Sunset Crater Volcano National Monument 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2005/004 

National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 

Sunset Crater Volcano National Monument 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2005/004 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

September 2005 

U.S. Department of the Interior 

Washington, D.C.
The Natural Resource Publication series addresses natural resource topics that are of interest 

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Printed copies of reports in these series may be produced in a limited quantity and they are 

only available as long as the supply lasts. This report is also available from the Geologic 

Resource Evaluation Program website (http://www2.nature.nps.gov/geology/inventory/

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

Please cite this publication as: 

Thornberry-Ehrlich, T. 2005. Sunset Crater Volcano National Monument Geologic Resource 

Evaluation Report. Natural Resource Report NPS/NRPC/GRD/NRR—2005/004. National 

Park Service, Denver, Colorado. 

NPS D-54, September 2005 
 SUCR Geologic Resource Evaluation Report iii

Table of Contents 

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

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

Introduction ................................................................................................................... 3

Purpose of the Geologic Resource Evaluation Program ............................................................................................3

Geologic Setting .........................................................................................................................................................3

Geologic Issues............................................................................................................. 6

Recreation Demands..................................................................................................................................................6

Slope Failures and Erosion ........................................................................................................................................6

Pumice Mining Issues.................................................................................................................................................6

Seismicity and Volcanism...........................................................................................................................................7

Noise Pollution............................................................................................................................................................7

Water Issues...............................................................................................................................................................7

Wind Erosion and Deposition .....................................................................................................................................8

General Geology ........................................................................................................................................................8

Air Issues....................................................................................................................................................................8

Geologic Features and Processes............................................................................... 9

Sunset Crater .............................................................................................................................................................9

Archaeological Geology..............................................................................................................................................9

Ecosystem Rebound ..................................................................................................................................................9

Unique Volcanic Features ........................................................................................................................................10

Map Unit Properties .................................................................................................... 14

Map Unit Properties Table........................................................................................................................................15

Geologic History.......................................................................................................... 19

References................................................................................................................... 23

Appendix A: Geologic Map Graphic .......................................................................... 25

Appendix B: Scoping Summary................................................................................. 27

Attachment 1: Digital Geologic Map CD 
 NPS Geologic Resources Division iv 

List of Figures 

Figure 1: Location of Sunset Crater Volcano National Monument..................................................................................5

Figure 2: Aerial view of Sunset Crater Volcano............................................................................................................11

Figure 3: Aerial view of Sunset Crater Volcano............................................................................................................11

Figure 4: View of lava flow in Sunset Crater Volcano National Monument...................................................................12

Figure 5: Photo of a fumarole deposit near the summit of Sunset Crater Volcano.......................................................12

Figure 6: Photo of a lava tube entrance .......................................................................................................................13

Figure 7: Geologic time scales.....................................................................................................................................21

Figure 8: Major uplifts and basins present during the Pennsylvanian age in the southwestern United States.............22

Figure 9: Cross section of Sunset Crater Volcano National Monument. ......................................................................22
 SUCR 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 Sunset Crater Volcano National Monument. It contains 

information relevant to resource management and scientific research. 

Between A.D. 1064 and 1180, a series of earthquakes and 

volcanic eruptions brought the dormant San Francisco 

Volcanic Field back to life. These events were the only 

eruptions in the Southwest indisputably witnessed by 

early native peoples. The earthquakes and eruptions 

probably profoundly changed their way of life. Billowing 

ash, falling cinders, and forest fires blackened the 

landscape. When the volcanism was over, a classic 

example of a cinder cone, Sunset Crater Volcano, 

loomed over an altered land of lava flows, ash layers, and 

cinders. 

Today Sunset Crater Volcano National Monument 

represents the Colorado Plateau’s most recent volcanic 

eruption. Much of the ground surface is covered by lava 

flows or deep volcanic ash and cinder deposits (all of 

alkali olivine basalt composition). The landscape still 

appears stark and inhospitable. However, within the 

volcanic geologic features are small islands of pine and 

aspen trees, desert shrubs, and wildflowers that provide 

small but unique habitats for wildlife. The ecosystem is 

adapting to the new landscape. 

The experience of Sunset Crater Volcano begins with the 

geological processes that established the groundwork 

from which present- day environments and scenery arise. 

Understanding the geologic resources can directly 

impact resource management decisions pertaining to the 

park, future scientific research projects, interpretive 

needs, and economic resources associated with Sunset 

Crater Volcano National Monument. Humans have 

modified the forest landscape surrounding Sunset Crater 

Volcano and consequently have modified its geologic 

system. This system is dynamic and obviously capable of 

noticeable change within a human life span. 

Geology provides the foundation of the entire 

ecosystem. The geology at Sunset Crater Volcano is 

dominated by volcanic rock. The crater is the youngest, 

best- preserved cinder cone in the San Francisco 

Volcanic Field. It is not surprising that some of the 

principal geologic issues and concerns pertain to 

protecting the park’s delicate volcanic features. 

The following features, issues, and processes were 

identified as having the most geological importance and 

the highest level of management significance within the 

park: 

• Slope failures and erosion. 

Dry, volcanic environments are especially susceptible 

to slumping and landslides because they lack 

stabilizing plant growth. Intense seasonal storms 

produce flash floods that dramatically alter the 

landscape, creating new hazard areas in the process. 

Road and trail construction also impacts the stability 

of a slope. Predominantly unconsolidated units such as 

the cinders and ash forming the slopes of Sunset 

Crater are prone to fail when saturated with water. 

Erosion degrades the slopes of the cinder cone. The 

loose, unconsolidated volcanic debris is easily washed 

away during a storm. Lava flows and other large blocks 

of volcanic ejecta can be undercut by erosion. When 

this happens, large blocks of the overlying rocks can 

collapse. Rockfalls and slope failures are likely almost 

anywhere these units are exposed on a slope. 

• Pumice mining issues. 

Pumice mines dot the landscape around Sunset Crater 

Volcano National Monument, affecting the viewshed 

of the park. Mining and illegal removal of unique and 

delicate volcanic specimens from within the park are a 

concern for resource management. 

• Recreation demands. 

In northern Arizona the population is increasing the 

environmental impacts of recreation. Certain trails 

within the monument have had to be closed due to 

preferential erosion. Off- road recreational vehicles 

are being used just outside the monument boundaries. 

Their use affects the monument’s viewshed and 

creates noise, dust, and engine exhaust. Resource 

management concerns include balancing the 

preservation of the environment with recreational 

demands of visitors to the monument area. 

• Seismicity and volcanism. 

Seismicity is often a precursor to volcanic activity. The 

chances for further activity in the San Francisco 

Volcanic Field are great. The recurrence interval for 

the volcanoes in Arizona is approximately 1,000 years, 

making long term prediction difficult. Seismographs 

like the one on Sunset Crater Volcano measure seismic 

waves and can help predict upcoming volcanic activity. 

Earthquakes can also create hazardous landslide and 

rockfalls. Unconsolidated material on the slopes of 

Sunset Crater Volcano is especially susceptible to 

failure.
 NPS Geologic Resources Division 2 

Other geologic parameters and issues including wind 

erosion and deposition, noise pollution, air pollution, 

geological research, and water issues were also identified 

as management issues for Sunset Crater Volcano 

National Monument. These are listed in detail on pages 

6- 8 along with recommendations for inventories, 

monitoring, and research. 

Geologic interpretation is an important part of visitor use 

in the park. A detailed geologic map and road log and a 

guidebook to tie Sunset Crater Volcano National 

Monument to other parks in the Colorado Plateau would 

enhance visitors’ appreciation of the geologic history and 

dynamic processes that created Sunset Crater Volcano 

and the spectacular landscape of the entire region. 

Strategically placed wayside exhibits would help explain 

the geology to the visitor. 
 SUCR Geologic Resource Evaluation Report 3

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 

Geologic features and processes serve as the foundation 

of park ecosystems and an understanding of geologic 

resources yields important information needed for park 

decision making. The National Park Service Natural 

Resource Challenge, an action plan to advance the 

management and protection of park resources, has 

focused efforts to inventory the natural resources of 

parks. Ultimately, the inventory and monitoring of 

natural resources will become integral parts of park 

planning, operation and maintenance, visitor protection, 

and interpretation. The geologic component is carried 

out by the Geologic Resource Evaluation (GRE) Program 

administered by the NPS Geologic Resources Division. 

