National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 

Black Canyon of the Gunnison National Park & 

Curecanti National Recreation Area 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2005/001 

Black Canyon of the Gunnison National Park & 

Curecanti National Recreation Area 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2005/001 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

January 2005 

U.S. Department of the Interior 

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

and applicability to a broad readership in the National Park Service and to others in the 

management of natural resources, including the scientific community, the public, and the NPS 

conservation and environmental constituencies. Manuscripts are peer-reviewed to ensure that 

the information is scientifically credible, technically accurate, appropriately written for the 

intended audience, and is designed and published in a professional manner. 

Natural Resource Reports are the designated medium for disseminating high priority, current 

natural resource management information with managerial application. The series targets a 

general, diverse audience, and may contain NPS policy considerations or address sensitive 

issues of management applicability. Examples of the diverse array of reports published in this 

series include vital signs monitoring plans; "how to" resource management papers; 

proceedings of resource management workshops or conferences; annual reports of resource 

programs or divisions of the Natural Resource Program Center; resource action plans; fact 

sheets; and regularly-published newsletters. 

Views and conclusions in this report are those of the authors and do not necessarily reflect 

policies of the National Park Service. Mention of trade names or commercial products does 

not constitute endorsement or recommendation for use by the National Park Service. 

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. Black Canyon of the Gunnison National Park & Curecanti 

National Recreation Area Geologic Resource Evaluation Report. Natural Resource Report 

NPS/NRPC/GRD/NRR—2005/001. National Park Service, Denver, Colorado. 

NPS D-105, January 2005 
 BLCA-CURE 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

Uranium and Mining Issues ........................................................................................................................................6

Alluvial Reaches.........................................................................................................................................................7

Slope Failures.............................................................................................................................................................7

Swelling Clays ............................................................................................................................................................7

Paleontological Issues................................................................................................................................................8

Water Issues...............................................................................................................................................................8

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

General Geology and Interpretation ...........................................................................................................................9

Geologic Features and Processes............................................................................. 10

Black Canyon ...........................................................................................................................................................10

Curecanti Dams........................................................................................................................................................10

Gunnison Uplift.........................................................................................................................................................11

Curecanti Needle......................................................................................................................................................11

Dillon Pinnacles........................................................................................................................................................11

Faults........................................................................................................................................................................11

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

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

Geologic History.......................................................................................................... 18

References................................................................................................................... 28

Appendix A: Geologic Map Graphic .......................................................................... 31

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

List of Figures 

Figure 1: Location of Black Canyon of the Gunnison National Park – Curecanti National Recreation Area .................5

Figure 2: View of Black Canyon of the Gunnison........................................................................................................12

Figure 3: Sequence of events .....................................................................................................................................13

Figure 4: View of the Precambrian rock walls .............................................................................................................17

Figure 5: Distribution of lithofacies during the Upper Devonian ..................................................................................21

Figure 6: Lithofacies map of the Lower Mississippian Period......................................................................................22

Figure 7: Paleogeographic map of the Lower Triassic ................................................................................................23

Figure 8: Paleogeographic map of the Lower Jurassic Period ....................................................................................24

Figure 9: Upper Jurassic Period paleogeography .......................................................................................................25

Figure 10: Laramide foreland map ..............................................................................................................................26

Figure 11: Geologic Time Scale..................................................................................................................................27
 BLCA-CURE 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 Black Canyon of the Gunnison National Park and Curecanti 

National Recreation Area in Colorado. It contains information relevant to resource 

management and scientific research. 

The Black Canyon of the Gunnison's unique and 

spectacular landscape was formed slowly by the action of 

water and rock scouring down through hard 

Precambrian metamorphic and igneous crystalline rock. 

Few other canyons in the world combine the narrow 

opening, sheer walls, and startling depths offered by 

Black Canyon. It is so deep and narrow that little sunlight 

reaches the bottom, making the walls look black. In the 

canyon, the Gunnison River drops an average of 29 m (96 

ft) per mile. 

Sweeping mesas, deep canyons, and fjord- like lakes 

abound in Curecanti, attracting recreational enthusiasts 

from around the world. Curecanti’s three reservoirs, 

named for corresponding dams on the Gunnison River, 

form the center of Curecanti National Recreation Area. 

Blue Mesa Lake is Colorado's largest body of water. 

Morrow Point Lake marks the beginning of the Black 

Canyon of the Gunnison. Below these two, Crystal Lake 

is the site of the Gunnison Diversion Tunnel, a National 

Historic Civil Engineering Landmark. 

Geology provides the foundation of the entire 

ecosystem. Mesas are topped with layers of Tertiary 

volcanics and the depths of the Black Canyon are walled 

with hard, crystalline Precambrian rocks. Slumps, slides 

and block falls line the bottom of the canyon with recent, 

unconsolidated sediments. 

Understanding the geology of Black Canyon - Curecanti 

enhances one’s understanding of the unique relationship 

between geology and the environment. In Black Canyon 

- Curecanti geologic surface exposures consist primarily 

of Precambrian, Jurassic, Cretaceous, and Tertiary age 

rocks. These rocks record the coming and going of 

oceans, the blowing of desert sands, and the passing of 

lakes and rivers. 

Geologic processes initiate complex responses that give 

rise to rock formations, surface and subsurface fluid 

movement, soil, and canyon formation. These processes 

develop a landscape that can either welcome or 

discourage human use. 

Preservation of the canyons, ledges, and assorted mesas 

that make up Black Canyon of the Gunnison National 

Park and Curecanti National Recreation Area is 

absolutely necessary to inspire wonder in visitors to the 

sites. Geologic resources and the natural history of the 

area deserve emphasis and should be interpreted to 

enhance the visitor’s experience. 

The incredible canyons and reservoirs of Black Canyon – 

Curecanti attracted over 1,066,754 visitors in the year 

2002. These visitors place increasing demands on the 

resources available each year. In recent history, humans 

have modified the landscape surrounding Black Canyon 

and consequently altered its geologic system. This system 

is dynamic and capable of noticeable change within a 

human life span. It is not surprising then that some of the 

principal geologic issues and concerns for Black Canyon 

– Curecanti pertain to protecting geologic resources and 

features. 

The following features, issues, and processes are of 

primary geological importance and have the highest level 

of management significance to the parks: 

• Uranium and mining issues. The region within and 

surrounding Black Canyon – Curecanti has been a 

source of mining interest since the 1870’s. The 

metamorphic and igneous Precambrian age rocks are 

host to gold, silver, titanium, copper, vanadium, and 

other metallic ores. The Jurassic Morrison Formation 

contains uranium deposits. Mining activity can lead to 

water contamination that may impact the parks’ 

ecosystem. 

• Slope failures and processes. Dry environments are 

especially susceptible to slumping and landslide 

problems during intense seasonal storms due to the 

lack of stabilizing plant growth. In addition, road and 

trail construction can impact the stability of a slope. 

Mudstone- rich units such as the Mancos Shale and 

Morrison Formation are typically found in outcrop as 

slopes. These slopes are prone to fail when water 

saturated. Slope failure also occurs along the 

incredibly steep walls of Black Canyon where large 

blocks break loose every year. 
2 NPS Geologic Resources Division 

• Water Issues. Western Colorado receives on average 

only 8 to 10 inches of precipitation per year. This 

defines the semi- arid climate that makes water such an 

important resource. The Gunnison River watershed is 

relatively confined to the area immediately 

surrounding the river. This is due to the Gunnison 

Uplift which diverts tributaries away from the 

Gunnison. Managing the 3 reservoirs of Curecanti 

National Recreation Area ensures an ample, reliable 

water source for the surrounding areas. This source 

must be protected and monitored for quality. 

Other geologic parameters and issues such as swelling 

clays, wind erosion and deposition, and paleontological 

resources, were also identified during scoping sessions as 

critical management issues for Black Canyon of the 

Gunnison National Park and Curecanti National 

Recreation Area. These are detailed on pages 11- 14. 
 BLCA-CURE 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 (NPS) 

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 called for in Natural 

Resources Inventory and Monitoring Guideline (NPS75) and the NPS Strategic Plan. 

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 

Black Canyon of the Gunnison National Park and 

Curecanti National Recreation Area consist of 30,244 

acres and 41,972 acres, respectively that straddle the 

Gunnison River in west- central Colorado between the 

towns of Gunnison and Montrose. Black Canyon of the 

Gunnison National Monument was established on 

March, 2, 1933 and was elevated to National Park Status 

through a proclamation by President Bill Clinton on 

October 21, 1999. Curecanti National Recreation Area 

was established in 1965 with the completion of Blue Mesa 

Dam. 

Black Canyon of the Gunnison National Park and 

Curecanti National Recreation Area straddle the locally 

indistinct boundary between two physiographic 

provinces, the southern Rocky Mountains to the east and 

the Colorado Plateau to the west. The area displays 

complex geologic features, such as broad flat- topped 

mesas, sharp ridges, and canyons, which are in many 

ways representative of both provinces (Hansen, 1965). 

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. This physiographic province is also known 

for its laterally extensive monoclines (figure 1). Basins 

adjacent to the steep limbs of the monoclines have been 

filled with sediment eroded from these folds. The 

characteristic uplifts and basins of the Colorado Plateau 

formed as a result of the Upper Cretaceous- mid Tertiary 

Laramide orogeny. The structural fabric of gently 

warped, rounded folds in the Colorado Plateau contrasts 

with the intense deformation and faulting of bordering 

terranes. 

Located to the northeast and east of the Colorado 

Plateau are the jagged peaks of the Rocky Mountains. 

The laccolithic peaks and volcanic mesas of the West Elk 

Mountains border the park to the northeast, with high 

points at Mt. Gunnison, Mt. Lamborn, and West Elk 

Peak. The Gunnison River cuts through the Gunnison 

uplift, a relatively recent geologic addition to the 

landscape (Hansen 1965). 

