part of the Moenkopi Formation. Channels are filled with 

angular and subangular chert and sandstone conglomerate or 

breccia deposits derived from the Kaibab Formation.

Erosion has exposed about 2,300 ft (700 m) of Mesozoic 

strata in the eastern half of the map area and removed most of 

these rocks from the western half. In ascending order, Mesozoic rocks present are the Moenkopi Formation (Lower and 

Middle(?) Triassic); the Chinle Formation (Upper Triassic); 

the Glen Canyon Group consisting of the Moenave Formation 

(Upper Triassic(?) to Lower Jurassic), the Kayenta Formation 

(Lower Jurassic age from Doelling and others, 2000), rocks 

of the Kayenta Formation-Navajo Sandstone transition zone 

(Lower Jurassic), and the Navajo Sandstone (Lower Jurassic 

age from Doelling and others, 2000); and the San Rafael Group 

consisting of the Carmel Formation (Middle Jurassic) and the 

Entrada Sandstone-Cow Springs Sandstone, undivided (Middle 

Jurassic). Unconformably overlying the Jurassic rocks are the 

Dakota Sandstone (Upper Cretaceous) and the Mancos Shale 

(Upper Cretaceous age from Doelling and others, 2000). All 

Mesozoic strata undergo rapid facies and thickness changes in 

all directions in the Moenkopi and Kaibito Plateau areas.

Moenkopi Formation

Overlying the Kaibab Formation is a sequence of red 

sandstone ledges and siltstone slopes of the Moenkopi Formation. The Moenkopi Formation forms extensive outcrops on the 

southern part of the Marble Plateau east of the Little Colorado 

River Gorge and north-south along the Echo Cliffs to Cedar 

Ridge and as scattered outcrops on the northern part of Marble 

Plateau. Prior to Cenozoic erosion, the Moenkopi Formation covered the entire map area as thick as 1,000 ft (300 m) 

(Billingsley and others, 2006). Deposits gradually thin eastward 

to about 350 ft (107 m) in the Moenkopi Wash and Echo Cliffs 

areas (Repenning and others, 1969) and thicken northward to 

about 460 ft (140 m) northwest of the map area and to less than 

220 ft (67 m) at Cedar Ridge at the north-central edge of the 

map area.

 The Moenkopi Formation is subdivided into three members south of the Little Colorado River as described by McKee 

(1954) and Hager (1922) and mapped by Billingsley and others 

(2007). In ascending order they are the Wupatki Member, the 

Shnabkaib Member, and the Holbrook and Moqui Members, 

undivided. The Moenkopi Formation in northwestern Arizona 

and southern Utah, as mapped by Billingsley and Workman 

(2000) and Billingsley and others (2008), used the subdivisions of Stewart and others (1972). North of the map area, the 

Moenkopi is divided into three parts, in ascending order, as the 

lower members, undivided, the Shnabkaib Member, and the 

upper red member as mapped by Billingsley and Priest (2010). 

The Little Colorado River is a convenient geographic boundary 

for separating Moenkopi Formation nomenclature south and 

southeast of Cameron from nomenclature north and northwest 

of Cameron. Facies changes are numerous and common in all 

Moenkopi Formation map units along a southeast-northwest 

direction across the map area. The Wupatki Member southeast 

of Cameron is the lateral equivalent of the lower members, 

undivided, northwest of Cameron. The lower massive sandstone is the lateral equivalent of the Shnabkaib Member and the 

Holbrook and Moqui Members are the lateral equivalent of the 

upper red member.

The Moenkopi Formation forms a continuous outcrop 

north of the map area along the Echo Cliffs to Lees Ferry and 

then west along the Vermilion Cliffs into Utah and northwestern Arizona and south of the map area into the Little Colorado 

River Valley. The nomenclature of both McKee (1954) and 

Stewart and others (1972) used for this map is based on tracing 

and correlating the stratigraphic units of each member across 

northern Arizona and observing the facies changes from the 

Little Colorado River Valley to the Vermilion Cliffs and west to 

Fredonia.

The Wupatki Member is the approximate equivalent of 

the lower red Virgin Limestone and middle red members of the 

Moenkopi Formation of northwestern Arizona and is mapped 

as the lower members, undivided (^mlm), in Billingsley and 

Priest (2010). The Virgin Limestone Member is present at Cedar 

Ridge and in the Yon Dot Mountains on Marble Plateau as a 

light-gray, thin-bedded, fine-grained limestone about 6 in thick 

but is too thin and discontinuous to show at map scale. It does 

provide a stratigraphic marker bed between the lower red and 
6

middle red members for correlation purposes at the northern 

edge of the map area.

Mapping along the Vermilion Cliffs northwest of Marble 

Plateau (Billingsley and Priest, 2010) visibly demonstrates that 

the Shnabkaib Member undergoes a facies change from a thick 

white siltstone, gypsiferous sandstone, and limestone sequence 

to a yellowish-white, crossbedded, ledge-forming, fine- to 

coarse-grained calcareous sandstone and thin limestone southward along the Echo Cliffs to the Little Colorado River Gorge. 

The Shnabkaib Member continues a facies change southward 

to a light-red, fine-grained, cliff-forming, crossbedded fluvial 

sandstone southeast of the Little Colorado River Gorge and into 

the Little Colorado River Valley south of the map area where 

McKee (1954) describes the unit as the lower massive sandstone 

member. Thus, the lower massive sandstone member and the 

Shnabkaib Member are one and the same, representing a shoreward facies change from marine to coastal tidal flat from northwestern Arizona southeast to the Little Colorado River Valley.

Southeast of the map area, the Holbrook and Moqui 

Members (McKee, 1954; Hager, 1922) erode to a uniform, 

mostly covered slope below the cliff-forming sandstones of 

the Holbrook Member. A variable and sometimes discontinuous boundary exists between the members. The Holbrook and 

Moqui Members are approximately correlative to the upper red 

member of the Moenkopi Formation in northwestern Arizona 

and southern Utah (McKee, 1954; Repenning and others, 1969) 

and the upper red member of Billingsley and Priest (2010) 

and may, in part, be Middle(?) Triassic age. The Holbrook and 

Moqui Member nomenclature (Billingsley and others, 2007) 

is used on this map because the unit exhibits similar lithology, 

topographic expression, stratigraphic position, and proximity to 

the Little Colorado River Valley. The unit undergoes a rapid and 

complex northward facies change in the eastern part of Marble 

Plateau between the Little Colorado River Gorge and Cedar 

Ridge and thins northward along the Echo Cliffs to Lees Ferry.

The Moenkopi Formation was deposited from shallow tidal 

flats and fluvial floodplains that drained northwest toward southern Utah (Blakey and Ranney, 2008). This coastal setting was 

followed by a northwest fluvial drainage system that deposited 

the overlying Chinle Formation. The streams and valleys began 

to accumulate mud, sand, gravel, and conglomerate deposits 

of the Shinarump Member of the Chinle Formation. Drainages 

eroded into the Moenkopi Formation average about 30 ft (10 m) 

deep and locally as much as 100 ft (30 m). This unconformity 

is known as the T-3 unconformity (Blakey, 1994). The Moenkopi Formation is unconformably overlain by the light-brown, 

cliff-forming sandstone and conglomeratic sandstone and purple 

to light-red siltstone of the Shinarump Member of the Chinle 

Formation.

Chinle Formation

The Chinle Formation is the most colorful unit in the map 

area and is subdivided into three members seen along the Echo 

Cliffs. In ascending order they are the Shinarump Member, the 

Petrified Forest Member, and the Owl Rock Member as defined 

by Akers and others (1958) and Repenning and others (1969). 

The Shinarump Member includes an informal sandstone and 

siltstone member as defined by Repenning and others (1969). 

The Shinarump Member is thickest in the Painted Desert along 

U.S. Highway 89 where accumulations are between 180 and 

200 ft (55 and 60 m) thick. Basal, tan, conglomeratic, ledgeforming sandstone beds contain numerous petrified logs and 

wood fragments and lenses of well-rounded quartzite and chert 

pebbles. The upper informal sandstone and siltstone sequence 

is predominantly a lenticular maze of thin to thick interbedded 

stream-channel and flood-plain deposits of light-brown conglomerate and dark-purple, gray, and dark-red lenticular crossbedded siltstone and sandstone. The sandstone and siltstone 

member is a transitional unit between the Shinarump Member 

and the Petrified Forest Member. The sandstone and siltstone 

member sequence is not as crossbedded or as conglomeratic as 

the underlying basal Shinarump Member and gradually thins 

and pinches out northward to Cedar Ridge. The thickness of the 

Shinarump Member and sandstone and siltstone member, undivided, is variable due to widespread local channel pinch outs 

and thinning of various lenticular units. The contact between the 

Shinarump and sandstone and siltstone unit and the overlying 

Petrified Forest Member is gradational and approximate.

The Petrified Forest Member forms the multicolored blue, 

red, white, and grayish-green mud hills of the Painted Desert 

badlands between the Little Colorado River Gorge and Moenkopi Wash and northward along the Echo Cliffs Monocline and 

U.S. Highway 89. Locally, the Petrified Forest Member can be 

subdivided into three units based on slight lithologic and color 

differences according to Akers and others (1958), but these units 

are herein mapped together as the Petrified Forest Member of the 

Chinle Formation because the gradational boundaries between 

them is arbitrary. The three units are, in descending order, a red 

mudstone and sandstone, a gray mudstone and sandstone, and a 

blue mudstone. The Petrified Forest Member generally maintains 

a thickness between 300 and 400 ft (92 and 122 m).

Gradationally overlying the Petrified Forest Member is the 

Owl Rock Member. The Owl Rock Member consists of an interbedded sequence of gray, ledge-forming, siliceous limestone and 

light-red to yellowish-gray, slope-forming, calcareous siltstone 

beds that form Ward Terrace in the southeast corner of the map 

area (fig. 1, sheet 3). The contact between the Petrified Forest 

and Owl Rock Members is arbitrary and generally marked about 

10 to 15 ft (3 to 4.5 m) below the lowest gray limestone bed of 

the Owl Rock Member. The contact of the Owl Rock Member 

with the overlying Moenave Formation is unconformable and 

marked by a sharp contrast in lithology and color change from 

gray mudstone, siltstone, and limestone to orange-red fluvial 

sandstone of the Moenave. This regional unconformity is known 

as the J-O unconformity (Pipiringos and O’Sullivan, 1978; Peterson and Pipiringos, 1979) and separates Triassic strata from the 

overlying Jurassic rocks. The Owl Rock Member gradually thins 

northward along the Echo Cliffs Monocline.

Moenave Formation

The type section of the Moenave Formation is near the 

community of Moenave, west of Tuba City. The Moenave 
7

Formation originally included, in ascending order, the Dinosaur 

Canyon Member (Colbert and Mook, 1951) and the Springdale 

Sandstone Member, originally described by Gregory (1950) as 

part of the Chinle Formation and redefined as the upper member 

of the Moenave Formation by Harshbarger and others (1958). 

More recently, the Springdale Sandstone Member was reassigned to the basal part of the Kayenta Formation (Beik and 

others, 2007). Thus, the Dinosaur Canyon Member represents 

the entire Moenave Formation within this quadrangle. The Moenave Formation is a red, slope-forming unit that gradually thins 

north and northeast of the map area and is removed by modern 

erosion southwest of the map area.

Kayenta Formation

The Kayenta Formation unconformably overlies the Moenave Formation. This unconformity is the sub-Kayenta Formation unconformity (J-sub-K) as defined by Riggs and Blakey 

(1993) and Blakey (1994). Erosional relief is generally less than 

6 ft (2 m) in the map area but can be as much as 50 ft (15 m) 

north of the map area (Nation, 1990). The Kayenta Formation 

includes, in ascending order, the Springdale Sandstone Member 

and an upper slope-forming sequence of siltstone and sandstone. 

The Springdale Sandstone forms an orange-red, thick-bedded 

sandstone cliff overlain by the purple-red, slope-forming 

siltstone and sandstone of the upper Kayenta Formation from 

southwest of Tuba City and northwest along the Echo Cliffs. 

The upper sequence undergoes a facies change northward to 

a series of light-red sandstone ledges and small, red siltstone 

slopes at Cedar Ridge.

Kayenta Formation-Navajo Sandstone Transition 

Zone

The Kayenta Formation grades upward into a sequence 

of interbedded red and white crossbedded sandstone ledges 

and purple-red mudstone and siltstone slopes mapped as the 

Kayenta-Navajo transition zone. The crossbedded sandstone 

cliffs within the transition zone in the map area grade northward into the Navajo Sandstone. The purple-red mudstone and 

siltstone slopes grade southward into the Kayenta Formation. 

Blakey (1994) subdivided the Navajo Sandstone of this region 

into two parts, as suggested by Marzolf (1983). The lower part 

is equivalent to and intertongues with eolian and fluvial deposits 

of the Kayenta-Navajo transition zone and the upper part is the 

eolian cliff-forming Navajo Sandstone found above the youngest documentable horizon of intertonguing. This subdivision of 

the Navajo Sandstone is recognized by Marzolf (1983) as the 

“wet lower part” and the “dry upper part.”

The Kayenta-Navajo transition zone is about 240 ft (73 

m) thick in the map area and grades laterally northwestward 

to become the basal part of the Navajo Sandstone near Cedar 

Ridge. The succession of fluvial, eolian, and lacustrine strata 

become more frequent as the Kayenta Formation thins in the 

zone of facies change southeast of the map area (Middleton and 

Blakey, 1983; Sargent, 1984; Long, 2008). Several springs and 

seeps are associated with the basal Navajo Sandstone tongues 

within the Kayenta-Navajo transition zone in the Tuba City, 

Moenave, and Moenkopi areas. The lowest sandstone cliff 

marks the approximate contact between the Kayenta Formation 

and the Kayenta-Navajo transition zone. The upper contact of 

the Kayenta-Navajo transition zone is marked at the base of the 

massive overlying Navajo Sandstone.

Navajo Sandstone

The Navajo Sandstone consists of red and white, cliffforming, eolian, crossbed sets and is the upper part of the 

Navajo Sandstone as proposed by Blakey (1994). The Navajo 

Sandstone includes several shallow lake horizons represented 

as thin-bedded, silica-cemented sandy limestone 1 to 2 ft (0.5 

to 1.2 m) thick that are highly lenticular and have limited lateral 

extent. These resistant limestone beds are at various stratigraphic levels within the Navajo Sandstone and locally form 

cherty limestone ledges, ridges, or small hills on the Kaibito and 

Moenkopi Plateaus. The number of limestone ledges increases 

southeast of the map area. The Navajo Sandstone thins south 

and east of the map area and is gradually removed by Cretaceous erosion southeast of the map area.

