Navajo National Monument 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2007/005 

National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 
THIS PAGE: 

The Navajo Sandstone forms steep cliffs above its contact with the 

Kayenta Formation in Long Canyon and throughout Navajo NM, AZ. 

ON THE COVER: 

Photo of the Betatakin Ruins in Navajo NM, AZ . 

USGS Photos 
Navajo National Monument 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2007/005 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

June 2007 

U.S. Department of the Interior 

Washington, D.C.
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gre_publications) on the internet, or by sending a request to the address on the back cover. 

Please cite this publication as: 

Graham, J. 2007. Navajo National Monument Geologic Resource Evaluation Report. Natural 

Resource Report NPS/NRPC/GRD/NRR—2007/005. National Park Service, Denver, 

Colorado. 

NPS D- 53, June 2007 
 NAVA Geologic Resource Evaluation Report iii

Table of Contents 

List of Figures .............................................................................................................. iv

Executive Summary ...................................................................................................... 1

Introduction ................................................................................................................... 2

Purpose of the Geologic Resource Evaluation Program ............................................................................................2

Regional Location and Geology..................................................................................................................................2

Park History................................................................................................................................................................3

Geologic Issues............................................................................................................. 9

Rockfall Hazards ........................................................................................................................................................9

Flash Flooding, Floodplain Degradation, and Erosion................................................................................................9

Hydrogeology ...........................................................................................................................................................10

Regolith ....................................................................................................................................................................10

Geologic Features and Processes............................................................................. 13

Alcoves.....................................................................................................................................................................13

Navajo Sandstone ....................................................................................................................................................13

Betatakin Unit and Visitor Center..............................................................................................................................13

Keet Seel Unit...........................................................................................................................................................14

Inscription House Unit ..............................................................................................................................................14

Map Unit Properties .................................................................................................... 18

Map Unit Properties Table........................................................................................................................................19

Geologic History.......................................................................................................... 21

Triassic Period..........................................................................................................................................................21

Jurassic Period.........................................................................................................................................................22

Cretaceous Period....................................................................................................................................................23

Late Cretaceous-Early Tertiary.................................................................................................................................24

Tertiary Period..........................................................................................................................................................24

Quaternary Period ....................................................................................................................................................24

Glossary....................................................................................................................... 28

References................................................................................................................... 30

Appendix A: Geologic Map Graphic .......................................................................... 33

Appendix B: Scoping Summary................................................................................. 35

Attachment 1: Geologic Resource Evaluation Products CD 
 NPS Geologic Resources Division iv 

List of Figures 

Figure 1a: Location map of Navajo National Monument. ...............................................................................................4 

Figure 1b: Detailed location map of Navajo National Monument....................................................................................5

Figure 2. Regional physiographic features associated with Navajo National Monument. ..............................................6

Figure 3: Geologic time scale.........................................................................................................................................7

Figure 4. Keet Seel ruins................................................................................................................................................8

Figure 5. Joints along the Aspen Forest Trail...............................................................................................................11

Figure 6. Erosion in front of Keet Seel .........................................................................................................................12

Figure 7. Betatakin ruins in an alcove formed in the Navajo Sandstone ......................................................................15

Figure 8. Keet Seel ruins..............................................................................................................................................16

Figure 9. Inscription House. .........................................................................................................................................17

Figure 10. Late Triassic paleogeography .....................................................................................................................25

Figure 11. Early Jurassic paleogeography ...................................................................................................................26

Figure 12. Cretaceous paleogeographic map ..............................................................................................................27
 NAVA Geologic Resource Evaluation Report 1

Executive Summary 

This report has been developed to accompany the digital geologic map produced by Geologic 

Resource Evaluation staff for Navajo National Monument in Arizona. It contains 

information relevant to resource management and scientific research. 

Navajo National Monument lies entirely within the 

Navajo Reservation in northeast Arizona. The 

monument preserves the most intact cliff dwellings of 

the Ancestral Puebloan people in three separate units: 

Betatakin Unit (160 acres), Keet Seel Unit (160 acres), and 

Inscription House Unit (40 acres). These Pueblo villages, 

built in natural alcoves eroded into the Navajo 

Sandstone, date to the late 13th Century. 

Navajo National Monument is located on the Shonto 

Plateau, part of the larger Colorado Plateau 

Physiographic Province. Uplift and erosion have carved 

deeply incised canyons into this part of the Colorado 

Plateau. The Organ Rock Monocline, an uplift 

underlying U.S. Highway 160 between Cow Springs and 

Kayenta, Arizona, forms the border between the Shonto 

Plateau and the Black Mesa region to the south. The 

Black Mesa region includes about 5,400 square miles 

(14,000 sq km) in northeastern Arizona and has a diverse 

topography of flat plains, mesas, and incised drainages. 

Navajo National Monument is in the Tsegi Canyon 

system, the primary drainage of the eastern part of the 

Shonto Plateau. Tsegi Canyon exposes nearly flat- lying 

Mesozoic sedimentary strata. Mesozoic strata at Navajo 

National Monument record marine, nearshore, and 

continental depositional environments. These 

environments formed in response to tectonic activity on 

the western margin of North America. The three main 

formations exposed in the canyon include, from 

youngest to oldest, the Navajo Sandstone, the Kayenta 

Formation, and the Wingate Sandstone. Isolated 

exposures of the Chinle Formation are found in the 

canyon bottom, with unconsolidated alluvial deposits 

overlying bedrock. 

Rock- fall and cliff collapse pose the greatest geologic 

issue for resource management at the monument. 

Because of the steep canyon walls, significant rock- fall 

hazards threaten cultural resources in alcoves as well as 

visitor safety. The Aspen Forest Trail leading to 

Betatakin Ruins was closed in 1982 due to rock- fall and 

currently remains closed. 

Flash flooding and erosion in the canyon bottoms, 

groundwater and surface- water quantity and quality, 

and regolith compaction are also management concerns. 

Flash flooding threatens cultural resources, erodes 

stream banks, and promotes vertical incision of the 

arroyos. Hikers and grazing livestock trample stream 

banks, compacting the regolith, and accelerating erosion. 

The Navajo Sandstone is the primary aquifer for the 

Black Mesa area. As visitation increases at the monument 

and coal mining activities increase on Black Mesa, 

groundwater withdrawal from the Navajo aquifer is an 

increasing concern at Navajo National Monument. 

The primary geologic features at Navajo National 

Monument are the alcoves in which the Ancestral 

Puebloans built their dwellings. Geologic factors such as 

the presence of springs and seeps, large sweeping crossbeds in the Navajo Sandstone, and vertical fractures that 

serve as conduits for water, all contribute to the 

formation of alcoves. Springs and seeps occur at the 

contact between the porous and permeable Navajo 

Sandstone and the less permeable Kayenta Formation. 

Groundwater flows laterally in the subsurface when it 

encounters the Kayenta, emerging as springs and seeps 

along the canyon walls. The discharged water dissolves 

the carbonate cement holding the sand grains of the 

Kayenta Formation together and subsequent erosion 

removes the grains. Undercutting of the Navajo 

Sandstone controlled by both cross- bedding and vertical 

fractures, leads to cliff collapse. 
 NPS Geologic Resources Division 2 

Introduction 

The following section briefly describes the regional geologic setting and the National 

Park Service Geologic Resource Evaluation program. 

Purpose of the Geologic Resource Evaluation Program 

The Geologic Resource Evaluation (GRE) Program is 

one of 12 inventories funded under the NPS Natural 

Resource Challenge designed to enhance baseline 

information available to park managers. The program 

carries out the geologic component of the inventory 

effort from the development of digital geologic maps to 

providing park staff with a geologic report tailored to a 

park’s specific geologic resource issues. The Geologic 

Resources Division of the Natural Resource Program 

Center administers this program. The GRE team relies 

heavily on partnerships with the U.S. Geological Survey, 

Colorado State University, state surveys, and others in 

developing GRE products. 

The goal of the GRE Program is to increase 

understanding of the geologic processes at work in parks 

and provide sound geologic information for use in park 

decision making. Sound park stewardship relies on 

understanding natural resources and their role in the 

ecosystem. Geology is the foundation of park 

ecosystems. The compilation and use of natural resource 

information by park managers is called for in section 204 

of the National Parks Omnibus Management Act of 1998 

and in NPS- 75, Natural Resources Inventory and 

Monitoring Guideline. 

To realize this goal, the GRE team is systematically 

working towards providing each of the identified 270 

natural area parks with a geologic scoping meeting, a 

digital geologic map, and a geologic report. These 

products support the stewardship of park resources and 

are designed for non- geoscientists. During scoping 

meetings the GRE team brings together park staff and 

geologic experts to review available geologic maps and 

discuss specific geologic issues, features, and processes. 

Scoping meetings are usually held for individual parks 

and on occasion for an entire Vital Signs Monitoring 

Network. The GRE mapping team converts the geologic 

maps identified for park use at the scoping meeting into 

digital geologic data in accordance with their innovative 

Geographic Information Systems (GIS) Data Model. 

These digital data sets bring an exciting interactive 

dimension to traditional paper maps by providing 

geologic data for use in park GIS and facilitating the 

incorporation of geologic considerations into a wide 

range of resource management applications. The newest 

maps come complete with interactive help files. As a 

companion to the digital geologic maps, the GRE team 

prepares a park- specific geologic report that aids in use 

of the maps and provides park managers with an 

overview of park geology and geologic resource 

management issues. 

For additional information regarding the content of this 

report and up to date GRE contact information please 

refer to the Geologic Resource Evaluation web site 

(http://www2.nature.nps.gov/geology/inventory/). 

Regional Geology 

Navajo National Monument is located in the western 

section of the Navajo Reservation in northeastern 

Arizona (figures 1a and 1b). The monument consists of 

three noncontiguous sections: the Betatakin Unit (160 

acres), the Keet Seel Unit (160 acres), and Inscription 

House Unit (40 acres). The elevation of the Betatakin 

Visitor Center is 7,400 feet (2,220 m). The Keet Seel 

section is located about 8 miles (13 km) northeast of 

Betatakin and contains one of the most important large 

Pueblo ruins in the Southwest. The Inscription House 

section is located 40 miles (64 km) west of Betatakin in 

Nitsin Canyon. 

Navajo National Monument is part of the Colorado 

Plateau Physiographic Province, an uplifted area that 

encompasses portions of Colorado, Utah, Arizona, and 

New Mexico. Uplift and subsequent erosion have carved 

deeply incised canyons into relatively horizontal layers of 

sandstone and exposed colorful, flat- lying sedimentary 

rock formations in this part of the Colorado Plateau. 