The San Juan Mountains and the anticlinal Monument 

Upwarp lie to the south of Black Canyon and Curecanti 

forming the western border of Blanding Basin, a 

coincident synclinal downwarp. Locally rock layers, 

while gently folded into anticlines and synclines, remain 

relatively undisturbed by faulting except in areas 

associated with salt structures or dissolution of salt 

structures. 

Giant monoclines, laccoliths, and other features present 

in the Colorado Plateau – Rocky Mountain area today 

were molded by the processes of erosion. The 

destructive forces of wind and rain, running water, and 

freezing temperatures continue to breakdown the uplifts 

and volcanoes characteristic of this area. 
4 NPS Geologic Resources Division 

The effects of erosion were probably negligible while the 

land lay very near sea level in the Early Tertiary Period. 

However, following a fairly abrupt increase in elevation 

from near sea level to several thousand feet above sea 

level in the Late Tertiary, the pace of erosion accelerated. 

During this time erosion worked to carve down the rocks 

and carry away the strata. 

This erosion created incredible topographic relief. For 

example, from High Point in Black Canyon of the 

Gunnison National Park, the Uncompahgre Valley sits 

some 762 m (2,500 ft) below (Hansen, 1965). This 

effectively dissected the topography and created the 

modern landscape known today as Black Canyon – 

Curecanti. 
 BLCA-CURE Geologic Resource Evaluation Report 5

Figure 1: Location of Black Canyon of the Gunnison National Park – Curecanti National Recreation Area relative to Colorado Plateau 

and Rocky Mountain physiographic features. The light gray area signifies the aerial extent of the Colorado Plateau. Dark gray and 

black areas represent uplifts and mountains. 
6 NPS Geologic Resources Division 

Geologic Issues 

A Geologic Resource Evaluation scoping session was held for Black Canyon of the 

Gunnison National Park and Curecanti National Recreation Area on August 26, 1998, 

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. 

Uranium and Mining Issues 

The Paradox Basin, southwest of Black Canyon has been 

the site of uranium mining for nearly nine decades. The 

principal host rocks for the radium, vanadium, and 

uranium deposits exposed at Black Canyon of the 

Gunnison and Curecanti National Recreation Area are 

the Jurassic Morrison Formation, the Cretaceous Dakota 

Sandstone, and Precambrian pegmatite. In the Morrison, 

gray, poorly sorted, fine- to coarse- grained, calcareous, 

arkosic, quartz sandstone of the Salt Wash Member 

contains uranium ore. Historically, over 1.2 million kg of 

uranium oxide have been produced from the Gunnison 

area, mostly from the Cochetopa and Marshall Pass 

districts. Uranium deposits are often associated with 

fault and shear zones in the Mesozoic rocks of the area. 

Local occurrences are in pegmatites and shear zones in 

Precambrian rocks and some Tertiary sandstones 

(Goodknight 1981). 

A threat specific of uranium mining is that of radon gas 

exposure. Radon is a product of uranium’s radioactive 

decay. This tasteless, odorless gas is a known carcinogen 

that usually concentrates in low lying areas like 

basements and mine shafts. 

In addition to uranium resources, the Precambrian rocks 

exposed at Black Canyon contain deposits of metal ores 

such as gold, silver, copper, manganese, vanadium, 

sulfides, and tellurium. Additionally, low- grade niobium, 

titanium, and vermiculite deposits are associated with the 

carbonatite and pyroxene of the Iron Hill stock 

(Hedlund and Olson, 1975). At least 98 thorium- bearing 

veins and dikes have been examined and found to have 

radioactive levels 2- 250 times background. At the Little 

Johnnie mine, the thoria content of high- grade samples 

is as much as 4 percent (Olson and Wallace, 1956). 

Thorium veins are commonly located along shear and 

breccia zones within Precambrian rocks. The thorium 

vein system west of the Old Lot mine, about 3 miles north 

of Powderhorn, follows a fault for about 8,000 feet. Rare 

earth elements and niobium are found in elevated 

amounts in the thorium- bearing veins (Hedlund and 

Olson, 1975). 

Veins containing gold, silver, copper, and telluride 

minerals occur in the Dubois Greenstone in a zone 

across the northern part of the area called the Gunnison 

gold belt. The scant production from these veins 

probably totaled several hundred thousand dollars, 

chiefly from the Good Hope- Vulcan mines. These 

mines, located near the northeast edge of the 

Powderhorn quadrangle, were worked from 1898- 1904 

and during several other short periods. Mining extended 

down to approximately 700 feet. At a depth of about 90 

feet the shafts were reported to have penetrated a pocket 

of native sulfur, which then graded into massive pyrite at 

the water level, about 105 feet below the ground surface 

(Hedlund and Olson, 1975). 

South and southeast of Spencer, are the Headlight, 

Gunnison, Anaconda, and Ironcap Mines. The Headlight 

mine was excavated chiefly for its copper, whereas the 

other mines yielded relatively small tonnages of goldbearing ore. About one- half mile east of Midway, 

Colorado is the Ute Trail mine. This mine was developed 

in a quartz vein that runs along a nearly vertical breccia 

zone near the contact of chloritized granite and felsite 

(Hedlund and Olson, 1975). 

Vermiculite is sporadically distributed in altered 

pyroxenite as random segregations and in dike- like 

(linear) bodies. The vermiculite deposits, which are most 

likely a weathering product of biotite in the pyroxenite, 

occur in plates as much as 4 inches across. Most of the 

surface stripping for vermiculite has been between North 

Beaver and Deldorado Creeks and at the head of Stone 

Gulch (Hedlund and Olson, 1975). 

Abandoned mines pose a serious potential threat to any 

ecosystem. Even in semi- arid environments, surface 

water and groundwater can become contaminated with 

high concentrations of heavy metals, leached from mine 

tailings. Heavy metals may also contaminate nearby soils. 

Contaminated soil and water are likely to have negative 

impacts on both plant and animal life in the surrounding 

ecosystems. 

Inventory, Monitoring, and/or Research Needs 

• Conduct periodic water (surface and groundwater) 

and soil monitoring for uranium. Drinking water is 

especially important to sample, test, and monitor. 

• Research uranium bearing beds throughout the parkrecreation area. Include descriptions, uranium content 

tests, and locations, i.e. where the beds are exposed 

and accessible to the public, flora, and fauna. 

• Complete inventory of the uranium content in modern 

unconsolidated deposits and soils as well as uranium 

bearing stratigraphic units (Morrison Formation). 
 BLCA-CURE Geologic Resource Evaluation Report 7

• Monitor heavy metal concentrations in surface and 

groundwater. 

• Monitor any new mining activity in the area. 

• Install new monitoring wells around the parkrecreation area to better determine contaminant levels 

in drinking water aquifers. 

Alluvial Reaches 

The Black Canyon of the Gunnison River includes 

several characteristics of an alluvial river in addition to its 

gorge- like features. Several reaches of the river exhibit 

fluvially deposited banks and bars, riffle- pool channel 

geometry, and accompanying riparian ecosystems. These 

ecosystems and the alluvial reaches they depend on are 

sensitive to changes in streamflow. Sediment sources for 

these areas include debris from talus slopes, rockfalls, 

and minor tributary debris which are reworked and 

redeposited for riparian vegetation growth (Elliott and 

Hammack, 1999). 

Inventory, Monitoring, and/or Research Needs 

• Determine where alluvial reaches exist, and monitor 

yearly changes based on a GIS derived map. 

• Collect geomorphic and sedimentologic data at all 

alluvial reaches in the Black Canyon. Calculate the 

entrainment potential of a large range of sediment 

sizes and correlate them with the underlying 

geomorphic surfaces. 

• Use estimates of water- surface elevations, flow 

depths, and hydraulic conditions to determine the 

hydrologic regime in alluvial reaches. 

• Monitor streamflow over several years to establish a 

pattern at specific alluvial reaches and monitor 

sensitive vegetation changes within the riparian 

ecosystems. 

Slope Failures 

Landslide and rockfall potential exists along most roads 

and trails at Black Canyon of the Gunnison National 

Park and Curecanti National Recreation Area. Highway 

50 is subject to ongoing slides and Route 92 has potential 

slides on the north side of the park. 

These events can endanger the public and cause road 

problems or closures in the parks. Certain cliff forming 

units such as the Entrada and Dakota Sandstones, and 

the Burro Canyon Formation are especially prone to 

landslides and rockfalls when undercut by a road or trail. 

Slumps and other forms of slope failure are common for 

units that are not necessarily associated with cliffs. Rocks 

rich in mudstone for instance, like the Morrison 

Formation and the Mancos Shale, are especially 

vulnerable to failure when exposed on a slope. Torrential 

rains which produce flash flooding in the Black Canyon 

area also act to mobilize material on slopes that lack 

stabilizing plant and tree roots. The rock and soil, when 

suddenly saturated with water, can slip down slope 

causing a slump, mudslide, or flow. 

The precipitous slopes of Black Canyon make for 

arduous and potentially dangerous hiking. Rockfalls and 

slides are continuous slope processes that affect all levels 

of the canyon. In the hard Precambrian rocks exposed 

on the walls of Black Canyon, numerous faults, joints, 

and other fractures combine with frost action and root 

wedging to weaken the integrity of the units and increase 

the potential for block falls into the canyon. Any 

earthquakes (seismic activity) can increase this hazard. 

Inventory, Monitoring, and/or Research Needs 

• Perform a comprehensive study of erosion/weathering 

processes active at Black Canyon of the Gunnison 

National Park and Curecanti National Recreation 

Area, 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 to aid 

planning efforts for future developments and current 

resource management of trails, buildings, and 

recreational use areas. 

• Perform a shoreline investigation for slumps and 

rockfalls at Curecanti. A slope classification map could 

be derived from digital elevation data. 

• Use high resolution Global Positioning System (GPS) 

to detect current movement, swelling, and collapsing 

in areas of the parks. 

• Obtain access to regular seismic activity reports or a 

seismometer to measure activity in the area. 

Swelling Clays 

Swelling soils associated with bentonitic shales of the 

Morrison and Mancos Formations may be a concern to 

present and future developments and management at 

Black Canyon of the Gunnison National Park and 

Curecanti National Recreation Area. 