The goal of the GRE Program is to provide each of the 

identified 274 “Natural Area” parks with a digital 

geologic map, a geologic resource evaluation report, and 

a geologic bibliography. Each product is a tool to support 

the stewardship of park resources and is designed to be 

user friendly to non- geoscientists. In preparing products 

the GRE team works closely with park staff and partners 

(e.g., USGS, state geologic surveys, and academics). 

GRE teams hold scoping meetings at parks to review 

available data on the geology of a particular park and to 

discuss specific geologic issues affecting the park. Park 

staff are afforded the opportunity to meet with experts 

on the geology of their park during these meetings. 

Scoping meetings are usually held for individual parks 

although some meetings address an entire Vital Signs 

Monitoring Network. 

Bedrock and surficial geologic maps and information 

provide the foundation for studies of groundwater, 

geomorphology, soils, and environmental hazards. 

Geologic maps describe the underlying physical habitat 

of many natural systems and are an integral component 

of the physical inventories stipulated by the National 

Park Service (NPS) in its Natural Resources Inventory 

and Monitoring Guideline (NPS- 75) and the 1997 NPS 

Strategic Plan. The NPS GRE is a cooperative 

implementation of a systematic, comprehensive 

inventory of the geologic resources in National Park 

System units by the Geologic Resources Division, the 

Inventory and Monitoring (I&M) Program of the 

Natural Resource Information Division, the U.S. 

Geological Survey, and state geological surveys. 

For additional information regarding the content of this 

report please refer to the Geologic Resources Division of 

the National Park Service, located in Denver, Colorado 

with up- to- date contact information at the following 

website: http://www2.nature.nps.gov/geology/inventory/ 

Geologic Setting 

John Wesley Powell named “Sunset Mountain” in 1892 

during his famous expedition (Colton, 1945). President 

Herbert Hoover established Sunset Crater Volcano as a 

National Monument on May 26, 1930, to protect both the 

delicate volcanic features and any archaeological 

resources in the area. The land was transferred from the 

U.S. Forest Service to the National Park Service August 

10, 1933, and was renamed on November 16, 1990. The 

primary natural resources of the park are the volcanic 

flows, ashfalls, craters, and ridges. 

This park is part of the Geologic Resource Evaluation 

program because of the unique geologic resources and 

human impacts to these resources. Information gathered 

at this park may also be used to represent other parks 

with similar resources or patterns of use, especially when 

the findings are evaluated for Servicewide implications. 

At an average elevation of 305 m (1,000 ft) above the 

valley floor, the rim of Sunset Crater Volcano dominates 

the landscape of the 3,040 acre national monument. It is 

part of a N 60 W trending 10 km long chain that includes 

Rows of Cones, Gyp Crater, and Vent512 (Blaylock, 

1996). The base of the volcano is at 2,134 m (7,000 ft) 

above sea level (Hodges, 1962). The monument, located 

in north- central Arizona, is along the very southern edge 

of a feature called the Colorado Plateau Province (Figure 

1). Covering parts of Colorado, Utah, Arizona, and New 

Mexico, the Colorado Plateau is a region of high plateaus 

and broad, rounded uplands separated by vast 

rangelands. The rangelands are underlain by large 

elliptical stratigraphic basins. 

The structural fabric of gently warped, rounded folds 

contrasts with the intense deformation and faulting of 

the terranes bordering the Colorado Plateau. Northeast 

and east of the Colorado Plateau are the jagged peaks of 

the Rocky Mountains. The Mesozoic- age overthrust belt 

marks the west- northwest edge of the Colorado Plateau 

(Figure 1). The extensional, normal- faulted Basin and 

Range Province borders the Colorado Plateau to the west 

and south. The Rio Grande Rift, tearing a ragged scar in 

the landscape, forms the southeastern border. 

The Colorado Plateau is also known for its laterally 

extensive monoclines that formed during the Late 

Cretaceous – Tertiary (Figure 1). The basins adjacent to 

the steep limbs of the monoclines have been filled with 

sediment eroded from these folds. 

Many of the features present on the Colorado Plateau 

today were molded by the processes of erosion. The 

destructive forces of wind and rain, running water, and 

freezing temperatures attacked the uplifts as soon as all 
 NPS Geologic Resources Division 4 

the tectonic havoc started in the Late Cretaceous. The 

Colorado Plateau has been uplifted about 3,660 m 

(12,000 ft) since the end of the Cretaceous about 66 

million years ago (Fillmore, 2000). Some of this uplift 

occurred geologically rapidly. 

The rate of erosion increased as the rate of uplift 

increased. The Colorado River carved its present course 

within the last 6 million years. With uplift, streams 

throughout the Colorado Plateau began to dissect the 

topography with unprecedented vigor, carving the rocks 

and carrying away the dismantled strata into the 

landscape we see today. The Grand Canyon located 

northwest of Sunset Crater Volcano is a relatively recent 

development on the plateau. However, few geologic 

features are more recent than the cinder cone at Sunset 

Crater Volcano National Monument, the youngest 

volcano in Arizona. 

Last erupting around A.D. 1064, Sunset Crater Volcano is 

part of northern Arizona’s San Francisco Volcanic Field, 

much of which lays within Coconino and Kaibab 

national forests. This is an area of young volcanoes. 

Volcanism dates from late Miocene or Pliocene to recent 

(Hodges, 1962). Nearly all the hills and mountains 

between Flagstaff and the Grand Canyon are the young 

(geologically) but extinct volcanoes of the San Francisco 

Volcanic Field. The field covers about 4,662 square km 

(1,800 square miles) of northern Arizona’s piñon- juniper 

and ponderosa pine to fir and bristlecone pine forested, 

semi- arid landscape. 

This field has produced more than 550 basaltic vents 

during its 6 million years of volcanic activity (Holm and 

Moore, 1987). Extreme volcanic activity has created a 

topographically varied landscape. The most prominent 

regional landmark is San Francisco Mountain. This 

stratovolcano rises to 3,851 m (12,633 ft). As Arizona’s 

highest peak, it dominates the high, semi- arid horizon. 

Most volcanoes are located near boundaries of the 

Earth’s lithospheric tectonic plates, including the 

Cascades in Washington and Oregon and the New 

Zealand volcanoes. However, Arizona is well within the 

interior of the North American Plate. Similar to 

Yellowstone National Park, a site of localized melting, or 

“hot spot,” is fixed deep within the Earth beneath 

northern Arizona. 

As the North American Plate moves slowly westward 

over this stationary source of hot, molten rock in 

Arizona, eruptions produce volcanoes that extend 

progressively eastward in a roughly linear fashion. This is 

similar to the string of volcanics crossing southern Idaho 

including Craters of the Moon National Monument. 

The first volcanoes began to erupt about 6 million years 

ago in the vicinity of the current Williams, Arizona. 

Following these early eruptions, a belt (several km wide) 

of successively younger eruptions migrated eastward for 

about 80 km (50 mi). At present the belt of volcanoes 

stretches just beyond the area of modern Flagstaff. 

Although there has been no significant volcanic activity 

in the San Francisco Volcanic Field for nearly 1,000 

years, it is likely that eruptions will continue in the 

future. The average interval between large eruptions is 

several thousand years. Predicting future events is 

difficult. 

Future activity may produce a cinder cone like the one at 

Sunset Crater Volcano. Cinder cones are relatively small 

structures. They are usually less than 1,000 feet tall and 

form quickly, within months to years. They are built as a 

result of gas- charged frothy blobs of basalt magma rising 

quickly to the surface. These blobs are erupted as an 

upward spray or lava fountain. As projectiles during 

flight, the lava blobs cool and fall back to the ground. As 

the fragments accumulate, they build a cone- shaped hill. 

