Geology and Geomorphology of the 

Southwestern Moenkopi Plateau arid 

Southern Ward Terrace, Arizona 

U.S. GEOLOGICAL SURVEY BULLETIN 1672 
Geology and Geomorphology of the 

Southwestern Moenkopi Plateau and 

Southern Ward Terrace, Arizona 

By G.H. BILLINGSLEY 

U.S. GEOLOGICAL SURVEY BULLETIN 1672 
DEPARTMENT OF THE INTERIOR 

DONALD PAUL HODEL, Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1987 

For sale by the 

Books and Open-File Reports Section 

U.S. Geological Survey 

Federal Center, Box 25425 

Denver, CO 80225 

Library of Congress Cataloging-in-Publication Data 

Billingsley, George H. 

Geology and geomorphology of the southwestern 

Moenkopi Plateau and southern Ward Terrace, Arizona 

U.S. Geological Survey Bulletin 1672 

Bibliography 

Supt. of Docs. No.: 119.3:1672 

1. Geology-Arizona-Moenkopi Plateau. 2. 

Geomorphology-Arizona-Moenkopi Plateau. 3. 

Geology-Arizona-Ward Terrace. 4. GeomorphologyArizona-Ward Terrace. I. Title. II. Series: Geological 

Survey Bulletin 1672. 

QE75.B9 No. 1672 557.3 s 86-607947 

[QE86.M6] [557.91] 
CONTENTS 

Abstract 1 

Introduction 1 

Stratigraphy 4 

Surficial deposits 6 

Sedimentology of bedrock and surficial units 6 

Geomorphic interpretations 12 

References cited 17 

FIGURES 

1. Index map showing location of study area 2 

2. Graph showing percentage of year when wind velocity exceeded 15 mi/hr on 

Moenkopi Plateau from each of 16 compass directions, 1980 through 

1984 3 

3. Graph showing cumulative percentage of potential sand movement on 

Moenkopi Plateau from each of 16 compass directions, 1980 through 

1984 4 

4. Aerial photograph of Paiute Trail Point of Red Rock Cliffs 7 

5-9. Maps showing: 

5. Sample localities 8 

6. Probable positions of cliffs and drainages immediately after Black Point 

basalt flow entered Little Colorado River channel, about 2.4 m.y. ago 13 

7. Probable positions of cliffs and drainages at end of Tertiary time (about 

1.8 to 2.0 m.y. ago) 14 

8. Probable positions of cliffs and drainages about 1 m.y. ago 15 

9. Present positions of cliffs and drainages 16 

TABLES 

1. Sedimentary rocks 5 

2. Composition of bedrock samples 9 

3. Composition of surficial samples 10 

m 
Geology and Geomorphology of the 

Southwestern Moenkopi Plateau and 

Southern Ward Terrace, Arizona 

By G.H. Billingsley 

Abstract 

In the study area, sedimentary rocks of Permian 

through Jurassic age dip 1° to 2° from the Little 

Colorado River northeastward to the Moenkopi 

Plateau. Tributary drainages, however, flow 

southwestward from the plateau, opposite the 

direction of the strong southwesterly winds. Several 

levels of resistant strata have formed a series of 

scarps and cuestas slightly inclined toward the 

Moenkopi Plateau. Subsequent drainages are 

entrenched within resistant strata near the base of 

retreating scarps, leaving a visual record of scarp 

retreat and development toward the Moenkopi Plateau 

during the past 2.4 million years. Sand eroded from 

local sedimentary strata was wind transported from 

the Little Colorado and its tributaries onto the 

Moenkopi Plateau about 2.4 million years ago, when 

the river valley was 680 ft higher, than at present and 

the plateau was about 5 mi closer to the river. Today 

the plateau averages about 1,000 ft higher, and the 

current supply of sand no longer reaches its surface. 

INTRODUCTION 

Fluvial erosion, influenced and modified by 

eolian activity, has been the primary agent in shaping 

the modern landscape of the study area, located in 

northeastern Arizona between the Little Colorado 

River and the Moenkopi Plateau. Since late Tertiary 

time--and possibly before--geomorphic relations 

between fluvial and eolian processes have been 

reflected both by drainage patterns on northeasterly 

dipping sedimentary rocks and by the northeastward 

retreat of cuestas along the southwest margin of the 

Moenkopi Plateau. 

The study area extends from the Little Colorado 

River northeastward to the s~mit of the Moenkopi 

Plateau, encompassing 300 mi (fig. 1). Its bedrock 

and surficial geology have been mapped at a scale of 

1:31,680 (Billingsley, 1987). The area lies within the 

Navajo and Hopi Indian Reservations, about 45 mi 

northeast of Flagstaff. Elevations range from 4,200 ft 

at the Little Colorado River to 5,660 ft on the 

Moenkopi Plateau, over a horizontal distance of about 

16 mi. The southwest edge of the plateau is defined by 

the Adeii Eechii Cliffs, an erosional scarp. Other 

major erosional scarps, to the southwest, are the Red 

Rock Cliffs and the southwest edge of Ward Terrace. 

These scarps, as well as many canyons of red 

sandstone, add beauty to the desolate area, but 

severely restrict travel through it. 

Tohachi Wash and lesser drainages flow from the 

Adeii Eechii Cliffs southwestward to the Little 

Colorado in a direction nearly opposite that of strong 

seasonal southwesterly winds. These drainages, and 

the Little Colorado itself, are commonly dry for 

several months in spring and early summer. 

Sedimentary rocks are interbedded limestone, 

silica-cemented sandstone, and multicolored shale that 

dip 1° to 2° to the northeast, forming northwesttrending ledges and cliffs. Bedrock is easily eroded by 

streams and winds. An abundant supply of loose 

sediment is thus available for redeposition, and much 

of the bedrock is mantled by alluvium and windblown 

sand. 

The present climate of the study area is 

semiarid. The area's southern latitude, high rate of 

evaporation, and wind all contribute to the general 

aridity, while its elevation controls variations in 

precipitation and temperature. Slightly more 

precipitation falls on the Moenkopi Plateau than on 

Ward Terrace, whose elevation is lower, but the mean 

annual precipitation of the area is less than 10 in. The 

wetter seasons are winter and summer; fall and spring 

are relatively dry. Mean annual temperature is just 

above 51 °F (Sellers and Hill, 1974, p. 306-307). March 

through June are characterized by strong winds that 

produce blowing sand or duststorms. 

Since 1980, weather data from an automated 

remote-monitoring geometeorological (GEOMET) 

station near Gold Spring on the Moenkopi Plateau have 

been collected by the U.S. Geological Survey 

(McCauley and others, 1984). Yearly data from this 

1 
2 

STUDY AREA--

FLAGSTAFF. 

ARIZONA 

0 

Figure 1. Index map showing location of study area. 

5 10 15 MILES 
3.4 

a:: 3.2 ~ 

0 EXPLANATION :I: 

a:: 3.0 

w -1980 a.. 

en 2.8 w ~1981 

::E = 2.6 

It) ~ 1982 .... 

0 2.4 w ++++ 1983 0 

w 2.2 w 

u T""'V'T 1984 

X 

w 2.0 

>- !::: 

u 1.8 

0 

...J 

w 1.6 > 

0 

z 1.4 

~ 

z 

w 1.2 :I: 

~ 

a:: 

< w 

>- 0.8 LL 

0 

w 0.6 C) 

< 1- 0.4 z 

w 

u 

a:: 

w 

a.. 

0 

N NNE NE ENE E ESE SE SSE s SSW sw WSW w WNW NW NNW N 

0.47 0.24 0.14 0.09 0.12 0.14 0.20 0.40 0.69 1.27 1.83 1.84 2.53 1.98 0.49 0.59 0.47 

DIRECTION FROM WHICH WIND BLEW AND FIVE-YEAR AVERAGE FOR EACH DIRECTION 

Figure 2. Percentage of year when wind velocity exceeded 15 mi/hr on Moenkopi Plateau from each of 16 

compass directions, 1980 through 1984. Data from Desert Winds Project, U.S. Geological Survey, Flagstaff, 

Ariz. 

station on wind and potential sand movement are given 

in figures 2 and 3 and summarized below. 