Navajo National Monument is located north of U.S. 

Highway 160 on the Shonto Plateau, a subregion of the 

Colorado Plateau (figure 2). The Organ Rock Monocline, 

an uplift that underlies U.S. Highway 160, separates the 

largely Jurassic and Triassic rocks exposed at the surface 

of the Shonto Plateau from the Cretaceous rocks of Black 

Mesa. Black Mesa encompasses 5,400 square miles 

(14,000 sq km) of flat plains, mesa, and incised drainages 

south of U.S. Highway 160 (Kamilli and Richard 1998; 

Blakemore and Truini 2000). 

Tsegi Canyon is the primary drainage of the eastern part 

of the Shonto Plateau. It contains three major branches 

and countless side branches cut deeply into the Navajo 

sandstone. Betatakin and Keet Seel are located in two of 

the arteries of the canyon. Side canyons contain 

numerous other prehistoric ruins (NPS 2001). 

Tsegi Canyon has eroded into Triassic- Jurassic strata 

(figure 3). The primary formations are part of the Jurassic 

Glen Canyon Group. The formations in the Glen Canyon 

Group are, from youngest to oldest: the pale salmoncolored, cross- bedded Navajo Sandstone that formed 

from an ancient sand dune field; the purplish siltstones 

and cross- bedded sandstones of the Kayenta Formation 

which record the remnants of a large river delta or 

floodplain; and the cross- bedded Wingate Sandstone, 

another preserved sand dune field (Cooley et al. 1969; 

Chronic 1983; Peterson 1994). 
 NAVA Geologic Resource Evaluation Report 3

Springs and seeps are associated with the contact 

between the cliff- forming Navajo Sandstone and the 

underlying Kayenta Formation. The Navajo Sandstone is 

porous and permeable and serves as a regional aquifer, 

while the Kayenta is the confining bed. At the contact, 

groundwater moves laterally, emerging as springs along 

the canyon walls. 

Three layers of alluvial deposits are present in Tsegi 

Canyon and comprise the following formations: the 

Jeddito Formation (late Pleistocene), the Tsegi 

Formation (early Quaternary about 2000 B.C. to A.D. 1), 

and the Naha Formation (A.D. 1450- 1880) (Schafer et al. 

1974; Karlstrom 1982). A buried paleosol marks the 

erosional boundary between the Jeddito and Tsegi. The 

younger Tsegi - Naha boundary is marked by terrace 

relationships (Karlstrom 1982). The type localities for the 

Tsegi and Naha Formations are in Tsegi Canyon, which 

is one of the few places in the southwest where the 

beginning of arroyo cutting is well documented. Tsegi 

Canyon is now part of the Tsegi Canyon Navajo Tribal 

Park (NPS 2003). These formations are represented on 

the GRE digital geologic map as Quaternary alluvium 

(map symbol: Qal). 

The Colorado Plateau is a relatively rigid lithospheric 

block that, while uplifted, has not experienced the severe 

deformation present in the surrounding Rocky 

Mountain or Basin- and- Range physiographic provinces. 

While extensive thrust faults deformed the Rocky 

Mountains during the Laramide Orogeny (Late 

Cretaceous – Middle Tertiary) and rifts in the earth’s 

crust pulled apart the Basin- and- Range (Miocene 

Epoch), the Colorado Plateau was bent and folded into 

broadly warped anticlines and regionally extensive 

monoclines. The entrance drive to the monument climbs 

the Organ Rock Monocline that rises from the east to 

west onto barren outcrops of the Navajo Sandstone. 

Once on the crest of the monocline, the strata dip only 

two to three degrees to the southwest (Cooley et al. 

1969). 

Park History 

Four American Indian tribes have cultural associations 

with the area of Navajo National Monument: Hopi, 

Navajo, San Juan Paiute, and Zuni (NPS 2003). Each of 

these tribes has a distinct set of beliefs and a relationship 

with the sites, geography, and landscapes of the 

monument. 

Ancestors of the Hopi (Hisatsinom) have lived in the 

Southwest for millennia and in the lands of present- day 

Navajo National Monument from about A.D. 950 to A.D. 

1300 (NPS 2003). Betatakin is known to the Hopi as 

Talastima, the “Place of the Blue Corn Tassels,” and is a 

Flute and Deer Clan village. Keet Seel (Kawestima) is a 

Fire Clan village, and Inscription House (Tsu’ovi) is a 

Rattlesnake, Sand, and Lizard Clan village. For the Hopi, 

these sites remain active spiritual and physical links to 

the past, the present, and the future. 

Athabaskan- speaking Diné, ancestors of the Navajo, 

migrated to the Southwest sometime between the 11th and 

15th centuries (NPS 2003). Navajo tribal leaders signed a 

treaty with the United States in 1868, establishing the 

Navajo Reservation, which encompasses Navajo 

National Monument. In 1960, the Navajo Tribal Council 

Advisory Committee created Tsegi Canyon Tribal Park 

to protect all lands within the Tsegi Canyon System. The 

Navajo know Betatakin as Bitát’ahkin, which means 

“ledge house,” Keet Seel as Sits’il (“broken pottery”), and 

Inscription House as Tsah Bii Kin. The Navajo have a 

long history of using the monument and adjacent lands 

for both sacred and personal purposes, such as 

harvesting nuts and berries (NPS 2003). 

Several centuries ago, the San Juan Paiute inhabited areas 

that are now managed by Navajo National Monument, 

settling along drainages in the Tsegi Canyon System. One 

group settled in Nitsin Canyon, and the San Juan Paiute 

still maintain a strong connection to Nitsin Canyon and 

surrounding areas in the region. 

The Zuni also have lived in the Southwest for many 

centuries, establishing settlements throughout the Four 

Corners region. Tsegi Canyon is an essential part of their 

traditions. The Tsegi Canyon Region is known as the 

“northern canyons” from which several of their clans 

migrated to their present location at Zuni Pueblo in New 

Mexico. They traveled through Tsegi Canyon to reach 

the salt mines located near the Grand Canyon. Today, 

Zuni elders still visit Batatakin because this site figures 

prominently in their past. 

In the mid- 1850s, trapper, hunter and guide, Captain 

Joseph Walker, and his party traveled through much of 

what is now called the Navajo Nation (NPS 2003). The 

Wetherill brothers, who explored the cliff dwellings at 

Mesa Verde National Park, also found the Keet Seel 

dwellings in 1895 (figure 4). Excavation of the site began 

in 1897. The Wetherills and University of Utah professor 

Byron Cummings encountered Inscription House and 

Betatakin ruins in 1909. 

President Taft established Navajo National Monument 

on March 20, 1909, in hopes of protecting Keet Seel, the 

largest cliff- dwelling in America (Presidential 

Proclamation No. 873). This proclamation included not 

only Keet Seel but also sites in Monument Valley; Tsagtat- sosa canyon; Navajo Creek, Moonlight Creek, and 

Laguna Creek canyons. Presidential Proclamation No. 

1186 on March 14, 1912, provided for a boundary 

adjustment to its present size of 360 acres. John Wetherill 

became the first park employee, but the monument 

entrance road wasn’t constructed until 1965. 
 NPS Geologic Resources Division 4 

Figure 1a: Location map for Navajo National Monument. 
 NAVA Geologic Resource Evaluation Report 5

Figure 1b. Detailed location map showing units of Navajo National Monument and water quality data collection sites. Figure 

reproduced from USGS Open File Report OFR-03-287, Water-Quality Data for Navajo National Monument, Northeastern Arizona--2001-

02 by Blakemore E. Thomas. 
 NPS Geologic Resources Division 6 

Figure 2. Regional physiographic features associated with Navajo National Monument. 
 NAVA Geologic Resource Evaluation Report 7

Figure 3. Geologic time scale; adapted from the U.S. Geological Survey and International Commission on Stratigraphy. Red lines 

indicate major unconformities between eras. Included are major events in life history and tectonic events occurring on the North 

American continent. Absolute ages shown are in millions of years. 
 NPS Geologic Resources Division 8 

Figure 4. Keet Seel ruins. Photo courtesy of the National Park Service, www.nps.gov (12/6/06). 
 NAVA Geologic Resource Evaluation Report 9

Geologic Issues 

A Geologic Resource Evaluation scoping session was held for Navajo National 

Monument on June 25 and June 28, 2001, to discuss geologic resources, address the status 

of geologic mapping, and assess resource management issues and needs. The following 

section synthesizes the scoping results, in particular, those issues that may require 

attention from resource managers. 

Rockfall Hazards 

The most pressing geologic issues facing resource 

management at the monument are the potential loss of 

cultural resources in alcoves, from rockfalls and cliff 

collapse, and visitor safety in these areas. Precipitation, 

groundwater infiltration, and freeze- thaw cycles, all 

affect the integrity of the sandstone comprising the cliffs. 

Significant rock- fall hazards exist on some north- facing 

walls and within alcoves in the Betatakin unit, as well as 

along the trail and in alcoves in the Keet Seel and 

Inscription House units (NPS 2003). 

Although the Navajo Sandstone bedrock is weakly 

cemented by calcite and iron oxides, it is strong enough 

in some places to form steep- sided canyons such as 

Betatakin Canyon. The strength of the rock mass, and 

thus, its susceptibility to failure, is directly related to the 

number and orientation of joints, fractures, faults, and 

bedding planes. Local zones of weakness can be 

generated by the occasional presence of water. The 

presence of caliche (a carbonate crust) infilling joint 

systems indicates the frequent passage of groundwater 

through the steeply dipping joints. 

Significant rockslides along the Aspen Forest Trail 

(figure 5) to Betatakin Ruins made it necessary to close 

the trail because of visitor safety concerns. Rock- falls on 

the trail began shortly after construction in 1963, and in 

1982, two rock- falls, the first exceeding 9.5 tons and the 

second estimated at 200- 300 tons, blocked the trail in 

the steep overhung section just below the locked gate. In 

1983, another large rock- fall covered the trail and sent 

rocky debris to the valley floor near Saucer Cave. The 

trail was closed in April 1982 and an alternative route to 

the Betatakin ruins, using the Tsegi Point Road, was 

initiated in 1985. 

The failures noted along the Aspen Forest Trail occurred 

during wet periods in winter and spring, suggesting that 

water infiltrating joints may destabilize rock slopes 

(Wieczorek and Harp 2000). Rockfalls occur more 

frequently on north- facing walls than on the southfacing walls in Betatakin Canyon. 

Along the now closed Aspen Forest Trail, bedding in the 

Navajo Sandstone generally dips about 26 degrees E- SE. 