The eruptive activity at Sunset Crater was no doubt 

witnessed by Native Americans inhabiting the Wupatki 

area. The rapid geomorphological change must have 

affected their way of life. The aftermath of a volcanic 

eruption is pristinely preserved at Sunset Crater Volcano 

National Monument. 
 SUCR Geologic Resource Evaluation Report 5

Figure 1: Location of Sunset Crater Volcano National Monument relative to Colorado Plateau physiographic features. The light gray 

area signifies the areal extent of the Colorado Plateau. Dark gray and black areas represent uplifts and mountains. 
 NPS Geologic Resources Division 6 

Geologic Issues 

A Geologic Resource Evaluation scoping session was held for Sunset Crater Volcano 

National Monument on June 28- 29, 2001, to discuss geologic resources, to address the 

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

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

require attention from resource managers. 

Recreation Demands 

Sunset Crater Volcano National Monument is located 19 

km (12 mi) north of Flagstaff, Arizona, and 241 km (150 

mi) north of Phoenix, a rapidly growing metropolitan 

area of more than 2 million people. The Flagstaff 

community has a population of approximately 55,000. 

Flagstaff acts as the focal point of providing numerous 

services for the extensive ranching, lumber, and tourist 

activities of north- central Arizona. 

Sunset Crater Volcano National Monument is a 

relatively small space within a geographic area 

dominated by the Coconino National Forest. The 

preservation of the regional ecosystem requires close 

coordination with the U.S. Forest Service. The private 

lands between Flagstaff and Sunset Crater Volcano 

National Monument are subject to increasing residential 

and business development. These increased urban 

influences threaten to degrade the integrity of the natural 

systems and processes. Furthermore, as population and 

development increase both locally and regionally, 

demand for all types of recreation on public lands will 

increase accordingly. 

Although volcanic features and natural resources within 

monument boundaries remain relatively undisturbed, the 

situation is quite different immediately outside the 

monument boundaries. An off- highway vehicle use area 

is located just adjacent to the monument within the 

Coconino National Forest. Heavy use of this popular 

area causes increased noise levels, dust clouds, and longterm scarring and erosion to the landscape of cinder 

cones and other geological features. These features are 

closely related to the Sunset Crater Volcano eruption. 

The impact of these vehicular scars is long- lasting and 

not easily remedied. 

Inventory, Monitoring, and/or Research Needs for 

Recreation Demands 

• Perform a comprehensive study of the surrounding 

recreation demands and determine their potential 

threats to the monument’s ecosystem and 

preservation. 

• Initiate a spatter cone inventory to discern the current 

condition of each cone and which cones should be 

closed to visitors in an attempt to better stabilize and 

preserve them. 

Slope Failures and Erosion 

The potential for landslides and rockfalls exists along 

most, if not all, roads and trails at Sunset Crater Volcano 

National Monument. These movements can cause road 

and trail problems and closures at the monument. 

Similarly, slumps and other forms of slope failure are 

common for volcanic units. Loosely packed or 

unconsolidated materials are especially vulnerable to 

failure when exposed on a slope. Precipitation necessary 

to produce flash flooding at Sunset Crater Volcano 

loosens rock and soil on slopes lacking stabilizing plant 

and tree roots. Rock and soil suddenly saturated with 

water slip down the slope to cause a slump or flow. 

Steep cinder cones are highly susceptible to erosion and 

are especially hazardous when undercut by a road or a 

trail. Hiking is prohibited on the cinder cone. The trail 

that once existed to the top of Sunset Crater Volcano was 

closed in 1973 because of excessive erosion. Similar to 

most trails over delicate volcanic features, foot traffic and 

erosion had turned the trail into a hip- deep rut. The 

trace is still clearly visible on the side of the volcano 

despite intensive efforts to obliterate the trail. 

Inventory, Monitoring, and/or Research Needs for Slope 

Failures and Erosion 

• Perform a comprehensive study of the 

erosion/weathering processes active at Sunset Crater 

Volcano National Monument, taking into account 

rock formations, slope aspects, location, and 

likelihood of instability. 

• Create a rockfall susceptibility map using rock unit 

versus slope aspect in a GIS; use the map in 

determining future developments and current 

resource management including trails, buildings, and 

recreational use areas. 

Pumice Mining Issues 

Pumice is mined for industrial use and landscaping 

materials. Pumice mining on the slopes of San Francisco 

Mountain affects the viewshed of Sunset Crater Volcano 

National Monument. This is particularly noticeable from 

the Lava Flow trail. 

The Lava Flow trail is the most interpretive trail in the 

park where the story of Sunset Crater Volcano and its 
 SUCR Geologic Resource Evaluation Report 7

relation to the greater San Francisco Volcanic Field is 

explained. The trail probably receives the most visitors 

interested in the geological history of the area. 

Visitors can also have an impact on the volcanic rock 

resources within the park. Rocks are at risk of being 

removed from the park as souvenirs because there are 

unique, freshly preserved, volcanic rocks present. 

Inventory, Monitoring, and/or Research Needs for Pumice 

Mining Issues 

• Work closely with local mining companies to remedy 

the viewshed problems. Plant trees and create other 

buffers to help alleviate the situation. 

• Inventory the unique volcanic rock “hotspots” along 

roads, trails, near picnic areas, restrooms, etc. to 

determine visitor removal of these resources. 

Seismicity and Volcanism 

Prior to the 1065 A.D. eruption, the local inhabitants 

probably felt the earth shake in a number of seismic 

events leading up to the volcanic release. Seismicity is 

often a precursor to volcanic activity because of the 

rising tensions and pressures within the earth caused by 

the movement of molten material (magma) and the 

buildup of gas pressure as the magma approaches the 

surface. 

Seismographs measure movements within the earth and 

can predict, in part, upcoming volcanic activity. 

Seismographs located on many of the Cascade volcanoes 

aided in the Mt. Saint Helens evacuation. There is a 

seismograph on the crater rim at Sunset Crater Volcano 

National Monument. It measured eight different seismic 

events in one day on October 18, 1998. 

The chances for further activity in the San Francisco 

Volcanic Field are great because of the successive nature 

of hotspot volcanism. An excellent example of hotspot 

activity is in the Hawaiian Islands. The Pacific 

lithospheric plate is moving over the hotspot and 

creating a linear chain of islands. A new island is being 

formed off the coast of Hawaii. The recurrence interval 

for the volcanoes in Arizona is approximately 1,000 

years, making long- term prediction difficult. The 

seismograph at Sunset Crater Volcano will give a shortterm warning of an impending event. 

Earthquakes can also create hazardous landslides and 

rockfalls. Unconsolidated material found on the slopes 

of Sunset Crater Volcano is especially susceptible to 

failure when the earth trembles. 

Inventory, Monitoring, and/or Research Needs for Seismicity 

and Volcanism 

• Perform engineering studies using a strain meter to 

assess possible hazards of slope collapse and to 

evaluate the potential for new volcanism. 

• Use high resolution Global Positioning System (GPS) 

to detect moving, swelling, and collapse in areas of the 

monument. 

• Obtain and evaluate regular seismic activity reports in 

the surrounding areas to measure and monitor activity 

in the region. 

Noise Pollution 

The off- road vehicle use area just outside the monument 

boundaries creates significant noise pollution. Low flying 

military jet aircraft often cause sonic booms in low 

population density areas of northern Arizona. Sonic 

booms are so powerful they can affect geological 

features. Much like seismic waves, sound waves are 

transmitted through rock. In an area with delicate, 

unconsolidated, pristine volcanic features such as those 

on the slopes of Sunset Crater Volcano National 

Monument, any disturbance is of concern to 

management. 

Inventory, Monitoring, and/or Research Needs for Noise 

Pollution 

• Monitor decibel levels in the monument. 

• Contact local, military, and other groups to establish a 

working relationship to help alleviate some of the 

noise pollution problems. 

• Conduct stress studies to determine effects of sound 

waves on the cinder cone slopes. 

Water Issues 

The area around Sunset Crater Volcano National 

Monument is semi- arid and receives an average of 270-

300 mm of precipitation annually (Doolittle, 1998). Water 

resource management is an important task at the 

monument. The regional water table occurs 

predominantly in the Coconino Sandstone at altitudes of 

about 1,524 m (5,000 ft) above sea level at Sunset Crater 

Volcano. The groundwater flow is generally 

northeastward. Some perched aquifers persist in the 

Moenkopi Formation, but these are not reliable water 

sources for the monument (Cosner, 1962). 