Bentonite, a clay derived from altered volcanic ash 

deposits, is responsible for road failures at Mesa Verde 

National Park and in numerous other locations. 

Bentonite has the ability to absorb large quantities of 

water into its structure causing it to swell when wet and 

shrink upon drying. Any structures, roads, trails, 

facilities, etc., found on soils with large concentrations of 

this mineral will be profoundly impacted and potentially 

destroyed by the force exerted by the clays shrinking and 

swelling. 

This shrink- swell characteristic of bentonite produces 

interesting construction and road maintenance 

problems. Nonetheless, bentonite is valuable to the oil 
8 NPS Geologic Resources Division 

industry which uses the clay to cool drilling bits and seal 

fractures. 

Inventory, Monitoring, and/or Research Needs 

• Determine which trails, roads and buildings are 

underlain by bentonitic units using GIS. 

• Identify high risk areas where future development 

should be avoided. 

• Perform an exhaustive mapping study to locate 

specific bentonitic beds in the Morrison Formation 

and Mancos Shale. This will allow for more precise 

hazard assessment. 

Paleontological Issues 

A detailed description of the paleontology and 

biostratigraphy of Black Canyon of the Gunnison 

National Park and Curecanti National Recreation Area is 

beyond the scope of this inventory. It is however 

important to note that the fossil rich Morrison 

Formation is exposed within Black Canyon - Curecanti 

and that dinosaur fossils continue to be found locally in 

this formation. Other units, such as the Mancos Shale 

and the Dakota Sandstone, also contain fossils that 

should be catalogued. 

Inventory, Monitoring, and/or Research Needs 

• Encourage research projects that would help identify 

the paleontological resources of the park as an aid to 

the GRD paleontological survey. 

Water Issues 

Today as in the past surface water and groundwater play 

key roles in defining and shaping the Black CanyonCurecanti landscape. Flowing water carves the deep 

canyons and forms the mesas and spires that are so 

prevalent on the Colorado Plateau. Groundwater 

dissolves the cement that binds individual grains together 

and transports the cementing elements out of the system 

through seeps and springs. Erosion undercuts cliffs 

forming alcoves and causing rocks to topple to the base 

of canyons. Groundwater and surface water also expand 

and contract, as part of the freeze thaw cycle, widening 

joints and fractures in the bedrock and causing the 

eventual breakdown of even the most resistant rocks. In 

addition, the quality and quantity of water dictates 

biodiversity and the success of human occupation in an 

area. 

The climate of Black Canyon - Curecanti is one of 

relatively low precipitation and high evaporation rates. 

Consequently, recharge to groundwater aquifers is low. 

Precambrian crystalline rocks contain water only in 

fractures and consolidated sedimentary rocks yield little 

or no water to wells at Curecanti. Wells drilled into 

Tertiary age volcanic rocks generally yield less than 5 

gallons of water per minute. Unconsolidated Quaternary 

age deposits yield as much as 50 gallons per minute to 

wells, but again, these near surface sources are easily 

depleted and slow to recharge (Boettcher, 1971). This lack 

of a plentiful and stable water supply prompted 

construction of the three dams at Curecanti to provide 

for the needs of the region. 

The three dams in Curecanti National Recreation Area 

work as a system to store water, produce electricity, and 

regulate water flow for downstream irrigation and flood 

control. This system of dams has dramatically altered the 

natural environment by placing checks and regulations 

on the once wild Gunnison River. Because the river 

dominates the area, the hydrogeologic system has 

completely changed as a result of these dams. Dam 

maintenance and integrity in turn play a large role in 

management concerns at Curecanti. 

Inventory, Monitoring, and/or Research Needs 

• Conduct hydrogeologic studies to delineate subsurface 

flow patterns, regional and local flow systems, and the 

conductivity and transmissivity of the strata at Black 

Canyon - Curecanti. 

• Monitor water quality on a multiple sample location 

basis within the parks; drinking water sources are 

especially important. 

• Develop an understanding of groundwater and surface 

water flow in relation to erosion rates. 

• Identify the hydrology of the area and of seeps along 

with the water quality, to establish a baseline for 

comparison. 

• Install additional wells for testing and drinking water 

access. 

• Determine the impacts of heavy metal and uranium 

mining on water quality. 

• Identify and study potential sources for impacts to 

groundwater quality. 

• Install transducers and dataloggers in wells. 

• Investigate additional methods to characterize 

groundwater recharge areas and flow directions. 

Wind Erosion and Deposition 

In addition to water, 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 is important in the Black 

Canyon area and can be affected by human activities. 

Ecosystem health is dependent on the retention of soil 

and soil resources, accelerated losses of these resources 

can indicate degradation of arid- land ecosystems. 

Sand and soil from disturbed surfaces can blow onto 

undisturbed ground, burying and killing vegetation. Even 

biological soil crusts can be damaged or destroyed by 
 BLCA-CURE Geologic Resource Evaluation Report 9

wind blown sediment, exposing more soil to erosion. 

Because park management practices limit or prohibit 

off- road travel, human impacts within the parks are 

primarily associated with off- trail hiking in high- use 

areas. Where livestock grazing or trailing is still 

permitted, accelerated soil erosion can be more 

extensive. However, wind erosion and sediment 

transport in Black Canyon – Curecanti may be strongly 

impacted by land- use practices outside park boundaries. 

Inventory, Monitoring, and/or Research Needs 

• Monitor movement of soil materials. 

• Investigate impacts to the ecosystem of soil movement. 

• Investigate natural range of variability of soil 

movement in relation to landscape configuration and 

characteristics. 

General Geology and Interpretation 

The unique geology of Black Canyon of the Gunnison 

National Park and Curecanti National Recreation Area 

lends itself to potential scientific research projects 

addressing Precambrian rocks, Mesozoic and Cenozoic 

stratigraphy, the regional and local hydrology, and 

weathering/erosion rates. The incredible geologic 

exposures within the Black Canyon and along the mesas 

at Curecanti offer an unparalleled record of geologic 

history for investigation. 

Inventory, Monitoring, and/or Research Needs 

• Perform a comprehensive study of the canyon wall 

rocks to determine the Precambrian history of the 

area. 

• Identify unconformity- bounded stratigraphic 

packages in order to better define past depositional 

systems. 

• Investigate geomorphological changes driven by 

raising and lowering the reservoir level. 

• Develop an exhibit depicting the geologic history of 

the rock formations, including the depositional 

environment surrounding visitor center. 

• Date talus cones inside the canyon using lichen 

growth. 

• Determine the age of rim gravels with regards to the 

timing of downcutting, and their chemical alteration. 

• Develop more graphics and brochures emphasizing 

geology, targeting the average enthusiast. 

• Develop an informative trail guide based on the 

detailed GIS- NPS geologic map which has been 

published for Black Canyon - Curecanti. This would 

accent the strong geological component of the park 

and enhance the visitor’s experience while at the 

parks. 

• Determine a timeline of canyon incision on the 

Colorado Plateau. The timing of canyon incision on 

the Colorado Plateau is an important topic of 

discussion among Quaternary geologists. Incision and 

erosion are directly related to weathering rates and 

regional tectonic regimes. 

• Perform rock color studies. 

• Complete maps of areas north of Curecanti, possibly 

an EDMAP project 
10 NPS Geologic Resources Division 

Geologic Features and Processes 

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

and processes in Black Canyon of the Gunnison National Park and Curecanti National 

Recreation Area. 

Black Canyon 

The park’s namesake, is the dominant feature of the 

landscape. In contrast to most of the canyons in the 

western United States, the Black Canyon is in many 

places deeper than it is wide (Figure 2). The average 

depth of the canyon is 610 m (2,000 ft), with a maximum 

width of 823m (2,700 ft), just north of Warner Point to a 

minimum of 533 m (1,750 ft) at The Narrows. The 

Gunnison River has an usually steep gradient over the 

length of the gorge. It falls about 655 m (2,150 ft) from the 

canyon head at Sapinero to the mouth at the junction 

with North Fork, a distance of just 80 km (50 miles). This 

is an average drop of 13 m (43 ft) per mile (Hansen, 1965). 

For comparison, the Colorado River in the Grand 

Canyon only descends an average of 2.3 m (7.5 ft) per 

mile. 

Many geologic processes acted in concert to create the 

precipitous depths of the Black Canyon. The most 

obvious processes evident today include the turbidity of 

the river carrying mud and debris, occasional rockfalls 

from high cliffs, and the relentless movement of 

landslides into the depths. Other more subtle processes 

such as gullying, frost action, and chemical weathering 

(acid rain) increase the material available for the river to 

wash away. 

The process of erosion is responsible for the excavation 

of the canyon. However, the coincidental interplay of 

several other geologic factors was necessary to remove 

more than 25 cubic miles of rock from the landscape 

along such a narrow course through incredibly hard 

metamorphic rocks (Figure 3). Prior to the Gunnison 

Uplift, the Gunnison River followed a course through 

relatively soft Mesozoic and Cenozoic volcanic and 

sedimentary rocks. The present path of the river is 

controlled by this previous course; it has been impressed 

on the hard, underlying Precambrian rocks due to 

relatively rapid Gunnison Uplift event. 

Volcanic evidence indicates that the Gunnison River did 

not begin to incise its canyon until the cessation of 

volcanic activity in the West Elk and San Juan 

Mountains. The rocks of the Hinsdale Formation are the 

youngest to clearly predate the canyon. The age of this 

formation is generally regarded as Pliocene (about 11 to 1 

million years ago). This means the relative age of the 

Black Canyon is fairly young, making the excavation 

even more remarkable (Hansen, 1965). 

The tributaries of the Gunnison River flow from small 

catchment basins. If the tributaries were larger, they 

would tend to widen the canyon and undermine the 

erosive capability of the main river. Tributary streams 

such as Grizzly Gulch only flow intermittently. 