Carmel Formation

The beveled upper surface of the Navajo Sandstone is 

an erosional unconformity known regionally as the J-1 and 

J-2 unconformity (Pipiringos and O’Sullivan, 1978; Blakey, 

1994). At Coal Mine Mesa in the southeast corner of the 

quadrangle, as much as 30 ft (9 m) of erosional relief separates 

the Navajo Sandstone from the overlying Jurassic Entrada 

Sandstone-Cow Springs Sandstone, undivided. The erosional 

channels are filled with conglomerate and sandstone that are 

likely correlative to the southernmost extent of the Carmel 

Formation (Jc) at Middle Mesa north of Coal Mine Mesa 

(east-central edge of the quadrangle) where about 30 ft (9 

m) of the Carmel Formation overlies the Navajo Sandstone. 

The Carmel Formation is also present northeast of the Red 

Lake Monocline in the northeast corner of the quadrangle. 

The Carmel Formation has been removed from much of the 

Kaibito Plateau by modern erosion.

Entrada Sandstone-Cow Springs Sandstone

Strata overlying the Navajo Sandstone in the southeast 

corner of the map area consists mostly of white and interbedded, red and white, crossbedded Entrada Sandstone overlain 

by a yellowish, crossbedded cliff of Cow Springs Sandstone, 

undivided (Je). This sandstone sequence includes thin red beds 

of the Carmel Formation at the base that extend a short distance 

southward into the subsurface of Coal Mine Mesa and then 

pinch out. The upper part of the sandstone sequence, above the 

interbedded red and white sunstone beds, is a yellowish-white, 

cliff and slope of planar crossbedded sandstone that is a southern extension of the Cow Springs Sandstone (Harshbarger and 

others, 1958).
8

The lower part of the Entrada Sandstone consists of massive, white, very fine grained, cliff- and slope-forming sandstone that weathers steel gray and contains multiple small-scale, 

low-angle trough crossbeds at Moenkopi Plateau, southeastern 

quarter of the map. In the northeast quarter of the quadrangle, 

a red and white, flat-bedded sequence of cliff-forming sandstone makes up a middle red sandstone sequence of the Entrada 

Sandstone. These red siltstone and sandstone beds increase to 

more reddish sandstone north of the quadrangle and pinch out 

south of Coal Mine Mesa on Moenkopi Plateau in the southeast 

quarter of the quadrangle.

The Entrada Sandstone-Cow Springs Sandstone, undivided, is unconformably overlain by the Cretaceous Dakota 

Sandstone in the eastern Coal Mine Mesa area and northeast 

of the quadrangle and are overlain by Tertiary gravels (Tgs) in 

the western part of Moenkopi Plateau. The Jurassic-Cretaceous 

unconformity is widespread east, northeast, and southeast of the 

map area.

Dakota Sandstone

The Dakota Sandstone crops out at Coal Mine Mesa on 

Moenkopi Plateau in the southeast corner of the map area and 

on White Mesa in the northeast corner. The Dakota Sandstone is 

subdivided into three informal units. In ascending order they are 

the lower sandstone member, the middle carbonaceous member, 

and the upper sandstone member. All are present at Coal Mine 

Mesa and have gradational contacts between them (O’Sullivan 

and others, 1972). All three members are too small to show at 

map scale and are collectively mapped as the Dakota Sandstone 

(Kd).

A coal bed, locally several feet thick, was mined from 

this unit at Coal Mine Canyon for use at Tuba City in the early 

1900s. The Dakota Sandstone has a gradational and arbitrary 

contact with the overlying Mancos Shale.

Mancos Shale

The lower part of the Mancos Shale is present at Coal 

Mine Mesa on the Moenkopi Plateau. Modern erosion has 

removed most of the bluish-gray, thin-bedded, slope-forming 

Mancos Shale from Coal Mine Mesa and White Mesa. Remnants of the Mancos Shale are now largely covered by extensive 

deposits of Pleistocene and Holocene eolian and fluvial sand, 

silt, and mud. At White Mesa, much of the Dakota Sandstone 

and Mancos Shale deposits have been removed by Tertiary erosion. What remains is partly overlain by gravels and sedimentary deposits of Tertiary age.

Cenozoic Volcanic Rocks

 Shadow Mountain, located about 1 km south of the southcentral edge of the map, is an isolated Pleistocene pyroclastic 

cone with associated basalt flows that are chemically and 

petrologically similar to rocks of the San Francisco volcanic 

field. This cone represents the northernmost extent of this 

volcanic field. Shadow Mountain has a K-Ar age of 0.649±0.23 

Ma (Damon and others, 1974; Condit, 1974; Ulrich and Bailey, 

1987; Wolfe and others, 1987). These deposits (Qi, Qsb, Qsp) 

adjoin those of the Cameron 30′ x 60′ quadrangle (Billingsley 

and others, 2007) at the south-central edge of the map area. 

Older intrusive dikes (Ti) are oriented generally northsouth in Moenkopi Wash southwest of Tuba City, in Hamblin 

Wash south of The Gap, at Tuba Butte northwest of Tuba City, 

and at Wildcat Peak northeast of Tuba City. A new 40Ar/39Ar 

age from a dike at Wildcat Peak yields an age of 19.05±Ma 

(Peters, 2011). This north-south dike is similar in composition and orientation to the other three dike locations mentioned 

above and are all assumed to be a similar Miocene age. This age 

may reflect the southernmost extent of the 21 to 26 Ma volcanic laccolithic mountains in southern Utah, Navajo Mountain, 

and the Henry Mountains. The 19 Ma age also explains why 

there are no volcanic surface flows associated with these dikes, 

because any flows that may have occurred have been eroded 

away during Late Tertiary and Quaternary erosion along with 

much of the upper bedrock that exposes these dikes today.

Pliocene-Pleistocene Gravel Deposits

The oldest gravel and sediment deposits (Tgs) cap mesas 

or ridges as much as 50 ft (17 m) thick, mainly in the eastern part of the quadrangle. These deposits commonly form a 

cap-rock deposit on Middle Mesa, on Coal Mine Mesa, and at 

Crooked Ridge. The deposits rest unconformably on beveled 

surfaces of the Navajo Sandstone and the Carmel Formation. 

Gravel clasts within the sandstone and siltstone sediments are 

composed of well-rounded pebbles and cobbles of chert, quartzite, sandstone, limestone, some fossil wood fragments, and 

reworked marine fossils derived mainly from Cretaceous rocks 

and perhaps some Jurassic rocks east of the map area.

Younger old terrace gravel deposits (QTg5, QTg6, QTg7) 

are present at three different levels above Moenkopi Wash and 

below the oldest gravel and sediment deposits (Tgs) capping 

Middle Mesa and Moenkopi Plateau east of Tuba City. These 

deposits reflect various stages of incision into the Navajo 

Sandstone by an ancestral Moenkopi Wash probably within the 

last few hundred thousand years. In the Grand Canyon, gravel 

(QTg5) and sediment deposits of Quaternary age, but with a 

different lithology, form isolated, well-consolidated terrace 

deposits about 400 to 450 ft (122 to 137 m) above the Colorado 

River.

Quaternary Surficial Deposits

Surficial Mapping Technique

Surficial deposits on the Colorado Plateau have largely 

been ignored because their role on the landscape was not recognized. Today we are learning how significant these deposits are 
9

on biology, soil science, and climate studies as well as on the 

evolutionary development of the landscape.

Surficial sedimentary deposits have accumulated over the 

last several hundred thousand years. They generally occur as 

unconsolidated or weakly consolidated deposits of local extent 

overlaying bedrock. They are usually a thin veneer but can be 

as much as several tens of meters thick. Surficial deposits have 

accumulated mainly as a result of running water (fluvial or 

alluvial deposits), wind (eolian deposits), or a combination of 

both. Steep slopes near buttes and mesas often have landslide, 

talus, and rockfall deposits. Deposits in alluvial valleys, washes, 

and floodplains are often remobilized by wind forming adjacent 

sand dune and sand sheet deposits.

Mapping surficial deposits across an area as large as 

the Tuba City 30′ x 60′ quadrangle poses unique challenges. 

Although a fairly recent age is obvious, very little data is available to confidently assign the deposits to Holocene, Pleistocene, 

or older. A map-unit naming scheme that combines information 

about lithology and genesis was needed. To accommodate these 

criteria, the materials are classified and named using genesis 

(for example, alluvium, eolian, talus, landslide), geologic 

age (for example, Holocene, Pleistocene), and lithology (for 

example, sand, gravel). This strategy has evolved from previous 

surficial mapping in the Grand Canyon region (Billingsley and 

Workman, 2000; Billingsley and Wellmeyer, 2003; Billingsley 

and others, 2006, 2007, 2008).

Information about surficial deposits was obtained mainly 

by aerial photo interpretations. Ages are based mostly on 

geomorphologic criteria, such as relative position in local 

alluvial-terrace sequences, degree of alluvial fan dissection, and 

superposition or stabilization of dune and sand sheet deposits. 

The discontinuous aspect of surficial deposits does not lend 

itself to easy correlation. Therefore, all age assignments for surficial materials are provisional and the age of a specific unit in 

one area may not be correlative to the same unit in another area. 

Unit names with time implications, such as young, intermediate, old, and older, are intended only to indicate local relative 

stratigraphic position, not age uniformity, throughout the map 

area. A few eolian units common to both the Cameron and Tuba 

City 30′ x 60′ quadrangles were adjusted to a younger age for 

this publication and, therefore, are not the same color as on the 

Cameron 30′ x 60′ quadrangle (Billingsley and others, 2007).

Local Surficial Deposits

Surficial fluvial deposits are found throughout parts of 

the western map area and tend to be isolated because of steep 

topography and rapid modern erosion. In contrast, extensive 

eolian deposits cover large areas of the Kaibito and Moenkopi Plateaus in the eastern part of the map, where the Navajo 

Sandstone is the primary source for surficial sand sheet and sand 

dune deposits. Not all sand deposits are individually shown. In 

several areas, such as north and east of Tuba City, sand deposits are mapped as an undifferentiated unit consisting of various dune types and small pockets of bedrock. These extensive 

eolian deposits are transported northeastward across Moenkopi 

and Kaibito Plateaus by southwesterly winds. In many areas, 

these eolian deposits are continually recycled; storm runoff 

erodes then redeposits them in enclosed ponded (Qps) depressions, where wind moves them back onto and across the plateau. 

Eventually, much of the eolian sand is fluvially transported by 

fluvial processes into main drainages, such as Moenkopi Wash 

and Hamblin Wash, that drain into the Little Colorado River, 

through the Grand Canyon, and out of the region.

Other surficial deposits include travertine deposits that 

originate from springs in the Grand Canyon and form travertine 

dams in the bed of the Little Colorado River Gorge that are 

too small to show at map scale. Numerous landslide (Ql) and 

talus and rockfall (Qtr) deposits are below the rims of the Little 

Colorado River Gorge, Marble Canyon, and Grand Canyon and 

along the Echo Cliffs east of U.S. Highway 89. Diversion dams, 

stock tanks, gravel pits, and a landfill east of Tuba City are 

mapped to show the human impact upon the landscape.

Structural Geology

Structural deformation of the Paleoproterozoic (X), Mesoproterozoic (Y), and Neoproterozoic (Z) rocks at the bottom 

of Grand Canyon are well illustrated by Timmons and others 

(2007) showing the multiple extensional and folding events of 

Mesoproterozoic and Neoproterozoic time that largely corresponds with the deposition of Unkar and Chuar Group rocks. 

Rocks of the Unkar Group were faulted and slightly tilted as 

coherent blocks then were beveled by a period of erosion that 

lasted nearly 300 million years. Deposition of the overlying 

Chuar Group resulted in an angular unconformity between the 

Unkar and Chuar Groups (Timmons and others, 2007). During 

Neoproterozoic time, the Chuar Group was subjected to additional folding and, most importantly, west-down normal slip on 

Butte Fault formed a deep Chuar Group depocenter; drag along 

this fault produced the Chuar Syncline of Neoproterozoic age 

(Timmons and others, 2007).

Large high-angle to nearly vertical normal-fault separations 

in Proterozoic basement rocks set the stage for structural deformation of younger Paleozoic and Mesozoic strata. Compressional folding of Paleozoic and Mesozoic rocks along reactivated 

Proterozoic high-angle faults began in Late Cretaceous and early 

Tertiary time—a period known as the Laramide Orogeny that 

peaked about 65 Ma. Numerous northeast- to east-dipping sinuous monoclines in the western half of the map area are the result 

of Laramide compression along Proterozoic faults. Concurrent 

and subsequent erosion has removed much of the Mesozoic 

strata that once covered the entire map area (Huntoon, 1990, 

2003; Huntoon and others, 1996; Timmons and others, 2007).

The East Kaibab Monocline has elevated the landscape 

to the west forming the topographic highlands of the Walhalla 

and Kaibab Plateaus (fig. 1, sheet 3). The East Kaibab Monocline extends northwestward into Utah and forms the structural 

boundary between the Kaibab Plateau and House Rock Valley 

to the east (Billingsley and others, 2008). The monocline also 

extends southeast of the map area to Gray Mountain (Billingsley and others, 2007). Strata along the East Kaibab Monocline 

dip northeast between 20° and 80° with the steepest dip in the 
10

lower part of the fold in Grand Canyon (Timmons and others, 

2007). Vertical relief of Paleozoic strata along the East Kaibab 

Monocline and Butte Fault in Grand Canyon averages about 

1,000 ft (305 m) up to the west.

The Echo Cliffs Monocline, another major fold, extends 

from Cedar Ridge at the north-central edge of the map southeastward along U.S. Highway 89 and the Echo Cliffs to about 

Hidden Springs northwest of Moenave. From Hidden Springs, 

the Echo Cliffs Monocline bends southwest into the Painted 

Desert, where it gradually broadens and terminates just south 

of the south-central edge of the map. In this area, the southwest 

trend of the Echo Cliffs Monocline is structurally aligned with 

the northeast trend of the Mesa Butte Fault located about 12 mi 

(19 km) south of the map edge (Billingsley and others, 2007). 

The Echo Cliffs Monocline continues north of the quadrangle 

to Lees Ferry and then northwest into southern Utah. Permian, 

Triassic, and Jurassic strata that outcrop along the Echo Cliffs 

Monocline dip east 12° to 18° along the north half of the structure and southeast 3° to 4° along the south half.