1980 

1981 

1982 

1983 

1984 

Percentage of year 

when wind velocity 

from all directions 

exceeded 15 mi/hr 

13.37 

10.75 

14.20 

12.51 

13.49 

5-year 

average 13.02 

Percentage of 

potential sand 

movement from 

all directions 

97 

95 

95 

97 

101 

96.8 

Measurements from the beginning of 1980 

through 1984 (fig. 2) show that the strongest winds 

having the greatest potential for sand movement have 

come from the southwest to west-northwest. The 

southwest and west-southwest directions are reflected 

in the alignment of all dune types of the area, but the 

west and west-northwest directions are not. A 

possible explanation is that the winds from 

approaching cold fronts during dry conditions are the 

southwester lies; as the fronts pass and the winds veer 

to the north, sufficient precipitation may occur to 

retard sand movement. 

Vegetation is restricted mainly to the Moenkopi 

Plateau and the flood plain of the Little Colorado 

River. Several species of grasses and shrubs thrive on 

the sandy plateau, whose eolian veneer retains 

sufficient moisture to sustain growth. Here the 

dominant shrub, Ephedra (Mormon tea), traps moving 

sand in small mounds, forming coppice dunes. On the 

Little Colorado flood plain, sagebrush and tamarisk 

(saltcedar) trees compete for space and locally form 

almost impenetrable thickets. Lying between the 

floodplain and the plateau are Ward Terrace and the 

Red Rock Cliffs, which together have the greatest 

topographic relief in the study area; they support 

virtually no vegetation except along the banks of small 

ephemeral tributaries. 

3 
1-

z 

w 

u 

a: 

w 

Q.. 

~ 

1-. 

z 

w 

~ 

w 

> 

0 

~ 

c 

z 

< 

en 

...J 

~ 

1-

z 

w 

1-

28 

26· 

24 

22 

20 

18 

16 

14 

12 

10 

8 

~ 6 

4 

0· 

N 

3.0 

EXPLANATION 

1980 

8"8 1981 

....... 1982 

-+-+++ 1983 

..4...6.A. 1984 

s 

4.0 

ssw 

8.8 

SW 

15.6 

WSW 

18.8 

w 

21.2 

WNW 

14.8 

NW 

3.0 

NNW 

3.6 

N 

3.0 

DIRECTION FROM WHICH SAND MOVED AND FIVE-YEAR AVERAGE FOR EACH DIRECTION 

Figure 3. Cumulative percentage of potential sand movement (see text) on Moenkopi Plateau from each of 16 

compass directions, 1980 through 1984. Percentages are based on calculations using Lettau-Lettau sand-flux 

equation (Fryberger, 1978) that do not take into account precipitation, soil moisture, or vegetation. Data from 

Desert Winds Project, U.S. Geological Survey, Flagstaff, Ariz. 

STRATIGRAPHY 

Sedimentary rocks of Permian through Jurassic 

age are exposed in the study area and are described in 

table 1. The Kaibab Formation (Lower Permian) crops 

out on the flanks of the Black Point monocline west of 

the Little Colorado River. The contrast in color at the 

unconformity between the gray Kaibab and the 

overlying red Moenkopi Formation (Middle(?) and 

Lower Triassic) makes the Paleozoic-Mesozoic 

boundary conspicuous. 

Unconformably overlying the Moenkopi is the 

Chinle Formation (Upper Triassic), which is divided 

into three members whose contacts are gradational; 

from bottom to top they are the Shinarump, the 

Petrified Forest, and the Owl Rock. In the southern 

part of the study area, the Chinle grades upward into 

the Rock Point Member of the Upper Triassic Wingate 

Sandstone (Repenning and others, 1969); an arbitrary 

boundary is placed at the color change from the red 

and mottled shale of the Chinle to the yellow ish-red 

shale and siltstone of the Rock Point. The Rock Point 

is about 100 ft thick at Tohachi Wash in the 

southwestern part of the study area but lenses out 

northward. At its top is a conspicuous disconformity 

with the Lukachukai Member of the Wingate. Where it 

4 

is in contact with the Rock Point, the Lukachukai is 

primarily a flat-bedded sandstone with some smallscale crossbedding, but several miles to the east it is 

typically cross stratified. Like the Rock Point, the 

Lukachukai lenses out northward, leaving the Chinle 

and Moenave Formations in unconformable contact. 

Because of extensive sand cover, the contact of 

the Wingate with the overlying Moenave Formation 

(Upper Triassic?) is rarely exposed in the study area. 

Where it is seen, the two rock types intergrade; the 

contact is arbitrarily placed at the change from lightreddish-brown, massive-bedded sandstone of the 

Wingate to the darker red siltstone and sandstone of 

the Moenave. Where the Wingate is absent north of 

Tohachi Wash, the base of the Moenave is easily 

recognized because of contrasts with the Chinle in 

color, rock type, and topographic expression. 

The Moenave generally underlies gentle slopes 

smothered by dune sand; the Red Rock Cliffs formed 

in the Moenave owe their existence to a caprock of 

resistant silicified sandstone of the Kayenta Formation 

(Upper Triassic?). The dating of a dinosaur and other 

fossils by Colbert (1981, p. 56) suggests that the age of 

the Moenave, the Kayenta, and perhaps that of the 

lower part of the overlying Navajo Sandstone could be 

Late Triassic. The Moenave and Kayenta intertongue; 
Table 1. Sedimentary rocks 

[Color names and numbers from Munsell soil color charts (1954)] 

NAVAJO SANDSTONE (JURASSIC AND UP PER 

TRIASSIC(?))--White (5Y 8/2), medium-grained, 

well-rounded, medium-crossbedded, eolian 

sandstone. Several outcrops of freshwater cherty 

limestone beds occur within sandstone on 

Moenkopi Plateau, weather out as flat-topped 

ridges. Forms hummocky knobs along Adeii Eechii 

Cliffs. As much as 120 ft exposed but top eroded. 

NAVAJO SANDSTONE AND KAYENTA FORMATION, 

UNDIVIDED (JURASSIC AND UPPER 

TRJASSIC(?))--Pinkish-white (7 .5 YR 8/2), 

crossbedded, massive sandstone, interbedded with 

pale-red (lOR 5/3) fluvial siltstone and finegrained silty sandstone that contains authigenic 

quartz. Forms alternating steep slopes and 

cliffs. Approximately 200 to 280 ft thick. 

KAYENTA FORMATION (UPPER TRIASSIC?)--Palered (5R 5/4), fluvial siltstone and fine-grained 

silty sandstone with interbedded purplish-red 

(2.5 Y R 6/4) shale. Forms slopes of approximately 

480 ft maximum thickness. 

MOENAVE FORMATION (UPPER TRIASSIC?)--Red 

(2.5 YR 5/8), crossbedded, massive, fluvial 

siltstone and sandstone. Contains several thin 

beds of reddish-brown (2.5YR 5/4), fine-grained, 

crossbedded, fluvial and eolian siltstone and 

sandstone in lower part that may be interbeds of 

upper part of Wingate Sandstone. Unit forms 

cliffs and slopes of Red Rock Cliffs along eastern 

margin of Ward Terrace. Maximum thickness 300 

ft. 

WINGATE SANDSTONE (UPPER TRIASSIC) 

Lukachukai Member--Light-reddish-brown (5YR 

6/4), coarse- to fine-grained, fluvial and eolian 

sandstone; massive bedded; a few thin siltstone 

beds. Some crossbedding in upper part. Forms 

rounded knobs and cliffs as much as 120 ft thick. 

Conspicuous disconformity at base. Rests on 

Rock Point Member in southeastern part of study 

area and on Chinle Formation in central part. 

Pinches out northward. 

their contact is placed at the base of the lowermost 

purplish-gray, silicified sandstone or limestone of the 

Kayenta. 

Above the slope-forming red siltstone and 

sandstone and purple shale of the typical Kayenta is a 

transition zone about 200 to 280 ft thick of Kayenta 

red shale interbedded with white, cliff-forming 

sandstone beds of Navajo. This zone was mapped by 

Billingsley (1987) as Navajo Sandstone and Kayenta 

Formation, undivided. Its boundaries are arbitary; the 

lower contact is placed at the base of the lowermost 

WINGATE SANDSTONE-Continued 

Rock Point Member--Yellowish-red (5 YR 5/8), finegrained, thick-bedded, fluvial siltstone and shale. 