The erosive power of these tributaries is negligible 

compared to that of the Gunnison River. The lack of 

major tributaries is a result of the Gunnison Uplift which 

diverts larger streams away from the canyon. This makes 

the Gunnison River the only deep course and helps to 

create the steep walls of Black Canyon. 

Curecanti Dams 

The three dams of Curecanti make up what is called the 

Wayne N. Aspinall Storage Unit. This is one of the four 

main units of the Upper Colorado River Storage Project 

(UCRSP). Other notable dams in this project include 

Navajo Dam in New Mexico, Flaming Gorge Dam in 

Utah, and Glen Canyon Dam in Utah. The primary 

purpose of this project is to provide reliable water 

storage to the Upper Colorado River Basin states of 

Colorado, Wyoming, New Mexico and Utah. 

Blue Mesa Dam 

Blue Mesa Dam is a 119 m (390 ft). high earth and rock fill 

dam. It was built as the first large dam on the Gunnison 

River in 1965. The largest body of water in Colorado, 

Blue Mesa Reservoir, is 32 km (20 mi) long with 155 km 

(96 mi) of shoreline. While Blue Mesa Dam does 

produce some hydroelectricity, with a power capacity of 

around 80,000kw, its primary purpose is to store water. 

Morrow Point Dam 

Completed in 1967, Morrow Point Dam lies 19 km (12 mi) 

below Blue Mesa Dam creating a deep, narrow reservoir 

between the steep walls of the Black Canyon. The dam is 

a concrete, double curvature, thin arch dam 143 m (469 

ft). high, the first of its type built by the Bureau of 

Reclamation. The Morrow Point Dam was built 

primarily for the production of hydroelectricity. It has 

two 83,000kw generators, making its power capacity 

around 172,000kw, almost twice the power capacity of 

Blue Mesa Dam. 
 BLCA-CURE Geologic Resource Evaluation Report 11

Crystal Dam 

Crystal Dam was completed in 1976. This dam, like 

Morrow Point Dam, is a concrete, double curvature, thin 

arch dam. Crystal Dam is located 9.6 km (6 mi) below 

Morrow Point Dam. Just below the dam is the eastern 

boundary of Black Canyon of the Gunnison National 

Park through which the river runs unimpeded. The 

purpose of Crystal Dam is to stabilize the flow of water 

through the Black Canyon of the Gunnison although it 

produces some hydroelectricity as well. 

Gunnison Uplift 

The Gunnison uplift first took form about 60 million 

years ago during the Late Cretaceous- Early Tertiary 

mountain building event known as the Laramide 

orogeny. It is the dominant structural feature of the area 

and is responsible for the relatively tiny watershed of the 

Gunnison River. All would be tributaries, are diverted by 

the swell, while the Gunnison River cuts directly through 

the Black Canyon. 

The Gunnison uplift is mainly an upfaulted but partly 

arched block. The Laramide orogeny reactivated 

previous fault block surfaces with new stresses in the 

Precambrian basement rocks. The crest of the Gunnison 

uplift is gently bowed and in areas rocks are sharply 

folded along faults. Locally the block is tilted 5 to 10 

degrees to the north- northeast (Hedlund and Olson, 

1981). 

The uplift was beveled flat by Tertiary erosion prior to 

regional volcanism (Hansen, 1964; 1965). The core of the 

uplift is exposed in the depths of the Black Canyon of the 

Gunnison. The unconformity seen at the canyon rim 

where ancient Precambrian Rocks are overlain by 

relatively young Upper Jurassic and Tertiary age rocks 

remains one of the more impressive geologic and 

physiographic features of the region. 

Curecanti Needle 

The Curecanti Needle is located about 7.2 km (4.5 mi) 

downstream from Blue Mesa Dam near Sapinero, 

Colorado. It is a spirelike monolith rising nearly 244 m 

(800 ft,) composed of an intrusive igneous rock called 

the Curecanti Quartz Monzonite. This name was applied 

by J. Fred Hunter in 1925. The quartz monzonite is 

Precambrian in age and forms an irregular, rather flat 

laccolith, roughly centered around Curecanti Needle. 

The laccolith is a pluton roughly 5.6 km (3.5 mi) across 

from west to east and 3.2 km (2 mi) from north to south 

(Hansen, 1964). 

Dillon Pinnacles 

The Dillon Pinnacles are comprised of West Elk Breccia. 

The West Elk Breccia contains solidified lava flows 

intermixed with coarse fragments of material resulting 

from the explosive destruction of previous volcanic 

features. The volume of the West Elk Breccia is 

enormous, remnants of the formation exceed 305 m 

(1000 ft) in thickness and conservative estimates of the 

formations original volume exceed 625 cubic km (150 

cubic miles). 

Exposures of West Elk Breccia are especially good in the 

headward part of the Black Canyon, along Highway 92 

and U.S. Highway 50. The Dillon Pinnacles typify the 

erosional formations contained within the West Elk 

Breccia. Cliffs, crags, pillars, windows and assorted 

erosional hoodoos abound. 

Faults 

Dominant high- angle fractures in Black Canyon trend 

west- northwest and north- northeast. These fractures 

are minor in comparison to parallel faults in the area. The 

largest, named the Cimarron Fault, is part of a left- lateral 

couple in the area, showing lateral displacement and 

trending west- northwest for at least 64 km (40 mi) 

(Hansen, 1964). This fault bounds the Gunnison Uplift 

on the south and is well exposed along the Lake Fork of 

the Gunnison River, where Mancos Shale is faulted 

downward against much older Precambrian rocks 

(Hedlund and Olson, 1981). Laramide movement along 

the Cimarron Fault resulted in at least 610 m (2,000 ft) of 

displacement. Red Rocks fault trends northnortheastward 32 km (20 mi) or more from the head of 

Red Rock Canyon to the west of Blue Creek (Hansen, 

1965). 

These fault surfaces were present prior to the Laramide 

orogeny forcing the Gunnison uplift to rise. Movement 

along these faults ceased before the end of the Tertiary. 

Most major faults in the area show a high degree of 

topographic relief across them. This is not due to recent 

movement, but rather to differential erosion between 

different rock types on either side of the fault (Hansen, 

1965). 
12 NPS Geologic Resources Division 

Figure 2: View of narrow, deep Black Canyon of the Gunnison. Photograph by Trista L. Thornberry-Ehrlich, Colorado State University. 
 BLCA-CURE Geologic Resource Evaluation Report 13

Figure 3: The block diagrams above summarize the sequence of events responsible for the formation of the Black Canyon of the 

Gunnison. Please note, the diagrams are not to scale. 
14 NPS Geologic Resources Division 

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 Black Canyon of the Gunnison National 

Park and Curecanti National Recreation Area. The table in this section 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. 

Through incredible erosion, the Gunnison River has 

exposed a wide range of rock types, from 1.7 billion year 

old gneiss and schist to Mesozoic – Cenozoic 

fossiliferous sedimentary rocks and modern 

unconsolidated sediments. 

The steep, “black” walls of the canyon are composed of 

Precambrian granites, gneisses, gabbros, diorites, 

pegmatites, and schists (Figure 4). The canyon itself is 

considered one of the best exposures of these ancient 

rocks in the world. 

Directly atop the Precambrian rocks, lie Mesozoic and 

Cenozoic sedimentary strata. No Paleozoic sedimentary 

rocks exist in the Black Canyon – Curecanti area. The 

absence of Paleozoic strata creates an unconformity, 

indicating that approximately 370 million years of earth 

history are missing from this landscape. The Entrada 

Sandstone, Wanakah Formation, and Morrison 

Formation represent Jurassic time in the area. The fossils 

and depositional structures within these rocks record a 

vast array of Jurassic climates and environments. 

 

Above the Jurassic rocks are the Cretaceous sandstones, 

shales, and coal beds of the Dakota Sandstone and Burro 

Canyon Formation. The muds of the Mancos Shale, the 

volcanic breccia of the Cimarron Ridge Formation, and 

the brown shales and calcareous sandstones of the 

Fruitland Formation and Pictured Cliffs Sandstone 

complete the Cretaceous strata at Black Canyon – 

Curecanti. 

At the end of the Laramide orogeny volcanic activity 

erupted across the area resulting in large deposits of 

volcanic ash, tuff, and breccia. These and other Tertiary 

igneous rocks cap the regions mesas today. Specific 

formations include West Elk Breccia, Blue Mesa Tuff, 

Dillon Mesa Tuff, and Carpenter Ridge Tuff. 

Today, Quaternary silts, sands, and gravels are preserved 

in the canyons and surface depressions of Black 

Canyon- Curecanti as terrace deposits, alluvium, and 

colluvium. They represent only a fraction of the deposits 

that once spread across this area, only to be subsequently 

stripped from the region by the relentless process of 

erosion. 