One major joint set (J1) dips about 60 degrees to the 

north and another major joint set (J2) is nearly vertical. 

In the section of the trail immediately upslope of the 

gate, north dipping joint set J1 has the potential for planar 

sliding (Wieczorek and Harp 2000). Conditions are also 

favorable for sliding where the joint set J1 intersects other 

joints sets. 

The opposite (south- facing) cliffs of Betatakin Canyon 

are much more massive and relatively free of rockfalls. 

The cliffs near the Aspen Forest Trail show “moderate” 

to “high” susceptibility for failure (Wieczorek and Harp 

2000). The area of the trail most at risk for future failure 

is the overhung section (figure 5). In a 2000 assessment 

study, the USGS recommended construction of a 

covered catwalk with anchors emplaced in drill holes on 

the south- facing canyon wall. If construction of a 

covered catwalk isn’t feasible, USGS suggested that the 

logical alternative is using the route into Betatakin Ruins 

from the Tsegi Point Trail (Wieczorek and Harp 2000). 

This is the strategy currently employed by the park for 

providing visitors safe access to the Betatakin Ruins. 

Flash Flooding, Floodplain Degradation, and Erosion 

Flash flooding, floodplain degradation, and erosion are 

related geological processes at Navajo National 

Monument. In arid environments, flash floods cause 

major erosion damage to stream banks destabilized by a 

lack of vegetation. An eyewitness hiking in Tseigi Canyon 

in July 1980 documented a flash flood that washed 

boulders downstream and eroded a large sandstone 

block. The main flood event, from the initial wave to the 

time when travel was once again safe, lasted four hours. 

However, even after the flood waters passed they 

reportedly “turned the stream bottom into pockets of 

mud (quicksand) in which I was sinking up to my waist” 

(memorandum from Richard M. Bryant, Canaveral 

National Seashore 1987). 

Conditions in the canyons today are similar to the 

conditions that may have led the Ancestral Puebloans to 

leave the area 700 years ago. Arroyo- cutting has gouged 

out the valley floor (figure 6) impacting tributaries and 

promoting the erosion and destruction of cultural 

resources (e.g., middens), especially during times of 

intense thunderstorms. 

Floodplain degradation is aggravated by upstream 

grazing, trampling of stream banks, and subsequent 

reduction of ground cover outside the monument (NPS 

2003). Flash flooding and bank collapse have lead to 

severe erosion of the alluvial fill at Keet Seel and 

Inscription House (NPS 1995; NPS 2003). At Inscription 

House, severe erosion of the alluvial fill in the canyon 
 NPS Geologic Resources Division 10 

bottom, flash flooding, bank collapse, and the removal of 

ground cover allow continued arroyo- cutting. Soil along 

the stream banks below Inscription House is considered 

to be “extremely unstable” (NPS 2003, p. 15). The impacts 

of severe flash flooding and stream bank collapse on 

monument resources are addressed in the 1995 Resource 

Management Plan for Navajo National Monument. 

Hydrogeology 

Groundwater, Springs, and Surface Water 

Groundwater, springs, and perennial and intermittent 

streams are important features in Navajo National 

Monument. Groundwater from the Betatakin no. 2 well 

provides drinking water for the monument. Springs and 

streams provide important habitat for plants and animals 

as well as drinking water for domestic and wild animals. 

Springs and streams also were the source of drinking and 

irrigation water for the Ancestral Puebloans about eight 

hundred years ago. 

Groundwater withdrawal and availability are important 

issues in the monument and Black Mesa area because of 

increasing visitation, continued use by plants and 

wildlife, and a growing population. An average annual 

precipitation of only about 6 to 14 inches (15- 36 cm) 

raises concerns about groundwater recharge rate, as well 

(Truini et al. 2005). 

Regional groundwater levels appear to be dropping at 

Keet Seel and Inscription House (NPS 2003). If the water 

table drops further, these units could experience, longterm adverse effects on wildlife and the native 

vegetation. Without plant roots to help stabilize the soil, 

stream bank instability may increase, accelerating 

erosion and arroyo- cutting. Continued erosion of the 

arroyo at Inscription House has the potential to 

destabilize the entire cliff (NPS 2003). 

The strata of Monument Valley and northern part of the 

Black Mesa area contain several aquifers in one or more 

formations. The aquifers stack vertically and generally 

are not hydraulically connected. Primary aquifers used 

for public, domestic, and livestock use include the lower 

Triassic C aquifer; Jurassic N aquifer; 

Jurassic/Cretaceous D aquifer; a Cretaceous aquifer 

composed of the Yale Point Sandstone, Toreva and 

Wepo Formations; and the Quaternary alluvium aquifer 

(Levings and Farrar 1977; Blakemore and Truini 2000; 

Truini et al. 2005). The N aquifer is the only significant 

aquifer in the monument region and is the main water 

source for industry and municipalities in the Black Mesa 

area. Although water from the C aquifer may be used for 

domestic purposes, the aquifer is at considerable depth. 

Three hydraulically connected formations comprise the 

N aquifer: the Navajo Sandstone, the Kayenta 

Formation, and the Lukachukai Member of the Wingate 

Sandstone (figure 3) (Cooley et al. 1969; Levings and 

Farrar 1977; Christensen 1979; Blakemore and Truini 

2000; Truini et al. 2005). The principal industrial user is 

the Peabody Western Coal Company (PWCC), and the 

principal municipal users are the Navajo Nation and the 

Hopi Tribe. Groundwater movement through the 

aquifer is about 2 to 4 feet (0.6 to 1.2 m) per year 

(Christensen 1979). 

A groundwater monitoring program in Black Mesa 

designed to determine the long- term effects of 

groundwater withdrawals from the N aquifer for 

industrial and municipal uses has been operating since 

1971 (Blakemore and Truini 2000; Truini et al. 2005). The 

monitoring program measures: groundwater pumping 

rates, groundwater levels, spring discharge, surface water 

discharge, and groundwater chemistry. Total 

withdrawals increased by about 12 percent from the mid1960s to 2003. (Truini et al. 2005). 

Betatakin Ruins, Keet Seel Ruins, and Inscription House 

Ruins all have seeps and springs associated with alcoves 

and sandstone walls. The seeps and springs appear to be 

in good condition (NPS 2003). While groundwater 

discharge to the surface is fairly constant throughout the 

year, runoff from rainfall and snowmelt varies widely 

(Blakemore and Truini 2000). 

Water Quality 

The status of water quality within and around the 

monument is not well studied or documented 

(Blakemore 2003; NPS 2003). Livestock grazing within 

the watershed environment of both Keet Seel and 

Inscription House contributes to the deterioration of 

water quality within the monument even though most 

grazing occurs outside monument boundaries. 

Trampling of stream banks, by livestock, hikers, and 

motorized vehicles, promotes erosion and increased 

sedimentation into surface water. Increased 

sedimentation combined with accumulations of urine 

and fecal matter causes deterioration in water quality 

(NPS 2003). 

Keet Seel appears to be the most affected site by all of 

these outside impacts, especially grazing and trampling. 

Algae blooms occur throughout the stream system and 

the stream banks continue to be unstable. Water quality 

at Betatakin may be impacted by rain and runoff events 

that transport pollutants from the parking lot to the 

groundwater table. 

Each year, as part of the Black Mesa monitoring 

program, water samples are collected from selected wells 

and springs that discharge from the N aquifer. Water 

samples are analyzed for dissolved solids, specific 

conductance, chloride, and sulfate. Data are available 

from the USGS water- quality database 

(http://waterdata.usgs.gov/az/nwis/qw). 

Regolith 

At Betatakin hikers compact the regolith 

(unconsolidated material above bedrock) and break the 

biological soil crusts. Vibrations from vehicles and from 

trail and road maintenance lead to rockfalls and to local 

disturbances of surficial deposits and vegetative cover 

(NPS 2003). Generally, maintenance, construction, or 
 NAVA Geologic Resource Evaluation Report 11

recreational activities cause minor, short- term adverse 

effects, but specific construction projects could result in 

long- term impacts. 

To limit these impacts, the monument uses mitigation 

measures during maintenance and construction projects. 

Some of these measures include “using previously 

disturbed sites for staging and stockpiling, returning the 

disturbed site to its previous grade, salvaging of local 

plants, and revegetating with native species immediately 

after a project is finished” (NPS 2003, p. 103). At 

Betatakin, a boundary fence to eliminate grazing has 

provided a long- term, beneficial impact by reducing 

erosion and protecting biotic communities (NPS 1995; 

NPS 2003). 

Hiking, horses, grazing, trampling, and use of motorized 

vehicles at Keet Seel and Inscription House have 

adversely affected the regolith around and within the 

riparian areas. Instability has led to increased erosion 

and once this unconsolidated surface material becomes 

unstable, it is difficult, if not impossible, to restore. 

Figure 5. Numerous joint discontinuities are found along the overhung section of Aspen Forest Trail. Photograph from Wieczorek and 

Harp, 2000. 
 NPS Geologic Resources Division 12 

 

 A) 1934 B) 1976 

Figure 6. Erosion in front of Keet Seel in 1934 (A) and the arroyo cut by 1976 (B). From Navajo National Monument: An Administrative 

History; available at http://www.nps.gov/archive/nava/adhi/adhit.htm, access 12/11/2006. 
 NAVA Geologic Resource Evaluation Report 13

Geologic Features and Processes 

This section provides descriptions of the most prominent and distinctive geologic features 

and processes in Navajo National Monument. 

Alcoves 

The primary geologic features of interest at Navajo 

National Monument are the alcoves that formed due to 

groundwater flow, dissolution of carbonate cement, 

gravity, and wind erosion (figure 7). The Navajo 

Sandstone is porous and permeable but the underlying 

Kayenta Formation is not. The Kayenta, therefore, acts 

as a barrier to vertical groundwater flow. Water 

infiltrating into the sandstone on the Shonto Plateau 

moves laterally at the Navajo- Kayenta interface and 

emerges as springs along the canyon walls. 

The carbonate matrix holding the sand grains of the 

Kayenta Formation together slowly dissolves as a result 

of ground water flow. Loosened grains destroy the 

integrity of the rock, undermining the cliffs of Navajo 

Sandstone lying above. Over time, slabs of the Navajo 

Sandstone break away into the canyon, eventually 

forming alcoves. These alcoves, especially ones with a 

spring at the Navajo/Kayenta interface, were attractive 

sites for occupation by prehistoric peoples. 