Forms moderate to gentle slopes as much as 100 

ft thick in southwestern part of study area. 

Pinches out northward near center of area. 

CHINLE FORMATION (UPPER TRIASSIC) 

Owl Rock Member--Mottled reddish-gray (lOR 6/1) 

and pale-red (lOR 6/1) to red (5R 5/3) interbedded 

limestone and calcareous siltstone. Widespread on 

Ward Terrace. Forms steep slopes as much as 240 

ft thick with intervening thin ledges of resistant 

cherty limestone. 

Petrified Forest Member--Multicolored claystone 

and siltstone and light-gray (2.5 Y N 7 /0), mediumto coarse-grained, fluvial sandstone. Forms 

hummocky rounded knolls or gentle slopes. 

Maximum thickness about 380 ft. 

Shinarump Member--Pale-red (lOR 6/4), coarsegrained and granular, cross-bedded, fluvial 

sandstone and conglomerate; conglomerate 

contains small pebbles of quartz; thin lenses of 

siltstone. Forms low cliffs or ledges 5 to 45 ft 

thick in area of Little Colorado River. 

Unconformity at base. 

MOENKOPI FORMATION (MIDDLE(?) AND LOWE]{ 

TRIASSIC)--Light-red (lOR 6/6) siltstone and finegrained sandstone. Contains veinlets and string-ers 

of gypsum and thin-bedded layers of green and red 

claystone. Basal conglomerate contains angular 

pebbles of white chert derived from underlying 

Kaibab Formation. Forms slope as much as about 

400 ft thick with a few ledges. Crops out along 

Little Colorado River in southwestern part of 

study area. Unconformity at base. 

KAIBAB FORMATION (LOWER PERIVJIAN)--Yellow to 

light-gray (lOY R 8/6), calcareous sandstone and 

sandy, medium-bedded limestone interbedded with 

dolomitic limestone. Forms resistant surface of 

Black Point monocline. Thickness about 230 ft 

(Moore and others, 1974, p. 516). 

white sandstone bed, and the upper contact is at the 

top of the uppermost bed of red shale. 

The Navajo Sandstone, of Jurassic and Late 

Triassic(?) age, underlies the Moenkopi Plateau. It 

erodes to rounded knobs and ledges and is largely 

mantled by surficial deposits. Local outcrops of thinbedded siliceous sandstone and limestone at various 

elevations on the plateau surface probably represent 

interdunal lake beds formed during deposition of the 

Navajo (Gilland, 1979; Stokes, 1983). These resistant 

beds are eroded into elongated or circular flat-topped 

5 
forms. Some outcrops of the Navajo have attained the 

classic elongated aerodynamic shape of bedrock 

yardangs in other arid regions (Breed and others, 

1984). 

The youngest bedrock unit in the study area is 

the Black Point basalt flow of Pliocene age. This flow 

forms Black Point west of the Little Colorado River 

(see figs. 5-9). 

SURFICIAL DEPOSITS 

Unconsolidated and weakly consolidated surfic~al 

deposits cover large parts of the study area. Fluvial 

deposits near the Little Colorado River have been 

described by Childs (1948), Rice (197 4), and Hereford 

(1979). Eolian materials include sand sheets and dunes 

(barchan, parabolic, linear, and complex), some of 

which have been described by Hack (1941), Breed and 

Breed (1979), and Breed and others (1984). The age o~ 

the fluvial and eolian deposits below the Moenkopi 

Plateau is considered to be Holocene and Pleistocene, 

undivided (Billingsley, 1987). Many units are 

contemporaneous and they intertongue. Sand sheets 

and dune deposits that cover the Moenkopi Plateau 

may be older than Pleistocene. Other surficial 

material consists of localized landslide debris from the 

Black Point basalt flow. 

Present-day stream deposits are primarily mud, 

silt sand and gravel. During seasonal dry spells in 

lat~ sprin~ and early summer, sand and silt are blown 

from stream channels, primarily Tohachi Wash, onto 

adjacent flood plains and higher terrain. Much of the 

sand occurs in sheets that advance northeasterly. 

Where the sand is sparse or relatively thin, it forms 

well-defined barchan or parabolic dunes; thicker sand 

sheets tend to form complex dunes. Some of the sand 

blown by wind from washes, however, is tr~nsported_by 

streams back into the washes. Th1s recycling 

operation, described by Breed and othe~s (1984), takes 

place in all drainages east of the Little Colorado 

River regardless of their orientation. Eventually most 

of th~ recycled sand and eroded material is removed 

by the Little Colorado River. 

Persistent southwesterly winds in the fall and 

spring have effectively reshaped Tohachi Wash a!'ld 

other channels. When the Little Colorado and 1ts 

tributaries are dry for several months, the winds blow 

sand and silt toward the centers and northeast margins 

of the channels. Here these deposits accumulate, 

especially where vegetation retards or slows sand 

movement and form elongated ridges similar to 

natural l~vees. These ridges divert intermittent 

streamflows back and forth across the channels, 

eroding and widening them and enlarging the source 

areas from which new sand sheets and dunes can 

develop. 

Fluvial deposits of silt, coarse sand, and gravel 

form terraces adjacent to the Little Colorado at 

heights of 10 to 240 ft above the river (Rice, 1974; 

Hereford 1979). A few angular boulders 10 to 15 ft 

across of Kaibab Formation are embedded in the 

terrace deposits (Haines and Bowles, 1976). Deflation 

has winnowed most of the finer particles from the 

surfaces of these terraces and nearby alluvial fans, 

6 

leaving behind lag gravels that are coated by desert 

varnish. 

Many other sand dunes and sand-sheet deposit~ 

originate at or just above outcrops of the Lukachukai 

Member of the Wingate Sandstone. The weakly 

cemented sandstone of the Wingate and overlying 

Moenave Formation erodes relatively easily, providing 

materials for eolian transport. In contrast, the 

underlying Chinle Formation yields little sand t~ the 

winds and forms a nearly flat surface that neither 

collects sand nor retards its movement. 

As windblown sand continues to migrate 

northeastward, it encounters the scarps and mesas east 

of the Little Colorado River. As the sand is blown 

over these partial barriers, it commonly forms 

climbing and falling dunes (Hack, 1941). Climbing 

dunes have reached the level of the Kayenta 

Formation, the caprock of the Red Rock Cliffs, at 

Paiute Trail Point (fig. 4). Elsewhere along these 

cliffs, however, climbing dunes general_ly reac_h the 

level of the Kayenta only where maJor dramages 

dissect the cliffs southeast of the study area. Above 

the Red Rock Cliffs, the Adeii Eechii Cliffs form a 

second barrier to the northeastward migration of sand 

from lower elevations. 

Sand sheets and alluvium cover large areas on 

the Moenkopi Plateau (Billingsley, 1987). Analysis of 

well data (Breed and others, 1984) indicates that the 

average depth of the sand sheets and alluvial veneer on 

the Moenkopi Plateau today is almost 30 ft. 

The linear (longitudinal) dunes on the Moenkopi 

Plateau are now topographically isola ted from a 

formerly abundant sand supply and have been mostly 

stabilized by vegetation (Breed and others, 1984). 

These dunes form slightly sinuous ridges, commonly as 

long as 6,000 ft, of very fine to medium sand on which 

vegetation is moderate to sparse. Linear dunes on the 

Moenkopi Pla te!lu are mostly inactive except near the 

Adeii Eechii Cliffs, where sand eroded by wind from 

the Navajo Sandstone has formed an active deposit 

along crests of the older dunes. This surface s~nd 

differs in color, grain size, composition, and sortmg 

from the sand that forms the main body of the linear 

dunes (Breed and Breed, 1979; table 3, samples 1 and 

2). 

Along the Adeii Eechii Cliffs, sand derived from 

the Navajo Sandstone forms parabolic dunes that 

coalesce at their upwind edges and extend downwind to 

merge with preexisting linear dunes. Other parabolic 

dunes on the plateau have formed downwind of 

deflation hollows and stock tanks; many of these dunes 

are now stabilized by vegetation. The parabolic dunes 

below the pla te·au near the Red Rock Cliffs have 

complex combinations of barchanoid and parabolic 

shapes and form downwind of sandstone outcrops and 

streambeds that yield loose sand. 