The following pages present a tabular view of the 

stratigraphic column and an itemized list of features for 

each map 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. 
Map Unit Properties Table 

Age Unit Name (Symbol) Features and Description Erosion Resistance Suitability for Development Hazards Potential Paleontologic Resources Potent

Cultur

Resour

QUATERNARY 

Alluvium & surficial deposits (Qa); Alluvial & colluvial deposits (Qac), Eolian deposits (Qe); Fan deposits (Qf); Landslides, mudflows, debris flows (Ql); Active landslide deposits (Qla); Earthflow & mudflow lobes (Qlm); Talus, slope wash & colluvium (Qts); Volcanic ash (Qvb); Travertine (Qtr), Boulder gravel deposits near T50N,R9W (Qbo), Terrace and alluvial fan deposits in Bostwick Park & vicinity (Qtb); Terrace and pediment gravel (Qg); Pediment deposits (Qpa); Highest pediment remnant (Qpb); Older stream gravel (Qsg); Terrace deposits - undifferentiated (Qt); Terrace deposits of Cimarron & Blue Creek drainages (Qtx); 

Terrace and pediment deposits of Alkali Creek, Onion Valley and Crystal Creek (Qtax); Terrace and pediment deposits related to the Uncompahgre River (Qtux); Boulder gravel deposits - Bostwick Park (QTbg); High level gravel remnants (QTg); Older landslide deposits on Waterdog Peak (QTl) 

Unconsolidated sands, silts, clays, pebbles, gravels and boulders; refer to BLCA GLG.hlp (Windows help file) included with the digital geologic map coverages on the accompanying CD 

Low 

Unconsolidated surficial deposits, should be fine for most development; very permeable 

Potential for slumping, mass wasting and other slope processes 

Recent fossils 

Foundatifor dwellingstools & other artifacts; campsitepossible 

Hinsdale Formation (Th), gravel (Thg); Carpenter Ridge Tuff (Tc); tuffaceous breccia (Tcb); nonwelded pumiceous tuff (Tcn); vitrophyre (Tcv); Tuff of Long Gulch (Tlo); Rat Creek Tuff (Tr); Fish Canyon Tuff (Tf); nonwelded tuff (Tfn); vitric tuff (Tfv), coarse gravel (Tfg); Sapinero Mesa Tuff (Ts); nonwelded tuff (Tsn); black vitrophyre (Tsv), gravel (Tsg); Dillon Mesa Tuff (Td), tuff breccia (Tdb); vitrophyre (Tdv), gravel (Tdg), Blue Mesa Tuff (Tb); black vitrophyre (Tbv); gravel (Tbg); Gravel Deposits 

Undifferentiated (Tg); Talus, slope wash, or colluvium, undivided (Tgt); Jasper or siliceous sinter (Tj); Travertine (Ttr); Lake Fork Formation- hornblende rhyo dacite flows (Tl), andesite flows and autobreccia (Tla); andesitic to quartz- latitic breccia (Tlb); porphyritic andesite (Tlba); rhyodacite dikes (Tld); quartz latite flows and breccia (Tll); rhyodacite flows (Tlr); pumiceous tuff (Tlt); coarse gravel (Tlg). 

Volcanic deposits; various welded, to non- welded tuff with phenocrysts; some unconsolidated gravel deposits; refer to BLCA GLG. hlp file for individual unit descriptions 

Moderate None Some rockfall potential None None 

TERTIARY 

West Elk Breccia (Tw), ash- flow tuff (Twa), brecciated rhyodacitic flows (Twf), volcanic conglomerate (Twc), laharic volcanic and tuff breccia (Twt), coarse gravel (Twg) 

Volcanic deposits; Relatively thin flows of pyroxene and hornblende andesite and hornblende dacite and associated flow breccias, tuffs, and gravels 

Moderate None Some rockfall potential None None 

Cimarron Ridge Formation (Kcr), Camptonite (Kc), Fruitland Formation (Kf), Pictured Cliffs Sandstone (Kpc) 

Kcr - volcanic breccia; Kc - lamprophyric sills; Kf - carbonaceous brown shale; Kpc - calcareous sandstone 

Moderate 

Shale beds may fail when exposed on a slope if weathered 

Some rockfall potential, and slumping 

Kf and Kpc contain coal beds with plant fossils None 

Mancos Shale (Km) 

Dark- gray silty clay shale with lenses of friable gray sandstone and scattered calcareous siltstone concretions 

Low 

Bentonite beds (swelling clays) render unit unstable along slopes; slippery when wet 

Potential for slumping, mass wasting and other slope processes 

Scaphites depressus, Exiteloceras jenneyi, Didymoceras cheyennense, idymoceras nebrascens, marine mollusks 

None 

CRETACEOUS 

Dakota Sandstone and Burro Canyon Formations (Kdb) 

Generally light- brown, medium- to coarse- grained sandstone; upper reaches, carbonaceous shale beds generally less than 6 inches thick interbedded with silty sandstones 

Moderate 

to high None 

Some rockfall potential where unit is undercut 

Some plant impressions, worm burrows, petrified wood 

Chert soufor tool making 
Age Unit Name (Symbol) Features and Description Erosion Resistanc e Suitability for Development Hazards Potential Paleontologic Resources Potent

Cultur

Resour

JURASSIC Morrison Formation (Jm) 

Mudstone, siltstone, thin lenticular sandstone beds; upper part is lightgreen to gray mudstone and siltstone with very thin intercalated silty sandstone beds; lower half red to purple mudstone with thin lenticular sandstone beds 

Low to 

moderate 

Bentonite beds (swelling clays) render it unstable along slopes; very slippery when wet 

Potential for slumping, mass wasting and other slope processes 

Dinosaurs, other reptiles, and a variety of plant fossils 

Chert soufor tool making 

Wanakah Formation ((Jw), Junction Creek Sandstone Member (Jwjl) 

Interbedded sandstone, siltstone, gypsum, and mudstone in upper beds; Jwj is a discontinuous finegrained friable highly cross- bedded light- gray to light- yellowish- gray to pink eolian sandstone, mapped locally 

Moderate 

to high 

Gypsum and mudstone beds may fail on weathered slopes. 

Potential for slumping, mass wasting and other slope processes; rockfalls where unit is undercut 

Fossil algae, freshwater clams, snails Chert sou

for tool making 

JURASSIC 

Entrada Sandstone (Je) 

Yellow fine- grained sandstone with some scattered medium to coarse, well- rounded grains; basal conglomerate, detritus from underlying Precambrian rocks 

High None 

Some rockfall potential where unit is undercut 

None 

Possible petroglypalong cliffaces 

PRECAMBRIAN 

- CAMBRIANORDOVICIAN Diabase dikes (OCd) Trachyte & Trachyte Porphyry Dikes(CpCt); Intrusive breccia (CpCbx); Iron Hill Alkaline complex (CpC); Carbonatite (CpCc); Nepheline syenite (CpCns); Pyroxenite- nepheline syenite hybrid rock (CpCps); Ijolite (CpCi); Melanite- orthoclase rock (CpCmo); Magnetite- ilmenite- perovskite dikes (CpCmt): Pyroxenite (CpCpy); Rocks altered to fenite (Caf). Various intrusive igneous rocks present as dikes, breccias, and irregular veins and complexes; Refer to BLCAGLG.hlp for specific descriptions for individual units High None Some rockfall potential None None PRECAMBRIAN 

Fine- to Medium- grained Granite (pCfg); Syenite & Related Rocks (pCxx); Granite & quartz syenite of Wolf Creek (pCwe); Quartz syenite, syenite, & granite (pCsy); Fine- grained melasyenite (pCfs); Porphyritic augite syenite (pCas); Biotite syenite (pCbs); Gray porphyritic syenite (pCps); Melasyenite (pCms); Biotite syenite and hornblende syenite (pCcs); Leucosyenite (pCls); Minette (pCmi); Curecanti Quartz Monzonite (pCe); Lamprophyre (pCl); Vernal Mesa Quartz Monzonite (pCv); Gabbro (pCga); Olivine Pyroxenite (pCop); Undifferentiated Granitic Rocks (pCx); Metarhyolite (pCmr); Pegmatite (pCp); Quartz monzonite or granite (pCqm); Granite & quartz syenite of Carpenter Gulch (pCcg); Granite, leucogranite, & quartz monzonite (pCg); Granophyre (pCgr); Porphyritic granite (pCpg); Quartz veins (pCqv), Trachyte Dikes (pCt); Powderhorn Granite (pCpo); Granite of Tovlar Peak (pCtp); Quartz Diorite- to- Monzonite of Gold Basin (pCgb); Lamprophyre (pCl); Pitts Meadow Granodiorite (pCpm); Lightcolored, gneissic granodiorite or quartz diorite (pCpm): Darkcolored, gneissic granodiorite or quartz diorite (pCpv); Granite of South Beaver Creek (pCsb); Granite to grano- diorite ((pCsb); Granite to quartz monzonite porphyry (pCsbp); Diorite or Quartz Diorite (pCqd); Quartzite & metachert (pCqt); Black Canyon Schist & Gneiss (pCb); Schist and gneiss, undifferentiated (pCsg); Amphibolite (pCa); Quartz- biotite gneiss & migmatite (pCbt); Quartzofeldspathic gneiss (pCf); Migmatitic gneiss (pCgm); Layered quartzitic gneiss (pCgl); Massive quartzitic gneiss (pCgq); Hornblende schist & amphibolite (pCh); Mica schist (pCm); Quartzofeldspathic & quartz- sericite schist (pCqf); Quartzite (pCqt); Quartz- biotite schist, gneiss & migmatite (pCs); Dubois Greenstone (pCdb); Quartz- biotite- calcite schist (pCdb); Amphibolite, metadiorite, & metagabbro (pCda); Amphibolitegranite hybrid rock of Carpenter Gulch (pCdag); Quartzite conglomerate (pCdc); Felsite & felsite porphyry (pCdf), Metavolcanic hornblende schist & amphibolite (pCdh); Quartzite (pCdq), Quartz- sericite schist & quartzite (pCdqs); Interlayered greenstone & metasedimentary rocks (pCds) 

Granites, diorites, syenites, quartz monzonite, gabbros, pegmatites, gneisses and other assorted metamorphic and intrusive igneous rocks; Specific unit descriptions are too lengthy to include here, please refer to BLCAGLG.hlp for detailed information about each unit listed. BLCAGLG.hlp (Windows help file) is included on CD with digital geologic map coverages 

High 

Steep slopes: inaccessible for development 

Some rockfall potential None None 
 BLCA-CURE Geologic Resource Evaluation Report 17

Figure 4: View of the Precambrian rock walls forming Black Canyon of the Gunnison. Photograph by Trista L. Thornberry-Ehrlich,

Colorado State University. 
 NPS Geologic Resources Division 18 

Geologic History 

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

in Black Canyon of the Gunnison National Park and Curecanti National Recreation 

Area 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. 