Inventory, Monitoring, and/or Research Needs for Water 

Issues 

• Conduct hydrogeologic studies to define subsurface 

flow patterns, regional and local flow systems. 

• Monitor water quality at multiple sample locations 

within the monument. Drinking water sources are 

especially important for monitoring. 

• Install wells for testing and for access to drinking 

water. 
 NPS Geologic Resources Division 8 

• Identify and study potential sources that could impact 

groundwater quality for the entire monument. 

• Install transducers and dataloggers in wells. 

• Investigate additional methods to characterize 

groundwater recharge areas and flow directions. 

Wind Erosion and Deposition 

Wind is a major force that can redistribute soil and soil 

resources (e.g., litter, organic matter, and nutrients) 

within and among ecosystems. Erosion and deposition 

by wind are important at Sunset Crater Volcano and can 

be accelerated by human activities. Accelerated losses of 

soil and soil resources by erosion are degrading to aridland ecosystems because ecosystem health is dependent 

on the retention of these resources. Park management 

practices limit or prohibit off- road vehicular travel so 

human impacts within the parks are primarily associated 

with off- trail hiking in high- use areas. 

Wind erosion and sediment transport may be strongly 

affected by land- use practices outside the parks. Eolian 

sand from disturbed surfaces may saltate onto 

undisturbed ground, burying and killing vegetation 

and/or biological soil crusts, or breaking biological soil 

crusts to expose more soil to erosion. 

Inventory, Monitoring, and/or Research Needs for Wind 

Erosion and Deposition 

• Monitor movement of soil materials. 

• Investigate ecosystem consequences of soil movement. 

• Investigate natural range of variability of soil 

movement in relation to landscape configuration and 

characteristics. 

General Geology 

The unique geology of Sunset Crater Volcano National 

Monument lends itself to scientific research. Included 

are aftermath of volcanic eruptions, regional and local 

volcanic features and ejecta types, dating of different 

flow and eruption events, lava composition, and 

weathering/erosion rates. 

The landscape was profoundly affected by the eruption 

of Sunset Crater Volcano. The ecosystem response to 

such a recent event is of interest to geologists and 

biologists alike. In a landscape that looks barren and 

inhospitable, islands of vegetation and animal life are 

testament to the adaptation of the biological components 

to the geologic processes. 

Low volume volcanoes like Sunset Crater were 

previously thought to produce monogenetic flows and 

ejecta- - very simple compositions with little variability 

throughout the eruption. Geologists are questioning 

whether or not this scenario is the case at Sunset Crater 

where the different compositions of the lava flows, 

cinders, pyroclastic flows, etc. are of continuing scientific 

interest (Larson and Holm, 1989; Smith et al., 1996; 

Blaylock, 1996). 

Inventory, Monitoring, and/or Research Needs for General 

Geology 

• Perform rock color studies. 

• Develop more graphics and brochures emphasizing 

geology for the average enthusiast. 

• Perform an archaeological inventory of any artifacts 

found within and around the monument. 

• Inventory the different rock compositions at macro 

(outcrop) and micro (thin section) scale. Create a 

digital coverage of the variability in composition to 

determine a sequence of events based on chemical 

genesis. 

Air Issues 

Harmful chemicals and particulates are responsible for 

increased acid deposition in northern Arizona. Sources 

of these contaminants include the numerous power 

plants supplying electricity to the ever increasing local 

population. 

Acid rain can dramatically affect the geologic landscape 

by preferentially eroding and weathering soluble rock 

layers including carbonates, intergranular cements, and 

entire rock units. This preferential erosion, accelerated 

by the increasing acidity of precipitation, can destabilize 

slopes and cliffs and result in a greater frequency of rock 

falls and slope failures. 

Inventory, Monitoring, and/or Research Needs for Air Issues 

• Monitor rainwater pH, noting spikes or changes. 

• Establish a working relationship with the appropriate 

industries in an attempt to decrease the level of 

pollutants in the air over the monument. 
 SUCR Geologic Resource Evaluation Report 9

Geologic Features and Processes 

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

and processes in Sunset Crater Volcano National Monument. 

Sunset Crater 

The eruption responsible for Sunset Crater produced a 

300 m (1,000 ft) high asymmetrical cinder cone that lies 

on the base of the east slope of the San Francisco Peaks 

(Figures 2 and 3) (Smiley, 1960). The crater rim encloses 

the main crater which is more than 120 m (400 ft) deep 

(Holm and Moore, 1987). The cinder cone was 

constructed when hot volcanic cinders and ash (1100-

1200 degrees Centigrade) were blown into the air and 

settled around the fissure or vent (Breed, 1976). This 

northwest- trending fissure was 5 km (3 mi) long at the 

beginning of eruptive activity, extending from Janus 

Crater to Yaponcha Crater, but quickly localized directly 

beneath present day Sunset Crater Volcano (Smiley, 

1960; Hodges, 1962; Amos et al., 1981). Cinder material of 

the cone is loose and poorly sorted. The average particle 

size is 4 mm, intermixed with very fine ash and scattered 

ejecta of block size (more than 32 mm) (Hodges, 1962). 

Formation of the cinder cone was accompanied by the 

eruption of dark, basaltic lava flows (present in Bonito 

Canyon and a small wash toward the Little Colorado 

River) (Figure 5). The Kana- a flow moved northeast, and 

the Bonito flow moved northwest (Smiley, 1960; Breed, 

1976). The lava flows likely breached the edges of the 

original cone, rendering its asymmetrical shape (Holm, 

1987). The flows were subsequently covered with more 

ash. 

The alkali olivine basalt cone and lava flows cover ~8 

square km. The extended, fallout, cinder cover blankets 

close to 2,000 square km (Breed, 1976; Ort et al., 2001). At 

the very end of the volcanic activity at Sunset Crater 

Volcano, hot springs and vapors escaped from the vent 

and deposited the brilliantly colored minerals near the 

top of the crater including gypsum, magnetite, hematite, 

sulfur, cuprite (?), opal, jarosite, voltaite, ralstonite, 

alunogen, ilmenite, barite, and celestine (Hanson, 2000). 

The yellows, oranges, and reds of these minerals give the 

crater the appearance of a perpetual sunset, hence the 

monument’s name. This coloration is enhanced by the 

overall oxidation of iron that lends a reddish cast to the 

entire cinder cone. 

This eruption was small in scale relative to the Mt. Saint 

Helens explosion in 1980 or Krakatoa in 1883, but the 

eruption completely altered the existence of the peoples 

living in the area (now referred to as the Sinagua 

(Reynolds, 1982)). 

Archaeological Geology 

The eruption began late in 1064 A.D. and may have 

continued intermittently until 1067 A.D. In 2 years, a 

mountain was born. Whatever settlements, including 

pithouses, existed in the immediate area were buried 

(Nichols, 1944). Two pithouses were excavated in 1930 

(Smiley, 1960). This created a setting similar to that at 

Pompeii, Italy, where an entire city was buried. The 

native inhabitants at Sunset Crater Volcano no doubt had 

a much smaller, more agriculturally based existence. 

Basalt clasts contain casts of ears of corn possibly left in 

the path of a flow as a sacrificial offering in one masonry 

structure 6 km (3.7 mi) west of the monument. People 

witnessed this eruption and had to adapt ways of dealing 

with its aftermath (Ort et al., 2001). This very recent event 

provides a unique opportunity to study the effects of an 

eruption on a population. 

Some single room structures still standing and those 

buried beneath the ash indicate that there was a small 

agricultural population in the area before and during the 

eruption. The ancient peoples no doubt fled the spewing 

ash, lava, and gas but resettled the area as early as A.D. 

1071, once the landscape had cooled (Doolittle, 1997). 

The recent volcanism continues to affect regional 

agriculture. Some archaeologists surmise that the dry 

farming/mulching practices used by the Hopi in today’s 

sand dune cultivation are directly related to techniques 

perfected after the Sunset Crater Volcanic eruption. 