Northeast-trending high-angle normal faults intersect the 

Echo Cliffs Monocline just south of Cedar Ridge where strata is 

folded to a near vertical position and partially faulted as much 

as 100 ft (30 m). Folding along the Echo Cliffs Monocline has 

elevated Marble Plateau an estimated 1,700 ft (518 m) up to the 

west at Cedar Ridge in the north half of the quadrangle and less 

than 500 ft (152 m) west of Moenkopi Wash in the south half of 

the quadrangle. Oddly enough, the average elevation of Marble 

Plateau west of the Echo Cliffs Monocline is nearly at the same 

average elevation, about 6,200 ft (1,890 m), as the Moenkopi 

and Kaibito Plateaus east of the monocline.

Blue Spring Monocline is a small northwest-trending fold 

displaying northeast-dipping Paleozoic and Mesozoic strata in 

the southwest quarter of the map area. Relief along this monocline is generally less than 200 ft (60 m) and the average dip 

of strata is about 5°. Several collapse structures align along 

the northwest trend of the Blue Spring Monocline, suggesting 

enhanced karst solutioning of the Redwall Limestone (Wenrich 

and Huntoon, 1989; Wenrich and Sutphin, 1989). The Blue 

Spring Monocline is one of the most important hydrological 

structures within the map area because Blue Spring and several 

associated springs issue from the top part of the Redwall Limestone at the northwest extent of the Blue Spring Monocline at 

the bottom of the Little Colorado River Gorge. Numerous northwest-trending joints, fractures, and small faults associated with 

the Blue Spring Monocline form a major hydrologic avenue for 

groundwater transport from regions southeast of the map area 

to Blue Spring. Blue Spring is the largest natural flowing spring 

in Arizona. Daily discharge is nearly 200 ft3/s (Don Bills, oral 

commun., 2012).

On the eastern side of the quadrangle, a few broad northnorthwest-trending folds roughly parallel the Echo Cliffs Monocline. The Tuba City Syncline extends from Coal Mine Mesa 

north to and beneath Crooked Ridge and north of the map area. 

The White Point Fault (Cooley and others, 1969) is not very 

evident in the crossbedded Navajo Sandstone where reverse 

fault drag along the fault makes it difficult to locate strata, 

which may dip west as much as 22° between White Point Mesa 

and Preston Mesa. The White Point Fault gradually disappears 

beneath sand deposits north and south of White Point. Northeast of White Point is the Preston Mesa Anticline (Cooley and 

others, 1969). This anticline trends northwest-southeast through 

Preston Mesa with strata dipping less than 5°. The Red Lake 

Monocline trends northwest-southeast at the northeast corner of 

the quadrangle between Wildcat Peak and White Mesa. Strata 

along Red Lake Monocline dip 15° to 20° east in the vicinity of 

Kaibito just north of the map area.

During the Miocene, Pliocene, and Pleistocene, east-west 

extension reactivated deep-seated faults along some monoclines, producing normal faults that reversed Cretaceous and 

Tertiary offset, as well as accentuated the dip of the monoclines by reverse drag along the faults (Huntoon, 1990, 2003). 

Extensional faulting during the late Pliocene produced many 

graben structures. A time frame of less than 3 m.y. is inferred, 

based on similar extensional fault evidence along the Hurricane 

and Toroweap Faults west and south of the map area (Billingsley and Workman, 2000; Billingsley and Wellmeyer, 2003; 

Billingsley and others, 2006, 2007, 2008), but this is not well 

constrained. North- and northeast-trending grabens and faults 

in the Little Colorado River Gorge and Marble Plateau areas 

appear to be the most recent tectonic structures in the area based 

on minor offset of Pleistocene and Holocene(?) alluvial deposits 

and Pleistocene volcanic rocks south of the map (Billingsley 

and others, 2007). Several sinkholes have developed along fractures and joints associated with the faults and grabens. These 

sinkholes have temporarily interrupted runoff to some small 

tributaries of the Little Colorado River.

The Laramide erosional period starting about 60 Ma began 

to transform the landscape to its current configuration, but 

Neogene Tertiary and Quaternary erosion greatly deepened and 

broadened the Grand Canyon. The meandering Little Colorado 

River occupied a strike valley in soft Mesozoic rocks between 

the East Kaibab Monocline and Marble Plateau and has been 

superimposed as a subsequent stream into the resistant rocks of 

the Kaibab Formation in the southern part of Marble Plateau, 

preserving the older meander pattern. At about the same time, 

an unnamed drainage from the northeast was meandering on 

the Navajo Sandstone along a strike valley that parallels the 

Echo Cliffs Monocline in the vicinity of The Gap. This drainage 

system is responsible for at least two of the topographic gaps in 

the Echo Cliffs. Well-rounded sandstone and chert pebbles and 

cobbles of Jurassic and Cretaceous age suggest that the Crooked 

Ridge drainage originated from the Black Mesa area east or 

northeast of the quadrangle and that pebble imbrication of the 

gravels in the sandy sediment indicate a southwest-flowing 

stream that deposited the Crooked Ridge stream sediments 

toward the Echo Cliffs Monocline, then meandered southeast 

along a monoclinal strike valley towards the Tuba City area. 

Lag gravels scattered on the Kaibito Plateau northeast and near 

Tuba City are evidence of this drainage.

The Little Colorado River and its tributaries became 

integrated with the Colorado River sometime in late Miocene 

or early Pliocene time after about 6 to 9 Ma (Lucchitta, 1979, 

1990; Ranney, 2005). Continued headward erosion of the Little 

Colorado River, caused by erosional deepening of the Colorado River in Grand Canyon, has gradually extended the Little 

Colorado River Gorge upstream toward Cameron and into the 
11

eastern half of the map area. Headward erosion from the Colorado River continues westward into the Kaibab and Walhalla 

Plateaus and has greatly enhanced the widening process of 

eastern Grand Canyon along the East Kaibab Monocline.

Circular bowl-shaped depressions in the Kaibab and Moenkopi Formations, characterized by inward-dipping strata, are 

likely to be the surface expression of collapse-formed breccia 

pipes created by dissolution of the Mississippian Redwall Limestone at depth. Collapse features are indicated by a black dot on 

the map and may or may not represent breccia pipes at depth. 

Drilling is needed to confirm breccia pipes within collapse 

structures. Exposed breccia pipes are indicated by red dots.

Large-scale collapse depressions may be the result of several interconnecting smaller collapse features or breccia pipes, 

such as the Shadow Mountain collapse on the Marble Plateau at 

the south-central portion of the quadrangle (fig. 1, sheet 3). The 

Shadow Mountain collapse is a circular, alluvial-filled structural 

basin about 0.6 mi (1 km) in diameter. The Chinle Formation 

dips between 5° and 18° toward the center of the collapse. Breccia pipes have the potential for uranium and other minerals at 

depth, but not all breccia pipes are mineralized (Wenrich and 

Sutphin, 1989; Wenrich, 1992). Only circular collapse features 

that have inward-dipping strata are marked on the map as potential breccia pipes at depth.

Gypsum dissolution in the Harrisburg Member of the 

Kaibab Formation has resulted in several sinkholes on the 

Kaibab Plateau. The sinkholes are likely Pleistocene and 

Holocene in age because they disrupt local drainages and are 

commonly filled with locally derived, fine-grained sediments. 

Gypsum deposits within the Kaibab and Toroweap Formations 

are thickest along the west edge of the map as evidenced by the 

increase in sinkholes of that area.

Acknowledgments

We appreciate the cooperation and support of the Water 

Resource Division and the Geologic Division of the National 

Park Service, Fort Collins, Colorado, and the Grand Canyon 

Science Center, National Park Service, Grand Canyon National 

Park, Arizona. We appreciate the Navajo Nation Minerals 

Department and the Hopi Tribe for permission to publish 

those portions of this map involving Navajo Nation and Hopi 

Tribal lands. We also appreciate the advice, revisions, and 

geologic information provided by Mark Timmons of New 

Mexico Bureau of Mines and Mineral Resources, Socorro, New 

Mexico, and Karl Karlstrom of the University of New Mexico, 

Albuquerque, New Mexico. We are indebted to Dr. Charles L. 

Powell, II, and Jan Zigler of the U.S. Geological Survey, Menlo 

Park, California, for their technical advice and assistance in the 

preparation of this map and report.

DESCRIPTION OF MAP UNITS

SURFICIAL DEPOSITS

Pliocene(?), Pleistocene, and Holocene surficial deposits are differentiated from one another chiefly 

based on differences in morphologic character and physiographic position on 1:24,000-scale, 1968, black 

and white; 1:24,000-scale, 2005, color; and 1:40,000-scale, 2005, color aerial photographs and on field 

observations of the lithology. Older alluvial and eolian deposits generally exhibit extensive erosion, have 

greater topographic relief, and in some areas have developed a carbonate soil subhorizon. Younger deposits are actively accumulating material or are lightly eroded. On Moenkopi and Kaibito Plateaus, extensive eolian sand sheet and dune deposits are stabilized by vegetation during wet conditions and become 

destabilized and mobile when disturbed by livestock or human activity. These deposits are also partially 

reactivated during severe drought conditions or spring wind events. Young surficial deposits are actively 

accumulating material and are vulnerable to wind or water erosion. Eolian and alluvial contacts are provisional and arbitrary.

Qaf Artificial fill and quarries (Holocene)—Excavated alluvium and bedrock material removed 

from barrow pits and trenches to build livestock tanks, drainage diversion dams, landfills, 

roads, and other construction projects (not all road and construction excavations are shown)

Qs Stream-channel deposits (Holocene)—Poorly sorted, interbedded mud, silt, sand, pebbles, and 

gravel. Intertongue with or inset against young, intermediate, and old alluvial fan (Qa1, 

Qa2, Qa3), young, intermediate, and old terrace-gravel (Qg1, Qg2, Qg3), and upper part 

of valley alluvial (Qv) deposits; overlaps and intertongues with flood-plain (Qf) and ponded 

sediment (Qps) deposits. Stream channels subject to high-energy flows and flash floods. 

Little or no vegetation in stream channels, except for some salt cedar (tamarisk), Russian 

olive, and cottonwood trees. Contacts with adjacent alluvial or eolian deposits are approximate. Stream-channel deposits of Moenkopi and Hamblin Washes do not necessarily reflect 

stream-channel deposits of today owing to low-gradient channel changes caused by yearly 

fluctuations in stream levels and flooding events. Thickness, 3 to 30 ft (1 to 9 m)
12

Qf Flood-plain deposits (Holocene)—Gray, brown, to light-red interbedded lenses of clay, mud, 

silt, and sand. Include minor lenticular gravel deposits, partly consolidated by gypsum and 

calcite cement. Intertongue with or overlap stream-channel (Qs), valley-fill (Qv), young 

terrace-gravel (Qg1), and young alluvial fan (Qa1) deposits. Subject to stream-channel erosion or overbank flooding in lateral and vertical sense. Similar to valley-fill (Qv) deposits in 

small tributary drainages; subject to widespread and frequent overbank flooding along Colorado River, Little Colorado River, Moenkopi Wash, and Hamblin Wash areas. Support thick 

growths of sagebrush and grass, tumble weed, desert shrubs, and tamarisk trees. Subject to 

temporary ponding and often mixed with ponded sediments (Qps) or mixed alluvium and 

eolian (Qae) deposits in broad drainages on Moenkopi and Kaibito Plateaus. Thickness, 3 to 

30 ft (1 to 9 m)

Qes Sand sheet deposits (Holocene)—White, gray, fine- to coarse-grained, windblown sand composed mainly of quartz and chert grains derived primarily from the Navajo Sandstone and 

Moenave Formation. Deposits form extensive cover over gently sloping terrain on Moenkopi and Kaibito Plateaus in eastern third of map. Also form thin sand sheets on alluvial 

fan slopes below the Echo Cliffs parallel to U.S. Highway 89. Commonly intertongue with 

mixed alluvial and eolian (Qae) deposits that share a gradational lateral and vertical contact. 

Support moderate growths of grass and small high-desert shrubs that tend to stabilize the 

deposits. Thickness, 1 to 15 ft (0.3 to 4.5 m)

Qd Dune sand and sand sheet deposits (Holocene)—Grand Canyon, Coconino Plateau, and Marble 

Plateau areas: White, gray, and light-red, fine- to coarse-grained, windblown sand composed 

mainly of quartz, feldspar, and chert grains derived from Proterozoic, Paleozoic, and Mesozoic sand and gravel deposits that accumulate in stream-channel (Qs) or valley-fill (Qv) 

deposits and are transported by wind to form lumpy, undefined geometric sand dunes or sand 

sheet deposits on flood-plain (Qf) and young terrace-gravel (Qg1) deposits near washes in 

west half of map. Support moderate growths of grass and sagebrush

Moenkopi and Kaibito Plateau areas: White, gray to light-red, fine- to coarse-grained 

sand composed mainly of quartz, chert, and minor feldspar derived from nearby Triassic 

and Jurassic sedimentary rocks east of U.S. Highway 89. Include topographically controlled 

climbing and falling dunes, complex dunes, parabolic dunes, barchan dunes, and sand sheets 

that mantle bedrock slopes north and south of Moenkopi Wash, along the Echo Cliffs, and 

within drainages on Moenkopi and Kaibito Plateaus. Navajo Sandstone (Jn) is the primary 

source of sand on Moenkopi and Kaibito Plateaus. Unit has arbitrary and gradational contacts, in the lateral and vertical sense, with adjacent surficial deposits and bedrock outcrops. 