Preserved Precambrian history began in the Colorado 

Plateau – Rocky Mountain area in the Proterozoic about 

1,800 – 2,000 million years ago (Ma) when muddy 

sandstones (graywacke), shales, and volcanic rocks were 

deposited in a vast oceanic environment. Erupting 

volcanoes formed a chain of islands in this ancient ocean 

beyond the southern edge of the North American craton 

(Reed et al., 1987; Scott et al., 2001). It was in a back- arc 

basin that volcanic and sedimentary deposits collected 

between 1,710 and 1,740 Ma. This collection of deposits 

would later comprise the Black Canyon Precambrian 

terrane, one of four early Proterozoic terranes identified 

in Colorado (Knoper et al., 1987) 

About 1,740 Ma a period of compressive mountain 

building folded the Precambrian strata into tight, 

chevron- like folds and metamorphosed the rocks to 

gneisses as the volcanic islands collided with the 

southern end of what is now Wyoming (Hutchinson, 

1976; Tweto, 1980; Warner, 1980; Gregson, 1992; Scott et 

al., 2001). Metamorphosed sedimentary and volcanic 

rocks over 1,800 million years old are present in exposed 

terranes throughout Colorado and in the buried 

basement of the Colorado Plateau (Tweto, 1980). 

Gneisses, schists, granites, pegmatites, and other rocks 

that dominate the walls of Black Canyon are all 

Precambrian in age. 

Late Proterozoic rifting created a new continental 

margin along western North America. During the Late 

Precambrian and Cambrian, deposits of shallow- water, 

marine sediments thousands of feet thick accumulated 

along a passive plate- tectonic margin on the western side 

of the Transcontinental Arch. The arch was an upland 

that stretched from northern Minnesota southwestward 

across Nebraska, Colorado and northwestern New 

Mexico (Speed, 1983; Sloss, 1988). 

Throughout the Paleozoic Era, Africa, and South 

America were approaching North America as the two 

great landmasses, Laurasia and Gondwana, collided. The 

ancient continent of Gondwana included Australia, 

Antarctica, Africa, South America, and India south of the 

Ganges River, plus smaller islands. Laurasia, located in 

the northern hemisphere contained the present northern 

continents. The union of Gondwana and Laurasia 

formed the supercontinent, Pangaea, which was 

centered on the equator. 

What happened geologically in the Ordovician Period 

(438- 505 Ma) and the Silurian Period (408- 438 Ma) in 

southwestern Colorado remains somewhat of a mystery 

because no Ordovician or Silurian rocks are present 

there today. It is known that the end of the Ordovician 

Period (438 Ma) marks one of the five most extensive 

mass extinctions of all time (see Figure 11). 

The other four occurred at the end of the Devonian 

Period, the end of the Permian Period, at the close of the 

Triassic, and most recently at the Cretaceous – Tertiary 

boundary. There is a significant period of time missing 

from the rock record at Black Canyon where 

Precambrian rocks are covered by Mesozoic age rocks. 

This juxtaposition means more than 370 million years of 

the rock record is missing in central Colorado. The 

following brief discussion draws from areas surrounding 

Black Canyon – Curecanti where the rock record is more 

complete. 

By the beginning of the Devonian Period, the seas that 

had covered most of the continent had receded far to the 

west. The first pulses of the Antler orogeny in the west 

and the Acadian orogeny in the east (part of the 

Appalachian orogeny) began to be felt as landmasses 

accreted onto both the western and eastern borders of 

North America. To the west of Colorado, a subduction 

zone formed. As lithospheric plates collided their rocks 

were bent, folded, and thrust- faulted into a north- south 

trending mountain range stretching from Nevada to 

Canada. The Roberts Mountains Thrust marks the 

easternmost thrust sheets generated by the Antler 

orogeny (figure 5). 

As the highlands to the west were thrust above sea level 

at the beginning of the Mississippian Period, warm 

marine water gave rise to extensive deposits of carbonate 

rocks (figure 6) (De Voto, 1980A; Poole and Sandberg, 

1991). The structural effects of compression on the 

western margin, however, were evident as far inland as 

southwestern Colorado where local uplifts caused 

regression and erosion. Aggressive tectonism in the 

Pennsylvanian Period built mountains (the Ancestral 

Rocky Mountains) in Colorado with as much as 3,000 m 

(10,000 ft) of relief (De Voto, 1980B). 

The Permian was a time of worldwide changing 

environments. In the area southwest of Black Canyon - 

Curecanti, beyond the Uncompahgre Mountains, broad 

lowlands extended toward an ocean to the west (Baars, 

2000). The close of the Permian also brought the third, 

and most severe, major mass extinction of geologic time. 

(Becker et al., 2001). It is hypothesized that a large comet 

colliding with the earth wiped out 300 million years of 

history. 
 BLCA-CURE Geologic Resource Evaluation Report 19

In the Early Triassic (240 to 245 Ma), volcanic activity 

decreased on the western margin of the supercontinent 

(Christiansen et al., 1994). The depositional 

environments in the Early Triassic represent a transition 

from marine and marginal marine environments in 

western Utah and Nevada to terrestrial (above sea level) 

environments in western Colorado. 

Throughout the Early Triassic the region around Black 

Canyon - Curecanti remained above sea level and red 

beds (rocks of terrestrial origin with relatively high iron 

contents) were deposited over the area (figure 7) 

(Stewart et al., 1972A; Christiansen et al., 1994; Doelling, 

2000; Huntoon et al., 2000). 

As Pangaea began to break apart in the late Triassic and 

early Jurassic, the monsoonal climate changed. The 

Western Interior of North America was slowly rotating 

into a position farther north of the equator. Soon, the 

Colorado Plateau – Rocky Mountain region was to 

become a Sahara- like desert. 

The mesas on the North Rim of Black Canyon along 

Highway 92 in Curecanti reveal exposures of rocks 

deposited during the Mesozoic. Just downstream of 

Black Canyon the thin strip of pink or yellow rock 

present at the northern lip of the canyon is the Entrada 

Sandstone. This rock formed when massive sand dunes 

covered much of this region. Extensive eolian sand seas, 

called ergs, blew across the Colorado Plateau during the 

Lower Jurassic (figure 8). The region was located about 

18o

 north latitude at the beginning of the Jurassic and 

about 30- 35o north latitude at the end of the Jurassic 

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

latitude of the trade wind belt. 

The western edge of the continent was marked by a 

continental- margin volcanic arc, a product of 

subduction processes that began during the Triassic 

(Dubiel, 1994) and reached its maximum development in 

the Cretaceous. At the beginning of the Middle Jurassic 

Period, the western Elko highlands emerged to the west 

of the Utah- Idaho trough recording an irregular, pulsed 

orogeny (Peterson, 1994). 

Middle Jurassic strata in the area represent a complex 

interfingering of marine and nonmarine environments. 

The sediments were deposited during five major 

transgressive- regressive cycles (Peterson, 1994). A 

picture emerges of broad tidal flats marginal to a shallow 

sea that lay to the west (Wright et al., 1962). As plate 

tectonic activity increased at the end of the Middle 

Jurassic and beginning of the Late Jurassic (about 157 

Ma), a major transgression of the inland seaway covered 

the vast eolian dune fields of the Colorado Plateau region 

(Kocurek and Dott, 1983). Tidal flats covered the area as 

marine environments pushed south and the extensive 

Upper Jurassic, Morrison Formation was deposited 

across the continental Western United States (figure 9). 

Morrison depositional environments were quite varied. 

Sediments were deposited in mudflats, overbank 

floodplains, stream channels, small eolian sand fields, 

and scattered lakes and ponds (Peterson, 1994). The best 

place to find the Morrison Formation in Black Canyon – 

Curecanti is along the shore of Blue Mesa Reservoir. 

During the Jurassic, the subducting oceanic slab (named 

the Farallon plate - precursor to the Pacific plate) sliding 

eastward beneath the continental lithosphere is thought 

to have changed its angle of descent becoming steeper. 

This change caused the volcanic arc to shift its position 

farther to the west near the present- day border of 

California and Nevada. The late Jurassic and earliest 

Cretaceous magmatic activity associated with this 

volcanic arc is known as the Nevadan orogeny. The 

Nevadan orogeny spread volcanic ash across the 

Colorado Plateau and evolved into the late Cretaceous 

Sevier orogeny as the rate of lithospheric plate 

movement increased. 

The Sevier orogeny formed a roughly north- south 

trending thrust belt that is well defined in present- day 

southern Nevada, central Utah, and western Montana 

(figure 10). A series of eastward- directed overthrusts 

carried upper Precambrian and lower Paleozoic 

sedimentary rocks over upper Paleozoic and lower 

Mesozoic rocks (Stewart, 1980). 

As mountains rose to the west and the roughly northsouth foreland trough expanded, the Gulf of Mexico 

separating North and South America continued to rift 

open in the south, and marine water began spilling into 

the basin. At the same time, marine water began to 

transgress from the Arctic region. The sea advanced, 

retreated, and readvanced many times during the 

Cretaceous until the most extensive interior seaway ever 

to cover the continent drowned much of western North 

America. The Western Interior Seaway was an elongate 

basin that extended from today’s Gulf of Mexico to the 

Arctic Ocean, a distance of about 4,827 km (3,000 mi) 

(Kauffman, 1977). During periods of maximum 

transgression, the width of the basin was 1,600 km (1,000 

mi). The basin was relatively unrestricted at either 

terminus (Kauffman, 1977). 

Deposited above the Jurassic Morrison is the Cretaceous 

Dakota Sandstone. This buff- colored rock forms 

prominent outcrops in the roadcuts along Highway 50 

just west of Elk Creek. Coarse conglomeratic sandstones, 

cross- stratification, petrified wood fragments, and 

erosional topography are characteristic of the lower 

Dakota Sandstone in the Black Canyon – Curecanti area. 

This suggests that the sediments were deposited by 

fluvial processes in paleovalleys (Ekren and Houser, 

1965; Condon, 1991; Elder and Kirkland, 1994). 

At the beginning of Late Cretaceous time, the interior 

seaway had advanced to cover the eastern third of the 

Colorado Plateau. Gradually, as sea level rose, the soft, 

sparsely fossiliferous, dark- gray muds of the Mancos 

Shale were deposited in the deepening basin above the 

Dakota Sandstone. 
 NPS Geologic Resources Division 20 

By the end of the Cretaceous, tectonic plates were 

jockeying for position on the western margin of the 

North American continent. From late Jurassic to late 

Cretaceous plutons, of the Sierra Nevada batholith, were 

emplaced beneath the Sierra Nevada Mountains. 