They trace the technique back to ancient lithic covered 

fields (Doolittle, 1997). Volcanic ash serves as excellent 

lithic mulch to maintain moisture in the soil longer. 

Farmers (including migrating Anasazi from the Mesa 

Verde area) returned to the area almost immediately after 

the eruption and used the new ash layers to grow 

relatively prolific crops. They moved east, leaving multiroom dwellings behind as the ash layers were depleted 

and/or blew away (Reynolds, 1982; Doolittle, 1997; Ort et 

al., 2001). 

Ecosystem Rebound 

The eruption responsible for the cinder cone volcano at 

Sunset Crater Volcano National Monument changed the 

area’s landscape forever. A blanket of smothering ash 

and pyroclastic flow covered the area, burning and/or 

burying everything for kilometers around. The 

introduction of so much volcanic material had a 

profound effect on the ecosystem. 

Entire species populations may have been eradicated 

from the area. Sunset Crater Volcano offers the unique 

opportunity to study the ecosystem changes inherent 

with volcanic eruptions (Breternitz, 1967). Because the 

event was so recent, plant and animal species populations 

are still in the process of adapting to the new landscape. 
 NPS Geologic Resources Division 10 

This volcano and its relatively undeveloped landscape 

provide an unparalleled opportunity to study plant 

succession and ecological change in a dry volcanic 

landscape. 

Unique Volcanic Features 

In addition to the cinder cone and fresh lava flows, other 

phenomena associated with volcanism including lava 

bombs, lava tubes, and xenoliths are abundant at Sunset 

Crater Volcano National Monument. Xenoliths of the 

host or country rock including limestones and 

sandstones are embedded in the flows. They are easily 

recognized by their contrast in color with the lava. 

Lava bombs are large blobs of molten rock ejected during 

violent eruptions. During their fall to earth, they revolve, 

spin, and become elongate. They often form football or 

other rounded shapes and range in size from a few 

centimeters to several meters in diameter. These bombs 

can be ejected quite far from the volcano’s center. They 

are found littering the slopes and lava flows of Sunset 

Crater Volcano. 

A crust builds over the top of the lava as it flows downhill 

(Breed, 1976). Beneath the crust, the molten lava is still 

flowing. When the source is depleted or the flow diverts 

elsewhere, the material remaining under the crust drains 

and the remnant tube or lava conduit remains hollow. 

The tube at Sunset Crater is commonly referred to as an 

“ice cave” because the air inside is usually below freezing. 

Any water present in the tube freezes and typically 

remains frozen due to the insulating properties of the 

lava (Breed, 1976). 
 SUCR Geologic Resource Evaluation Report 11

Figure 2: Aerial view of Sunset Crater Volcano. 

Figure 3: Aerial view of Sunset Crater Volcano. 
 NPS Geologic Resources Division 12 

Figure 4: View of lava flow in Sunset Crater Volcano National Monument. 

Figure 5: Geoscientist Sarah Hanson examining a fumarole deposit near the summit of Sunset Crater Volcano. 
 SUCR Geologic Resource Evaluation Report 13

Figure 6: A lava tube entrance in the Bonito lava flow at Sunset Crater Volcano National Monument. 
 NPS Geologic Resources Division 14 

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 Sunset Crater Volcano 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. 

Though entirely covered by volcanics, Sunset Crater 

Volcano National Monument is underlain almost 

entirely by Triassic and Permian age, clastic, sedimentary 

rocks. The sedimentary strata include the Permian 

Kaibab Limestone and red sandstone with minor shale 

and conglomerate of the Triassic Moenkopi Formation. 

Locally, these beds include the Permian Coconino 

Sandstone and Toroweap Formation. 

A variety of volcanic rocks are deposited atop these 

sedimentary rock units. These include the fallout and 

flows of the Sunset Crater Volcano eruption (alkali 

olivine basalt flows, pyroclastic sheets, and cinders); the 

earlier O’Leary Peak flows and pyroclastics; the 

Deadman Mesa flows; the San Francisco Mountain 

basalts, ash and flows from Strawberry; and O’Neill 

craters and various other vents, cones, and fissures 

within the vast San Francisco Volcanic Field of northern 

Arizona. 

Quaternary terrace gravels, alluvium and colluvium, are 

exposed where not covered along stream beds, at the 

bases of slopes, and in ancient abandoned fields. Eolian 

deposits, blown into dunes of fine- grained sand derived 

from the fresh volcanic cinders of the Sunset Crater 

eruption, are the most recent additions to the landscape. 

The following pages present a table view of the 

stratigraphic column and an itemized list of features per 

rock unit. This sheet includes several properties specific 

to each unit present in the stratigraphic column 

including: map symbol, name, description, resistance to 

erosion, suitability for development, hazards, potential 

paleontologic resources, cultural and mineral resources, 

potential karst issues, recreational use potential, and 

global significance. 




 SUCR Geologic Resource Evaluation Report 19

Geologic History 

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

in Sunset Crater Volcano 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. 

Striking geologic features including stark black lava 

flows, eolian sand dunes, and cinder cones dominate the 

landscape of Sunset Crater Volcano National 

Monument. In geologic time, the eruption responsible 

for the present day landscape was practically 

instantaneous - a snapshot in time. The story of Sunset 

Crater Volcano National Monument begins much 

earlier. The sedimentary strata in the monument region 

record the growth of the North American continent as 

part of the geological region known as the Colorado 

Plateau. 

The geologic history of the area began in the 

Precambrian Era when sediments and volcanic rocks 

were deposited in oceans and scattered island arcs 

(Figure 7). These deposits, once buried to great depths, 

were changed by heat and pressure. The deposits became 

metamorphosed and were further intruded by large 

bodies of molten magma solidifying into granite. Rocks 

of this age are exposed in the deepest depths of the 

Grand Canyon (Reynolds, 1982). 

Shallow seas covered the region about 1.1 billion years 

ago. The sedimentation responsible for the Grand 

Canyon Supergroup occurred at this time along with 

intrusions and eruptions of basaltic lava. The region 

became part of a Western Interior Basin as land accreted 

to the western margin of the North American continent 

during the Paleozoic faulting and deformation.. A 

shallow sea covered the area leading to vast deposits of 

mudstones, sandstones, limestones, and siltstones 

(Reynolds, 1982). The 240 million- year- old Kaibab 

Formation is made of Permian limestone deposited in the 

large inland seas. The ancestral Rocky Mountains were 

uplifted and supplied sediment to the Sunset Crater 

Volcano area near the end of the Paleozoic as the crustal 

landmasses on the globe sutured together into one big 

supercontinent, Pangaea. 

The Uncompahgre Uplift was part of the Ancestral 

Rocky Mountains that formed as the last land masses 

sutured together to form the supercontinent, Pangaea, 

beginning in the Pennsylvanian Period. South America 

joined with the southern part of North America near 

Texas and Oklahoma, generating the Ouachita Orogeny. 

The Marathon- Ouachita- southern Appalachian 

mountain chain resulted from this event. 

The effects were felt in the interior of the continent as 

well, where jagged peaks split the skyline as the Ancestral 

Rocky Mountains were thrust from the plain. Two 

principal mountain ranges, the Uncompahgre and the 

Front Range uplifts (Figure 8), formed along northwestsoutheast trending high- angle reverse faults. 

The broad coastal plain present in the area during the 

early part of the Mesozoic Era was the site of the 

deposition of the Triassic age Moenkopi Formation, 

present at Sunset Crater Volcano National Monument. 

Well- preserved ripple patterns, abundant mud cracks, 

and fossilized burrow traces are seen in the layered 

sandstone and shale of the formation. This deep red rock 

layer reflects a period of meandering rivers, tidal flats, 

and other near- shore deposits laid down on top of the 

Kaibab after the ocean regressed westward. 

Following Moenkopi deposition, the area to the south 

experienced a mountain- building event otherwise 

known as an orogeny. This orogeny created an erosional 

surface, and the stream- carried deposits resulting from 

that erosion form the Chinle Formation. 

As Pangaea began to break apart in the late Triassic 

Period and the landmasses began to drift to their present 

positions, the climate affecting the monument area 

became more humid. Sand dunes transformed into river 

systems, swamps, beaches, and broad level plains. 