SEDIMENTOLOGY OF BEDROCK AND SURFICIAL 

UNITS 

A reconnaissance sampling (fig. 5) of selected 

geologic units in the area was made to identify sources 

of the surficial deposits. Descriptive data based on 

binocular examination of bedrock and surficial samples 
Figure 4. Aerial photograph of Paiute Trail Point (see fig. 5 for location) of Red Rock Cliffs, looking in 

direction of wind transport (northeast). Fluvial erosion is reducing this salient to a mesa. Prevailing 

southwesterly winds have piled sand against the 200-ft-high cliffs and upward onto the Kayenta Formation that 

caps them. Adeii Eechii Cliffs and Moenkopi Plateau appear in distant background. Width of foreground about 3 

mi. Photograph by CarolS. Breed, U.S. Geological Survey. 

are presented in tables 2 and 3, respectively. Because 

of lithologic variations within each geologic unit, none 

of the samples should be considered typical of an 

entire unit, but the reconnaissance data suggest the 

following general conclusions. 

The Navajo Sandstone (samples 3 and 8, table 2) 

contains mostly medium to fine, very well rounded, 

well-sorted, frosted sand grains of clear quartz. These 

grains are easily discriminated from those of other 

potential source rocks in the area. The Navajo-derived 

grains make up about 18 percent of sample 22 from a 

sand sheet on the Moenkopi Plateau 1.5 mi east of the 

Adeii Eechii Cliffs at the GEOMET station (fig. 5), 

whereas they make up 37 percent of sample 2 from the 

active crest of a linear dune closer to the cliffs. Thus, 

wind erosion of the Navajo along the cliffs can be seen 

to supply sand grains to the linear dunes and to be the 

primary source of the present-day growth of dunes 

near the cliff edge. 

Grains derived from the Navajo are present in all 

sampled surficial deposits in the area (table 3). 

Sample 9, from an active barchan dune on Ward 

Terrace, contains 32 percent Navajo grains derived 

from an upwind source 6 mi away and 820 ft higher. 

The Navajo grains were transported downslope by 

runoff to Tohachi Wash and then carried by wind 

northeastward to the dune field. 

Two isola ted climbing dunes occur on high ridges 

of the Kayenta Formation about 1 mi upwind and 400 

ft below the nearest outcrops of Navajo Sandstone. 

Sample 26 from the first dune contains 12 percent 

Navajo grains, and sample 28 from the second contains 

3 percent. Today these dunes are isola ted from any 

local sand source; they are relicts from a time when 

dunes climbed the Red Rock Cliffs. Navajo grains 

transported downslope by runoff to lower elevations 

are also contained in the following samples from other 

surficial deposits: 10, 11, 12, 13, 14, 16, 16B, 17, 18, 

19, 22A, 24, 29, 31, and 32. 

Other bedrock units in the area that have 

contributed large quantities of material to the 

surficial deposits are the Lukachukai Member of the 

Wingate Sandstone and the Moenave Formation. These 

units are composed largely of pale- to dark-red and 

'l 
111 °22'30" 

35°52'30" 

..,.. .. 

About 3 miles 

0 

111 °07'30" 

MOENKOPI 

PLATEAU 

5 MILES 

Figure 5. Sample localities (see tables 2 and 3). Arrow on Moenkopi Plateau indicates average of wind 

directions measured at remote-monitoring geometeorological station (location 22), 1980 through 1984. 

yellow quartz grains, which account for about 80 

percent of the Lukachukai (sample 25, table 2) and 

about 70 percent of the Moenave (samples 5, 6, and 7, 

table 2). The compositions of these units are so 

similar that they cannot be distinguished under the 

binocular microscope. Climbing dunes lower than the 

Lukachukai and Moenave outcrops contain 41 percent 

(sample 4) and 51 percent (sample 24) red and redstained quartz sand derived from these units. This 

material was first deposited by streams and then 

transported by wind back toward the parent outcrops. 

8 

Samples 18 and 19 from a climbing dune on the 

Kayenta surface just above the Moenave contain about 

25 percent Lukachukai-Moenave sand grains, indicating 

that this sand was blown by wind from these two lower 

lying units onto and over the Red Rock Cliffs. Further 

evidence of wind transport of Lukachukai-Moenave 

sand grains onto the Red Rock Cliffs can be seen in 

the composition of all other surficial samples taken 

from the cliffs (16B, 26, 27, 28, 29, 31, and 32). Even 

on the Moenkopi Plateau, at the GEOMET station more 

than 1 mi east of the Adeii Eechii Cliffs, the sand of 
Table 2. Composition of bedrock samples (in volume percent) 

Coarse grain 

(>1 .00) 

Fine grain 

(<1 .00) 

Sample 3. Navajo Sandstone, edge of Moenkopi Plateau 

Quartz sandstone grains ............. . 

Clear frosted quartz, 

well- to very well rounded...... 94 

Light-red quartz..................... 3 

0 

97 

3 

Sample 5. Moenave Formation, upper part, Gold Spring Wash 

Quartz sandstone grains.............. 5 

Dark-red quartz...................... 5 

Light-red quartz..................... 60 

Clear quartz......................... 10 

Dark- and light-green mineral? ...... . 

Red chert? ..........................• 

Biotite............................ 11 

Muscovite.......................... 3 

Magnetite? ........................ . 

0 

4 

45 

48 

trace 

trace 

1 

trace 

2 

Sample 6. Moenave Formation, middle part, Gold Spring Wash 

Red quartz sandstone grains .......... 50 

White quartz sandstone grains........ 1 

Red quartz. . . . . . . . . . . . . . . . . . . . . . . . . . . 48 

Black quartz with iron............... 1 

Biotite.............................. 0 

Gypsum............................... 0 

45 

2 

52 

trace 

trace 

Sample 7. Moenave Formation, lower part, Gold Spring Wash 

Light-red and yellow quartz .......... 44 

Dark-red quartz...................... 3 

Clear quartz, angular ................ 10 

Quartz sandstone grains .............. 15 

Schist fragments ..................... 12 

Milky quartz......................... 10 

White chert? and calcite............. 3 

Plagioclase .....................•.... 

Red chert ........................... . 

Gypsum............................... 1 

Biotite.............................. 0 

Muscovite. . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 

Green mineral?. . . . . . . . . . . . . . . . . . . • . . . 0 

58 

1 

11 

0 

4 

9 

4 

0 

trace 

0 

7 

5 

Sample 8. Navajo Sandstone and Kayenta Formation, undivided, 

upper part, shale, 1 mi south of The Landmark 

Clear quartz, angular (crystals) ..... 50 

Milky quartz (feldspar?)............. 8 

Red siltstone grains ................• 40 

Green mineral? ...................... . 

Biotite. . . . . . . . . . . . . . . . . . . . . . . . . . • . • . trace 

Red quartz........................... 1 

19 

40 

37 

trace 

1 

3 

sample 22 is about 39 percent Lukachukai-Moenave 

grains. Also on the plateau, Lukachukai-Moenave 

sand, silt, and clay particles average about 50 percent 

in surficial samples (1, 2, and 22A). 

The schist fragments found in small quantities 

(less than 1 percent) in a linear dune on the Moenkopi 

Plateau (samples 1 and 2) have a unique source in the 

lower part of the Moenave Formation (sample 7, table 

2). These fragments and the Lukachukai-Moenave 

grains could have reached the higher elevations on the 

Moenkopi Plateau only by wind transport earlier in 

geologic time, because their sources are lower lying 

and upwind of the plateau. 

Coarse grain 

(>1 .00) 

Fine grain 

(<1 .00) 

Sample 15. Chinle Format ion, Petrified Forest Member, near 

mouth of Tohachi Wash 

Clear quartz. . . . . . . . . . . . . . . . . . . . . . . . . 23 

Red quartz. . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Reddish-brown chert?. . . . . . . . . . . . . . . . . 13 

Gray siltstone grains ................ 61 

Muscovite............................ trace 

Biotite.............................. trace 

Green mineral?....................... trace 

Purple quartzite or chert? ........... trace 

2 

3 

1 

79 

2 

2 

1 

10 

Sample 20. Kayenta Formation, lower part, near Gold Spring 

Wash 

Clear quartz ........................ . 