Granitic plutons were developing in a southwestnortheast trend from southwestern Colorado to northcentral Colorado (Christiansen et al., 1994). The 

rearrangement of tectonic plates gave rise to the 

Laramide orogeny, the mountain- building episode that 

began the development of the modern Rocky 

Mountains. 

The Laramide orogeny began approximately 66 to 70 

million years ago, in the late Cretaceous, and continued 

intermittently until between 35 and 50 million years ago. 

The Laramide event transformed the extensive basin of 

the Cretaceous Interior Seaway into smaller interior 

basins bordered by high arches (anticlines and synclines 

on the scale of miles). The Gunnison uplift is an example 

of one of those arches. North of the Colorado Plateau, 

the stresses caused by colliding plates to the west forced 

several Precambrian crustal wedges upwards, forming 

the Colorado Front Range and the Southern Rocky 

Mountains. However, the Colorado Plateau region 

appears to have reacted as a single block to the crustal 

forces that buckled the rest of the central Rocky 

Mountains as the sedimentary strata on the Colorado 

Plateau were warped into broad anticlinal and synclinal 

folds with very little brittle faulting (Dickinson and 

Snyder, 1978; Chapin and Cather, 1983; Hamilton, 1988; 

Erslev, 1993). 

In some areas Laramide mountain building was 

accompanied by volcanic eruptions and magma 

emplacement. Tertiary volcanism deposited vast blankets 

of material in the Black Canyon area and is responsible 

for one of the most notable geologic features in 

Curecanti National Recreation Area, the Dillon 

Pinnacles. The Dillon Pinnacles, composed of 30 million 

year old West Elk Breccia, tower above the northern 

shore of Blue Mesa's Sapinero Basin. The West Elk 

Breccia formed as a result of a huge volcanic mud flow of 

ash and volcanic debris that spewed from violent 

eruptions in the West Elk Mountains. 

The West Elk Mountains were among several centers of 

igneous activity during the Tertiary. From about 26- 35 

Ma, in the Oligocene epoch, volcanic activity erupted 

across the region. The laccoliths that formed the Henry 

Mountains, La Sal Mountains, and Abajo Mountains 

were emplaced during the mid- Tertiary. A series of 

volcanic ash flows from the San Juan Mountains covered 

much of southern Colorado. 

The burning- hot ash and glass shards of these flows 

welded together to form a dense, resistant rock known as 

welded tuff. Today this serves as a resistant cap rock on 

the mesas of Curecanti National Recreation Area. 

A period of volcanic quiescence followed from about 16 

to 19 Ma. During this time, the western United States 

underwent a radical tectonic transformation wherein the 

compressional regime that had existed for millions of 

years became an extensional regime. As the crust was 

extended, the surface broke into the basin- and- range, 

block- faulted topography we see today in western Utah 

and Nevada. Extensional faulting and basaltic volcanism 

in the western United States continues into the present. 

The Tertiary uplift and volcanism established the 

headwaters for the Gunnison River. Snowmelt from the 

Sawatch Range to the east, the West Elk Mountains to 

the north and the San Juan Mountains to the south began 

to supply water to what would become the Gunnison 

Basin. The modern Gunnison River first established its 

current course 10 to 15 million years ago. During the 

uplift of the Colorado Plateau, between 5 and 10 Ma, the 

river cut through the thick layers of Tertiary volcanics 

and Mesozoic sedimentary rocks (Hintze, 1988). 

Early in the Quaternary (2- 3 Ma) a broad uplift of the 

entire region initiated another period of active erosion. It 

is at this point in geologic history that the profound 

scouring of the Black Canyon is thought to have 

occurred. Constrained in its own canyon of Tertiary and 

Mesozoic rocks, the river began to incise its bed, 

exposing the much harder Precambrian metamorphic 

and igneous rocks of the eroded Laramide age Gunnison 

Uplift. At the rate of approximately one inch per 

hundred years, the high volume, high- velocity Gunnison 

River slowly worked its way through the tough rock, as it 

carved the narrow, steep- sided Black Canyon. 

During the cooler, more humid climates of Pleistocene 

glaciation, streams cut headward into canyons, 

developing the drainage pattern seen today in the 

Colorado Plateau – Rocky Mountain area. Meltwater 

from glaciers brought more gravel deposits into the area. 

Spring meltwater continues to feed the Gunnison today 

as it winds through both parks. Today, the climate is 

drier and the Gunnison River no longer flows freely 

through the canyon. The three dams of Curecanti hold 

back the Gunnison’s yearly floods reducing erosion rates 

in the canyon. 
 BLCA-CURE Geologic Resource Evaluation Report 21

Figure 5: Distribution of lithofacies during the Upper Devonian, Frasnian stage of western United States. The red line is the strontium 

isotope line wherein 87Sr/86Sr = 0.706 and is interpreted to represent the break between continental and oceanic crust. Modified from 

Johnson et al., 1991. 
 NPS Geologic Resources Division 22 

Figure 6: Lithofacies map of the Lower Mississippian Period, Kinderhookian stage of the Western United States. While the lithofacies 

are complex in the foreland basin adjacent to the Antler orogenic highland, a broad carbonate platform developed to the east. Marine 

water breached the Transcontinental Arch through the Paleozoic Strait. Any Mississippian rocks that were deposited on the 

transcontinental Arch or ancestral Uncompahgre highland during this time have been eroded. Modified from Poole and Sandberg, 

1991. 
 BLCA-CURE Geologic Resource Evaluation Report 23

Figure 7: Paleogeographic map of the Lower Triassic, Moenkopi Formation during the second transgressive episode of the Early 

Triassic. Modified from Dubiel, 1994. 
 NPS Geologic Resources Division 24 

Figure 8: Paleogeographic map of the Lower Jurassic Period. Thick arrows indicate eolian transport of sand. Thin arrows indicate 

fluvial transport of sediments. Inverted “Vs” indicate the location of the volcanic arc. Solid triangles indicate the location of the 

subduction zone with the triangles on the overriding, upper lithospheric plate. Modified from Lawton (1994). 
 BLCA-CURE Geologic Resource Evaluation Report 25

Figure 9: Upper Jurassic Period paleogeography. Thin arrows indicate fluvial dispersal. Thick arrows indicate wind directions.

Sawteeth indicate the location of the subduction zone with the teeth on the overriding lithospheric plate. A marine environment

possibly covered continental environments to the east. The alluvial plain expanded to the east with time. Modified from Lawton (1994). 
 NPS Geologic Resources Division 26 

Figure 10: Location of Black Canyon of the Gunnison National Park and Curecanti National Recreation Area on a tectonic map of the 

Laramide foreland. The map illustrates the anastamosing nature of the basement-cored arches (regional-scale anticlines) and the

spatial relationships with the adjacent thrust belt, Colorado Plateau, and North American craton. From Gregson and Chure, 2000. 
 BLCA-CURE Geologic Resource Evaluation Report 27

Figure 11: Geologic Time Scale - Red lines indicate major unconformities between eras. Included are major events in life history and 

tectonic events occurring North American continent. Absolute ages shown are in millions of years and are from the United States

Geological Survey (USGS) time scale found at: http://geology.wr.usgs.gov/docs/usgsnps/gtime/timescale.html. 
 NPS Geologic Resources Division 28 

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. 

Baars, Donald L., 2000, The Colorado Plateau: 

University of New Mexico press, Albuquerque, NM, 

254 p. 

Becker, Luann, Poreda, Robert J., Hunt, Andrew G., 

Bunch, Theodore E., and Rampino, Michael, 2001, 

Impact event at the Permian- Triassic boundary: 

Evidence from extraterrestrial noble gases in 

fullerenes, in Science, Feb. 23, p. 1530- 1533. 

Boettcher, A.J., 1971, Evaluation of the Water Supply at 

Six Sites in the Curecanti Recreation Area, 

Southwestern Colorado. U.S. Geological Survey, Open 

File Report 71005, 28 p. 

Chapin, Charles, E. and Steven M. Cather, 1983, Eocene 

tectonics and sedimentation in the Colorado Plateau – 

Rocky Mountain area, in James Lowell, ed., Rocky 

Mountain Foreland Basins and Uplifts: Rocky 

Mountain Association of Geologists, Denver, CO., p. 

33- 56. 

Christiansen, Eric II, Kowallis, Bart J., and Barton, Mark 

D., 1994, Temporal and spatial distribution of volcanic 

ash in Mesozoic sedimentary rocks of the Western 

Interior: an alternative record of Mesozoic 

magmatism, in Mario V. Caputo, James A. Peterson, 

and Karen J. Franczyk, eds., Mesozoic Systems of the 

Rocky Mountain Region, USA: Rocky Mountain 

Section, SEPM (Society for Sedimentary Geology), 

Denver, CO., p. 73- 94. 

Condon, Steven, M., 1991, Geologic and structure 

contour map of the Ute Mountain Ute Indian 

Reservation and adjacent areas, southwest Colorado 

and northwest New Mexico: USGS Map I- 2083, 

Scale: 1:100,000. 

De Voto, R. H., 1980A, Mississippian stratigraphy and 

history of Colorado, in Harry C. Kent and Karen W. 

Porter, eds., Colorado Geology: Rocky Mountain 

Association of Geologists, p. 57- 70. 

De Voto, R. H., 1980B, Pennsylvanian stratigraphy and 

history of Colorado, in Harry C. Kent and Karen W. 

Porter, eds., Colorado Geology: Rocky Mountain 

Association of Geologists, p. 71- 102. 

Dickinson, W. R., and Snyder, W.S., 1978, Plate tectonics 

of the Laramide Orogeny, in V. Matthews III, ed., 

Laramide folding associated with basement block 

faulting in the western United States: Geological 

Society of America, Memoir 151, p. 355- 366. 