A textbook example of alcove formation is found at 

Betatakin ruins near the visitor center (figure 7). The 

ruins occupy an alcove that formed as the Navajo 

Sandstone, undermined by erosion of the less resistant 

Kayenta Formation, broke away in arching slabs. The 

arched ceiling of Betatakin ruins offers a unique acoustic 

experience, as whispers from one end of the ruins can be 

easily understood at the other. Vibrations off the arched, 

cross- bedded strata probably contribute to this 

phenomenon. 

Navajo Sandstone 

The Navajo Sandstone consists mostly of large- scale 

cross- bedded, pale salmon- colored, eolian sandstone 

with minor lenses of pink clay and light gray freshwater 

limestone that formed in small lakes and ponds during 

the Jurassic (Peterson 1994). The Navajo Sandstone 

thickens to the northwest and may reach 1,800 feet (550 

m) thick on the Navajo Reservation (Cooley et al. 1969). 

The Navajo Sandstone is one of the largest preserved 

eolian systems in the stratigraphic record, and along with 

its correlatives, the most widespread eolian deposit in 

North America (Blakey 1994; Peterson 1994). These 

Lower Jurassic dune sands are distributed from 

northwestern Wyoming and adjacent Idaho southward 

to southern Arizona and northern Mexico. 

Much of the surface of the Navajo Sandstone is barren of 

vegetation so that the preserved arcs and swirls of eolian 

cross- bedding in the preserved dunes are fully exposed. 

Several sets of vertical joints in the rocks were produced 

by strains and stresses of deep burial and subsequent 

uplift. The vertical joints are deeply incised and serve as 

watercourses for surface flow during rainstorms. Rows 

of miniature pools mark these watercourses. The pools 

fill with rainwater and serve as habitats for small plants 

and animals, many of them microscopic. By- products of 

these animals and plants include acids that dissolve the 

limy cement holding the sand grains together. Lichens 

secrete acids that also loosen grains that are blown away 

by wind. The barren patches are surrounded by thin soil 

that is hardly more than wind- blown sand held together 

by roots of trees, shrubs, and grass. 

A surface stain of manganese oxide and/or iron oxide 

known as desert varnish locally forms a brown or black 

coat on the bare Navajo Sandstone (figure 7). Ancestral 

Puebloans used this desert varnish as a backdrop for 

their petroglyphs. Pictographs were also drawn on the 

salmon- colored sandstone. 

Betatakin Unit 

Betatakin Canyon is a side canyon that connects to Tsegi 

Wash. Tsegi Wash flows into Laguna Wash near US 

Highway 160. Both of these streams ultimately drain into 

the San Juan River at Mexican Hat (Chronic 1983). 

Betatakin Canyon contains the Betatakin cliff dwelling, 

Kiva Cave cliff dwelling, and the remains of the Wetherill 

cabin (NPS 2003). Tree- ring dating indicates that the 

alcove was occupied around A.D. 1250. 

Betatakin contains about 135 rooms tucked into a cliffside alcove 452 feet (138 m) high and 370 feet (113 m) wide 

(figure 7). Vegetation surrounds a small spring at the 

Navajo- Kayenta interface at the base of the alcove. The 

spring has likely accelerated cliff collapse in this area. 

The natural and cultural resources of the Betatakin Unit 

are protected from grazing by a boundary fence between 

the unit and Navajo land. 

Betatakin Canyon is visible from the visitor center. Thin 

beds of freshwater limestone in the Navajo Sandstone 

cap the highest hillocks near the Visitor Center. These 

limestones were probably deposited in ephemeral ponds 

in interdune areas similar to those in modern dune fields 

(e.g. Great Sand Dunes National Park). There are many 

small alcoves on switchbacks along the Aspen Forest 

Trail which is now closed to the public as a result of 

rockfall hazards. The sandy floors of these alcoves are 

marked by tracks and droppings of small animals. Crossbedding in the sandstone controls alcove shape, leading 

to a sloping ceiling or an arched ceiling like that at 

Betatakin. 
 NPS Geologic Resources Division 14 

Keet Seel Unit 

The Keet Seel site, located up a north- south trending 

side canyon in the Tsegi Canyon system, contains the 

largest cliff- dwellings in America: the Keet Seel cliff 

dwelling (figure 8) and the Turkey Cave cliff dwelling. 

Many of the features in Betatakin Canyon are present at 

Keet Seel. Like Betatakin, Keet Seel has a spring at the 

contact between the Navajo Sandstone and Kayenta 

Formation. Pictographs of birds are preserved in Turkey 

Cave. 

Pottery and tree- ring dating indicate that the ancient 

Puebloans lived here as early as A.D. 950. Inhabitants of 

Keet Seal did not come in groups, as at Betatakin, but 

arrived and departed randomly. As a result, Keet Seel 

contains more variation in room design and construction 

and more kivas than Betatakin. 

A surge in building activity in 1272 suggests the arrival of a 

new group of people. Population growth apparently 

taxed the capacity of the alcove and people began 

moving out. Those who remained converted abandoned 

rooms into granaries; however, they also left around 

1300. 

Inscription House Unit 

Inscription House was named for an inscription on one 

of the walls noted in 1909 by Byron Cummings and John 

Wetherill. This cliff dwelling lies at the base of a higharching sandstone cliff on the north side of an arm of 

Nitsin Canyon. The site has been closed to the public 

since 1968 because of urgent stabilization needs and 

because the local people desire privacy. 

The smallest of the three ruins, Inscription House 

contains about 74 living quarters, granaries, and kivas 

(figure 9). Other cliff dwellings at the site include Owl 

House and Snake House. A tree- ring date of 1274 

indicates that Inscription House was occupied about the 

same time as Betatakin and Keet Seel. 

As with the other sites, a spring is associated with the 

ruins. Inscription House Spring flows out of the Navajo 

Sandstone and into Navajo Creek, which flows 

northward into Lake Powell (Thomas 2003). 
 NAVA Geologic Resource Evaluation Report 15

Figure 7. Betatakin ruins in an alcove formed in the Navajo Sandstone, Betatakin Canyon, Navajo National Monument. Photograph from 

http://3dparks.wr.usgs.gov/2006/navajo/index2.htm, access 02/27/2007. 
 NPS Geologic Resources Division 16 

Figure 8. Keet Seel ruins in an alcove cut into the massive Navajo Sandstone. From www.ncdc.noaa.gov, access 12/6/2006. 
 NAVA Geologic Resource Evaluation Report 17

Figure 9. Inscription House. From the Stuart M. Young Collection, NAU.PH.643.1.59, Cline Library, Northern Arizona University, 

http://www.nps.gov/rabr/adhi/images/fig14.jpg, access 12/13/06. 
 NPS Geologic Resources Division 18 

Map Unit Properties 

This section provides a description for and identifies many characteristics of the map 

units that appear on the digital geologic map of Navajo National Monument. The table is 

highly generalized and is provided for informational purposes only. Ground disturbing 

activities should not be permitted or denied on the basis of information contained in this 

table. More detailed unit descriptions can be found in the help files that accompany the 

digital geologic map or by contacting the NPS Geologic Resources Division. 

The following Map Unit Properties Table identifies 

specific properties of the different map units exposed in 

Navajo National Monument. Geologic features and 

processes often occur in or can be restricted to a 

particular stratigraphic unit (group, formation, or 

member). This section ties together the geologic features, 

formation properties, and the accompanying digital 

geologic map. 

Sedimentary rocks exposed at Navajo National 

Monument are primarily Mesozoic- age sandstones and 

siltstones. The following table includes several properties 

specific to each unit in the stratigraphic column 

including the unit’s name, map symbol, a description of 

lithology, erosion resistance, hazards, potential cultural 

and paleontologic resources, water potential, mineral 

resources, and global significance. 
Map Unit Properties Table 

Age Map Unit (symbol) Features and Descriptions Erosion Resistance Hazards Potential Cultural Resources 

Quaternary Alluvium (Qal) Unconsolidated sand, mud, gravel; river bank deposits Low Flash flooding; stream bank collapse; canyon cutting None documented 

Regional Unconformity 

Gravel (tg) Unconsolidated gravel 

Tertiary Intrusive rocks 

(Ti) Igneous rocks 

Not exposed in 

monument NA NA 

Regional Unconformity 

Yale Point 

Sandstone (Ky) Marine sandstone Not exposed in monument 

Wepo Formation 

(Kw) 

Alternating beds of olive- gray siltstone, coal, yellowish- gray sandstone 

Not exposed in 

monument; caps Black 

Mesa 

Toreva Formation 

(Kt) 

Basal sandstone member, middle carbonaceous member, upper sandstone member. 

Mancos Shale 

(Km) Black shaly siltstone, shale, and gypsum 

Upper Cretaceous 

Dakota Sandstone 

(Kd) 

Interbedded buff sandstone, conglomerate, and siltstone 

Not exposed in 

monument 

NA NA 

Regional Unconformity 

Upper 

Jurassic Morrison Fm. (Jm) Red siltstone and fine sandstone Not exposed in monument NA NA 

Regional Unconformity 

Cow Springs 

Sandstone (Jcs) Eolian sandstone 

Summerville Fm 

(Js) 

Red siltstones and mudstones; scattered beds of gypsum; rare limestone; local sandstone 

Entrada 

Sandstone (Je) White, cross- bedded, eolian sandstone 

Middle 

Jurassic 

Carmel Fm. (Jc) Red and white, shaly siltstone 

Not exposed in 

monument NA NA 

Regional Unconformity 

Navajo Sandstone 

(JTRn*) 

Grayish- orange- pink even- grained, highly crossbedded, eolian sandstone. High - cliff former Fractures, rockfalls, cliff failure; rockslides; often undercut Alcoves contain cultural resources 

Kayenta Fm. 

(TRk*) 

Interbedded pale- red sandstone and red mudstone; Cross- bedded sandstones are flood- plain channel deposits; mudstones are overbank deposits; ledgy appearance farther north; may reach 700 ft (213 m) thick on the Navajo Reservation 

Moderate - Erosion of mudstone undercuts Navajo cliffs 

Erosion of Kayenta leads to rock- falls and cliff collapse in Navajo Sandstone 

None documented R

Wingate 

Sandstone 

(Lukachutai mbr.) 