Sand is generally transported northeast by southwesterly winds that erode local Triassic 

sandstone units and older sand deposits. Unit distributes a fresh veneer of sand over bedrock 

and older eolian deposits on Coal Mine Mesa. Support moderate growth of grass, Mormon 

tea, and high desert shrubs. Wet conditions stabilize all eolian deposits on Moenkopi and 

Kaibito Plateaus. Thickness, 3 to 200 ft (1 to 61 m)

Qdl Linear dune deposits (Holocene)—White, gray, light-red, fine- to medium-grained, well-sorted, 

unconsolidated sand accumulations that are aligned and generally trend northeast. Often 

merge with dune sand and sand sheet (Qd), sand sheet (Qes), parabolic dune (Qdp), and 

barchan dune (Qdb) deposits. Linear dunes are generally 40 to 80 ft (12 to 24.5 m) wide and 

less than 0.5 mi (0.8 km) long but can reach over 3 mi (5 km) or more in length on Moenkopi and Kaibito Plateaus. Individual linear dunes are mapped where they form prominent 

landscape features on Moenkopi and Kaibito Plateaus. Groups of linear dunes are mapped as 

linear dune and sand sheet deposits (Qdlu). Thickness, 6 to 40 ft (2 to 12 m)

Qdp Parabolic dune deposits (Holocene)—White, gray, light-red, fine- to coarse-grained, wellsorted, unconsolidated quartz sand arranged most commonly in complex interconnecting 

parabolic dune deposits or occasionally in individual parabolic dunes. Sandy ponded sediments (Qps) are commonly formed on upwind (southwest) side of dune complex. Bedrock 

or older sand accumulation is often exposed at southwest side of parabolic dunes. Contact 

merges with adjacent dune sand and sand sheet (Qd) and sand sheet (Qes) deposits, mixed 

alluvial and eolian (Qae) deposits, and local Mesozoic bedrock outcrops on Moenkopi and 

Kaibito Plateaus. Support little to sparse grassy vegetation. Thickness, 6 to 30 ft (2 to 9 m)

Qdb Barchan dune deposits (Holocene)—White, gray, light-red, fine- to coarse-grained, well-sorted, 

unconsolidated quartz sand that forms isolated barchan dunes or a cluster of interconnecting 

barchan dunes mainly northeast of Tuba city, on Kaibito Plateau. Subject to yearly change 
13

in extent and shape due to seasonal storms and sand mobility. Support little to sparse grassy 

vegetation. Thickness, 6 to 40 ft (2 to 12 m)

Qdm Mixed dune deposits (Holocene)—White, gray, light-red, fine- to coarse-grained, well-sorted, 

unconsolidated quartz sand derived primarily from the Navajo Sandstone (Jn). Parabolic 

and linear dunes are the dominant dune types and are often interconnected and associated 

with massive sand sheet (Qes) deposits. Linear dunes often form as downwind extension of 

parabolic dunes on Moenkopi and Kaibito Plateaus and parabolic dunes often attach to or are 

part of linear dunes. Include quite a few Navajo Sandstone (Jn) and ponded sediment (Qps) 

deposits too small to show at map scale. Often covered annually by active dune sand and 

sand sheet (Qd) deposits. Thickness, 6 to 40 ft (2 to 12 m)

Qdlu Linear dune and sand sheet deposits (Holocene)—White, gray, light-red, fine- to coarsegrained, well-sorted, unconsolidated quartz sand derived primarily from the Navajo Sandstone (Jn) on Moenkopi and Kaibito Plateaus. Unit is often a cluster or group of closely 

spaced linear dune and sand sheet deposits. Individual linear dunes often merge and separate 

as an interconnecting mass of dune forms with abundant sand sheet deposits between. Support little to sparse grassy vegetation. Thickness, 9 to 40 ft (3 to 12 m)

Qg1 Young terrace-gravel deposits (Holocene)—Light-brown, pale-red, and gray, well-sorted, 

interbedded clay, silt, sand, gravel, pebbles, cobbles, and some boulders. Include wellrounded clasts of quartzite, quartz, chert, sandstone, and limestone. Support light to moderate growths of grass, cactus, and desert shrubs. Subject to flash-flood erosion and overbank 

flooding. Locally overlap young alluvial fan (Qa1), flood-plain (Qf), and valley-fill (Qv) 

deposits. Often covered by dune sand and sand sheet (Qd) and sand sheet (Qes) deposits 

in east half of quadrangle. Support light vegetation, mainly grass, and a few desert shrubs. 

Form benches about 3 to 12 ft (1 to 3.5 m) above stream-channel (Qs) or flood-plain (Qf) 

deposits. Subject to frequent flash flood erosion. Thickness, 6 to 20 ft (2 to 6 m)

Qa1 Young alluvial fan deposits (Holocene)—In Grand Canyon: Reddish-gray to light-brown silt, 

sand, gravel, pebbles, cobbles, and boulders; partly consolidated by calcite and gypsum 

cement. All material is derived primarily from Precambrian and Paleozoic rocks and subject 

to flash-flood debris flows. Pebbles, cobbles, and boulders are subangular to rounded. Little 

to no vegetation cover. Thickness 10 to 30 ft (3 to 9 m)

On Marble Plateau: Gray-brown to red silt, sand, gravel, pebbles, cobbles, and boulders; partly consolidated by gypsum and calcite cement. Local outcrops of the Kaibab and 

Moenkopi Formations provide silt and sand and also supply calcite, gypsum, and some salt 

as cementing agents for most alluvial deposits on Marble Plateau. Support light growths of 

sagebrush, cactus, and grass. Thickness 3 to 20 ft (1 to 6 m)

In eastern third of map area: Gray, light-brown, and light-red, clay, silt, sand, pebbles, 

and cobbles of chert, limestone, and sandstone; unconsolidated. Unit often overlapped by 

stream-channel (Qs), ponded sediments (Qps), flood-plain (Qf), dune sand and sand sheet 

(Qd), and sand sheet (Qes) deposits. Intertongue with upper part of valley-fill (Qv), young 

terrace-gravel (Qg1), and mixed alluvium and eolian (Qae) deposits. Clay, silt, and sand are 

primarily derived from local outcrops of Triassic, Jurassic, and Cretaceous rocks. Subject 

to extensive sheet-wash erosion, wind erosion, flash flood debris flows, and arroyo erosion. 

Thickness, 3 to 30 ft (1 to 9 m)

Qg2 Intermediate terrace-gravel deposits (Holocene)—Gray and brown silt, sand, gravel, and 

lenses of pebbles or conglomerate; partly consolidated. Lithologically similar to young 

terrace-gravel (Qg1) deposits. Siltstone and fine-grained sandstone matrix is mixed with 

subangular to rounded pebbles and boulders derived from nearby bedrock. Form benches 

about 15 to 30 ft (4.5 to 9 m) above modern streambeds and about 6 to 20 ft (2 to 6 m) above 

young terrace-gravel (Qg1) deposits in upper reaches of tributary streams. Support growths 

of grass and a variety of high-desert shrubs. Subject to cutbank erosion. Locally intertongue 

with, overlain by, or inset into young and intermediate alluvial fan (Qa1, Qa2), valley-fill 

(Qv), mixed alluvium and eolian (Qae), talus and rockfall (Qtr), and landslide (Ql) deposits. 

Thickness, 6 to 25 ft (2 to 7.5 m)

Qa2 Intermediate alluvial fan deposits (Holocene)—Lithologically similar to young alluvial fan 

(Qa1) deposits; partly cemented by calcite, gypsum, and clay. Surface of unit is partly 

eroded by sheetwash erosion that incises as much as 3 to 10 ft (1 to 3 m). In eastern third of 

quadrangle, unit is often covered by dune sand and sand sheet (Qd) and sand sheet (Qes) 

deposits. Unit is commonly overlapped by young alluvial fan (Qa1) deposits and inter-
14

tongues or overlaps with valley-fill (Qv), talus and rockfall (Qtr), and young and intermediate terrace-gravel (Qg1, Qg2) deposits. Support light to moderate growths of grass, 

sagebrush, and cactus. Thickness, 6 to 50 ft (2 to 15 m)

Qps Ponded sediments (Holocene)—Gray or red-brown clay, silt, sand, and gravel; partly consolidated by calcite and or gypsum cement. Locally include small lenses of angular to subrounded chert and limestone fragments or pebbles in sandy matrix. Similar to flood-plain 

(Qf) deposits but occupy man-made ponded areas or natural internal drainage depressions 

caused by sinkhole development on plateau surfaces in western half of quadrangle. Deposits 

on Moenkopi and Kaibito Plateaus are commonly formed in depressions created by temporary sand dune dams or in wind deflation hollows of dune sand and sand sheet (Qd) and 

parabolic dune (Qdp) deposits. Desiccation cracks often develop on hardpan surfaces during 

dry conditions. Thickness, 5 to 30 ft (1.5 to 9 m)

Qg3 Old terrace-gravel deposits (Holocene)—Gray and light-brown, clay, silt, sand, gravel, cobbles, 

and boulders partly consolidated by clay, calcite, and gypsum cement; poorly sorted. Include 

abundant rounded and well-rounded clasts of quartzite, quartz, chert, sandstone, and limestone in Grand Canyon. Form terrace deposits adjacent to and as much as 400 ft (122 m) 

above the Colorado River. Thickness, 25 to 80 ft (7.5 to 24 m)

Qa3 Old alluvial fan deposits (Holocene)—Gray and light-brown, unsorted silt, sand, and gravel 

mixed with brecciated and subrounded pebbles and cobbles of red sandstone and gray limestone and chert; partly consolidated by calcite and gypsum cement. Unit often overlain by 

sand sheet (Qes) and mixed alluvium and eolian (Qae) deposits in eastern half of quadrangle. Include large boulders, small cobbles and pebbles of sedimentary rocks derived from 

nearby talus and rockfall (Qtr) and landslide (Ql) deposits in western half of map. Support 

moderate growths of grass, sagebrush, cactus, and various desert shrubs. Thickness, 5 to 25 

ft (1.5 to 7.5 m)

Qae Mixed alluvium and eolian deposits (Holocene)—Gray, light-red, fine- to coarse-grained interbedded sand, brown clay and silt, and lenses of pebbly or brecciated gravel. Include angular 

white chert fragments locally derived from Permian strata on Kaibab and Marble Plateaus; 

white, gray, brown, and red chert fragments derived from members of the Chinle Formation in Painted Desert area; and white to gray chert fragments and concretionary sandstone 

pebbles derived from Navajo Sandstone on Moenkopi and Kaibito Plateaus. Deposits accumulate by combinations of alluvial or eolian processes resulting in an interbedded sequence 

of mixed mud, silt, sand, and gravel. Deposit subject to sheetwash erosion and arroyo cutting 

during wet conditions and wind-blown sand accumulations during dry conditions. Sediments 

commonly accumulate on broad sandy flatlands or on gently sloping alluvial fans. Support 

light to moderate growth of grass, cactus, sagebrush, and high desert shrubs. Thickness, 3 to 

40 ft (1 to 12 m)

Qv Valley-fill deposits (Holocene)—Gray and light-brown silt, sand, and lenses of gravel; partly 

consolidated by gypsum and calcite. Include occasional rounded clasts of limestone, sandstone, and subrounded to angular chert derived from nearby bedrock; include abundant 

rounded chert or quartz pebbles derived from Shinarump Member of the Chinle Formation 

in Painted Desert area. Intertongue or overlap young and intermediate alluvial fan (Qa1, 

Qa2) deposits and young terrace-gravel (Qg1) deposits. Commonly reflect low-gradient, 

low-energy sediment accumulation in shallow drainages in all areas of the map area. Subject 

to sheetwash flooding and temporary ponding due to grasses at lower elevations; sagebrush, 

grass, cactus, and some forest trees at elevations above 6,000 ft (1,830 m); sagebrush and 

temporary blockage by eolian sand accumulation on Moenkopi and Kaibito Plateaus. Thickness, 3 to 30 ft (1 to 9 m)

Qt Travertine deposits (Holocene and Pleistocene(?))—Gray and tan, stained light-red, massive, 

porous, cliff-forming freshwater limestone. Include angular clasts of local talus breccia or 

stream gravel. Formed by rapid chemical precipitation of calcium carbonate from springwater discharge as encrustations on steep slopes or cliffs. Deposits are primarily near base of 

Cambrian Muav Limestone along east side of Colorado River and north side of Little Colorado River in Grand Canyon. Include numerous dams in bed of Little Colorado River too 

small to show at map scale. Include minor deposits at seeps along contact between Kayenta 

Formation-Navajo Sandstone transition zone (Jkn) and underlying Kayenta Formation (Jk) 

in Moenkopi Wash area that are too thin to show at map scale. Thickness, 6 to 60 ft (2 to 18 

m)
15

Qtr Talus and rockfall deposits (Holocene and Pleistocene(?))—In Grand Canyon: Gray to yellowish-red silt, sand, and gravel mixed with abundant angular limestone, sandstone, and chert 

rocks and boulders derived from steep-walled areas of Proterozoic and Paleozoic strata; 

partly cemented by calcite and gypsum.

Along Echo Cliffs: Red to yellow, silt and sand mixed with angular rocks and boulders 

of light-red or white sandstone and red to dark-red siltstone derived from Mesozoic outcrops 

along Echo Cliffs and Moenkopi wash; partly cemented by calcite. Unit often associated 

with or adjacent to landslide (Ql) deposits. Unit commonly grades downslope into young, 

intermediate, and old alluvial fan (Qa1, Qa2, Qa3) deposits or young and intermediate 

terrace-gravel (Qg1, Qg2) deposits. Thickness, 5 to 45 ft (1.5 to 14 m)

Ql Landslide deposits (Holocene and Pleistocene)—Landslides are unconsolidated to partly 

consolidated masses of angular unsorted rock debris. Include stratified blocks (slumps) that 

rotated backward against parent outcrop and slid downslope as loose incoherent masses of 

broken rock fragments and deformed strata; often form talus and rockfall (Qtr) deposits 

adjacent to and below landslide masses. Include individual car- and house-size boulders. 

Gradational and arbitrary contact with young, intermediate, and old alluvial fan (Qa1, Qa2, 

Qa3) and young, intermediate, and old terrace-gravel (Qg1, Qg2, Qg3) deposits. Subject to 

extensive sheetwash erosion, flash-flood debris flows, and arroyo erosion. Thickness, 10 to 

200 ft (3 to 61 m)

QTg4 Older terrace-gravel deposits (Pleistocene and Pliocene(?))—Gray and light-brown silt, sand, 

gravel and well-rounded flat pebbles and cobbles along higher beveled terraces of Navajo 

Sandstone (Jn) along Moenkopi Wash. Unit contains mud, silt, and sandy gravel derived 

from Cretaceous outcrops east of map area. Form terraced benches or ridges on Navajo 

Sandstone about 30 to 45 ft (9 to 14 m) above Moenkopi Wash. Unit is mainly exposed in 

cliff areas and commonly covered by thin dune sand and sand sheet (Qd) deposits. Thickness, 2 to 10 ft (0.5 to 3 m)

QTg5 Youngest old terrace-gavel deposits (Pleistocene and Pliocene(?))—Gray and light-brown 

clay, silt, sand, and gravel, poorly sorted; cemented by calcite on higher terrace levels along 

Moenkopi Wash. Contain rounded fragments of Cretaceous fossils and well-rounded flat 

quartzite, chert, sandstone, and limestone pebbles. Fossil fragments are derived from Cretaceous rocks east of the map area. Include iron-rich sandstone concretions probably derived 

from underlying Navajo Sandstone (Jn). Unit is covered by dune sand and sand sheet (Qd) 

deposits. Support moderate growths of grass and low desert shrubs. Thickness, 3 to 60 ft (1 

to 18 m)

QTg6 Intermediate old terrace-gravel deposits (Pleistocene and Pliocene(?))—Gray and lightbrown clay, silt, sand, and gravel, poorly sorted; cemented by calcite. Contain angular to 

subrounded chert, limestone, and sandstone pebbles derived from Cretaceous rocks east 

of the map area. Form isolated outcrops north of Moenkopi Wash and along U.S Highway 

160 east of Tuba City. Unit is mostly covered by extensive eolian sand deposits (Qd, Qes). 