Dinosaurs and other reptiles inhabited the region, and 

periodically ash drifted into the area from volcanoes far 

to the west. Rippling effects of lithospheric plate 

collisions on the western margin of North America 

caused the Western Interior of North America to be 

flexed into a shallow basin in the Cretaceous. 

By Late Cretaceous time, about 97 million years ago, the 

Western Interior Seaway or Basin had drowned the 

previously continental deposits, and the monument 

region was an ocean basin, collecting fine- grained 

sediments that drifted far from the shoreline to the west 

and southwest. This Western Interior Basin or Seaway 

was flooded by seawater from the Arctic region and from 

the ancestral Gulf of Mexico as Africa and South 

America rifted away from North America. Oscillations in 

the shoreline, either from increased sedimentation 

coming off the highlands to the west or from tectonic 

response to collisions on the western continental margin, 

caused the shoreline to prograde and recede several 

times during the next 13 million years. 

Thick sequences of shale, siltstone, and thin limestone 

beds accumulated on the margin deposited by streams, 

wind, and ocean currents. These make up the 

widespread San Rafael Group, Dakota Sandstone, and 

Mancos Shale. These units are useful in correlating 
 NPS Geologic Resources Division 20 

depositional environments across the Four Corners 

region. Mesaverde Group deposits of siltstone and shale 

were next deposited by the shallow seas pervasive during 

the late Mesozoic. 

Near the end of the Mesozoic Era as the Cretaceous 

Period came to a close, compressive forces outside the 

borders of the Colorado Plateau caused the region to 

bow upward as a relatively coherent unit during the Late 

Cretaceous to Mid- Tertiary Laramide Orogeny. The 

seas retreated from Arizona at this time. The Rocky 

Mountains rose to the east. Great folds and faults formed 

in the orogeny; the Doney fault and Black Point 

monocline in nearby Wupatki National Monument are 

examples of such features (Figure 9). The Black Point 

Monocline was not present in the late Paleozoic, but 

formed a broad, north- south trending, regional anticline 

during the Laramide Orogeny in late Cretaceous to 

Tertiary time. 

Regional uplift started the intense erosion whose 

resulting landforms define the Colorado Plateau. The 

magnificent canyons and sculptured rock formations 

began to develop with the plateau's mass of marine and 

coastal rocks now exposed to weathering by rain, river, 

and wind. Orogenic compression ceased about 35 - 40 

million years ago. 

Erosion stripped the Tertiary and Mesozoic strata from 

the area of Sunset Crater and left the older sedimentary 

rocks exposed at the surface. Most of the erosion 

occurred during the last 6 million years when the 

Colorado Plateau began to rise. The sea retreated from 

the continent, and horizontal forces thrust the Rocky 

Mountains skyward. As the plateau rose, the Colorado 

River and its tributaries cut through the relatively soft 

sedimentary rocks and effectively entrenched their 

meandering patterns into the underlying bedrock. 

River channels incised into the underlying sediments and 

filled with Tertiary gravels. Violent volcanic eruptions 

soon followed as the San Juan Mountains exploded in 

the mid- Tertiary followed by hot spot volcanism in the 

San Francisco Volcanic Field of northern Arizona. 

Extensional tectonics resulted in the opening of the Rio 

Grande Rift near the southeastern margin of the 

Colorado Plateau. 

As the mountains rose, the processes of weathering and 

erosion began to bevel the mountain front into a 

relatively flat landscape (peneplain) gently sloping to the 

southwest. A combination of glaciation, increased runoff, 

a rising Colorado Plateau, and a subsequent lowering of 

the Colorado River’s baselevel carved the present- day 

topography. 

During the Pleistocene Epoch of the Quaternary Period 

(1.64 million – 10,000 years before present) the climate of 

northern Arizona was wetter and cooler, and runoff from 

nearby glaciers caused massive, catastrophic flooding in 

the canyons. The hydraulic force of the rivers, coupled 

with other erosion processes such as frost wedging, root 

growth, and groundwater seepage, caused extreme 

erosion of the landscape. 

The Little Colorado River left terrace gravel deposits 

behind as it cut down through the sedimentary layers 

over the last two million years. These deposits form flattopped mesa- like caps of grayish gravel over many of the 

red Moenkopi hills. 

Geologic processes and resulting landforms continue to 

shape the ecosystem today. Volcanic mountain building 

continues with the formation of Sunset Crater Volcano 

only 900 years ago, a snapshot in geologic time 

(Reynolds, 1982). The slow, sometimes imperceptible 

erosional processes are still at work wearing down mesa 

tops and deepening the canyons. Uplift and buckling of 

the Colorado Plateau resulted in fracturing of the 

sedimentary rock layers. 

Water seeped through the cracks in the Kaibab 

limestone, dissolving the carbonate rock to form long, 

interconnected, vertical fractures, similar to how a cave 

forms. Small surface openings to this fracture system, 

called blowholes, breathe as the underground air 

responds to changes in the temperature and pressure. 

One such blowhole may be seen along the Wupatki 

Pueblo trail. 

The stratigraphic relationships, hydrology, and tectonics 

offer research projects that might benefit the park. They 

also create some potential geological issues that need to 

be addressed. The cinder cone and surrounding 

landscape at Sunset Crater Volcano National Monument 

stand as a monument to the grand expression of deep 

time, that time that surpasses our understanding but 

reminds us that Earth is not static but is subject to 

change. 
 SUCR Geologic Resource Evaluation Report 21

Figure 7: Geologic time scale; adapted from the U.S. Geological Survey. 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 22 

Figure 8: Major uplifts and basins present during the Pennsylvanian age in the southwestern United States. Sediment eroded from the 

uplifts was deposited in the adjacent basins. Modified from Rigby (1977). 

Figure 9: Cross section of Sunset Crater Volcano National Monument. Graphic shows a cross sectional view of the structures beneath 

Sunset Crater Volcano and Wupatki national monuments. Note regional Black Point Monocline and Doney Fault. Sedimentary layers 

dip towards Little Colorado River Basin. 
 SUCR Geologic Resource Evaluation Report 23

References 

This section provides a listing of references cited in this report. A more complete geologic 

bibliography is available and can be obtained through the NPS Geologic Resources 

Division. 

Amos, R.C., Self, S., Crowe, B., 1981, Pyroclastic activity of 

Sunset Crater; evidence for a large magnitude, high 

dispersal strombolian eruption. Eos, Transactions, 

American Geophysical Union, vol.62, no.45, p.1085. 

Blaylock, J., Smith, E.I., Holm, R., 1996, Geochemical 

investigation of Sunset Crater, Arizona; complex 

petrogenetic history of a low- volume magmatic 

system. Abstracts with Programs - Geological Society 

of America, vol.28, no.7, p.162. 

Breed, W.J., Collier, M., 1976, Molten rock and trembling 

Earth; the story of a landscape evolving. Plateau, 

vol.49, no.2, p.2- 13. 

Breternitz, D.A., 1967, The eruption(s) of Sunset Crater; 

dating and effects. Plateau, vol.40, no.2, p.72- 76. 

Christensen, P.K., 1982, The hydrogeology of Sunset 

Crater and Wupatki national monuments, Coconino 

County, Arizona. 138 p. 

Cosner, O.J., 1962, Ground water in the Wupatki and 

Sunset Crater national monuments, Coconino County, 

Arizona. U. S. Geological Survey Water- Supply Paper, 

Report: W 1475- J, p.357- 374. 

Cotton, H.S., 1945, Sunset Crater [Arizona]. Plateau, 

vol.18, no.1, p.7- 14. 

Damon, P.E., Shafiqullah, M., and Leventhal, J.S., 1974, 

K- Ar chronology for the San Francisco volcanic field 

and rate of erosion of the Little Colorado River, in 

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

R.L., eds., pt. I, Regional Studies, Geology of Northern 

Arizona: v. 6, no. 5, p.221- 235. 

Doolittle, W.E., 1998, Innovation and diffusion of sandand gravel- mulch agriculture in the American 

Southwest; a product of the eruption of Sunset Crater. 