(TRwl*) 

Reddish- brown, fine- grained cross- bedded eolian sandstone; calcareous cement; 0- 300 ft (91 m) thick 

Moderate - more resistant than Kayenta 

Farther north, the Wingate forms prominent cliffs prone to rock- fall 

Petroglyphs possible on exposed sandstone 

Lower Jurassic 

Regional Unconformity 
Age Map Unit (symbol) Features and Descriptions Erosion Resistance Hazards Potential Cultural Resources 

Upper Triassic Chinle Fm. (Church Rock & Owl mbrs.) (TRcco) 

Church Rock mbr: reddish- brown siltstone & silty 

sandstone & grayish- orange- pink mudstone. Owl Rock mbr: mottled light- gray & grayish- pink 

interbedded limestone & calcareous siltstone. Thins from Utah south into Arizona. Petrified Forest mbr: lavender and brown sandstones, 

variegated mudstones Two older members of the Chinle Fm found in N. Arizona are not exposed in the park. Chinle Fm. Is 850-1,500 ft (260- 460 m) thick on the Navajo Reservation 

Low especially during times of flash flooding. Occupies canyon bottoms. 

Mudstones are a potential hazard to any development in the canyon bottoms; bentonite in Petrified Forest member. 

Petrified wood and varicolored rocks may have interested ancient Native Americans. 

Bcpvho

Regional Unconformity 

Lower 

Triassic Moenkopi Formation (TRm) Reddish siltstone, sandstone and gypsum; about 200 ft (61 m) thick Not exposed in monument NA NA 

Regional Unconformity 

Permian Cutler Formation (Pc) Interlayered sandstones, mudstones, and limestones representing marine, fluvial, and eolian depositional environments. Not exposed in monument NA NA 

* Although the GIS map symbols indicate a Jurassic/Triassic age for the Navajo and a Triassic age for the Kayenta and Wingate Formations, advances in the science of geology since th

unconformity separates Triassic strata from Jurassic strata in the region (Peterson, 1994).
 NAVA Geologic Resource Evaluation Report 21

Geologic History 

This section highlights the map units (i.e., rocks and unconsolidated deposits) that occur 

in Navajo National Monument and puts them in a geologic context in terms of the 

environment in which they were deposited and the timing of geologic events that created 

the present landscape. 

The strata in Navajo National Monument record Upper 

Triassic through Lower Jurassic time, but rocks on the 

adjacent Black Mesa span the entire Mesozoic Era (Map 

Unit Properties Table; figure 3). The Mesozoic Era 

followed the most extensive mass extinction preserved in 

the geologic record - the end of the Permian Period 

when 96 percent of all species were eliminated (figure 3) 

(Raup 1991). At the beginning of the Mesozoic, shallow, 

marine water stretched from Utah to eastern Nevada 

over a relatively level continental shelf. 

Triassic Period (251-200 Ma) 

During the Triassic Period, the major land masses came 

together forming the supercontinent, Pangaea. On the 

western margin of Pangaea, a subduction zone formed 

that trended north- northwest to south- southeast with 

oceanic crust dipping eastward beneath the continental 

margin. In the Early Triassic, volcanic activity decreased 

on the western margin of Pangaea and igneous rocks 

were emplaced along this subduction zone (Saleeby et al. 

1992; Christiansen et al. 1994). 

Moenkopi Formation: 

The reddish siltstone, shales, and sandstones of the 

Moenkopi Formation were deposited in fluvial, mudflat, 

sabkha, and shallow marine environments that formed as 

the shallow sea withdrew from northeastern Arizona. 

Ripple marks and low- angle cross- bedding in the 

Moenkopi formed as a result of fluvial processes that 

leveled the area into a relatively flat plain. The presence 

of fossilized plants (reeds and Equiseta), trackways of 

reptiles and amphibians, and fossils of warm water 

marine invertebrates in strata above gypsum zones 

indicate a shift from a cool, dry climate to a warm, 

tropical climate in the Early Triassic (Stewart et al. 1972A; 

Dubiel 1994; Huntoon et al. 2000). 

In northern Arizona, red beds of the Holbrook Member 

of the Moenkopi Formation are lowermost Middle 

Triassic (235- 240 Ma) based on paleontologic evidence 

(Dubiel 1994). However, Middle Triassic rocks are 

generally absent in the Western Interior. Local deposits 

of lowermost Middle Triassic strata suggest that erosion, 

rather than nondeposition, is largely responsible for the 

absence of Middle Jurassic rocks. A regional 

unconformity separates the Lower Triassic from the 

Upper Triassic. 

Chinle Formation: 

Rocks of the Chinle Formation in the Western Interior of 

North America are a complex assemblage of fluvial, 

marsh, lacustrine, playa, and eolian deposits from the 

Late Triassic (208- 235 Ma) (figure 10) (Stewart et al. 

1972B). This suggests the Chinle was deposited in a 

densely vegetated flood plain or mud flat that contained 

localized shallow ponds and small, shallow, sinuous 

streams (Scott et al. 2001). 

Floodplain mudstones that completely encase fluvial 

sandstones in the Petrified Forest Member of the Chinle 

Formation signify deposition by high- sinuosity streams. 

Altered glass shards and bentonitic mudstones indicate 

that volcanic ash formed a significant component of the 

sediment (Dubiel 1994). Fossils of phytosaurs, lungfish, 

and lacustrine bivalves reflect river, lake, and marsh 

environments. The Petrified Forest Member grades 

upward into the Owl Rock Member. 

The knobby texture in the Owl Rock Member is thought 

to result from extensive bioturbation, an interpretation 

supported by the numerous crayfish burrows found 

locally in the Owl Rock. Owl Rock sediments were 

deposited in an extensive lacustrine and marsh 

environment in response to continued subsidence and to 

a reduction in clastic and volcanic sediment input 

(Stewart et al. 1972B; Dubiel 1994). Major fluvial 

environments, evident in the underlying members of the 

Chinle, are lacking in the Owl Rock Member, suggesting 

that the paleoflow in the lower part of the Chinle was 

disrupted so that rivers and streams backed up and 

formed ponds during deposition of the Owl Rock. 

Subaerial exposure in dry periods when lakes and 

marshes dried up, allowed soil formation processes to 

modify primary textures (Dubiel 1994). In places, the Owl 

Rock strata fills valleys eroded into the underlying 

Petrified Forest Member. 

Sandstones and mudstones of the overlying Church 

Rock Member were deposited by fluvial systems, on 

lacustrine or playa mudflats traversed by small fluvial 

systems, and as eolian sand sheets and dunes (Dubiel 

1994). The large- scale, eolian cross- stratification and 

mudcracks found in the Church Rock Member in 

northern Arizona and the Four Corners area indicate 

that dry periods became more prevalent during 

deposition of the uppermost part of the Chinle. 

The development of extensive fluvial, lake and marsh 

systems in the Triassic may be related to uplift associated 

with converging lithospheric plates along the west coast 

(Dubiel 1994). As the oceanic plate pushed beneath the 

overriding North American continent, magma was 

generated forming linear or arc- shaped belts of 
 NPS Geologic Resources Division 22 

volcanoes on the overriding plate, parallel to the 

subduction zone. Mount St. Helens and the other 

volcanoes in the Cascade Range formed in a similar way 

and lie parallel to an active subduction zone that extends 

from northern California to Canada. Triassic subduction 

and the evolution of an arc- shaped belt of volcanoes 

probably influenced the lake systems of the Owl Rock 

Member, causing drainage reversal in the Church Rock. 

Jurassic Period (200-146 Ma) 

In the present Four Corners region of Arizona, New 

Mexico, Colorado, and Utah, the Jurassic Period was a 

time of extensive dune formation (figure 11). The region 

was located about 18 degrees north latitude at the 

beginning of the Jurassic Period and moved to 30- 35 

degrees north latitude by the end of the Jurassic 

(Kocurek and Dott 1983; Peterson 1994). This is the 

latitude of the present day northeast trade wind belt 

where cool, dry air descends from the upper atmosphere 

and sweeps back to the equator in a northeast to 

southwest direction. The cool, dry air becomes warm, 

dry air causing intense evaporation. Most modern hot 

deserts of the world occur within the trade wind belt. 

The climate of the Colorado Plateau during the Jurassic 

appears similar to that of the modern Western Sahara of 

Africa. 

The Jurassic deserts that existed for roughly 40 million 

years (not counting the time represented by erosion) 

contained sand dunes that may be the largest ever 

recorded (Kocurek and Dott 1983). Similar to the modern 

Sahara, these ergs formed on a coastal and inland dune 

field. These dunes extended from present day southern 

Montana south and east into eastern Utah, westernmost 

Colorado, southwestern Colorado, northeastern 

Arizona, and northwestern New Mexico (Kocurek and 

Dott 1983; Peterson 1994). 

Volcanic islands formed an unknown distance west or 

southwest of the west coast of North America in the 

Middle Jurassic. During the Late Jurassic, these islands 

accreted to the North American plate (Busby- Spera 1988; 

1990; Marzoff 1990). Major tectonic plate reorganization 

in the Late Jurassic followed the Cordilleran magmagenerating episode of the Middle Jurassic. At this time, 

the Gulf of Mexico opened and the North American 

lithospheric plate rotated counterclockwise. To 

accommodate the plate motion, a large transform fault 

zone called the Mojave- Sonora megashear, developed 

along what is now the Mexico- United States border and 

truncated the southwestern margin of North America. 

This northwest- southeast trending megashear zone 

accommodated approximately 500 to 600 miles (800-

1000 km) of left- lateral displacement (Kluth 1983; 

Stevens et al. 2005; Anderson and Silver 2005; Haenggi 

and Muehlberger 2005). 

Wingate Sandstone: 

During the Lower Jurassic, the northern sea in the Arctic 

region did not encroach onto the continent as it had in 

the past. Paleozoic sandstones exposed from as far north 

as Montana and Alberta provided abundant sand 

transported by wind to the Colorado Plateau (Kocurek 

and Dott 1983). 

Westerly to southwesterly winds transporting sand from 

Alberta to Arizona may have been diverted to the south 

by a rising a volcanic arc off the western coast of North 

America (Kocurek and Dott 1983). Sediments from the 

volcanic arc to the west are missing from the dune sand 

on the Colorado Plateau. While the volcanic arc diverted 

the wind from Alberta, the trade winds probably swept 

the volcanic ash to the southwest, out to sea. Rivers 

flowing from the Ancestral Rockies may have provided 

an additional source of sand to the growing dune fields. 

The regional depositional geometry of the Wingate 

Sandstone, the high- angle cross- bedding and the wellsorted frosted quartz grains indicate that the Wingate 

was eolian (Peterson 1994). Regionally, six major erg 

sequences have been mapped in the Wingate (Nation 

1990; Blakey 1994). The six erg units vary in detail from 

one another, but generally, both the overall Wingate 

Sandstone succession and the individual erg sequences 

display an upward drying trend with small dunes and 

sandsheets of large cross- bedded dunes overlying 

sabkha and lacustrine deposits (Blakey 1994). 