Milky quartz ......•.................. 

Light -red quartz .................... . 

Dark-red quartz ..................... . 

Purple sandstone grains ............. . 

Muscovite .....••..................... 

Biotite ............................. . 

Green mineral? ...................... . 

Hematite? ........................... . 

8 

14 

8 

trace 

52 

4 

12 

50 

3 

18 

6 

11 

1 

8 

3 

trace 

Sample 21. Kayenta Formation, upper part, Gold Spring Wash 

Clear quartz, angular................ 0 

Milky quartz......................... 1 

Light -red quartz. . . . . . . . . . . . . . . . . . . . . 2 

Purple quartz or silica clay?........ 49 

Magnetite............................ 0 

Biotite.............................. 0 

Purple sandstone grains .............. 48 

Muscovite. • . . . . . . • . . . . . • . • • . . . . . . . . . . 0 

Green mineral?., ...... , , . , . . . . . . . . . . . 0 

8 

34 

13 

40 

2 

3 

0 

trace 

trace 

Sample 25. Wingate Formation, Lukachukai Member, 1/2 mi south 

of Tohachi settlement 

Yellow quartz........................ 14 

Dark-red quartz. • . . . . . . . . . . . • • . • . . • . . 2 

Light-red quartz..................... 2 

Pale-red sandstone grains .••.•.•..... 77 

Clear quartz. . . . . . . . . . . . . . . . . . . . . . . . . 2 

Gray chert?. . . . . . . . . . . . . . . . . . . . . . • . . . 3 

Hematite? .. . .. .. .. . .. .. . .. .. .. .. . .. . trace 

White sandstone grains .......••...... trace 

80 

1 

3 

12 

0 

trace 

1 

3 

Sample 30. Navajo Sandstone and Kayenta Formation, undivided, 

lower part, white sandstone, 1 mi southeast of The Landmark 

Clear quartz, angular ............... . 

Clear quartz, rounded ............... . 

Red-stained quartz .................. . 

Green mineral, stain? ............•..• 

Biotite ............................. . 

Gypsum ......•... , ..•••.•.........•... 

Smoky quartz? .................... ,, .. 

87 

2 

trace 

trace 

trace 

10 

1 

Basaltic ash fragments are found in most 

surficial deposits .of the area. Their source was 

intermittent volcanic eruptions (Moore and others, 

1976) in the San Francisco volcanic field southwest of 

the study area during late Tertiary and Qua ternary 

time. 

West of the Red Rock Cliffs, two sources of 

wind-transported sand can be distinguished. The first 

source was sediments along the Little Colorado 

River. Most of this sand was deposited within a few 

miles of the river; samples collected at progressively 

greater distances downwind (east) of the river contain 

progressively fewer river-sand grains and more grains 

9 
Table 3 .. Composition of surficial samples (in volume percent) 

[Asterisks indicate sand grains characteristic of: *, Navajo Sandstone; **, Lukachukai Member of Wingate Sandstone and Moenave Formation] 

Coarse grain 

(>1 .00) 

Fine grain 

( <1 .00) 

Sample 1. Interior of linear dune, edge of Moenkopi Plateau 

Quartz sandstone grains •............. 12 

Light- and dark-red quartz**········· 40 

Clear quartz, rounded* .....•......... 43 

Yellow quartz........................ 5 

Gray chert? . . . . . . . . . . . . . . . . .. . . . . . . . . trace 

Basaltic ash fragments •••.•........•. trace 

Schist fragments •.................... trace 

Sample 2. Surface of dune sampled above 

Quartz sandstone grains •....•...•..•. 

Clear quartz, rounded* •.•............ 

Milky quartz ........................ . 

Light- and dark-red quqrtz**········· 

Schist fragments .................... . 

Gray chert? ......................... . 

Basaltic ash fragments .............. . 

6 

48 

12 

25 

trace 

3 

6 

0 

69 

20 

6 

2 

2 

0 

27 

3 

65 

0 

3 

2 

Sample 4. Surface of climbing dune, base of Moenave Cliffs, 

Gold Spring Wash 

Red quartz**·· •...................... 33 

Clear quartz, rounded* •.............. 24 

Milky quartz......................... 18 

Quartz sandstone grains.............. 16 

White chert.......................... 2 

Red chert?. . . . . . . . . • . . . . . . . . . . . . . . . . • 4 

Basaltic ash fragments............... 2 

Schist fragments .....•............... 

Magnetite .....•...................... trace 

Gypsum. . • . • . . . . . . . . . . . . . . . . . . . . . . . . . . trace 

49 

20 

12 

0 

2 

5 

12 

0 

0 

0 

Sample 9. Slipface of barchan dune, active dune field on Owl 

Rock Member of Chinle Formation 

Dark-red quartz**···················· 3 

Light-red quartz**··················· 16 

Clear quartz, rounded* ............... 32 

Milky quartz......................... 29 

Green and black quartz............... 4 

Bluish-gray chert.................... 4 

Red chert?.. . . . . . . . . . . . . . . . . . . . . . . . . . 1 

White chert?......................... 5 

Biotite.............................. 0 

Muscovite . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 

Basaltic ash fragments............... 6 

Schist fragments ..................... trace 

5 

9 

32 

30 

4 

2 

2 

1 

2 

1 

12 

0 

Sample 10. Interior of terrace-gravel deposit, Black Falls 

roadcut about 7 mi southeast of Black Point 

Milky quartz.. . • . • . . . . . . • . . . . . . . . . . . . 70 

Quartz sandstone grains .............. 12 

Rose quartz... • • . . . . . • • • • • . • . . . . . • . . . 2 

Purple chert?........................ 2 

Black mineral quartzite.............. 3 

Clear quartz, angular................ 2 

Clear quartz, rounded*............... 4 

White chert? or calcite?............. 3 

Red quartz**·........................ 2 

Biotite.............................. 0 

Green mineral? .....•....•••...•....•. trace 

Light-red quartz**··················· trace 

10 

60 

0 

trace 

0 

9 

13 

6 

2 

2 

trace 

1 

7 

Coarse grain 

(>1 .00) 

Fine grain 

(<1 .00) 

Sample 11. Surface of sand sheet on Petrified Forest Member 

of Chinle Formation south of Tohachi Wash 

Basaltic ash fragments ..•............ 

Milky quartz ........................ . 

Clear quartz, rounded* ..........•.... 

Clear quartz, angular ............... . 

Light-red chert? .....•..•............ 

Red and black quartzite? •............ 

Light-red quartz**··················· 

White ash? or calcite? .............. . 

Smoky quartz ......................•.. 

Green mineral? ...................... . 

Muscovite ........................... . 

Biotite ............................. . 

30 

31 

10 

8 

7 

7 

4 

2 

trace 

1 

0 

0 

Sample 12. Surface of Tohachi Wash 1/4 mi 

Colorado River 

Clear quartz, well rounded* .........• 25 

Clear quartz, angular................ 8 

Feldspar, rounded.................... 4 

Light-red quartz**··················· 12 

Gray, brown, green chert? ............ 19 

Quartz with iron inclusions.......... 2 

Basaltic ash fragments............... 6 

Quartz sandstone grains.............. 5 

Siltstone flakes..................... 8 

White chert? or ash?................. 9 

Travertine crystals.................. 2 

Green mineral?....................... trace 

Biotite.............................. 0 

40 

31 

3 

10 

trace 

3 

6 

trace 

2 

3 

1 

from Little 

13 

31 

24 

18 

trace 

4 

0 

0 

4 

0 

2 

4 

Sample 13. Surface of Tohachi Wash 1/2 mi from Little 

Colorado River 

Clear quartz, rounded* ............... 8 11 

Clear quartz, angular •............... 42 78 

Dark-red quartz** .................... 1 

Light-red quartz** ............•..••.. 3 

Basaltic ash fragments ............... 16 

Quartz sandstone grains .•......•..... 10 0 

Siltstone mud curls ...•.............. 7 trace 

Milky quartz ...•••.....•............. 4 trace 

White mineral, calcite? .............. 3 trace 

Gray chert .............•.....•....... 3 trace 

Green mineral, apatite? .............. trace 2 

Biotite .•..........•................. trace 1 

Green chert? ..........•.............• 1 0 

Purple quartzite? or chert? .......... 2 trace 

Gypsum ...................•.....•..... trace trace 

Muscovite ......••.•...........•...... trace trace 

Schist fragments •.................... trace trace 

Sample 14. Surface of small modern dune in center of Little 

Colorado River 

Basaltic ash fragments .............. . 

