Rocky Mountain National Park 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2004/004 

National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 
THIS PAGE: 

Ypsilon Mountain, Rocky Mountain NP. 

ON THE COVER: 

Alpine Tundra looking west to the Never Summer 

Range, Rocky Mountain NP 

Photos by: NPS and Josh Heise 
Rocky Mountain National Park 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2004/004 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

September 2004 

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: 

KellerLynn, K. 2004. Rocky Mountain National Park Geologic Resource Evaluation Report. 

Natural Resource Report NPS/NRPC/GRD/NRR—2004/004. National Park Service, Denver, 

Colorado. 

NPS D-307, September 2004 
 ROMO Geologic Resource Evaluation Report iii 

Table of Contents 

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

Dedication and Acknowledgements............................................................................ 2

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

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

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

Geologic Issues............................................................................................................. 5

Alpine Environments...................................................................................................................................................5

Flooding......................................................................................................................................................................5

Hydrogeology .............................................................................................................................................................6

Mass Wasting.............................................................................................................................................................7

Minerals and Mining ...................................................................................................................................................8

Seismicity ...................................................................................................................................................................9

Water Diversion Projects ..........................................................................................................................................10

Wind-Blown Sediment ..............................................................................................................................................10

Potential Research, Inventory, and Monitoring Projects ...........................................................................................11

Geologic Features and Processes............................................................................. 14

Colorado River..........................................................................................................................................................14

Columnar Jointing.....................................................................................................................................................14

Exfoliation Domes and Ornate Erosion Features......................................................................................................14

Glacial Features .......................................................................................................................................................14

Glaciers ....................................................................................................................................................................15

Lakes........................................................................................................................................................................16

Meandering Streams ................................................................................................................................................16

Patterned Ground.....................................................................................................................................................16

Sackung ...................................................................................................................................................................17

Solifluction ................................................................................................................................................................17

Tors ..........................................................................................................................................................................17

Uplifted Erosion Surface...........................................................................................................................................17

Formation Properties.................................................................................................. 19

Formation Properties Table ......................................................................................................................................20

Geologic History.......................................................................................................... 23

References Cited......................................................................................................... 26

Appendix A: Geologic Map Graphic .......................................................................... 30

Appendix B: Evaluation of Comprehensive Interpretive Plan (2001)...................... 31

Attachment 1: Digital Geologic Map (CD) 
iv NPS Geologic Resources Division 
 ROMO Geologic Resource Evaluation Report 1 

Executive Summary 

The geologic features of Rocky Mountain National Park have long been under the careful 

scrutiny of many geologists. From their studies a great deal is known of the history, which is 

full of interesting events and shifting scenes. The park’s long geologic story continues today 

with geologic processes changing the present landscape. 

Three compelling stories encapsulate the nearly twobillion- year- old history of the park. The first story takes 

place during Precambrian time. This tale highlights the 

themes of “deep time” and understanding the origins of 

our physical surroundings, and perhaps our place in the 

world. The ancient metamorphic and igneous rocks—

most of which are between 1.4 and 1.7 billion years old—

in the park serve as a physical backdrop for this story. 

The second story is much more recent. Between 23 and 

29 million years ago, during the Oligocene Epoch the 

park was the scene of widespread volcanic activity. As 

uplift of the region continued throughout the Tertiary 

Period, volcanoes erupted, ash filled the air, faults 

formed, and granitic magma intruded what are now the 

Never Summer Mountains. The tale provides a sense of 

shifting scenes throughout time. A hike through Little 

Yellowstone on the west side of the park serves as a 

backdrop for this story. There are also roadside locations 

for telling this story, such as Lava Cliffs and Gore Range 

Overlook. 

The third story is an ice age one. The story of glaciation 

in Rocky Mountain National Park is still unfolding. The 

main characters left quite a bit of evidence, but geologists 

are still working out the timing of events. Two major 

valley glaciations, a smaller cirque glaciation, and periods 

of ice accumulation are recorded in the park. The two 

Pleistocene glaciations, Bull Lake and Pinedale, 

produced the rugged look of the topographic features of 

today’s high country. Many of the distinctive geologic 

features found throughout the park have a glacial origin. 