In: Volcanoes and man. Raynal, J.P., ed., Quaternaire 

(Paris), vol.9, no.1, p.61- 69. 

Hanson, S.L., Simmons, W.B., Falster, A.U., Morrison, 

S.J., 2000, Eruption history of Sunset Crater Volcano 

and associated fumarole deposits, northern Arizona. 

Abstracts with Programs - Geological Society of 

America, vol.32, no.7, p.501. 

Hodges, C.A., 1960, Comparative study of S.P. and Sunset 

craters and associated lava flows, San Francisco 

volcanic field, Arizona. In: The geology and dating of 

Sunset Crater, Flagstaff, Arizona. Smiley, T.L. ed., N. 

Mex. Geol. Soc., Guidebook, 9th Field Conf. 

Hodges, C.A., 1962, Comparative study of S.P. and Sunset 

Craters and associated lava flows. Plateau, vol.35, no.1, 

p.15- 35. 

Holm, R.F., 1987, Significance of agglutinate mounds on 

lava flows associated with monogenetic cones; an 

example at Sunset Crater, northern Arizona. 

Geological Society of America Bulletin, vol.99, no.3, 

p.319- 324. 

Holm, R.F., Moore, R.B., 1987, Holocene scoria cone and 

lava flows at Sunset Crater, northern Arizona. In: 

Rocky Mountain section of the Geological Society of 

America. Beus, S.S., ed., Geol. Soc. Am., Boulder, CO, 

United States (USA) p.393- 397. 

Larsen, G., Holm, R.F., 1989, Sunset Crater, Arizona; new 

petrological and geochemical data on Recent (A.D. 

1065- 1180) alkali- basaltic scoria and lava; 

characterization and origin. Abstracts of lectures and 

posters; the 67th annual meeting of the German 

Mineralogical Society, vol.1989, no.1, p.109. 

Larsen, G., Holm, R.F., 1989, Sunset Crater, southern 

Colorado Plateau, Arizona; new petrological and 

geochemical results indicating multiple magma sources 

for the 1065- 1180 eruption. Bulletin - New Mexico 

Bureau of Mines & Mineral Resources, Report: 131, 

p.159. 

Nichols, T., 1944, Sunset Crater [National Monument, 

Arizona]. Natural History, vol.53, no.10, p.448- 451. 

Ort, M.H., Elson, M.D., Hooten, J.A., Duffield, W.A., 

Champion, Duane E., 2001, Interaction between 

humans and the Sunset Crater eruption, northern 

Arizona. Abstracts with Programs - Geological Society 

of America, vol.33, no.6, p.294. 

Reynolds, S.J., 1982, Geologic features of northeastern 

Arizona. Fieldnotes from the State of Arizona, Bureau 

of Geology and Mineral Technology, vol.12, no.1, p.1- 8. 

Rigby, J.K., 1977, Southern Colorado Plateau: 

Kendall/Hunt Publishing Company, Dubuque, IA, 148 

p. 

Santucci, V.L., 2000, A survey of paleontologic resources 

from the National Parks and Monuments in Utah: in

D.A. Sprinkel, T.C. Chidsey, Jr., and P.B. Anderson, 

eds., Geology of Utah’s Parks and Monuments: Utah 

Geological Association Publication 28, p.535- 556. 
 NPS Geologic Resources Division 24 

Smiley, T.L., 1960, Geology and Dating of Sunset Crater, 

Flagstaff, Arizona. In: The geology and dating of 

Sunset Crater, Flagstaff, Arizona. Smiley, T.L. ed., N. 

Mex. Geol. Soc., Guidebook, 9th Field Conf. 

Smith, E.I., Blaylock, J., Boland, K., Morikawa, S., 

Sanchez, A., 1996, Complex behavior of low- volume 

mafic magma systems; polycyclic, polygenetic, and 

complex monogenetic quaternary cinder cones in the 

Western US and Mexico. Abstracts with Programs - 

Geological Society of America, vol.28, no.7, p.502. 

Ulrich, G.E., and Bailey, N.G., 1974, Geologic map of the 

SP Mountain quadrangle: U. S. Geol. Survey open- file 

map, p.74- 75. 
 SUCR Geologic Resource Evaluation Report 25

Appendix A: Geologic Map Graphic 

This image provides a preview or “snapshot” of the geologic map for Sunset Crater 

Volcano National Monument. For a detailed digital geologic map, see included CD. 
 NPS Geologic Resources Division 26 

The original map digitized by NPS staff to create this product was: Richard B. Moore and Edward W. Wolfe, 1974, Geologic Map of the 

Eastern San Francisco Volcanic Field, Arizona: U. S. Geological Survey, Miscellaneous Investigations Series Map, I-953 scale 1:50,000. 

For a detailed digital geologic map and cross sections, see included CD. 
 SUCR Geologic Resource Evaluation Report 27

Appendix B: Scoping Summary 

The following excerpts are from the GRE scoping summary for Sunset Crater Volcano 

National Monument. The scoping meeting occurred on June 28- 29, 2001; therefore, the 

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

contact to the Geologic Resources Division for current information. 

Executive Summary 

A geologic resources inventory workshop was held for 

the three Flagstaff area NPS units (Walnut Canyon NM, 

Wupatki NM, Sunset Crater NM) on June 28th and 29th, 

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 Flagstaff 

area office, Colorado State University, and United States 

Geologic Survey (GS) were present for the workshop. 

This was part of a multi- park scoping session also 

involving Petrified Forest NP, Pipe Spring NM, and 

Navajo NM.

On Friday June 29th, scoping involved a half- day field 

trip to view the geology of Sunset Crater NM and 

Wupatki NM, led by Sarah Hanson (Adrian College) and 

Helen Fairley (NPS). On June 28th scoping included 

another half- day session to present overviews of the 

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

Geologic Resources Division, and the on- going Geologic 

Resource Evaluation (GRE). Round table discussions 

involving geologic issues for Flagstaff area parks 

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 major geologic issues facing the Flagstaff 

area parks are as follows: 

• acquiring digital geologic maps at a large scale suitable 

for resource management needs; 

• production of an interpretive product that could be 

sold in visitor centers showcasing the geologic map of 

each area and its significance to the other resources; 

• evaluating potential volcanic hazards in the Flagstaff 

area and how they might affect park resources, and 

• an inventory of the paleontological resources at each 

park 

For a list of meeting attendees, see below (List of 

Attendees for Geological Resources Evaluation 

Workshop, June 25- 29, 2001) 

Geologic Mapping 

All three Flagstaff area parks are included on the USGS 

publication "Map Showing Geology, Structure, and 

Uranium Deposits of the Flagstaff 1 x 2 degree 

quadrangle, Arizona; USGS Map I- 1446; scale 1:250,000). 

While this small scale is not necessarily conducive for 

resource management, it is an excellent compilation map 

and was developed based upon larger scale mapping. 

However, larger scale mapping (at least 1:24,000 scale) is 

desirable for each of the three parks. 

Also, the USGS published the "Geologic Map of the 

Eastern San Francisco volcanic field, Arizona; USGS 

Map I- 953" that is at a scale of 1:50,000 that also covers 

the areas of the three parks, but does not necessarily 

include geologic mapping of each park. Specifically, the 

only park that is fully covered on this sheet is Sunset 

Crater NM. Walnut Canyon NM is completely 

uncovered and Wupatki NM is only partially covered. 

Park staff were interested in seeing a map showing 

travertine deposits because it has numerous implications 

for the cultural significance in population distributions 

and the history of water in the area, so it should be a 

component of any new mapping. 

Additionally, volcanic- and other features should be 

included (vents, flows, lava tubes, ice caves, etc.) as they 

are important in deducing a potential for volcanic 

hazards in the area as well as providing baseline data for 

what types of features exist in the park. 

Digital Geologic Map Coverage 

It is not known if any of the USGS maps (I- 953 and I1446) for the area have been converted to a digital format. 

If they have not it is suggested that they be scanned, 

registered and rectified for preliminary use in a GIS until 

new mapping is accomplished as they are the best 

available source of baseline geologic data for each park. 