Milky quartz .....••....•...•......... 

Clear quartz, angular ............... . 

Clear quartz, rounded* .............. . 

White quartz sandstone grains ....... . 

Red quartz sandstone grains**········ 

Light-red quartz**··················· 

Dark-red quartz**···················· Red chalcedony ......................• 

Green mineral? ......••............... 

Biotite ........•..................... 

Yellow quartz** ......•..........•...• 

Light-reddish-brown quartz**········· 

Gray chert •......•.....•...•••....•.. 

Red quartzite? .•..................... 

Hornblende? magnetite? ....•...•...... 

Siltstone mud curls ................. . 

20 

17 

22 

12 

6 

2 

3 

1 

2 

trace 

3 

4 

3 

4 

trace 

trace 

3 

2 

74 

10 

0 

0 

2 

3 

2 

3 

trace 

1 

0 

0 

trace 

0 

0 
Table 3. Composition of surficial samples--Continued 

Coarse grain 

(>1 .00) 

Fine grain 

( <1 .00) 

Sample 16. Interior of high terrace on Baah Lokaa Ridge 

White quartz sandstone grains ....... . 

Clear quartz, rounded* .............. . Clear quartz, angular ............... . 

Gray, red, white chert •.......•...... 

Basaltic ash fragments? ............. . 

Red quartz** ........................ . 

Yellow quartz** ..................... . 

Clear quartz with iron inclusions ... . 

Black chert? .........•............... 

Travertine crystals ••.•.•............ 

Feldspar .•........................... Biotite ...........•............•..... 

Green mineral? ..................•.... 

4 

3 

42 

30 

6 

7 

1 

2 

2 

1 

2 

0 

0 

0 

10 

39 

13 

7 

18 

4 

trace 

5 

trace 

trace 

3 

Sample 16B. Surface of sand sheet on Kayenta Formation, above 

Red Rock Cliffs 

Basaltic ash fragments............... 4 

Smoky quartz......................... 4 

Milky quartz? or feldspar? ........... 16 

Clear quartz, angular ................ 20 

Clear quartz, rounded*............... 8 

Quartz sandstone grains.............. 6 

Light-red quartz**................... 35 

Dark-red quartz**.................... 3 

Green mineral?....................... 4 

Biotite .•.•...•...................... trace 

6 

6 

10 

18 

6 

0 

37 

12 

Sample 17. Surface of undifferentiated dune on Kayenta 

Formation above Red Rock Cliffs 

Siltstone flakes .................... . Basaltic ash fragments .............. . Clear quartz, angular ..........•..•.. Clear quartz, rounded* .............. . 

Quartz sandstone grains ............. . 

Light-red quartz** .••.•••••.••.••.••• 

Dark-red quartz** .•..••.••••...•.••.. Milky quartz and feldspar ..•.....•... Smoky quartz .................•..•...• 

Biotite .........•...........•.••..... 

Muscovite .......•.••.•..•..•...•.••.. 

5 

5 

8 

7 

8 

53 

trace 

5 

7 

1 

0 

5 

25 

3 

0 

35 

20 

5 

4 

3 

trace 

Sample 18. Surface of upper part of climbing dune on Kayenta 

Formation above Red Rock Cliffs 

Yellow quartz** ..••....•••••••.•••... Dark-red quartz** ................... . 

Light-red quartz**··················· 

Quartz sandstone grains ............. . White quartz and feldspar ........... . 

Green mineral? .•..................... 

Fecal pellets ....•................... Clear quartz, rounded* .............. . 

Clear quartz, angular ...........•.... Dark smoky quartz with iron 

inclusions .............•..•.•...••. 

Biotite •....•.•......•.•.•..•........ Muscovite .........•.................. 

60 

1 

4 

9 

2 

trace 

16 

4 

2 

trace 

65 

3 

22 

trace 

2 

1 

0 

trace 

3 

4 

0 

0 

Sample 19. Surface of lower part of same dune as sample 18 

Quartz sandstone grains.............. 7 

Clear quartz, rounded*............... 3 

Clear quartz, angular................ 8 

Yellow quartz**...................... 72 

Dark-red quartz**.. . . . . . . . . . . . . . . . . . . 1 

Light-red quartz**··················· 3 

Iron (magnetite?).................... 1 

Smoky quartz. . . • • . . . • . • • • • . . . . . . . . . . . 4 

Milky quartz and feldspar ........... . 

Green mineral? ...........••••..•.•... trace Muscovite ..................•......... trace 

0 

trace 

23 

58 

2 

7 

4 

4 

1 

1 

0 

Coarse grain 

(>1 .00) 

Fine grain 

(<1 .00) 

Sample 22. Surface of sand sheet at GEOMET station, Moenkopi 

Plateau 

Light-red quartz**··················· Basaltic ash fragments ............•.. Dark-red quartz** ................... . 

Clear quartz, angular ...•..•......... Clear quartz, rounded* .............. . 

Gray chert? ............•..•.......•.. 

White milky quartz or ash? .......... . Muscovite ........................... . 

Biotite ........•..................... 

Red chert? .........•.....•........... 

50 

20 

2 

12 

10 

1 

4 

trace 

0 

1 

33 

18 

2 

20 

25 

1 

0 

0 

1 

0 

Sample 22A. Surface of active barchan dune on Garces Mesas 

about 6 mi southeast of study area (fig. 1) 

Clear quartz, angular ............... . Clear quartz, rounded* ..............• 

Clear quartz, stained light red**···· 

Dark-red quartz** ................... . Red siltstone** ..................... . 

Light-red quartz**··················· 

Milky quartz ......•.................. Volcanic glass or ash? ..•............ 

Quartz with iron inclusions ......... . 

Basaltic ash fragments •••........•••. Smoky quartz with iron inclusions .... 

Gray, red chert? •.•..•............... Muscovite ........................... . 

Biotite ........•..................... 

Green mineral? ...................... . 

10 

12 

63 

1 

2 

4 

1 

2 

trace 

2 

1 

2 

trace 

trace 

0 

0 

85 

0 

1 

0 

7 

trace 

trace 

0 

4 

1 

2 

0 

0 

trace 

Sample 24. Surface of climbing dune, base of Red Rock Cliffs 

Basaltic ash fragments .....•......... 4 no data 

Clear quartz, rounded* •.....••....... 7 no data 

Clear q1,1artz, angular .........•...... 15 no data 

Dark-red quartz** .••........••••..... 2 no data 

Light-red quartz** ................... 9 no data 

Milky quartz or chert? .......•....... 6 no data 

Smoky quartz ......................... 2 no data 

Red chert or quartzite .........•..••. 3 no data 

Red sandstone grains** ............... 1 no data 

Red-stained quartz** •.......••....... 51 no data 

Sample 26. Interior of dune 2 mi east of Paiute Trail Point 

Light-red quartz**··················· 8 

Dark-red quartz**··.................. 1 

Clear quartz, angular ................ 70 

Clear quartz, rounded* ............... 17 

Grayish-white chert.................. 4 

Black mineral (iron?) ................ trace 

8 

3 

72 

8 

7 

2 

Sample 27. Surface of climbing dune, 2 mi east of Paiute 

Trail Point 

Basaltic ash fragments .............. . 

Sands tone grains ......•............. 

Clear quartz, angular ....•........... 

Clear quartz, rounded* .•.•••....•.••. 

Light-red quartz**··················· 

Milky quartz ...........•..••....••... Biotite ............................. . 

Dark mineral? ••......••.•.•••...•.... 

Red and gray chert .................. . 