Thickness, 6 to 30 ft (2 to 9 m)

QTg7 Oldest old terrace-gravel deposits (Pleistocene and Pliocene(?))—Gray and light-brown clay, 

silt, sand, and gravel, poorly sorted; cemented by calcite. Lithology similar to youngest and 

intermediate old terrace-gravel deposits (QTg5, QTg6) at highest levels north of Moenkopi 

Wash and east of Tuba City. Unit may represent part of an extensive pediment surface that 

drained from Black Mesa area east of map and formed before incision of Moenkopi Wash. 

Thickness, 6 to 18 ft (2 to 6 m)

Tgs Gravel and sedimentary deposits (Pliocene(?) and Miocene(?))—Gray, brown, and white 

clay, sand, silt, and gravel, poorly sorted; consolidated. Unit consists mostly of fine-grained 

gray silty sand that includes scattered pebbles and cobbles of well-rounded gray sandstone 

and limestone derived from Jurassic and Cretaceous rocks east and northeast of the map 

area. Forms extensive thin veneer on Moenkopi Plateau that overlies beveled Jurassic and 

Cretaceous rocks of the Navajo Sandstone (Jn), Entrada Sandstone (Je), Dakota Sandstone 

(Kd), and Mancos Shale (Km), in southeast quarter of map. Forms consolidated caprock 

deposit on Middle Mesa that overlies beveled Jurassic rocks of the Carmel Formation (Jc) 

and Navajo Sandstone (Jn), east edge of map. Forms partly consolidated mixed sandstone, 

siltstone, mudstone, and minor pebble sediments on Crooked Ridge in northeast corner of 

map. Unit at all three localities forms the highest surficial fluvial deposits, have a similar 

lithology, and are at approximate similar elevations that may be Pliocene (?) age based on 
16

relevant elevations above younger fluvial deposits of Moenkopi Wash. Age may be Miocene(?) as suggested by Lucchitta (2011). Thickness, 6 to 100 ft (2 to 30 m)

VOLCANIC ROCKS

Shadow Mountain is an isolated pyroclastic cone with associated basalt flows and dikes at the southcentral edge of the map area. These volcanic rocks are chemically and petrologically similar to rocks of the 

San Francisco volcanic field, representing the northernmost volcanic rocks of that field, and have a K-Ar 

age of 0.649±0.23 Ma (Damon and others, 1974; Condit, 1974). Miocene dikes are exposed in Moenkopi 

Wash, in Hamblin Wash, at Tuba Butte, and at Wildcat Peak. A recent 40Ar/39Ar age from a dike at Wildcat 

Peak is 19.05±0.10 Ma (Peters, 2011). 

Qi Intrusive dikes of Shadow Mountain (Pleistocene)—Black olivine-labradorite basalt dikes, 1 to 

3 ft (0.5 to 1 m) wide

Qsp Pyroclastic deposits of Shadow Mountain (Pleistocene)—Black and red scoria, cinder, and ash 

of olivine-labradorite basaltic composition. Overlie associated basalt flows (Qsb) and the 

Petrified Forest and Shinarump Members (^cp, ^cs) of the Chinle Formation. Thickness, 3 

to 135 ft (1 to 40 m)

Qsb Basalt flows of Shadow Mountain (Pleistocene)—Black olivine-labradorite basalt largely 

covered by associated pyroclastic (Qsp) deposits. Basalts flowed into small graben north of 

main cone, providing evidence that the graben is older than the flow. Flow is offset by a fault 

suggesting that faulting has occurred within the last 65 k.y. Thickness, 40 ft (12 m)

Ti Intrusive dikes (Miocene)—Dark-gray basalt composed of plagioclase, clinopyroxene, olivine, 

and opaque oxides. Dikes occur in Moenkopi Wash southwest of Tuba City, in Hamblin 

Wash south of The Gap, at Tuba Butte northwest of Tuba City, and at Wildcat Peak northeast 

of Tuba City. Dikes are extensively weathered and are 2 to 6 ft (0.05 to 2 m) wide and 15 to 

33 ft (5 to 10 m) in height

SEDIMENTARY ROCKS

Km Mancos Shale (Upper Cretaceous)—Bluish-gray to light-gray, thinly laminated to thinbedded, slope-forming, carbonaceous claystone, siltstone, and mudstone with interbedded 

light-gray, fine- to medium-grained sandstone. Includes bentonitic claystone, siltstone, 

and some thin-bedded limestone. Locally fossiliferous with cephalopods that are laterally equivalent to those in the Tropic Shale in the lower part of Mancos Shale in southern 

Utah. Age as defined by Doelling and others (2000). Deposited on a shallow sea floor 

that transgressed southwest from the midcontinent. Gradational and arbitrary contact with 

underlying Dakota Sandstone (Kd). Deposit is mostly removed by Tertiary erosion on 

Moenkopi Plateau south of Moenkopi Wash. Erosion channels as deep as 20 ft (6 m) are 

filled with Tertiary gravel and sedimentary deposits (Tgs) and probably represent widespread alluvial pediment and stream-channel deposition. Largely covered by sand sheet 

(Qes) and dune sand and sand sheet (Qd) deposits at Coal Mine Mesa on Moenkopi Plateau in southeast corner of map (sheet 2) and on White Mesa in northeast corner of map 

(sheet 2). Thickness, 140 ft (43 m) 

Kd Dakota Sandstone (Upper Cretaceous)—Medium- to light-gray, slope-forming, laminated to 

thin-bedded mudstone, siltstone, and sandstone. Locally includes lower sandstone, middle 

carbonaceous, and upper sandstone members as defined by O’Sullivan and others (1972; 

northeast and southeast corners of map). Age as defined by Doelling and others (2000)

Lower sandstone member: Light-orange to light-gray silty sandstone and conglomeratic 

sandstone that forms cliffs as much as 20 ft (6 m) thick seen in channels eroded into underlying Entrada Sandstone-Cow Springs Sandstone, undivided (Je). Unit pinches out or thins 

in short lateral distance within channels. Clasts in sandstone are composed of red and gray, 

well-rounded chert and quartzite typically less than 2 in (5 cm) in diameter. The regional 

angular unconformity between the Dakota Sandstone and underlying Jurassic-Cretaceous 

rocks is based on the Dakota Sandstone overlying younger rocks north of the map area and 

overlying older rocks south and southeast of the quadrangle. Although these relations establish the angularity of the pre-Dakota Sandstone age unconformity, the dip is so small that it 

is not apparent at most outcrops within the area (Harshbarger and others, 1958)

Middle carbonaceous member: Dark-grayish-brown, carbonaceous, flat-bedded mudstone, siltstone, and coal and interbedded brown, conglomeratic, crossbedded lenticular 
17

sandstone. Coal beds are generally less than 2 ft (0.5 m) thick at east end of Coal Mine Mesa 

on Moenkopi Plateau (southeast corner of map). Coal was mined from thicker coal beds 

at the rim of Coal Mine Canyon. Coal-seam fires in the recent past add vibrant red color 

(baked clay) in upper cliffs of Coal Mine Canyon. Gypsum is a common constituent in the 

siltstones, appearing as thin veins and isolated crystals. The upper sandstone member is not 

present in the map area

Unit unconformably overlies Entrada Sandstone-Cow Springs Sandstone, undivided 

(Je), in eastern part of Coal Mine Mesa where lower sandstone member is not present (J-2 

unconformity of Pipiringos and O’Sullivan, 1978). Mostly covered by extensive dune sand 

and sand sheet (Qd) deposits. Overall thickness, 10 to 40 ft (3 to 12 m)

San Rafael Group (Middle Jurassic)—The San Rafael Group (Middle Jurassic) includes, in 

ascending order, the Carmel Formation (Jc) and the Entrada Sandstone (Je) that overlies 

beveled crossbeds of the Navajo Sandstone (Jn), known as the J-2 unconformity that is recognized primarily on differences in lithology and color change from white sandstone of the 

Navajo to red siltstone of the Carmel. The Carmel Formation represents a shallow marine 

environment within a seaway that moved southward from Canada into northern Arizona and 

extended to and pinches out in the subsurface of Coal Mine Mesa. Overlying the Carmel 

Formation are white and red sandstone deposits of the Entrada Sandstone-Cow Springs 

Sandstone, undivided (Je), that represent a coastal beach and marine tidal flat

Je Entrada Sandstone-Cow Springs Sandstone, undivided (Middle Jurassic)—White, lightgray, and yellowish, very fine grained, trough crossbedded sandstone. Includes interbedded 

(5 to 7 ft [1.5 to 2 m]) thick beds of red siltstone and sandstone representing southern extent 

of reddish Entrada Sandstone units just north of quadrangle that thin rapidly southward and 

pinch out near and just south of Coal Mine Mesa. Interval of uppermost red, flat-bedded 

siltstone and sandstone is likely equivalent to the Summerville Formation north of map area. 

Uppermost interval of yellowish-white, fine-grained, crossbedded sandstone is equivalent to 

the Cow Springs Sandstone northeast and east of quadrangle area. The Summerville Formation and Cow Springs Sandstone are equivalent to lower part of Morrison Formation north 

of the map area (Doelling and others, 2000) and east of the map area at Black Mesa (Cooley 

and others, 1969). Unit as a whole forms a cliff where overlain by resistant conglomeratic, 

coarse-grained sandstone lenses of Dakota Sandstone (Kd), or Tertiary conglomeratic gravel 

and sedimentary (Tgs) deposits. Unit thins south and southeast of map area and thickens 

rapidly north. Thickness, 115 to 250 ft (35 to 76 m)

Jc Carmel Formation (Middle Jurassic)—Red and light-gray, slope-forming sandstone, siltstone, claystone, and silty calcareous and gypsiferous sandstone at Middle Mesa (east edge 

of quadrangle), along Red Lake Monocline (northeast corner of quadrangle), and as isolated 

outcrops (northwest quarter of quadrangle). Unit thins southward and pinches out south and 

east of the Moenkopi Plateau. Present as dark red silty sandstone interval between base of 

Entrada Sandstone (Je) and top of Navajo Sandstone (Jn) at the east end of Coal Mine Mesa 

and is locally absent at west end of Coal Mine Mesa. Unconformably overlies upper beveled surface of Navajo Sandstone (Jn), known regionally as the J-2 unconformity; erosional 

relief is generally less than 15 ft (4.5 m) but can be as much as 30 ft (9 m). Ripple marks and 

abundant rounded sandy fecal pellets about 0.5 in (1 cm) diameter are found in lenticular, 

light-gray sandstone beds as much as 3 ft (1 m) thick. Locally contains white and red calcite 

and white barite crystals. Unit pinches out southward into subsurface of Moenkopi Plateau; 

locally removed by modern erosion from most of Kaibito Plateau. Unit gradually thickens 

north and northeast of quadrangle. Thickness, 0 to 30 ft (0 to 9 m)

Glen Canyon Group (Lower Jurassic)—Includes, in ascending order, Moenave Formation 

(Jm), Springdale Sandstone Member of Kayenta Formation (Jks), Kayenta Formation (Jk), 

the Kayenta Formation-Navajo Sandstone transition zone (Jkn), and the Navajo Sandstone 

(Jn). The Moenave Formation unconformably overlies the Triassic Chinle Formation. The 

unconformity between the Triassic and Jurassic is based primarily on differences in lithology, topography, and color change. The purple and white mudstone, sandstone, and gray 

limestone of the Owl Rock Member of the Chinle Formation (^co) is overlain by red mudstone, siltstone, and sandstone of the Moenave Formation (Jm). The basal light-red sandstone of the Moenave Formation may be a lateral equivalent of the Lukachukai Member of 

the Wingate Formation as mapped by Cooley and others (1969) but is herein included within 

the lower part of the Moenave Formation, because it is lithologically the same as the overly-
18

ing beds of the Moenave Formation and because the Wingate Sandstone thins southward 

from Utah and does not appear to reach the map area

About 20 mi (32 km) north of the map area, the upper boundary of the Glen Canyon 

Group is the J-2 unconformity between the Navajo Sandstone (Jn) and Page Sandstone 

(Doelling and others, 2000). At Middle Mesa, east central edge of the map area, the J-2 

unconformity is between the Navajo Sandstone and Carmel Formation (Jc), and in the 

extreme southeast corner of the map area, it is between the Navajo Sandstone and the 

Entrada Sandstone-Cow Springs Sandstone, undivided (Je)

Jn Navajo Sandstone (Lower Jurassic)—Red, white, and tan, cliff-forming, high-angle crossbedded, fine- to medium-grained, well-sorted sandstone. Includes massive horizontal or 

planar bedding. Quartz grains are frosted. Crossbeds are as much as 35 ft (11 m) thick. 

Includes many discontinuous thin beds of gray to light-purple siliceous limestone, dolomite, or dark-red sandy siliceous mudstone that form resistant ledges and flat-topped ridges 

or small mesas on surface of Moenkopi and Kaibito Plateaus. Siliceous beds were formed 

in playas or ponds between sand dunes and become increasingly common on Moenkopi 

Plateau. Crossbeds contain numerous small, rounded, black and reddish-black, pea-size 

hematite concretions as much as 3 in (7.5 cm) in diameter. Crossbed dip direction indicates 

paleowinds were generally from the north and northwest. Gradational and arbitrary contact 

with underlying Kayenta Formation-Navajo Sandstone transition zone (Jkn) marked at 

lowest white or red massive sandstone cliff. Unit rapidly thins east and southeast of map 

area and thickens north and northwest. Unit is removed by erosion in west half of map. 