Kayenta Formation: 

A change from eolian to fluvial deposition is recorded in 

the sandstones of the Kayenta Formation. In contrast to 

the sweeping eolian cross- beds of the underlying 

Wingate and overlying Navajo Sandstones, the crossbeds in the Kayenta are only a few feet thick. 

Interbedded sandstones, basal conglomerates, siltstones, 

and mudstones are typical channel and floodplain 

deposits. Paleocurrent studies show that during 

deposition of the Kayenta, rivers flowed in a general 

westward to southwestward direction (Morris et al. 

2000). The rocks of the Kayenta Formation display an 

excellent example of the effects of a climate change 

resulting in ergs of the Wingate Sandstone being 

reworked by fluvial processes (Blakey 1994). 

Navajo Sandstone: 

The Navajo Sandstone records a return to arid 

conditions and the development of extensive ergs on the 

Colorado Plateau (figure 11). Sand dune deposits reaching 

800 to 1,100 ft (240 to 340 m) high gradually overtook the 

fluvial systems of the Kayenta. The large- scale (18 m, 60 

ft), high- angle, cross- beds of the Navajo attest to the 

presence of Sahara- like sand dunes during the Early 

Jurassic (Morris et al. 2000). The paleolatitude of Navajo 

National Monument during the deposition of the Navajo 

Sandstone was near 20 degrees north latitude (Parrish 

and Petersen 1988; Chan and Archer 2000). Paleo- wind 

directions shifted more northerly giving rise to 

subtropical and monsoonal circulation patterns in the 

region. Studies of the cyclicity in Navajo dune sets 

suggest that the region experienced alternating wetter 

and drier periods on a decade scale in the Early Jurassic 

(Chan and Archer 2000). 
 NAVA Geologic Resource Evaluation Report 23

Lithospheric plate collisions intensified off the western 

coast in the Middle Jurassic causing rock layers on the 

continent side of the collision to bulge upward. 

Weathering and erosion stripped away the exposed 

rocks and a regional unconformity surface formed on the 

Navajo Sandstone. 

Carmel Formation: 

As plate tectonic activity increased, the sea lapped onto 

the continent from the north. The reddish siltstones and 

mudstones of the Carmel Formation (Middle Jurassic) 

were deposited on broad tidal flats marginal to a shallow 

sea that lay to the west. 

Entrada Sandstone: 

The Entrada Sandstone (Middle Jurassic) originally 

covered the entire Colorado Plateau. The Entrada is the 

most widespread of the preserved late Paleozoic and 

Mesozoic eolianites. The cross- bedded sandstone was 

deposited in an extensive dune field in a back- beach area 

(Kocurek and Dott 1983; Hintze 1988; Peterson 1994; 

Doelling 2000). Together, the Entrada Sandstone and 

Carmel Formation record three of the five transgressiveregressive episodes that deposited the Middle Jurassic 

strata on the Colorado Plateau. 

Summerville Formation and Cow Springs Sandstone: 

As lithospheric plate collision increased on the western 

margin, a major transgression of the inland seaway 

destroyed the vast eolian sand seas that once covered the 

Colorado Plateau. Tidal flats formed in the area as 

marine environments encroached from the north. 

Restricted marine and tidal flat deposits of the 

Summerville Formation (Middle Jurassic) mark the 

southern extent of the seaway. The Cow Springs 

Sandstone (now considered to be a member of the 

Entrada Sandstone) preserves the remnants of a once 

vast eolian sand sea (Kocurek and Dott 1983; Peterson 

1994). 

Morrison Formation: 

The Morrison Formation (Upper Jurassic), known for 

dinosaur fossils and for uranium occurrence (Peterson 

1994), was deposited across the western continental 

United States with the final regression of the Jurassic sea. 

The stratigraphy of the Morrison Formation reflects a 

mostly fluvial origin: mudflats, overbank and floodplain 

deposits, and stream channels, as well as small eolian 

sand fields, and scattered lakes and ponds. The Morrison 

with its banded pink, maroon, green, and gray shales is 

prominent and identifiable over much of the Colorado 

Plateau. 

Cretaceous Period (146-66 Ma) 

Fast- flowing streams from highlands to the southwest 

eroded the softer shales and siltstones of the Morrison 

Formation, creating a regional unconformity in the rock 

record between the Jurassic and Cretaceous Periods. 

However, Lower Cretaceous fluvial, floodplain, and 

lacustrine deposits, present elsewhere on the Colorado 

Plateau, have been eroded from the Black Mesa area. 

With plate collisions continuing on the western margin, 

the continental landscape experienced a dramatic change 

in the Upper Cretaceous. Mountains rose in the west and 

a north- south trough formed adjacent to the mountains. 

As the trough subsided, a shallow sea advanced onto the 

continent from both the Gulf of Mexico and the Arctic 

Ocean. The sea advanced and retreated many times 

during the Cretaceous until the most extensive interior 

seaway to cover the continent drowned much of western 

North America from about 95 to 64 Ma (figure 12). The 

advances and retreats of the Cretaceous Sea created a 

myriad of environments including incised river valley 

systems, estuaries, coal swamps, lagoons, delta systems, 

beaches, and shallow marine. These deposits are 

complex, and the rocks formed from these sediments 

include alternating and interfingering marine sandstones, 

shales, and coal beds forming the Dakota Sandstone, 

Mancos Shale, and the Mesaverde Group. 

Dakota Sandstone: 

In general, the Dakota Sandstone records shallow marine 

deposition with some intermittent mud flat and stream 

deposition. Coal swamps formed in the quiet backwaters 

of estuaries. Some of the sandstones may have been 

deposited in paleovalleys incised into the coastal plain 

during a regressive episode (Gardner and Cross 1994). 

With burial and increased temperature, the organic 

material of the Dakota Formation slowly transformed 

into coal and hydrocarbons. The coarse- grained 

sandstone layers are today reservoirs for oil and gas as 

well as and groundwater. 

Mancos Shale: 

The thick sequence of shale and siltstone with sandstone 

stringers and minor gypsum and limestone forming the 

Mancos Shale was deposited in the advancing 

Cretaceous seaway. For roughly ten million years, clay, 

silt, sand, and shell debris were deposited in the 

Cretaceous Interior Sea. At first glance, the formation 

appears to be 2000+ ft (700 m) of uniform, monotonous 

black and gray shales. Yet, the history of the Mancos on 

the Colorado Plateau reflects at least four major changes 

in depositional systems where shoreline and near- shore 

environments replaced with new environments created 

as sea level rose and fell (Aubrey 1991). 

Fossil evidence suggests that ocean currents within the 

Cretaceous Interior Sea were variable. At times, the 

currents circulated oxygenated water throughout the 

water column allowing life to prosper at all levels, 

including within the muddy sea bottom. Conversely, at 

other times, the circulation in the Seaway was restricted 

to the upper water layer, and black, organic- rich muds 

accumulated in the oxygen- poor sea bottom. In those 

environments, the fossil material includes very few, if 

any, bottom fauna. 

Torevo Formation and Wepo Formation: 

The Torevo Formation and Wepo Formation are part of 

four major transgressive- regressive marine cycles in the 

Upper Cretaceous (Elder and Kirkland 1994). The 

formations were deposited from approximately 91- 84 
 NPS Geologic Resources Division 24 

Ma and are slightly younger than the Point Lookout 

Sandstone at Mesa Verde National Park. The rest of the 

Cretaceous record, from 84- 66.4 Ma, is missing in the 

Black Mesa area. 

Aggrading fluvial deposits that formed the Toreva 

Formation record the early phases of transgression. The 

sediment sources for the Toreva were rifted uplands to 

the southwest and south (Elder and Kirkland 1994). The 

rivers flowed to a northwest- southeast trending 

shoreline that extended from southwest Utah, across 

northeastern Arizona, and into central New Mexico. 

The Wepo Formation resulted from a regressive interval 

following the transgression that deposited the Toreva 

Formation. Organic matter accumulated in lagoons and 

marshes that formed in a coastal- plain depositional 

system. With burial and elevated temperatures, the 

organic matter was transformed into coal. 

The Yale Point Sandstone is a marine sandstone and 

refelcts another transgression into the Western Interior 

Basin. Cretaceous strata deposited above the Yale Point 

Sandstone have been eroded from the Navajo National 

Monument area. 

Late Cretaceous-Early Tertiary (70-35 Ma) 

The North American lithospheric plate collided with the 

Farallon plate, producing the Laramide Orogeny (about 

70- 35 Ma). This event transformed the extensive basin of 

the Cretaceous Interior Seaway into smaller faultbounded basins. Thrust faulting during the Laramide 

Orogeny brought Precambrian plutonic and 

metamorphic basement rocks to the surface. 

Tectonic activity during this time warped the Colorado 

Plateau region into broad anticlinal and synclinal folds 

with very little large- scale (kms) faulting (Dickinson and 

Snyder 1978; Chapin and Cather 1983; Hamilton 1988; 

Erslev 1993). The Organ Rock Monocline that plunges 

the Navajo Sandstone beneath Black Mesa is a result of 

Colorado Plateau deformation during the Laramide 

Orogeny. 

With continued uplift in the late Tertiary and 

Quaternary, most of the Upper Cretaceous strata was 

eroded from the Black Mesa area. 

Tertiary Period (66-1.8 Ma) 

Near the end of the Laramide Orogeny, from about 35-

26 million years ago, in mid- Tertiary time, volcanic 

activity erupted across the Colorado Plateau. The 

laccoliths that formed the Sleeping Ute Mountain, La 

Plata Mountains, Henry Mountains, La Sal Mountains, 

and Abajo Mountains were emplaced during the midTertiary. 

Today, Late Cretaceous shoreline deposits are found on 

the Colorado Plateau at elevations of several thousand 

feet. Since the end of the Cretaceous Period 66 million 

years ago, the Colorado Plateau has risen about 12,000 ft 

(3,660 m) (Fillmore 2000). Some of this uplift occurred 

quite rapidly in geologic time. As the rate of uplift 

increased, so did the rate of erosion. The Colorado 

River, for example, carved its present course within the 

last 6 million years. 

Quaternary Period (1.8-0.01 Ma) 

In the Pleistocene (1.8- 0.01 Ma) ice ages, streams carved 

deep valleys and river channels into the Colorado 

Plateau. In the wetter climate, groundwater flow through 

the permeable Navajo Sandstone was restricted at the 

contact with less permeable shale and siltstone layers in 

the Kayenta Formation. The groundwater flowed 

laterally along the contact to the canyon walls forming 

seeps and springs. During this time, deep alcoves began 

to form in the Navajo Sandstone. 