10 

4 

76 

2 

3 

trace 

0 

trace 

5 

6 

0 

80 

trace 

1 

trace 

1 

II 
Table 3. Composition of surficial samples--Continued 

Coarse grain 

(>1 .00) 

Fine grain 

( <1 .00) 

Sample 28. Surface of dune 2 mi east of Paiute Trail Point 

Basaltic ash fragments............... 4 

Clear quartz, angular ......•......... 80 

Clear quartz, rounded*............... 4 

Milky quartz (chert?)................ 3 

Light-red quartz**··················· 6 

Dark-red quartz**···················· 2 

Gray chert. . . . . . . . . . . . . . . . . . . . • . . . . . . 1 

Iron? trace.......................... 2 

Biotite.............................. 0 

Green mineral?....................... 0 

trace 

82 

11 

2 

trace 

trace 

Sample 29. Interior of climbing dune, 1 mi south of The 

Landmark 

Red sandstone grains**··············· 8 

Light-red quartz**··················· 83 

Clear quartz, angular ............... . 

Clear quartz, rounded* .............. . 

Gray chert ....................•...... 

Milky quartz (chert?)................ 1 

Biotite.............................. 0 

Muscovite............................ 0 

Smoky quartz?. . . . . . . . . . . . . . . . . . . . . . . . 0 

0 

22 

73 

1 

2 

trace 

trace 

trace 

2 

Sample 31. Interior of climbing dune 1 mi south of The 

Landmark 

White sandstone grains............... 1 

Clear quartz, angular................ 82 

Clear quartz, rounded*............... 2 

Light-red quartz**................... 5 

Dark-red quartz**. . . . . . . . . . . . . . . . . . . . 2 

Gray and red chert................... 6 

Milky quartz or chert?............... 2 

Smoky quartz?.. . . . . . . . . . . . . . . . . . . . . . . trace 

trace 

91 

2 

3 

trace 

2 

Sample 32. Surface of climbing dune 1 mi south of The 

Landmark 

Smoky quartz?........................ 3 

Dark-red quartz**.................... 1 

Light-red quartz**................... 4 

Clear quartz, angular ................ 87 

Clear quartz, rounded*............... 4 

Milky quartz or chert? .............. . 

Green mineral or stain? .............. trace 

3 

1 

8 

85 

2 

trace 

of the local bedrock, mainly of the Chinle Formation 

(sample 15, table 2). The second source was tributary 

drainages containing grains derived from local bedrock 

(all samples listed in table 2). Nearly all of the windtransported sand has undergone one or more of the 

following processes: (1) derivation by headward erosion 

of Triassic sedimentary rocks; (2) derivation by direct 

wind deflation of rock outcrops; (3) transport in sand 

sheets and dunes, by strong southwesterly and westerly 

winds, northeastward from tributary drainages; and (4) 

transport by streams to the Little Colorado River and 

out of the area. 

GEOMORPHIC INTERPRETATIONS 

The gentle northeastward regional dip is the 

chief structural feature of the study area. As erosion 

removed bedrock, the resistant dipping strata formed 

hogbacks or cuestas that gradually retreated toward 

12 

the northeast. Prior to extrusion of the Black Point 

basalt flow about 2.4 million years ago (Damon and 

others, 1974), the channel of the ancestral Little 

Colorado River was near its present site but 680 ft 

higher (fig. 6). The eastern tributaries of the river had 

already reduced the surrounding landscape to a near 

peneplain sloping toward the river from the 

northeast. Linear dunes that may have been derived 

from the Little Colorado flood plain possibly 

contributed to the alignment of the early drainage 

development as mapped by Stokes (1964) elsewhere in 

northeastern Arizona. The Moenkopi Plateau at that 

time was about 400 ft higher than the river; thus the 

average gradient was only 31 ft/mi, the same as the 

gradient of the peneplained surface of the Moenkopi 

Plateau today. 

If the strongest winds 3 million years ago were 

from the southwest and were at least as effective as 

they are today, they could have easily transported sand 

from the Little Colorado channel and developing 

tributary washes up onto the surface of the ancestral 

Moenkopi Plateau, whose relief was much less than it 

is today (fig. 6). This transport was probably 

facilitated by ramps of sand formed by climbing 

dunes. Under the present wind regime, climbing dunes 

are ascending cliffs as high as 200 ft at elevations 600 

ft above the Little Colorado flood plain (Breed and 

others, 1984; fig. 4). 

About 2.4 million years ago, the channel of the 

Little Colorado River was diverted eastward more 

than a mile by the Black Point lava flow (compare figs. 

6 and 7). This diversion may have initiated the 

headward erosion of Tohachi Wash and other nearby 

tributaries as the river was forced to cut into the 

sloping peneplain, creating an erosional scarp. 

Beginning at about the end of Tertiary time, small 

subsequent drainages began to flow northeastward 

(opposite the major direction of drainage) on resistant 

dipping surfaces of developing cuestas and to turn 

along strike valleys until they reached a major 

drainage flowing southwest to the river (figs. 7-9). 

As downcutting continued, these strike-valley 

streams were incised into resistar:!:t.rock and trapped in 

place. Cuestas continued to retreat northeastward, 

allowing several sets of strike-valley streams to 

became sequentially entrenched as they developed. 

The earlier set of subsequent streams has migrated 

very little, if at all, because of entrenchment; today 

they provide evidence of past sequential drainage 

patterns and cuesta positions. Erosional retreat of the 

cuestas has resulted in the present series of steplike, 

subparallel cliffs east of the Little Colorado River: the 

west edge of Ward Terrace, the Red Rock Cliffs, and 

the west edge of the Moenkopi Plateau (fig. 9). 

After extrusion of the Black Point flow (about 

2.4 million years ago), the combination of downcutting 

and headward erosion into higher terrain enlarged 

natural barriers to the northeastward movement of 

sand onto the Moenkopi Plateau. Fluvial erosion 

gradually removed the once-plentiful sand supply 

faster than wind could build sand ramps up the 

scarps. Today, virtually no sand reaches the plateau 

along the Adeii Eechii Cliffs because most of it is now 

returned to the Little Colorado River and transported 

from the area. 
FEET A 

6000 

5000 

TERTIARY: 

Ta Older alluvium 

Tb Black Point basalt flow 

Td Older dune sand 

JURASSIC AND TRIASSIC(?): 

J"Rn Navajo Sandstone 

J"Rnk Navajo Sandstone and Kayenta 

Formation, undivided 

TRIASSIC(?): 

"Rk Kayenta Formation 

"Rmo Moenave Formation 

0 

EXPLANATION 

111°07'30" 

,-' 

•' 

.· 

/ .. J ~ 

5 MILES 

TRIASSIC: 

"Rw Wingate Sandstone (lukachukai and Rock 

Point Members) 

"Reo Chinle Formation (Owl Rock Member) 

"Rep Chinle Formation (Petrified Forest Member) 

"Res Chinle Formation (Shinarump Member) 

"Rm Moenkopi Formation 

PERMIAN AND OLDER: 

Pk Kaibab Formation 

pPk Pre-Kaibab formations 

.· 

Figure 6. Probable positions of cliffs and drainages immediately after Black Point basalt flow entered 

Little Colorado River channel, about 2.4 m.y. ago (Damon and others, 1974). 

13 
111°22'30" 

35°52'30" 

FEET 8 

6000 

0 

111°07'30" 

·MOENKOPI 

5 MILES 

I 

111°00' 

-~ J' 

:~ 

r' 

/ 

/ 

/ 

t-/ 

PLATEAU 

~ 

·6' 

8' 

J'Rn 

5000 =-!C=~:=?i~< ~-.lL~~==~~~~~~~~~~~J'Rnk 'Rk 

'Rmo 

RW 

Pk ------------------~ 

Elevations approximate; vertical exaggeration X7.4. Arrows indicate direction of relative movement of fault 

Figure 7. Probable positions of cliffs and drainages at end of Tertiary time (about 1.8 to 2.0 m.y. ago). Symbols 

for units explained in figure 6. (Normal fault at surface becomes a reverse fault at depth.) 