Thickness, 400 to 600 ft (122 to 183 m)

Jkn Kayenta Formation-Navajo Sandstone transition zone (Lower Jurassic)—Light-red and 

white, fine- to medium-grained, massive to crossbedded, cliff-forming beds of Navajo 

Sandstone lithology that intertongue with purple and light-red, slope-forming mudstone, 

siltstone, and sandstone beds of Kayenta Formation lithology. Forms sequence of red and 

white sandstone cliffs that alternate with purple and light-red mudstone and siltstone slopes 

resulting in arbitrary map contact. This zone is considered to be the lower “wet part” of the 

Navajo Sandstone by Marzolf (1983, 1991) and Blakey (1994). Gradually thins northward 

and becomes basal part of the Navajo Sandstone near Cedar Ridge. Individual red and 

white sandstone units thin or lens out into purplish siltstones of the Kayenta Formation 

south of the map area. Several springs and seeps issue from base of Navajo Sandstone 

along Echo Cliffs from Cedar Ridge to Tuba City and Moenkopi. Thickness, 0 to 240 ft (0 

to 73 m)

Jk Kayenta Formation (Lower Jurassic)—Includes an upper slope-forming light-purple, 

siltstone and sandstone and the basal orange-brown, cliff-forming Springdale Sandstone 

Member. The Springdale Sandstone was originally described as the upper member of the 

underlying Moenave Formation (Averitt and others, 1955; Stewart and others, 1972; Sargent 

and Philpott, 1987; Billingsley and others, 2004) but has since been reassigned as the basal 

part of the Kayenta Formation based on paleontological data and a prominent Jurassic 

unconformity at its base (Blakey, 1994; Marzolf, 1991; Lucas and Tanner, 2006; Tanner and 

Lucas, 2007; Biek and others, 2007)

Upper slope-forming unit: Purple, lavender, and light-red fluvial, crossbedded, finegrained mudstone, siltstone, and silty sandstone that undergo a northward facies change 

from mostly slope-forming siltstone, mudstone, and sandstone at Moenkopi Wash to mostly 

cliff-forming red sandstone and minor siltstone along Echo Cliffs at Cedar Ridge. Age is 

determined by Peterson and Pipiringoes (1979) and Biek and others (2000). Along Echo 

Cliffs, often covered by landslide (Ql) and talus and rockfall (Qtr) deposits caused when erosion of underlying Kayenta Formation undercuts overlying Navajo Sandstone cliffs allowing 

large blocks of both Navajo Sandstone and upper Kayenta Formation to fail as landslide 

masses; especially prevalent where joints and fractures nearly parallel Echo Cliffs (fig. 1). 

Unit is unconformable with underlying cliff-forming Springdale Sandstone Member (Jks). 

Thickness, 300 to 470 ft (92 to 143 m)

Jks Springdale Sandstone Member (Lower Jurassic)—Light-red to reddish-brown and darkred, cliff-forming, thin- to thick-bedded sandstone. Includes low-angle trough crossbed sets 

with fluvial conglomeratic sandstone lenses containing dark-red mudstone and siltstone 

rip-up clasts and poorly preserved petrified and carbonized fossil plant remains north of 

map area (Peterson and Pipiringos, 1979; Biek and others, 2000). Crossbeds are separated 
19

by thin-bedded to laminated dark-red siltstone and mudstone that locally contain mudstone 

pellets. Unconformable contact with underlying Moenave Formation (Jm). Light-red, finegrained, crossbedded sandstone filling channels eroded into top of Springdale Sandstone 

may represent southern extent of Wingate Sandstone. Thickness, 100 to 140 ft (30 to 43 m)

Jm Moenave Formation (Lower Jurassic)—Includes only the Dinosaur Canyon Member as 

redefined by Blakey (1994), Marzolf (1991), Lucas and Tanner (2006), Tanner and Lucas 

(2007), and Biek and others (2007) in the map area. Age is after Peterson and Pipiringos 

(1979) and Biek and others (2000, 2007). Forms reddish-brown slopes and ledges of thinbedded, flat-bedded, and crossbedded, fine- to coarse-grained fluvial siltstone and silty sandstone. Unconformable contact with underlying Owl Rock Member of the Chinle Formation, 

known as the J-O unconformity separating Triassic rocks from overlying Jurassic rocks. 

Commonly covered by landslide (Ql) or talus and rockfall (Qtr) deposits. Thickness, 80 to 

140 ft (25 to 43 m)

Chinle Formation (Upper Triassic)—Includes, in descending order, the Owl Rock Member, 

the Petrified Forest Member, and the Shinarump Member and the sandstone and siltstone 

member, undivided (Repenning and others, 1969)

^co Owl Rock Member (Upper Triassic)—Grayish-red and light-purple, slope- and ledge-forming, nodular siliceous limestone interbedded with purple, light-blue, and light-red calcareous 

siltstone and sandstone. Limestone beds are gray, cherty, lenticular, silty, irregular bedded, 

1 to 5 ft (0.5 to 1.5 m) thick; extend laterally for several miles and form resistant benches 

or ledges along Echo Cliffs and Ward Terrace (fig. 1, sheet 3). Number of limestone beds 

decreases northward from several at Ward Terrace to two at Cedar Ridge. Contains abundant 

mud pellets and silicified clay and concretionary chert nodules. Gradually thins northward 

along Echo Cliffs and thickens slightly southeast of map area. Unconformable contact 

between Owl Rock Member of the Chinle Formation and overlying Moenave Formation 

commonly marked by a distinct lithologic and color change from purple and white calcareous siltstone and sandstone and gray limestone of Owl Rock to dark-red and orange-red, 

coarse-grained sandstone of Moenave Formation. Gradational contact with underlying Petrified Forest Member placed at lowest laterally continuous limestone bed or at nodular calcareous grayish-yellow siltstone slope about 10 to 15 ft (3 to 4.5 m) below lowest prominent 

limestone bed. Thickness, 100 to 200 ft (30 to 60 m)

^cp Petrified Forest Member (Upper Triassic)—Purple, blue, light-red, greenish-gray, and 

grayish-blue, slope-forming mudstone and siltstone. Includes interbedded white, coarsegrained, lenticular, channel-fill sandstone. Includes three informal units of Akers and others 

(1958), in descending order: red mudstone and sandstone, gray mudstone and sandstone, and 

blue mudstone. Includes large lenticular erosion channels and large-scale, low-angle trough 

crossbeds. Petrified logs and wood fragments common in lower white or yellowish-white 

sandstone; alternately may be within upper part of Shinarump and sandstone and siltstone 

member, undivided. Gradational contact with underlying Shinarump Member and sandstone 

and siltstone member, undivided, at change from slope-forming multicolored mudstones of 

Petrified Forest Member to tan cliffs and purple slopes of coarse-grained sandstone of Shinarump Member. Weathers into rounded hills or slopes with a rough, puffy, popcorn surface 

caused by swelling of clay when wet. Thickness, 400 to 500 ft (122 to 153 m)

^cs Shinarump Member and sandstone and siltstone member, undivided (Upper Triassic)—

White, light-brown, tan, and yellowish-pink, cliff-forming, coarse-grained sandstone and 

conglomeratic sandstone. Includes cliff-forming, low-angle, crossbedded sandstone interbedded with slope-forming, poorly sorted, purple, light-red, and blue siltstone and mudstone. Lithology is highly variable locally but regionally homogeneous, consisting of about 

75% sandstone, 20% conglomerate, and 5% mudstone. Pebbles are generally brown, black, 

or light-colored, well-rounded quartz and siliceous composition. Petrified logs and wood 

fragments are generally scattered throughout unit but common at some localities. Unconformable contact with underlying red siltstone and sandstone of Moenkopi Formation. Unit 

is thickest in Painted Desert area; thins north along Echo Cliffs and thins south of map area. 

Thickness, 60 to 200 ft (18 to 60 m)

Moenkopi Formation (Middle(?) and Lower Triassic)—Includes, in descending order, the 

Holbrook and Moqui Members, undivided, Shnabkaib Member, and Wupatki Member. The 

basal Timpoweap Member of the Moenkopi Formation is present but too thin and limited in 

extent to show at map scale so is included in the Wupatki Member
20

The Moenkopi Formation is mostly eroded in the Grand Canyon area, but remnants 

form Cedar Mountain, Gold Hill, Yon Dot hills, Shinumo Altar (fig. 1, sheet 3), and several 

isolated outcrops on Marble and Coconino Plateaus

^mhm Holbrook and Moqui Members, undivided (Middle(?) and Lower Triassic)—Reddishbrown and tan, slope-forming, alternating sequence of claystone, siltstone, and sandstone 

(McKee, 1954). Unit is equivalent to upper red member of Stewart and others (1972) in 

northwestern Arizona. Siltstone and sandstone beds include large- to medium-scale trough 

crossbedding and abundant cusp-type ripple marks, interbedded thin limestone, lenses of 

conglomeratic sandstone, chert nodules, and thin veins of gypsum. Gradational contact with 

underlying Shnabkaib Member. Unit undergoes rapid facies change from red siltstone-sandstone sequence in northern part of map area to mostly tan sandstone sequence in the south. 

Tan sandstone beds increase in thickness north to south across the map and become similar 

to conglomeratic beds of the overlying Shinarump Member and sandstone and siltstone 

member, undivided (^cs). Include numerous channel lenses that are often confused with 

the Shinarump. Thus, uncertainties exist in the central part of the map where unconformities between similar sandstones are numerous and difficult to differentiate. Typically, small 

pebbles within a sandstone lens or bed denotes the Shinarump Member and sandstone and 

siltstone members, undivided, of the Chinle Formation. Thickness, 80 to 120 ft (25 to 37 m)

^ms Shnabkaib Member (Lower Triassic)—Yellowish-white and light-brown, cliff-forming, 

crossbedded, fine-grained, calcareous siltstone and coarse-grained sandstone. Unit is equivalent to lower massive sandstone member of the Moenkopi Formation as defined by McKee 

(1954) south of the map area (Billingsley and others, 2007). Lowermost ledge-forming 

sandstone undergoes a facies change from light-red calcareous sandstone south of map area 

to yellowish-white calcareous gypsiferous sandstone and dolomite north of map area. Gradational contact with underlying Wupatki Member marked at base of lowest tan or light-red 

sandstone cliff. Thickness, 50 to 100 ft (15 to 30 m)

^mw Wupatki Member (Lower Triassic)—Red and red-brown, slope-forming, thin-bedded, 

mudstone, siltstone, and sandstone as defined by McKee (1954). Interbedded sandstones as 

thick as 1 to 3 ft (0.5 to 1 m) form resistant ledges within crumbly red-brown mudstone/siltstone slopes. Bedding surfaces often contain small-scale ripple marks, salt crystal casts, mud 

cracks, and rain-drop impressions. Unit is equivalent to lower red member, Virgin Limestone 

Member, and middle red member of Stewart and others (1972) in northwestern Arizona. 

Virgin Limestone Member is present at Cedar Ridge and in Yon Dot Mountains on Marble 

Plateau but is too thin to show at map scale. Virgin Limestone beds consist of yellowishwhite, thin, platy, silty limestone and siltstone about 1 to 3 ft (0.3 to 1 m) thick and about 15 

to 20 ft (4.5 to 6 m) above Harrisburg Member of the Kaibab Formation (Pkh); represent 

the regional Permian/Triassic unconformity. Unit includes basal Timpoweap Member of 

the Moenkopi Formation. Timpoweap Member is composed of subangular to subrounded 

conglomerate in calcareous sandstone matrix; small, white, angular chert pebbles and fragments derived from Kaibab Formation occupy shallow depressions and channels eroded into 

underlying Harrisburg Member of the Kaibab Formation in western half of map. Thickness, 

30 to 85 ft (9 to 26 m)

Kaibab Formation (Cisuralian)—Includes, in descending order, the Harrisburg Member and 

Fossil Mountain Member as defined by Sorauf and Billingsley (1991)

Pkh Harrisburg Member (Cisuralian)—Reddish-gray and brownish-gray, ledge- and slopeforming, gypsiferous siltstone, calcareous sandstone, and thin-bedded sandy limestone. Top 

of unit near Little Colorado River Gorge includes white, low-angle, crossbedded, calcareous sandstone with mollusk fossils; elsewhere, upper part is primarily sandy, cherty limestone. Forms surface of Kaibab, Coconino, and Marble Plateaus and House Rock Valley in 

west half of quadrangle. Contact with underlying Fossil Mountain Member is gradational 

and marked at topographic break between grayish-white, slope- and ledge-forming sandy 

limestone and sandstone sequence of Harrisburg Member and underlying cliff-forming, 

gray to light-brown, thick-bedded, cherty limestone and sandy limestone of Fossil Mountain 

Member. Unit gradually thins west to east and undergoes shoreward facies change from 

mostly cliff- and slope-forming limestone and siltstone marine sediments in west half of 

quadrangle to mostly sandy marine calcareous sandstone east of Grand Canyon. Difficult to 

distinguish members in subsurface of eastern half of quadrangle. Thickness, 120 to 80 ft (37 

to 25 m)
21

Pkf Fossil Mountain Member (Cisuralian)—Light-gray, cliff-forming, fine- to medium-grained, 

thin- to medium-bedded (1 to 6 ft [0.3 to 2 m]), fossiliferous, cherty (25% to 30%), sandy 

limestone and dolomite. Weathers dark gray; cliff surfaces often stained by black magnesium 

oxide. Includes abundant gray and white, fossiliferous chert nodules and white chert breccia 

beds. Chert nodules may contain concentric black and white bands or fossil sponges. White, 

cliff-forming, chert breccia beds 4 to 10 ft (1 to 3 m) thick commonly present in uppermost 

part help establish contact between Harrisburg (Pkh) and Fossil Mountain (Pkf) Members. 