The Colorado Plateau as a whole has been subjected to 

repeated minor uplifts and stream rejuvenation since the 

end of the last ice age. Today, the climate is drier than 

during the Pleistocene ice ages yet the intermittent 

streams in the canyons are still actively downcutting, 

only at a slower rate than in the past. 

The Pleistocene Jeddito Formation and the Holocene 

Tsegi and Naha Formations are alluvial units in Tsegi 

Canyon in Navajo National Monument. The Jeddito 

Formation occurs as remnant high alluvial terraces below 

Holocene alluvial units. The Tsegi Formation rests on 

bedrock or locally on the Jeddito Formation (Clay- Poole 

1989). The Naha Formation is the youngest unit, forming 

a terrace 40- 50 feet (12- 15 m) above the stream floor and 

10- 15 feet (3- 5 m) below the Tsegi terrace. From carbon14 dating of wood fragments near the base of the Tsegi, 

deposition began around 5,389 years BP and ended about 

A.D. 1275- 1300. Erosion removed extensive areas of the 

Tsegi, often to bedrock. Naha deposition began after 

A.D. 1375 and continued until A.D. 1884. Fresh- water 

gastropods, pelecypods, and ostracods have been found 

in the Naha Formation (Briscoe 1974). A new cycle of 

erosion is in progress today (Clay- Poole 1989). 
 NAVA Geologic Resource Evaluation Report 25

Figure 10. Paleogeography of the southern part of the Western Interior basin during deposition of the Late Triassic Chinle Formation. A 

volcanic arc has formed along the western margin of North America by this time. NAVA: Navajo National Monument. UN: Uncompahgre

Highlands. FR: Front Range Highlands. SL: San Luis uplift. UN, FR, and SL are remnants of the upper Paleozoic Ancestral Rocky Mountains. 

Modified from Dubiel, 1994. 
 NPS Geologic Resources Division 26 

Figure 11. Paleogeography of the southern part of the Western Interior basin during deposition of the Early Jurassic Navajo Sandstone. 

NAVA: Navajo National Monument. Modified from Peterson, 1994. 
 NAVA Geologic Resource Evaluation Report 27

Figure 12. Paleogeographic map showing the extent of the Cretaceous Interior Sea. Shaded areas indicate land above sea level. NAVA: 

Navajo National Monument. S.O.B.: Sevier Orogenic belt of Mesozoic age. M.H.?: Mogollon Highland of southwestern Arizona. Modified from 

Rice and Shurr, 1983. 
 NPS Geologic Resources Division 28 

Glossary 

This glossary contains brief definitions of technical geologic terms used in this report. Not all 

geologic terms used are referenced. For more detailed definitions or to find terms not listed 

here please visit: http://wrgis.wr.usgs.gov/docs/parks/misc/glossarya.html. 

active margin. A continental margin where significant 

volcanic and earthquake activity occurs; commonly a 

convergent plate margin. 

alluvial fan. A fan- shaped deposit of sediment that 

accumulates where a high gradient stream flows out of 

a mountain front into an area of lesser gradient such as 

a valley. 

alluvium. Stream- deposited sediment that is generally 

rounded, sorted, and stratified. 

aquifer. Rock or sediment that are sufficiently porous, 

permeable, and saturated to be useful as a source of 

water. 

ash (volcanic). Fine pyroclastic material ejected from a 

volcano (also see tuff). 

basement. The undifferentiated rocks, commonly 

igneous and metamorphic, that underlie the rocks of 

interest. 

basin (structural). A doubly- plunging syncline in which 

rocks dip inward from all sides (also see dome). 

basin (sedimentary). Any depression, from continental 

to local scales, into which sediments are deposited. 

bed. The smallest sedimentary strata unit, commonly 

ranging in thickness from one centimeter to a meter or 

two and distinguishable from beds above. 

bedding. Depositional layering or stratification of 

sediments. 

calcareous. A rock or sediment containing calcium 

carbonate. 

carbonaceous. A rock or sediment with considerable 

carbon, esp. organics, hydrocarbons, or coal. 

clastic. Rock or sediment made of fragments or preexisting rocks. 

conglomerate. A coarse- grained sedimentary rock with 

clasts larger than 2 mm in a fine- grained matrix. 

continental crust. The type of crustal rocks underlying 

the continents and continental shelves; having a 

thickness of 25- 60 km (16- 37 mi) and a density of 

approximately 2.7 grams per cubic centimeter. 

continental shelf. The shallowly- submerged portion of a 

continental margin extending from the shoreline to the 

continental slope with water depths of less than 200 m 

(656 ft). 

continental slope. The relative steep slope from the 

outer edge of the continental shelf down to the more 

gently sloping ocean depths of the continental rise or 

abyssal plain. 

convergent boundary. A plate boundary where two 

tectonic plates are moving together (i.e., a zone of 

subduction or obduction). 

craton. The relatively old and geologically stable interior 

of a continent (also see continental shield). 

cross-bedding. Uniform to highly- varied sets of inclined 

sedimentary beds deposited by wind or water that 

indicate distinctive flow conditions. 

crust. The outermost compositional shell of Earth, 10- 40 

km (6- 25 mi) thick, consisting predominantly of 

relatively low- density silicate minerals (also see 

oceanic crust and continental crust). 

dip. The angle between a structural surface and a 

horizontal reference plane measured normal to their 

line of intersection. 

drainage basin. The total area from which a stream 

system receives or drains precipitation runoff. 

dune. A low mound or ridge of sediment, usually sand, 

deposited by wind. Common dune types include the 

barchan dune, longitudinal dune, parabolic dune, and 

transverse dune (see respective listings). 

eolian. Formed, eroded, or deposited by or related to the 

action of the wind. 

eolianite. A sedimentary rock consisting of consolidated 

wind blown (eolian) material; dune sand cemented by 

calcite. 

erg. A large tract of sandy desert; a sand sea. 

ephemeral stream. A stream that flows only in direct 

response to precipitation. 

estuary. The seaward end or tidal mouth of a river where 

fresh and sea water mix; many estuaries are drowned 

river valleys caused by sea level rise (transgression) or 

coastal subsidence. 

fault. A subplanar break in rock along which relative 

movement occurs between the two sides. 

formation. Fundamental rock- stratigraphic unit that is 

mappable and lithologically distinct from adjoining 

strata and has definable upper and lower contacts. 

graben. A down- dropped structural block bounded by 

steeply- dipping, normal faults (also see horst). 

horst. An uplifted structural block bounded by highangle normal faults. 

igneous. Refers to a rock or mineral that originated from 

molten material; one of the three main classes or rocks: 

igneous, metamorphic, and sedimentary. 

intrusion. A body of igneous rock that invades older 

rock. The invading rock may be a plastic solid or 

magma that pushes its way into the older rock. 

island arc. A line or arc of volcanic islands formed over 

and parallel to a subduction zone. 

joint. A semi- planar break in rock without relative 

movement of rocks on either side of the fracture 

surface. 

laccolith. A tack head- to arcuate- shaped, concordant 

pluton that domed or up- arched the overlying country 

rocks. 
 NAVA Geologic Resource Evaluation Report 29

lacustrine. Pertaining to, produced by, or inhabiting a 

lake or lakes. 

landslide. Any process or landform resulting from rapid 

mass movement under relatively dry conditions. 

lithification. The conversion of sediment into solid rock. 

lithosphere. The relatively rigid outmost shell of Earth’s 

structure, 50 to 100 km (31 to 62 mi) thick, that 

encompasses the crust and uppermost mantle. 

magma. Molten rock generated within Earth that is the 

parent of igneous rocks. 

magmatic arc. An arcuate line of igneous intrusions; 

volcanic rocks and/or active volcanoes usually formed 

by subduction 

member. A lithostratigraphic unit with definable contacts 

that subdivides a formation. 

monocline. A one- limbed flexure in strata, which are 

usually flat- lying except in the flexure itself. 

normal fault. A dip- slip fault in which the hanging wall 

moves down relative to the footwall. 

oceanic crust. Earth’s crust formed at spreading ridges 

that underlies the ocean basins. Oceanic crust is 6- 7 

km (3- 4 mi) thick and generally of basaltic 

composition. 

orogeny. A mountain- building event, particularly a wellrecognized event in the geological past (e.g. the 

Laramide orogeny). 

paleogeography. The study, description, and 

reconstruction of the physical geography from past 

geologic periods. 

Pangaea. A theoretical, single supercontinent that 

existed during the Permian and Triassic Periods (also 

see Laurasia and Gondwana). 

permeability. A measure of the ease or rate that fluids 

move through rocks or sediments. 

phytosaurs. Semi- aquatic reptiles resembling the 

modern crocodile. 

plateau. A broad, flat- topped topographic high of great 

extent and elevation above the surrounding plains, 

canyons, or valleys (both land and marine landforms). 

plate tectonics. The theory that the lithosphere is broken 

up into a series of rigid plates that move over Earth’s 

surface above a more fluid aesthenosphere. 

pluton. A body of intrusive igneous rock. 

plutonic. Describes igneous rock intruded and 

crystallized at some depth in Earth. 

porosity. The proportion of void space (cracks, 

interstices) in a volume of a rock or sediment. 

progradation. The seaward building of land area due to 

sedimentary deposition. 

red beds. Sedimentary strata composed largely of 

sandstone, siltstone, and shale that are predominantly 

red due to the presence of ferric oxide (hematite) 

coating individual grains. 

regolith. A general term for the layer or mantle of 

fragmental and unconsolidated rock material, whether 

residual or transported and of highly varied character, 

that nearly everywhere forms the surface of the land 

and overlies or covers the bedrock. It includes rock 

debris of all kinds, volcanic ash, glacial drift, alluvium, 

loess and eolian deposits, vegetal accumulations and 

soil. 

regression. A long- term seaward retreat of the shoreline 

or relative fall of sea level. 

rift valley. A depression formed by grabens along the 

crest of an oceanic spreading ridge or in a continental 

rift zone. 

ripple marks. The undulating, subparallel, usually smallscale, ridge pattern formed on sediment by the flow of 

wind or water. 

sabkha. A coastal environment in an arid climate where 

evaporation rates are high. 

sequence. A major informal rock- stratigraphic unit that 

is traceable over large areas and defined by a major sea 

level transgression- regression sediment package. 

slump. A generally large, coherent mass movement with 

a concave- up failure surface and subsequent 

backward rotation relative to the slope. 

strike. The compass direction of the line of intersection 

that an inclined surface makes with a horizontal plane. 

subduction zone. A convergent plate boundary where 

oceanic lithosphere descends beneath a continental or 

oceanic plate and is carried down into the mantle. 

subsidence. The gradual sinking or depression of part of 

Earth’s surface. 

tectonic. Relating to large- scale movement and 

deformation of Earth’s crust. 

tectonics. The geological study of the broad structural 

architecture and deformational processes of the 

lithosphere and aesthenosphere (also see structural 

geology). 

terraces (stream). Step- like benches surrounding the 

present floodplain of a stream due to dissection of 

previous flood plain(s), stream bed(s), and/or valley 

floor(s). 

thrust fault. A contractional, dip- slip fault with a 

shallowly dipping fault surface (<45o

) where the 

hanging wall moves up and over relative to the 

footwall. 

transgression. Landward migration of the sea due to a 

relative rise in sea level. 

trend. The direction or azimuth of elongation or a linear 

geological feature. 

unconformity. A surface within sedimentary strata that 

marks a prolonged period of nondeposition or 

erosion. 

uplift. A structurally high area in the crust, produced by 

movement that raises the rocks. 

weathering. The set of physical, chemical, and biological 

processes by which rock is broken down in place. 
 NPS Geologic Resources Division 30 

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USGS Professional Paper 691, 195 p. 