Other Desired GIS Data 

Nicole Tancreto had served as the Flagstaff GIS support 

person, but is now in a GIS position for the Southern 

Colorado Plateau network. She mentioned at the 

meeting that the boundary for Walnut Canyon NM was 

incorrect on our maps, so she supplied GRE staff with 

the correct boundary as ESRI shape files. 

Aerial photography is desired for the entire area and 

would assist in any future needed geologic mapping. It 

was suggested to contact the Vegetation Mapping 

program and the USFS to see if they have such data for 

the area.
 NPS Geologic Resources Division 28 

Miscellaneous Items of Interest 

Current natural resource staff at Flagstaff area parks are 

Helen Fairley (archeologist), Paul Whitefield, and Todd 

Metzger. 

Geothermal development is a hot topic for the Flagstaff 

area, and could have effects on each parks management 

plan. 

Sunset Crater National Monument 

• Dick Holm (NAU retired professor) has done research 

at SUCR on the lava flows. However, much of this 

work is not digital at the present time. His 1987 GSA 

article "Holocene scoria cone and lava flows at Sunset 

Crater, northern Arizona", has a map showing the vent 

deposits and lava flows and would be a good map to 

get into digital format. For the most part, it is the same 

map portrayed on I- 953. 

• Sarah Hanson (SUCR- GIP, Adrian College) has been 

assisting the park with their geological interpretation 

program for the past few summers, and has added 

important knowledge of the geochemistry of the park. 

She has been successful in translating her research into 

layman's terms for the park staff. 

• Steep cinder cones are very susceptible to erosion. 

Over the years, park visitors have used these resources 

for recreational activities and it has resulted in some 

degradation of the resources. It was suggested that a 

spatter cone inventory be initiated to attempt to 

discern what condition the cones are in and which 

ones should be closed to visitor use in an attempt to 

better stabilize them and protect them. 

Wupatki National Monument 

• An Arizona State University student (Amos) published 

on "Pyroclastic activity of Sunset Crater; evidence for a 

large magnitude, high dispersal strombolian eruption" 

in 1981. According to Michael Ort (NAU- Geology 

Department), this produced a map that is now digital 

and can be supplied to the NPS from him. It also has 

isopach lines that the parks are interested in obtaining 

digitally. 

• Daniel McCormack (NAU) published "The geology of 

Wupatki National Monument, northern Arizona" as 

his masters thesis; a copy of this is desired by GRE staff 

and could serve as the geologic map for WUPA as it 

was apparently done at 1:24,000 scale and encompasses 

the Doanie Cliffs area. 

• Cynthia Blythe (NAU, 1995) did a Masters thesis on 

gravels east of the Doanie Cliffs. 

• A paper on the structural geology of the region is 

"Geomorphology and structure of the East Kaibab 

monocline," Arizona and Utah: Geological Society of 

America Bulletin, No. 2; Scale: 1:160,000. 

• Dick Holm (NAU- retired) mapped along Deadman 

Wash for the cinder cones, however its not known if 

this was published or not. 

• Gorden Haxel (USGS) may have worked on an 

interpretive guide for Wupatki with the Arizona GS; 

we need to contact the AZ GS for specifics. 

• Karst features including Earth cracks, lava tubes and 

ice caves are a unique geologic feature in the Wupatki 

area and are of concern because of risks to visitor 

safety. It has been suggested that a cave inventory be 

completed for the area, as it is known that WUPA 

contains one of the largest caves in northern Arizona. 

Nicole Tancreto mentioned that many of these 

features have had GPS locations taken for them, so 

they exist in a digital layer. 

• Many of the blowholes at WUPA have been negatively 

affected over the years because of serving as dumping 

grounds and now some need restoration work. 

Additionally, they may also be potential hazards 

because of their depth. 

• There are also several borrow pits (~12) that need 

restoration; Dave Steensen (NPS- GRD, Disturbed 

Lands Program) has made numerous 

recommendations on how best to reclaim these areas. 

• The Water Resources Division (USGS or NPS ??) has 

been studying recharge in the area as it is critical to 

sustaining wildlife populations. Contact is 

Christiansen; unsure of first name though. 

Additionally, it was noted that the existing water well 

at WUPA is approximately 1500- 1700 feet deep and the 

water quantity and quality leaves much to be desired. 

• Helen Fairley (archeologist) is interested in 

determining the provenance of the various clays and 

stones used in mortars over the years and how it 

relates to the cultural and geologic resources of the 

area. It was suggested that this would make a good MS 

topic. 

Both WUPA and SUCR have gravel deposits that are 

considered by many to have commercial value and 

external pressure may be exerted to exploit these 

resources and could cause resource management 

problems in the future. 

• There may be uranium and petroleum potential on 

WUPA lands. Mineral rights were not acquired for the 

area when the land became federal. Any mineral rights 

apparently belong to the Arizona land office. 
 SUCR Geologic Resource Evaluation Report 29

Walnut Canyon National Monument 

• General geology of WACA consists of the Kaibab, 

Toroweap, Coconino, Moenkopi formations, as well 

as some igneous cinders. 

• I- 953 does not cover the geology of WACA, and thus a 

large- scale geologic map is definitely needed. 

• Paleontological resources do exist in exposures along 

WACA trails and have been subjected to pilferage over 

the years. A paleontological survey is advised for the 

park. 

• Detailed studies of the alluvial deposits in the canyons 

are desired. Richard Hereford (USGS) is the most 

likely qualified candidate to do this and should be 

consulted for his interest. 

• George Billingsley mentioned that there is a dam in the 

park that should be restored and incorporated into the 

parks interpretive story. 
 NPS Geologic Resources Division 30 

List of Scoping Meeting attendees with contact information 

NAME AFFILIATION PHONE E- MAIL 

John Graham Colorado State University 970- 225- 6333 Jpgraham250@msn.com 

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 

George Billingsley USGS 928- 556- 7198 Gbillingsley@usgs.gov 

Della Snyder NPS, GRCA 928- 226- 0163 Della_snyder@nps.gov 

Allyson Mathis NPS, GRCA Interpretation 520- 638- 7955 Allyson_mathis@nps.gov 

Debra Block USGS 928- 556- 7138 Dblock@usgs.gov 

Jessica Wellmeyer USGS 928- 556- 7267 Jwellmeyer@hotmail.com 

John Rihs NPS, GRCA Hydrologist 520- 638- 7905 John_rihs@nps.gov 

Scott Graham USGS 928- 556- 7270 Sgraham@usgs.gov 

Tracey Felger NPS, GRCA GIS 520- 556- 7164 Tracey_felger@nps.gov 

Bill Parker PEFO Paleontologist William_parker@nps.gov 

Karen Beppler NPS, PEFO 928- 624- 6228, 

ext. 263 Karen_beppler@nps.gov 

Sid Ash PEFO 505- 856- 5852 Sidash@aol.com 

Sue Clements NPS, PEFO Tecumseh@selway.umt.edu 

Sarah Hanson SUCR GIP 520- 526- 0502 

517- 264- 3944 Slhanson@adrian.edu 

Dave Sharrow NPS, PISP 435- 644- 4318 Dave_sharrow@nps.gov 

Helen Fairley NPS, Flagstaff Area 928- 526- 1157 Helen_fairley@nps.gov 

Michael Ort Northern Arizona University 928- 523- 9363 Michael.ort@nau.edu 

Nicole Tancreto NPS, Flagstaff 928- 556- 7466, 

ext. 240 Nicole_tancreto@nps.gov 

Paul Whitefield NPS, Flagstaff area parks 928- 526- 1157 Paul_whitefield@nps.gov 

Ron Hiebert NPS, NAU- CESU 520- 523- 0877 Ron.hiebert@nau.edu 

Todd Metzger NPS, Flagstaff Todd_metzger@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. 

Sunset Crater Volcano National Monument 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2005/004 

NPS D-54, September 2005 

National Park Service 

Director • Fran P. Mainella 

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 • Trista Thornberry-Ehrlich

Editing • Paul Vohs and Sid Covington 

Digital Map Production • Stephanie O’Meara and Todd Sander 

Map Layout Design • Melanie Ransmeier 
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