14 
FEET C 

6000 

0 

111 °07'30" 

MOENKOPI PLATEAU 

5 MILES 

C' 

Td JRn 

5000 

~~~~~J"'Pnk Rk 

"'Pmo 

~00 RW 

Pk 01 

Elevations approximate; vertical exaggeration X 7.4. Arrows indicate direction of relative movement of fault 

Figure 8. Probable positions of cliffs and drainages about 1 m.y. ago. Symbols for bedrock units explained in 

figure 6. Surficial deposits of Quaternary age: Qa, younger alluvium; Qd, younger dune sand; Ql, landslide 

deposits. Surficial deposits of Tertiary age: Td, older dune sand, Ta, older alluvium. 

15 
111°22'30" 

35°52'30" 

35°37'30" 

FEET D 

6000 

5000 

4000 

111 °07'30" 

MOENKOPI PLATEAU 

0 5 MILES 

Adeii Eechii Cliffs D' 

1 Td 

Ward Terrace 

i Qd 

Rmo 

RCP RW 

Pk Ql 

Elevations approximate; vertical exaggeration X7.4. Arrows indicate direction of relative movement of fault 

Figure 9. Present positions of cliffs and drainages. Symbols for bedrock units explained in figure 6. Surficial 

deposits of Quaternary age: Qa, younger alluvium; Qd, younger dune sand; Ql, landslide deposits. Surficial 

deposits of Tertiary age: Td, older dune sand; Ta, older alluvium. 

16 
Sand of climbing dunes piled against the lower 

cliff faces has modified fluvial and mass-wasting 

erosion patterns along the scarps. Climbing dunes are 

thickest and most common along salients of the Red 

Rock Cliffs, where the Moenave Formation that forms 

the cliffs is protected by a cap of resistant Kayenta 

Formation. It is no coincidence that these salients are 

all downwind (northeast) of large drainages where 

thick deposits of windblown sand are readily 

available. These deposits have slowed fluvial erosion 

enough to help produce the salients. Headward erosion 

of drainages is rapidly advancing around and behind 

these salients to create potential mesas (fig. 4), a 

process that is probably similar to the erosion of 

earlier periods (figs. 6-8). 

Below the Moenkopi Plateau, seasonal fluvial 

erosion removes most of the eolian deposits from the 

washes (Breed and others, 1984). On the plateau, 

however, eolian deposits are largely isolated from 

fluvial transport except along the Adeii Eechii Cliffs. 

The plateau's veneer of surficial deposits and 

stabilizing vegetation has helped preserve this ancient 

surface by preventing runoff and slowing erosion rates. 

The present stabilized linear dunes on the 

Moenkopi Plateau are considered to be of Pleistocene 

age (Breed and others, 1984) on the basis of the 

occurrence in a dune of volcanic ash that these 

workers have correlated with an eruption 730,000 

years ago. Stokes (1964) attributed the development 

of parallel stream courses in other parts of northern 

Arizona to topographic control by linear dunes; he 

suggested that such dunes may be as old as one million 

years. Detailed geologic mapping (Billingsley, 1987), 

analyses of dune sands and source materials, 

geomorphic relations of cliff retreat, present drainage 

patterns, and the known age of the Black Point basalt 

flow ali indicate that the eolian veneer on the 

Moenkopi Plateau is at least 2.4 million years old. 

REFERENCES CITED 

Billingsley, G. H., 1987, Geologic map of the 

southwestern Moenkopi Plateau and southern Ward 

Terrace, Coconino County, Arizona: U.S. 

Geological Survey Miscellaneous Investigations 

Series Map 1-1793, scale 1:31,680. 

Breed, C.S., and Breed, W.J., 1979, Dunes and other 

windforms of Central Australia (and a comparison 

with linear dunes on the Moenkopi Plateau, 

Arizona), in El-Baz, Farouk, and Warner, D.M., 

eds., Apollo-Soyuz Test Project Summary Science 

Report, v. 2, Earth Observations and 

Photography: National Aeronautics and Space 

Administration Special Publication 412, p. 319-

358. 

Breed, C.S., McCauley, J.F., Breed, W.J., McCauley, 

C.K., and Cetera, A.S., 1984, Eolian (windformed) landforms, in Smiley, T.L., and others, 

eds., Landscapes Of Arizona--the geological 

story: Lanham, Md., New York, and London, 

University Press of America, Inc., p. 359-413. 

Childs, O.E., 1948, Geomorphology of the valley of the 

Little Colorado River, Arizona: Geological 

Society of America Bulletin, v. 59, p. 353-388. 

Colbert, E.H., 1981, A primitive Ornithischian dinosaur. 

from the Kayenta Formation of Arizona: Museum 

of Northern Arizona, Flagstaff, Bulletin, ser. 53, 

61 p. 

Damon, P.E., Shafiqullah, Muhammad, and Leventhal, 

J.S., 1974, K-Ar chronology for the San 

Francisco volcanic field and rate of erosion of the 

Little Colorado River, in Karlstrom, T.N. V., 

Swann, G.A., and Eastwood-;-R.L., eds., Geology of 

northern Arizona with notes on archeology and 

paleoclimate, Part 11--Area studies and field 

guides: Geological Society of America, Rocky 

Mountain Section Meeting, Flagstaff, Arizona, p. 

221-235. 

Fryberger, S.G., 1978, Techniques for the evaluation of 

surface wind data in terms of eolian sand drift: 

U.S. Geological Survey Open-File Report 78-405, 

25 p. 

Gilland, J.K., 1979, Paleo-environment of a carbonate 

lens in the lower Navajo Sandstone near Moab, 

Utah: Utah Geology, v. 6, no. 1, p. 29-18. 

Hack, J.T., 1941, Dunes of the western Navajo 

country: Geographical Review, v. 31, no. 2, p. 

240-263. 

Haines, D. V., and Bowles, C. G., 1976, Preliminary map 

and sections of the Wupatki NE quadrangle, 

Coconino County, Arizona: U.S. Geological 

Survey Open-File Report 76-703, scale 1:24,000. 

Hereford, Richard, 1979, Preliminary geologic map of 

the Little Colorado River valley between 

Cameron and Winslow, Arizona: U.S. Geological 

Survey Open-File Report 79-1574, scale 1:250,000. 

McCauley, J.F., Breed, C.S., Helm, P.J., Billingsley, 

G.H., MacKinnon, D.J., Grolier, M.J., and 

McCauley, C.K., 1984, Remote monitoring of 

processes that shape desert surfaces: The Desert 

Winds Project: U.S. Geological Survey Bulletin 

1634, 19 p. 

Moore, R.B., Ulrich, G.E., and Wolfe, E.W., 1974, Field 

guide to the geology of the eastern and northern 

San Francisco volcanic field, Arizona, in 

Karlstrom, T.N. V., Swann, G. A., and Eastwood, 

R.L., eds., Geology of northern Arizona with notes 

on archeology and paleoclimate, Part 11--Area 

studies and field guides: Geological Society of 

America, Rocky Mountain Section Meeting, 

Flagstaff, Arizona, p. 495-520. 

Moore, R.B., Wolfe, E.W., and Ulrich, G.E., 1976, 

Volcanic rocks of the eastern and northern parts 

of the San Francisco volcanic field, Arizona: U.S. 

Geological Survey Journal of Research, v. 4, no. 5, 

p. 549-560. 

Munsell Color Company, 1954 [revised 1975], Munsell 

soil color charts: Baltimore, Md., 20 p. 

Repenning, C.A., Cooley, M.E., and Akers, J.P., 1969, 

Stratigraphy of the Chinle and Moenkopi 

Formations, Navajo and Hopi Indian Reservations, 

Arizona, New Mexico, and Utah: U.S. Geological 

Survey Professional Paper 521-B, 34 p. 

17 
Rice, R.J., 1974, Terraces and abandoned channels of 

the Little Colorado River between Leupp and 

Cameron, Arizona: Plateau, v. 46, no. 3, p. 102.-

119. 

Sellers, W.D., and Hill, R.H., eds., 1974, Arizona 

climate 1931-1972.: Tucson, University of Arizona 

Press, 616 p. 

18 

Stokes, W.L., 1964, Incised, wind-aligned stream 

patterns of the Colorado Plateau: American 

Journal of Science, v. 2.62., p. 808-816. 

1983, Silicified trees in the Navajo Sandstone, east-

-- central Utah [abs.]: Geological Society of 

America, Abstracts with Programs, v. 15, no. 5, p. 

2.86. 
!3illingsley~GEOLOGY, GEOMORPHOLOGY, SOUTHWESTERN MOENKOPI PLATEAU AND WARD JER~ACE, ARIZONA~U.S. Geological Survey Bulletin 1672