Truini, M., J.P. Macy, and T.J. Porter. 2005. GroundWater, Surface- Water, and Water- Chemistry Data, 

Black Mesa Area, Northeastern Arizona – 2003- 04. 

USGS Open- File Report 2005- 1080, 54 p. 

Wieczorek, G.F., and E.L. Harp. 2000. Rock- Fall Hazard 

Assessment of the Aspen Forest Trail, Navajo National 

Monument, Arizona. USGS Open- file Report 00- 305, 

11 p. 
 NAVA Geologic Resource Evaluation Report 33

Appendix A: Geologic Map Graphic 

The following page provides a preview or “snapshot” of the geologic map for Navajo 

National Monument. For a poster size PDF of this map or for digital geologic map data, 

please see the included CD or visit the GRE publications webpage: 

http://www2.nature.nps.gov/geology/inventory/gre_publications.cfm 

 NAVA Geologic Resource Evaluation Report 35

Appendix B: Scoping Summary 

The following excerpts are from the GRE scoping summary for Navajo National 

Monument. The scoping meeting occurred June 25 and June 28, 2001; therefore, the 

contact information and Web addresses referred to herein may be outdated. Please 

contact the Geologic Resources Division for current information. 

Summary 

A geologic resources inventory workshop was held for 

Navajo NM (NAVA) on June 25th and 28th, 2001 to view 

and discuss the park’s geologic resources, to address the 

status of geologic mapping for compiling both paper and 

digital maps, and to assess resource management issues 

and needs. Cooperators from the NPS Geologic 

Resources Division (GRD), NPS Navajo NM, Colorado 

State University, University of Wyoming and United 

States Geologic Survey (USGS) were present for the 

workshop. This was part of a multi- park scoping session 

also involving Petrified Forest NP, Pipe Spring NM, 

Sunset Crater NM, Wupatki NM, and Walnut Canyon 

NM. 

On Monday June 25th, scoping involved a half- day field 

trip to view the geology of the Navajo NM Betatakin 

Ruin area led by Sherrie Landon (University of 

Wyoming). Additionally, on June 28th another half- day 

scoping session to present overviews of the NPS 

Inventory and Monitoring (I&M) program, the Geologic 

Resources Division, and the on- going Geologic 

Resources Inventory (GRI) took place. Round table 

discussions involving geologic issues for Navajo NM 

included interpretation, natural resources, the status of 

geologic mapping efforts, sources of available data, 

geologic hazards, and action items generated from this 

meeting. 

Currently, the greatest issue facing park resource 

management is dealing with the potential threats of 

resource loss from fractures in the alcove ruins that are 

causing geologic rockfall and collapse. Because of this, it 

is desired to increase the scale of existing geologic maps 

of the area from 1:125,000 scale to larger 1:24,000 scale as 

it would aid in defining areas at highest risk to resource 

damage. 

For a list of meeting attendees, see the list of attendees at 

the end of the appendix. 

Geologic Mapping 

George Billingsley (USGS- Flagstaff, AZ) informed the 

scoping participants of an existing USGS publication that 

contains geologic maps covering Navajo NM. (Cooley, 

M.E., Harshbarger, J.W., Akers, J.P., Hardt, W.F., and 

Hicks, O.N., 1969, Regional hydrogeology of the Navajo 

and Hopi Indian Reservations, Arizona, New Mexico, 

and Utah: U.S. Geological Survey, Professional Paper 

521- A, scale 1:125,000). 

Unfortunately, these maps are small scale and not 

necessarily conducive to resource management goals. 

Additionally, the maps are not on a topographic base. 

Thus larger scale mapping on a topographic base is 

desirable for the six quadrangles of interest to NAVA. 

NAVA contains 3 separate units totaling approximately 

500 acres. The quadrangles of interest are as follows: 

• Tall Mountain 

• Keet Seel Ruin 

• Inscription House Ruin 

• Shonto NW 

• Betatakin Ruin 

• Marsh Pass 

Sherrie Landon (NAVA- GIP, University of Wyoming), 

through her work as a volunteer geologist- in- the- park 

at NAVA and her graduate studies at the University of 

Wyoming, is interested in doing the large scale mapping 

for the park. This could probably be funded through a 

contract or an EDMAP project through her university. It 

was agreed that she is the most likely person to be able to 

complete this geologic mapping for NAVA because of 

her experience in the area and her interest in seeing the 

project completed. This needs follow- up through GRI 

staff. 

It would be most desirable to have the entire six 

quadrangles mapped, but that will likely be costly and 

time consuming. Thus, if the three separate units were 

mapped in detail to the park boundary, it might suffice in 

the interim. A scale of 1:24,000 is considered the 

minimum acceptable scale for any new mapping of the 

area. Given the size of the monument, perhaps even 

larger scale 1:12,000 mapping would be best. 

Digital Geologic Map coverage 

At present, a digital coverage of the 1969 maps has not 

been found. However, George Billingsley has heard 

rumors from a Navajo Nation representative that those 

geologic maps had been digitized, but he is not sure of 

the source. This information will try to be located as 

there are numerous sheets, and it would be redundant to 

re- digitize these maps if the effort has already been 

undertaken. Tim Connors will attempt to discern if this 

information is available digitally from the Navajo Nation. 

In the event that digitized versions of the existing maps 

are not found, and until new larger scale mapping can be 

accomplished for the NAVA area, it is suggested that the 
 NPS Geologic Resources Division 36 

existing 1:125,000 scale maps be scanned, registered, 

rectified and digitized (if necessary) for use in a GIS. 

While the scale is crude, it can serve as the best 

"preliminary" baseline geologic map until new, larger 

scale mapping is completed. 

If the mapping for NAVA is completed at the larger scale, 

it would also be digitized as per the NPS Digital Geologic 

Map model as demonstrated during the scoping sessions. 

Other desired GIS data 

Since NAVA does not have a full- time dedicated GIS 

person at the park, they are dependent on the 

Intermountain Region GIS staff in Denver for support. 

They have been receiving assistance to date from 

Jennifer McCollum. 

Miscellaneous Items of interest 

• Many of the park trails have had problems with 

rockslides in the recent past and Betatakin Trail has 

had to limit hikers because of this problem. A geologic 

map should help delineate these troublesome areas in 

the monument. 

• Another resource management issue is the effect of 

deeper canyon cutting in the monument. Arroyo 

cutting is effecting tributaries and cultural resources 

(middens) are being washed away and destroyed. 

According to George Billingsley, Margaret Hiza 

(USGS- Denver) is currently working with the Navajo 

Nation on erosion issues and the park may want to 

contact her for assistance. 

• The nearby Black Mesa Coal Mine is interested in 

pumping more water from the regional aquifer for 

their industrial uses. This could negatively effect park 

water quantity and is thus a pressing issue at the 

current time. 

• Current natural resource staff at Navajo NM are Irv 

Francisco, Kevin Harper, and Brenton White. 

Scoping Meeting Attendees 

NAME AFFILIATION PHONE E- MAIL 

John Graham Colorado State University 970- 225- 6333 rockdoc250@comcast.net 

Tim Connors NPS, GRD 303- 969- 2093 Tim_connors@nps.gov 

Sherrie Landon NAVA 307- 755- 1336 Slandon@uwyo.edu 

Brenton White NPS, NAVA 520- 672- 2720 Brenton_White@nps.gov 

Kevin Harper NPS, NAVA Archeologist 520- 672- 2720 Kevin_harper@nps.gov 

James Charles NPS, NAVA 

Superintendent 928- 672- 2700 James_charles@nps.gov 
The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides scientific and other 

information about those resources; and honors its special responsibilities to American Indians, Alaska Natives, and affiliated Island 

Communities. 

Navajo National Monument 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2007/005 

NPS D-53, June 2007 

National Park Service 

Director • Mary A. Bomar 

Natural Resource Stewardship and Science 

Associate Director • Michael A. Soukup 

Natural Resource Program Center 

The Natural Resource Program Center (NRPC) is the core of the NPS Natural Resource Stewardship and 

Science Directorate. The Center Director is located in Fort Collins, with staff located principally in 

Lakewood and Fort Collins, Colorado and in Washington, D.C. The NRPC has five divisions: Air 

Resources Division, Biological Resource Management Division, Environmental Quality Division, Geologic 

Resources Division, and Water Resources Division. NRPC also includes three offices: The Office of 

Education and Outreach, the Office of Inventory, Monitoring and Evaluation, and the Office of Natural 

Resource Information Systems. In addition, Natural Resource Web Management and Partnership 

Coordination are cross- cutting disciplines under the Center Director. The multidisciplinary staff of NRPC 

is dedicated to resolving park resource management challenges originating in and outside units of the 

national park system. 

Geologic Resources Division 

Chief • David B. Shaver 

Planning Evaluation and Permits Branch Chief • Carol McCoy 

Credits 

Author • Dr. John Graham

Editing • Sid Covington and Paul Vohs 

Layout • Melanie Ransmeier 

Map Digitizing • Stephanie O’Meara, Rachel Johnson, Rob Thompson, and Todd Sander
Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, CO 80225 

http://www.nature.nps.gov/geology/inventory/ 

(303) 969-2090 

EXPERIENCE YOUR AMERICATM 

National Park Service 

U.S. Department of the Interior