Unit gradually thins eastward and undergoes a shoreward facies change from limestone, 

dolomite, and sandy limestone to calcareous sandstone and sandy limestone similar in 

texture, composition, and appearance to overlying Harrisburg Member. Unit commonly 

forms cliff below slopes and ledges of Harrisburg Member along rim of Grand Canyon, 

Marble Canyon, and Little Colorado River Gorge. Unconformable contact with underlying 

Toroweap Formation (Pt) attributed in part to solution and erosion of gypsiferous siltstone 

in Toroweap but mostly to channel erosion; average erosional relief about 10 ft (3 m). Unit 

gradually thins east and southeast in subsurface of map area, becoming indistinguishable 

from upper Harrisburg Member. Thickness, 230 to 180 ft (70 to 55 m)

Pt Toroweap Formation, undivided (Cisuralian)—Includes, in descending order, the Woods 

Ranch, Brady Canyon, and Seligman Members, undivided, as defined by Sorauf and Billingsley (1991). All three members are present on western side of Marble Canyon and Grand 

Canyon. All three members undergo a rapid shoreward (eastward) facies change from cliff 

and slope units west of Colorado River to cliff units east of Colorado River. Unit gradually 

thins east and southeast in subsurface of map area and thickens west (Billingsley, 2000; 

Billingsley and Wellmeyer, 2003; Billingsley and others, 2007). Eastern extent is unknown 

but likely extends to or pinches out at eastern margin of map. Thickness, 200 to 250 ft (60 to 

76 m)

Ptw Woods Ranch Member (Cisuralian)—Grand Canyon and Marble Canyon areas: gray and 

light-red, slope-forming gypsiferous siltstone, gray gypsum, and gray sandstone interbedded 

with gray, thin-bedded limestone. Weathers to reddish-gray slope. Bedding locally distorted 

due to dissolution of gypsum and gypsiferous siltstone. Erosional undercutting of overlying 

Kaibab Formation results in numerous landslides and large open cracks near canyon rims 

that tend to be accentuated along pre-existing joint and fracture systems. Unit undergoes 

shoreward (eastward) facies change to mostly brown, cliff-forming, calcareous sandstone 

and dolomite that weathers dark brown. Contact with underlying Brady Canyon Member is 

gradational and marked at lithologic and topographic break between slope-forming gypsiferous siltstone and sandstone of Woods Ranch and cliff-forming limestone of Brady Canyon 

in western two-thirds of Marble Canyon and Grand Canyon area; becomes indistinguishable 

from underlying Seligman and Brady Canyon Members in eastern third of Marble Canyon, 

southeastern Grand Canyon, and Little Colorado River Gorge and subsurface of Marble 

Plateau. Thickness, 100 to 180 ft (30 to 55 m)

Ptb Brady Canyon and Seligman Members, undivided (Cisuralian)—

Brady Canyon Member: Gray to brown, cliff-forming, thin- to medium-bedded (1 to 

5 ft [0.05 to 1.4 m]), fine- to coarse-grained, limestone and sandy limestone. Weathers light 

gray. Contains white and gray chert nodules that make up less than 5% of unit. Gradational 

contact with underlying Seligman Member marked at base of limestone cliff in western part 

of quadrangle. Becomes indistinguishable from other Toroweap Members east of Marble 

Canyon, Grand Canyon, and Little Colorado River Gorge. Thickness, 20 to 30 ft (6 to 9 m)

Seligman Member: Gray, light-purple, and yellowish-red, slope-forming, thin-bedded 

dolomite, sandstone, gypsum, and calcareous sandstone. Forms slope or recess between 

overlying Brady Canyon Member and underlying Coconino Sandstone (Pc) in Marble 

Canyon and Grand Canyon. Undergoes easterly shoreward facies change similar to Brady 

Canyon and Woods Ranch Members; pinches out before reaching Little Colorado River 

Gorge. Sharp unconformable contact with underlying white, cliff-forming Coconino Sandstone. Coconino Sandstone intertongues with lower part of Seligman Member west and 

north of map area (Fisher, 1961; Schleh, 1966; Rawson and Turner, 1974; Billingsley and 

Wellmeyer, 2003; Billingsley and others, 2006). Undergoes gradual shoreward (eastward) 

facies change along with overlying Brady Canyon and Woods Ranch Members, making 

all indistinguishable from one another east of Colorado River where they are mapped as 

Toroweap Formation, undivided (Pt). Thickness, 10 to 20 ft (3 to 6 m)
22

Pc Coconino Sandstone (Cisuralian)—Tan to white, cliff-forming, fine-grained, well-sorted, crossbedded quartz sandstone. Thin red sandstone beds at base of Coconino Sandstone in Little 

Colorado River Gorge are likely the northern edge of the Schnebly Hill Formation as defined 

by Blakey (1990) in the Verde Valley south of the quadrangle. Contains large-scale, highangle, planar crossbeds that average about 11 m (35 ft) thick. Locally includes amphibian 

trackways and low-relief wind ripple marks on crossbed surfaces. Unconformable contact 

with underlying Hermit Formation (Ph) is sharp and planar with relief generally less than 3 

ft (1 m) but locally as much as 8 ft (2.5 m); marked by distinct color and topographic change 

between white, cliff-forming sandstone of Coconino Sandstone and dark-red, slope-forming 

siltstone of Hermit Formation. Unit is exposed only in walls of the Grand Canyon but is 

present in the subsurface of eastern half of map. Unit gradually thickens east and southeast 

of map area and significantly thins to the north and west. Thickness, 200 to 600 ft (60 to 183 

m)

Ph Hermit Formation (Cisuralian)—Red, slope-forming, fine-grained, thin- to medium-bedded 

siltstone and sandstone. In Little Colorado River Gorge, upper part contains red, massive, 

low-angle, cross-stratified calcareous sandstone and siltstone beds that may be equivalent, in 

part, to Schnebly Hill Formation in Verde Valley south of map area (Blakey, 1990). Siltstone 

beds throughout unit weather dark red and crumbly and fill widespread shallow erosion 

channels; form recesses between thicker sandstone beds. Contains poorly preserved plant 

fossils in channel-fill deposits in lower part of unit at Grand Canyon. Red cliffs and ledges 

of sandstone immediately below contact with Coconino Sandstone (Pc) are often bleached 

yellowish-white color owing to groundwater seepage from Coconino Sandstone. Unconformably overlies Esplanade Sandstone (Pe) with erosional relief generally less than 10 ft (3 

m). Unit thins southeast of Grand Canyon to less than 40 ft (12 m) at Little Colorado River 

Gorge and may extend into subsurface of eastern part of map area. Unit thickens north and 

west of map area. Thickness, 40 to 360 ft (12 to 110 m)

Supai Group (Cisuralian, Pennsylvanian, and Upper Mississippian)—Includes in descending 

order, the Esplanade Sandstone and Wescogame, Manakacha, and Watahomigi Formations, 

undivided

Pe Esplanade Sandstone (Cisuralian)—Light-red and pinkish-gray, cliff-forming, fine- to 

medium-grained, medium- to thick-bedded (3 to 10 ft [1 to 3 m]), well-sorted calcareous 

sandstone. Includes interbedded dark-red, thin-bedded, crumbly, recessive and slope-forming 

siltstone beds in upper and lower part. Crossbeds are small to medium scale, low- and highangle planar. Unconformable contact with underlying Pennsylvanian and Upper Mississippian 

rocks (*Ms) marked by erosion channels as much as 30 ft (9 m) deep in Grand Canyon and 

Little Colorado River Gorge area. Thickness, 350 to 400 ft (107 to 122 m)

*Ms Wescogame (Upper Pennsylvanian), Manakacha (Moscovian), and Watahomigi (Bashkirien and Serpukhovian) Formations, undivided—Includes, in descending order, 

the Wescogame, Manakacha, and Watahomigi Formations as defined by McKee (1982). 

Individual formations are difficult to identify because of similar lithology and topographic 

expression; unconformable contacts are shallow, difficult-to-find erosion channels. Herein, 

the three formations are shown as one map unit

Wescogame Formation: Light-red, pale-yellow, and light-gray upper slope unit and 

lower cliff unit. Upper slope unit consists mainly of dark-red, fine-grained siltstone and 

mudstone interbedded with light-red, coarse-grained, calcareous sandstone, dolomitic sandstone, siltstone, mudstone, and conglomerate. Lower cliff unit consists mainly of light-red 

to gray, high-angle, large- and medium-scale, tabular-planar, crossbedded sandstone and 

calcareous sandstone as much as 40 ft (12 m) thick. Unconformable contact with underlying Manakacha Formation marked by erosion channels 3 to 6 ft (1 to 2 m) deep in Grand 

Canyon area. Channels commonly filled with limestone/chert conglomerate west of map 

area. Thickness, 130 to 150 ft (40 to 45 m)

Manakacha Formation: Light-red, white, and gray upper slopes and ledges of sandstone, calcareous sandstone, dark-red siltstone, and thin gray limestone. Upper slope consists 

mainly of shaley siltstone and mudstone with minor interbedded, thin-bedded limestone and 

sandstone. Carbonate content increases west of map area forming numerous ledge-forming, 

thin and medium limestone beds at west edge of map. Upper slope is about 75 to 100 ft 

(23 to 30 m) thick in Grand Canyon. Lower cliff is dominated by reddish-gray, medium- to 

thick-bedded, crossbedded, calcareous sandstone and sandy limestone. Lower cliff is about 
23

60 ft (18 m) thick. Carbonate content increases west of map area, forming numerous gray 

limestone ledges (McKee, 1982). Unconformable contact between Manakacha Formation 

and underlying Watahomigi Formation marked at base of lower red sandstone cliff; erosional 

relief nearly flat, generally less than 3 ft (1 m). Thickness, 200 ft (60 m)

Watahomigi Formation: Gray and purple, slope-forming limestone, siltstone, mudstone, and minor conglomerate. Minor red chert lenses and nodules in lower limestone beds. 

Includes alternating gray, thin-bedded cherty limestone ledges interbedded with purplishgray siltstone and mudstone in upper part. Upper ledge/slope averages about 70 ft (21 m) 

thick. Lower slope consists mainly of purplish-red mudstone and siltstone, interbedded 

with thin-bedded, aphanitic to granular limestone with red chert veins and nodules. Fossil 

conodonts in lower thin limestone beds west of map area are Late Mississippian age (Martin 

and Barrick, 1999). Unit includes purple siltstone and gray limestone interbedded with reddish conglomeratic sandstone that fills small erosion channels cut into underlying Surprise 

Canyon Formation (Ms) or into Redwall Limestone (Mr). Lower Supai Group gradually 

thins eastward and gradually thickens westward in west half of map. Thickness, 100 to 120 

ft (30 to 37 m)

Ms Surprise Canyon Formation (Serpukhovian)—Dark-reddish-brown, massive to thin-bedded, 

poorly sorted siltstone, sandstone, thin-bedded gray limestone, dolomite, and a basal gray 

and white conglomerate of subrounded chert clasts derived from Redwall Limestone in 

dark-red or black sandstone matrix. Unit is locally absent throughout map area and limited 

to deposits within paleovalley and karst caves eroded into top half of underlying Redwall 

Limestone (Billingsley and Beus, 1999). Unit is likely present in subsurface of eastern part 

of map area. Sandstone and siltstone beds contain plant and bone fossils, mud cracks, and 

ripple marks. Thickness, 0 to 100 ft (0 to 30 m)

Mr Redwall Limestone, undivided (Mississippian)—Includes, in descending order, Horseshoe 

Mesa, Mooney Falls, Thunder Springs, and Whitmore Wash Members, with no middle Mississippian as defined by McKee (1963) and McKee and Gutschick (1969). Members are too 

small to show at map scale because of steep topography in Grand Canyon. Unit overall is 

light- to dark-gray, cliff-forming, thin- to thick-bedded, fine- to coarse-grained, fossiliferous 

limestone and dolomite. Includes thin-bedded gray and white chert beds, lenses, and nodules. Exposed mainly as sheer cliff in Grand Canyon; gradually thins eastward in subsurface. 

Is an important aquifer because of solution caverns and joint and fracture systems. Thickness, 400 to 450 ft (122 to 137 m)

Horseshoe Mesa Member: Light olive-gray, ledge- and cliff-forming, thin-bedded, 

fine-grained limestone. Weathers to receding ledges. Gradational and disconformable contact with underlying massive-bedded limestone of Mooney Falls Member marked by thin, 

platy limestone beds that form recess about 3 to 9 ft (1 to 3 m) thick near top of Mooney 

Falls Member cliff. Fossils locally common. Includes distinctive ripple-laminated limestone, oolitic limestone, and some chert lenses. Unit locally absent in Paleozoic section 

where removed by Late Mississippian paleovalley erosion. Thickness, 50 to 100 ft (15 to 

30 m)

Mooney Falls Member: Light-gray, cliff-forming, fine- to coarse-grained, thick-bedded 

to very thick bedded (4 to 20 ft [1 to 6 m]), fossiliferous limestone. Limestone weathers dark 

gray; chert beds weather black. Upper part includes dark-gray dolomite beds, oolitic limestone, and chert beds. Karst caves in upper part contain red sandstone and siltstone deposits of Surprise Canyon Formation (Ms) in Marble Canyon. Disconformable contact with 

underlying Thunder Springs Member is distinguished by lithology; massive-bedded, gray 

limestone of the Mooney Falls Member overlies thin-bedded, dark-gray to brown dolomite 

and white chert beds of Thunder Springs Member. Thickness, 300 ft (75 m)

Thunder Springs Member: Roughly half of member is gray, cliff-forming, fossiliferous, thin-bedded limestone and half is brownish-gray, cliff-forming, thin-bedded (1 to 5 in 

[2 to 12 cm]), finely crystalline dolomite and fine- to coarse-grained limestone interbedded 

with thin beds of white chert. Locally includes large-scale crossbedding and irregular gently 

folded beds. Nautiloid fossils are common in upper 10 ft (3 m) of unit. The disconformable 

planar contact with the underlying Whitmore Wash Member is distinguished by a distinct 

lack of chert in Whitmore Wash Member. Thickness, 100 ft (30 m)

Whitmore Wash Member: Yellowish-gray and brownish-gray, cliff-forming, thickbedded, fine-grained dolomite. Weathers dark gray. Unconformable contact with underly-
24

ing Temple Butte Formation (Dtb) or Muav Limestone (_m) marked by low-relief erosion 

channels about 5 to 10 ft (2 to 3 m) deep. Contact generally recognized where major cliff of 

light-gray Redwall Limestone overlies stair-step ledges of dark-gray Devonian Temple Butte 

Formation in Grand Canyon, Little Colorado River Gorge, and Marble Canyon; locally overlies channel filled with reddish-purple mudstone and dark-gray contorted limestone beds of 

Temple Butte Formation within Marble Canyon. Otherwise unit most commonly overlies flat 

ledges of light-gray to greenish-gray, thin-bedded limestone of Cambrian Muav Limestone 

in Marble Canyon area. Thickness, 80 to 100 ft (25 to 30 m)

Dtb Temple Butte Formation (Upper and Middle Devonian)—Purple, reddish-purple, dark-gray, 

and light-gray, ledge-forming dolomite, sandy dolomite, sandstone, mudstone, and limestone, as defined by Beus (2003). Purple and light-gray, fine- to coarse-grained, thin- to 

medium-bedded, ripple-laminated ledges of mudstone, sandstone, dolomite, and conglomerate-fill channels eroded into the underlying Cambrian Muav Limestone; channels are as 

much as 40 to 120 ft (12 to 37 m) deep in Marble Canyon. Carbonate ledges weather to dark 

gray. Unconformity at base represents major stratigraphic break spanning about 100 m.y. in 

the Grand Canyon that includes part of Late Cambrian, all of Ordovician and Silurian, and 

most of Early and Middle Devonian. Unit thins east and north of the map area, thickens west 

and south, and is likely intermittent or discontinuous in the subsurface of the northeastern 

two-thirds of the map. Thickness, 0 to 120 ft (0 to 37 m)

Tonto Group (Middle and Lower(?) Cambrian)—Includes, in descending order, the Muav 

Limestone, Bright Angel Shale, and Tapeats Sandstone as defined by Noble (1922) and 

modified by McKee and Resser (1945). The age and depositional history of Cambrian rocks 

in Grand Canyon are explained by Rose (2003). Tonto Group overlies tilted strata of the 

Grand Canyon Supergroup of Mesoproterozoic age (1.4 to 1.1 Ma). Grand Canyon Supergroup rocks may be present only in the western part of the map. Otherwise, Tonto Group 

overlies igneous and metamorphic rocks of Paleoproterozoic age (1.7 to 1.6 Ma). This hiatus 

is known regionally as the Great Unconformity

_m Muav Limestone (Middle Cambrian)—Dark-gray to light-greenish-gray, brown, and orangered, cliff-forming, fine- to medium-grained, thin- to thick-bedded, mottled, fossiliferous, 

silty limestone, limestone, dolomite, and calcareous mudstone. Includes unnamed siltstone 

and shale beds of green and purplish-red, micaceous siltstone, mudstone, and thin beds of 

brown sandstone. Contact with underlying Bright Angel Shale is gradational and lithology 

dependent; marked at base of lowest prominent limestone cliff. Unit gradually thins west to 

east, thinning to an unknown thickness in subsurface of eastern two-thirds of quadrangle. 