Doelling, Hellmut H., 2000, Geology of Arches National 

Park, Grand County, 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. 11- 36. 

Dubiel, R. F., 1994, Triassic deposystems, 

paleogeography, and paleoclimate of the Western 

Interior, in Mario V. Caputo, James A. Peterson, and 

Karen J. Franczyk, eds., Mesozoic Systems of the 

Rocky Mountain Region, USA: Rocky Mountain 

Section, SEPM (Society for Sedimentary Geology), 

Denver, CO., p. 133- 168. 

Ekren, E.B. and Houser, F.N., 1965, Geology and 

petrology of the Ute Mountains area, Colorado: 

U.S.G.S. Professional Paper 481, scale 1:48,000. 

Elder, William P. and Kirkland, James I., 1994, 

Cretaceous paleogeography of the southern Western 

Interior Region, in Mario V. Caputo, James A. 

Peterson, and Karen J. Franczyk, eds., Mesozoic 

Systems of the Rocky Mountain Region, USA: Rocky 

Mountain Section, SEPM (Society for Sedimentary 

Geology), Denver, CO., p. 415- 440. 

Elliott, J.G., Hammack, L.A., 1999, Geomorphic and 

Sedimentologic Characteristics of Alluvial Reaches in 

the Black Canyon of the Gunnison National 

Monument, Colorado. U.S. Geological Survey, WaterResources Investigations Report 99- 4082, 67 p. 

Erslev, E. A., 1993, Thrusts, back- thrusts, and 

detachment of Rocky Mountain foreland arches, in C. 

J. Schmidt, R. B. Chase, and E. A. Erslev, eds., 

Laramide Basement Deformation in the Rocky 

Mountain Foreland of the Western United States: 

Geological Society of America, Special Paper 280, p. 

339- 358. 

Goodknight, C.S., 1981, Uranium in the Gunnison 

Country, Colorado, in New Mexico Geological Society 

Guidebook, 32nd Field Conference, Western Slope 

Colorado, Epis, R.C., Callender, J.F., eds, p. 183- 190. 

Gregson, J., 1992, Geology and tectonics of the Ancestral 

Uncompahgre Uplift and the Colorado Orogeny, in

Joe D. Gregson, ed., Uncompahgria Journal: Mesa 

State Geology Department, Grand Junction, Colorado, 

p. 19- 46. 
 BLCA-CURE Geologic Resource Evaluation Report 29

Hamilton, W. B., 1988, Laramide crustal shortening, in

C.J. Schmidt and W.J. Perry, Jr., eds., Interaction of the 

Rocky Mountain foreland and the Cordilleran thrust 

belt: Geological Society of America, Memoir 171, p. 27-

39. 

Hansen, W.R., 1964, Curecanti Pluton, an Unusual 

Intrusive Body in the Black Canyon of the Gunnison, 

Colorado. Geological Survey Bulletin 1181- D, 15 p. 

Hansen, W.R., 1965, The Black Canyon of the Gunnison 

Today and Yesterday: U.S. Geological Survey Bulletin 

1191, 76 p. 

Hedlund, D.C., and Olson, J.C., 1975, Geologic map of 

the Powderhorn Quadrangle, Gunnison and Saguache 

counties, Colorado: U.S. Geological Survey, 

Geological Quadrangle Map GQ- 1178, 1:24,000 scale. 

Hedlund, D.C., and Olson, J.C., 1981, Precambrian 

Geology along parts of the Gunnison Uplift of 

Southwestern Colorado, in New Mexico Geological 

Society Guidebook, 32nd Field Conference, Western 

Slope Colorado, Epis, R.C., Callender, J.F., eds, p. 267-

272. 

Hintze, L.F., 1988, Geologic history of Utah: Brigham 

Young University Studies Special Publication 7, 202 p. 

Huntoon, J. E., Stanesco, J. D., Dubiel, Russell F., and 

Dougan, J., 2000, Geology of Natural Bridges National 

Monument, 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. 233- 250. 

Hutchinson, R. M., 1976, Precambrian geochronology of 

western and central Colorado and southern Wyoming, 

in R. C. Epis and R. J. Weimer, eds., Studies in 

Colorado Field Geology: Professional Contributions, 

Colorado School of Mines, p. 73- 77. 

Kauffman, E. G., 1977, Geological and biological 

overview: Western Interior Cretaceous Basin: 

Mountain Geologist, v. 14, p. 75- 99. 

Knoper, M. W; Condie, K. C; Thacker, M.; Lanzirotti, A, 

1987, Early Proterozoic tectonic history in Colorado. 

Program with Abstracts - Geological Association of 

Canada; Mineralogical Association of Canada; 

Canadian Geophysical Union, Joint Annual Meeting, 

vol.12, p.63. 

Kocurek, G. and Dott, R. H. Jr., 1983, Jurassic 

paleogeography and paleoclimate of the central and 

southern Rocky Mountain region, in Mitchell W. 

Reynolds and Edward D. Dolly, eds., Mesozoic 

Paleogeography of the West- Central United States: 

Rocky Mountain Section, SEPM (Society for 

Sedimentary Geology), Denver, CO., p. 101- 118. 

Johnson, J.G., Sandberg, Charles A., and Poole, Forrest 

G., 1991, Devonian lithofacies of western United States, 

in John D. Cooper and Calvin H. Stevens, eds., 

Paleozoic Paleogeography of the Western United 

States – II: Society of Economic Paleontologists and 

Mineralogists (SEPM), Pacific Section, p. 83- 106. 

Lawton, Timothy F., 1994, Tectonic setting of Mesozoic 

sedimentary basins, Rocky Mountain region, United 

States, in Mario V. Caputo, James A. Peterson, and 

Karen J. Franczyk, eds., Mesozoic Systems of the 

Rocky Mountain Region, USA: Rocky Mountain 

Section, SEPM (Society for Sedimentary Geology), 

Denver, CO., p. 1- 26. 

Olson, J.C., and Wallace, S.R., 1956, Thorium and rareearth minerals in Powderhorn district, Gunnison 

County, CO: U.S. Geological Survey Bulletin 1027- 0, p. 

693- 723. 

Peterson, Fred, 1994, Sand dunes, sabkhas, stream, and 

shallow seas: Jurassic paleogeography in the southern 

part of the Western Interior Basin, in Mario V. Caputo, 

James A. Peterson, and Karen J. Franczyk, eds., 

Mesozoic Systems of the Rocky Mountain Region, 

USA: Rocky Mountain Section, SEPM (Society for 

Sedimentary Geology), Denver, CO., p. 233- 272. 

Poole, F.G., and Sandberg, C.A., 1991, Mississippian 

paleogeography and conodonts biostratigraphy of the 

western United States, in John D. Cooper and Calvin 

H. Stevens, eds., Paleozoic Paleogeography of the 

Western United States: Pacific Section, Society of 

Economic Paleontologists and Mineralogists (SEPM), 

v. 2, p. 107- 136. 

Reed, J. C., Jr., Bickford, M. E., Premo, W. R., Aleinikoff, 

J. N., and Pallister, J. S., 1987, Evolution of the Early 

Proterozoic Colorado province: Constraints from UPb geochronology: Geology, v. 15, p. 861- 865. 

Scott, R. B., Harding, A. E., Hood, W. C., Cole, R. D., 

Livaccari, R. F., Johnson, J. B., Shroba, R. R., 

Dickerson, R. P., 2001, Geologic map of Colorado 

National Monument and adjacent areas, Mesa County, 

Colorado: U.S. Geological Survey, Geologic 

Investigations Series I- 2740, 1:24,000 scale. 

Sloss, L.L., 1988, Tectonic evolution of the craton in 

Phanerozoic time, in L.L. Sloss, ed., Sedimentary 

Cover – North American Craton: U.S.: Geological 

Society of America, Geology of North America, Vol. 

D- 2, p. 25- 52. 

Speed, R.C., 1983, Evolution of the sialic margin in the 

central western United States, in J.S. Watkins and C.L. 

Drake, eds., Studies in continental margin geology: 

American Association of Petroleum Geologists 

Memoir 34, p. 457- 468. 
 NPS Geologic Resources Division 30 

Stewart, J.H., Poole, F.G., and Wilson, R.F., 1972A, 

Stratigraphy and Origin of the Triassic Moenkopi 

Formation and related Triassic strata in the Colorado 

Plateau region: U.S.G.S. Professional Paper 691, 195 p. 

Stewart, J. H., 1980, Geology of Nevada: Nevada Bureau 

of Mines and Geology, Special Publication 4, 136 p. 

Tweto, O., 1980, Precambrian geology of Colorado, in

Harry C. Kent and Karen W. Porter, eds., Colorado 

Geology: Rocky Mountain Association of Geologists, 

p. 37- 46. 

Warner, L.A., 1980, The Colorado Lineament, in H.C. 

Kent and K.W. Porter, eds., Colorado Geology: Rocky 

Mountain Association of Geologists, Denver, p. 11- 22. 

Wright, J.C., Shawe, D.R., and Lohman, S.W., 1962, 

Definition of members of Jurassic Entrada Sandstone 

in east- central Utah and west- central Colorado: 

American Association of Petroleum Geologists 

Bulletin, v. 46, no. 11, p. 2057- 2070. 
 BLCA-CURE Geologic Resource Evaluation Report 31

Appendix A: Geologic Map Graphic

This image provides a preview or “snapshot” of the geologic map for Black Canyon of 

the Gunnison National Park and Curecanti National Recreation Area. For a detailed 

digital geologic map, see included CD. 

Numerous original maps were digitized by NPS staff to create this product. Source maps are cited in full in the metadata 

accompanying the digital geologic map on the included CD. 
 NPS Geologic Resources Division 32 
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. 

Black Canyon of the Gunnison National Park & 

Curecanti National Recreation Area 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2005/001 

NPS D-105, January 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 • Sid Covington and Melanie Ransmeier 

Digital Map Production • Stephanie O’Meara and Anne Poole 

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 

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U.S. Department of the Interior