Thickness, 320 to 380 ft (97 to 115 m)

_ba Bright Angel Shale (Middle Cambrian)—Green and purple-red, slope-forming siltstone, 

shale, and red-brown to brown sandstone. Includes abundant green and purple-red, finegrained, micaceous, ripple-laminated, fossiliferous shale and siltstone; dark-green, mediumto coarse-grained, thin-bedded, glauconitic sandstone; and interbedded purplish-red and 

brown, thin-bedded, fine- to coarse-grained, ripple-laminated sandstone. Contact with 

underlying Tapeats Sandstone is gradational and marked at top of transition from dominantly 

green siltstone slopes to dominantly brown sandstone ledges above Tapeats Sandstone cliff. 

Unit generally maintains a uniform thickness across western part of map area based on exposures in Grand Canyon; gradually thins eastward in subsurface. Thickness, 200 to 300 ft (60 

to 90 m)

_t Tapeats Sandstone (Middle and Lower(?) Cambrian)—Brown and red-brown, cliff-forming, coarse-grained sandstone and conglomerate. Unconformable contact with the underlying Proterozoic surface is called the Great Unconformity. Tapeats Sandstone fills lowland 

areas between Proterozoic highlands and is locally absent on Proterozoic highlands. Variable 

thickness, 0 to 300 ft (0 to 91 m)

NEOPROTEROZOIC ROCKS

Neoproterozoic igneous and sedimentary rocks, as mapped by Timmons and others (2007), are 

exposed in the Grand Canyon and are likely present in the subsurface in the eastern part of the quadrangle.

Zs Sixtymile Formation, undivided (Neoproterozoic)—Informally divided into, in descending 

order, the lower, middle, and upper members (Elston, 1979). Lower member is composed of 

slumped blocks of dolomite surrounded by black shale exposed mainly in Sixtymile Canyon 
25

in eastern Grand Canyon. Middle member is thick sequence of white to red, laminated and 

thinly bedded siltstone, locally disrupted by intraformational brecciation and folding. Upper 

member contains intraformational breccias and red fluvial sandstones derived from the 

middle siltstone member. Unit unconformably overlain by Tapeats Sandstone. Thickness, 

196 ft (60 m)

Chuar Group (Neoproterozoic)—Includes, in descending order, the Kwagunt Formation and 

Galeros Formation as defined by Ford and Dehler (2003), modified by Timmons and others 

(2007). A correlation by long-distance lithologic comparison, micropaleontologic assemblages, paleomagnetism, and very limited isotopic dating suggests the Nankoweap Formation, Chuar Group, and Sixtymile Formation were deposited within the 1,000 to 700 m.y. 

period. The Cambrian Tonto Group overlies these tilted strata in the subsurface west and east 

of Grand Canyon in the Tuba City quadrangle (sheet 1); this hiatus is known regionally as 

the Great Unconformity 

Kwagunt Formation (Neoproterozoic)—Includes, in descending order, the Walcott, Awatubi, 

and Carbon Butte Members as mapped by Timmons and others (2007)

Zkw Walcott Member (Neoproterozoic)—Black to gray mudstone, gray dolomitic sandstone 

(12 to 31 ft [4 to 9.5 m] thick), brecciated dolomite and sandstone. A thin tephra deposit 

yielded a U-Pb zircon age of 742±6 Ma, providing an upper age limit for the Chuar Group 

(Karlstrom and others, 2000). Thickness, 838 ft (255 m)

Zka Awatubi Member (Neoproterozoic)—Red, green, blue, and light-brown mudstone, siltstone, and sandstone. A basal tan to light-brown stromatolite carbonate bed contains fossil 

biohermal dome features. Thin-bedded sandstone and siltstone contain ripple foreset beds 

and mud-crack casts. Near top of member, organic shale preserves the macroalgal fossil, 

Chuaria circularis, first described by Ford and Breed (1973). Thickness, 823 to 1,128 ft (252 

to 344 m)

Zkcb Carbon Butte Member (Neoproterozoic)—Interbedded sandstone and siltstone. Basal 

sandstone is brown, medium- to fine-grained, thick sandstone, forming a distinctive marker 

bed approximately 252 ft (76 m) thick, and includes abundant soft-sediment deformation 

features, interference ripple marks, and mud-crack casts (Ford and Breed, 1973). Above 

basal sandstone unit are thin, interbedded, multicolored, mudstone, siltstone, and sandstone. 

Thickness, 112 to 223 ft (34 to 68 m)

Galeros Formation (Neoproterozoic)—Includes, in descending order, the Duppa, Carbon 

Canyon, Jupiter, and Tanner Members as mapped by Timmons and others (2007)

Zgd Duppa Member (Neoproterozoic)—Fine-grained siliciclastic unit dominated by shale and 

interbedded thin-bedded siltstone. Includes interbedded calcareous siltstone beds about 3 ft 

(1 m) thick. Variable thickness, 571 to 2,050 ft (174 to 625 m)

Zgcc Carbon Canyon Member (Neoproterozoic)—Fine-grained, interbedded siliciclastic mudstone, siltstone, and sandstone. Includes several thin dolomite and sandstone marker beds, 

3 to 6 ft (1 to 2 m) thick. Sandstone beds contain symmetric and interference ripple marks, 

low-angle crossbeds, and mud-crack casts. Stromatolite fossils become more common 

toward top of unit. Thickness, 1,546 ft (471 m)

Zgj Jupiter Member (Neoproterozoic)—Fine-grained, interbedded siliciclastic mudstone, 

siltstone, sandstone, and dolomite. Dolomite and some sandstone beds form several marker 

beds throughout unit. Base of unit is stromatolitic dolomite, 40 ft (912 m) thick. Interbedded 

sandstone beds contain symmetric ripple marks, mud-crack casts, and raindrop impressions. 

Thickness, 868 to 1,516 ft (264 to 462 m)

Zgt Tanner Member (Neoproterozoic)—Very fine grained siliciclastic siltstone, sandstone, 

and thin dolomite. Include dark-brown dolomite at base of unit that unconformably overlies 

sandstone beds of the Nankoweap Formation. Thickness, 20 to 80 ft (6 to 24 m)

YZn Nankoweap Formation, undivided (Neoproterozoic to latest Mesoproterozoic)—Unconformity-bounded Nankoweap Formation separates rocks of the Neoproterozoic Chuar Group 

and Late Mesoproterozoic Unkar Group. Includes an upper and lower member, undivided 

(Gebel, 1978). Upper member is composed of siltstone and thick-bedded, fine-grained, red 

sandstone at base and more massive 3-ft-thick (1-m-thick) sandstone bed toward top of section, capped by white, fine-grained quartz sandstone. Unit contains trough crossbeds, ripple 

marks, mud cracks, soft-sediment deformation, and rare salt casts. Lower member is dominated by hematite-cemented quartzite sandstone and siltstone with lenses of lithic sandstone 

derived from underlying Cardenas Basalt. Thickness, 330 ft (100 m)
26

MESOPROTEROZOIC ROCKS

Mesoproterozoic igneous and sedimentary rocks, as mapped by Timmons and others (2007), are 

exposed in the Grand Canyon and are likely present in the subsurface in the eastern part of the quadrangle.

Unkar Group (Mesoproterozoic)—Includes, in descending order, Cardenas Basalt and the Dox 

Formation as defined by Hendricks and Stevenson (2003) and modified by Timmons and 

others (2007). Unkar Group rocks have been correlated to mafic intrusions of similar age 

and type in the southwestern United States (Howard, 1991). Cambrian Tonto Group overlies 

these tilted strata in the subsurface west and east of eastern Grand Canyon 

Yc Cardenas Basalt (Mesoproterozoic)—Includes informal members, in descending order: the 

lapillite, fan-jointed, and bottle-green members (Lucchitta and Hendricks, 1983). Lapillite 

member is composed of scoriaceous fragments of volcanic bombs and ash matrix interbedded in massive basalt flows a few meters to several tens of meters thick (Lucchitta and 

Hendricks, 1983). Includes diabase intrusions that intrude both the Unkar Group and crystalline basement rocks as dikes and sills from a few tens of meters to 981 ft (300 m); dikes 

are thinner and locally utilize fault planes; similar in texture, mineralogy, and chemistry to 

Cardenas Basalt, suggesting a shared and common source. Thickness, 163 to 294 ft (50 to 90 

m). Fan-jointed member is composed of porphyritic and vesicular basaltic andesite, approximately 163 ft (50 m) thick (Hendricks and Lucchitta, 1974). The bottle-green member consists of thin, discontinuous sequences of interbedded basalt flows and sandstone beds, highly 

altered, and contains secondary chlorite, epidote, talc, and zeolites; approximately 294 ft (90 

m) thick

Dox Formation (Mesoproterozoic)—Includes, in descending order, the Ochoa Point, Comanche Point, Solomon Temple, and Escalante Creek Members as mapped by Timmons and 

others (2007) and described by Hendricks and Stevenson (2003). Contacts between members 

of Dox Formation are gradational and based mainly on topographic expression, depositional 

environments, and color change

Ydo Ochoa Point Member (Mesoproterozoic)—Red slope- and cliff-forming micaceous mudstone that grades upward into red quartz sandstone and silty sandstone. Includes salt-crystal 

casts in mudstone and asymmetrical ripple marks and small-scale crossbeds in sandstone. 

Thickness, 250 to 300 ft (976 to 91 m)

Ydc Comanche Point Member (Mesoproterozoic)—Light-red, pale-green to white, slopeforming, mudstone and siltstone and minor thin-bedded sandstone. Includes mud cracks, 

ripple marks, salt casts, wavy to irregular bedding, and stromatolitic dolomite beds within or 

adjacent to white siltstone beds. Thickness, 508 ft (155 m)

Yds Solomon Temple Member (Mesoproterozoic)—Cyclical sequence of red mudstone, 

siltstone, and quartz sandstone. Includes thin beds of argillaceous dolomite or calcareous 

siltstone. Mud cracks and ripple marks are common. Thickness, 920 ft (280 m)

Yde Escalante Creek Member (Mesoproterozoic)—Light-brown to greenish-brown sandstone, 

calcareous sandstone, and arkosic sandstone. Includes an upper dark-brown to green shale 

and mudstone. Thickness, 1,278 ft (390 m)

Ys Shinumo Sandstone, undivided (Mesoproterozoic)—Includes five informal members, in 

descending order: the Seventy Five Mile Rapid, Cottonwood Camp, Papago Creek, Ribbon 

Falls, and Surprise Valley Members, undivided (Timmons and others, 2007). Consists of red, 

brown, purple and white, cliff-forming, fine- to coarse-grained, well-sorted quartz arenite 

and subarkose sandstone with siliceous cement. Upper massive sandstone shows dramatic 

contorted bedding. Unconformable contact with underlying Hakatai Shale truncates crossbeds and alluvial channel deposits. Thickness, 1,132 ft (345 m)

Yh Hakatai Shale, undivided (Mesoproterozoic)—Includes three informal members, in descending 

order: the Stone Creek, Cheops Pyramid, and Hance Rapids members based on lithology of 

Beus and others (1974) and Reed (1976). The Cheops and Hance Rapids members are red to 

bright-red, slope-forming, highly fractured, argillaceous mudstones and shale. Upper Hance 

Rapids member is purple and red, cliff-forming, medium-grained sandstone. Unit contains 

mud cracks, ripple marks, and tabular-planar crossbed structures. Gradational contact with 

underlying Bass Formation. Thickness, 448 to 981 ft (137 to 300 m)

Yb Bass Formation (Mesoproterozoic)—Gray and reddish-gray dolomite interbedded with arkose 

and sandy dolomite and siltstone interbedded with intraformational breccias and conglomerates throughout sequence. Interbedded with dolomite and mudstone beds. Beds of white, 
27

very fine grained tephra deposits with a U-Pb zircon age of 1254±2 Ma (Timmons and 

others, 2007) toward base of section. The basal Hotauta Conglomerate Member (Noble, 

1922) consists of rounded, gravel-sized clasts of chert, granite, quartz, plagioclase crystals, 

and micropegmatites in quartz sand matrix (Dalton, 1972). Contains biscuit-form and biohermal stromatolite beds (Nitecki, 1971). Unconformable contact with underlying Paleoproterozoic granites and schists. Thickness, 196 to 327 ft (60 to 100 m)

PALEOPROTEROZOIC ROCKS

Paleoproterozoic intrusive igneous and metasedimentary rocks, as mapped by Timmons and others 

(2007), are exposed in Grand Canyon and are likely present in the deep subsurface of the eastern part of the 

quadrangle.

Xg Granite (Paleoproterozoic)—Unfolded to weakly foliated, medium- to fine-grained muscovitebiotite, granitic pegmatite and aplite dikes, sills, and small plutons. U-Pb zircon ages range 

from 1,685 to 1,680±1 Ma (Hawkins and others, 1996)

Xgd Granodiorite-gabbro-diorite and granodiorite complexes (Paleoproterozoic)—Weakly to 

well-foliated, medium- to coarse-grained quartz-plagioclase and diorite-hornblende-bearing 

granitoids of probable volcanic arc origin (1.74 to 1.71 Ga)

Xv Vishnu Schist of Granite Gorge Metamorphic Suite (Paleoproterozoic)—Quartz-mica schist, 

pelitic schist, and meta-arenites of probable volcanic arc basin origin. Locally contains 

graded bedding and turbidite layering. Strongly foliated with multiple generations of folds 

and foliations (Ilg and others, 1996)

Xr Rama Schist and Gneiss of Granite Gorge Metamorphic Suite (Paleoproterozoic)—Quartzofeldspathic schist and gneiss of probable felsic to intermediate metavolcanic origin; 

strongly foliated; yields a U-Pb zircon age of 1,741±1 Ma (Hawkins and others, 1996)

Xbr Brahma Schist of Granite Gorge Metamorphic Suite (Paleoproterozoic)—Amphibolites, 

biotite-hornblende schist and biotite schist of probable mafic volcanic origin. Local metafelsite interbeds contain phenocrysts of quartz and feldspar; beds yield a U-Pb zircon age of 

1,750±2 Ma (Hawkins and others, 1996)

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28

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