(See Geologic Features and Processes section of this 

report.) 

The park’s geologic story continues to the present, with 

human activities influencing natural processes. Park 

planning must address development in high alpine 

environments: frost cracking and solifluction are two 

processes that require attention. The particular 

hydrogeology of the park and associated floods, water 

quality, and wetlands are important issues for planning, 

visitor safety, protection of resources, and compliance 

with section 404 of the Clean Water Act and the NPS 

Director’s Order #77- 1 (the policy directive addressing 

wetland protection in the National Park System). 

Notably human activities have impacted the park’s 

hydrogeology more water diversion projects than all 

other national parks combined. 

Although addressed in the late 1980s and early 1990s, an 

understanding of the park’s mining history is important 

for resource protection and visitor safety. Managers have 

gated mine openings with bat- friendly (not visitorfriendly) entrances, but an awareness of the locations of 

minerals (and possibly fossils) is important for resource 

protection. 

Park managers may also wish to take note of areas 

susceptible to mass wasting, including landslides, debris 

flows, rockfalls, and snow avalanches, because of human 

influences on these processes and visitor safety. In some 

cases, such as the “Holzwarth debris flow,” human 

activities (i.e., the diversion of water in the Grand Ditch) 

are a likely influence on the lobate mass of material 

deposited on the west side of the Kawuneeche Valley. 

No single mechanism causes slope failure, but 

researchers suggest that freeze- thaw processes cause 

rockfalls that form talus deposits at the base of all steep 

slopes in the park. The combination of areal extent and 

visitor safely makes mass wasting a significant geologic 

issue for the park. 

Less conspicuous than talus, although no less important 

with respect to sediment distribution, is wind- blown 

detritus. Wind- blown sediment is the dominant 

sediment source for alpine lakes in Colorado (Caine, 

1974). Aeolian dust is transported through alpine 

hillslope systems and is stored in alpine lakes and tundra 

soils (Caine, 1986). In the context of the park’s close 

proximity to metropolitan areas of the Front Range, this 

information is significant with respect to incoming 

pollutants, such as nitrogen. 

Finally, although the park is in a zone of minor seismic 

hazard, similar to most mountainous areas in Colorado, 

the largest historical earthquake in Colorado occurred in 

the vicinity of Estes Park. This earthquake predates 

seismographs, so an estimated magnitude of 6.5 is based 

on the size of the area over which the earthquake was felt 

(Colorado Geological Survey, unpublished data, 1999). A 

large earthquake near the park could cause rockfalls and 

landslides, and changes in springs and streamflow 

(Geoindicators report, unpublished data, 2001). 
2 NPS Geologic Resources Division 

Dedication and Acknowledgements 

William Alfred Braddock 

February 3, 1929–January 1, 2003 

Bill Braddock’s professional career spanned more than 

40 years and combined his life- long interests of geologic 

structures, teaching and training students in the 

challenging area of field investigations, and hiking in the 

high country of Colorado’s Front Range. Bill’s research 

contributions include the Geologic Map of Rocky 

Mountain National Park and Vicinity, Colorado. 

Colleagues remember Bill as providing “guidance, 

counsel, and friendship,” as a “born teacher,” as “one of 

the best minds in the [University of Colorado Geology] 

department,” and one of the “best field geologists.” 

Bill’s desire and gift for teaching extended beyond his 36 

years at the University of Colorado, particularly in 

connection with his geologic studies in Rocky Mountain 

National Park. He volunteered countless hours over 

many years to provide geology training for seasonal 

interpreters, to lead field trips, to conduct geology 

seminars for the Rocky Mountain Nature Association, 

and to provide counsel to park resource managers on 

geologic matters. This report represents the last geologic 

review he provided. His dedication and concern for park 

science continued until his death and will be appreciated 

far beyond. 

Acknowledgements 

In addition to staff at the NPS Geologic Resource 

Division, the following individuals deserve to be 

acknowledged with respect to their assistance with this 

report. Thanks to Bill Braddock, Jim Cole, and Rich 

Madole for their guidance and input during the overall 

review of the report. Larry Martin and Vince Matthews 

provided information on the park’s hydrogeology and 

structural geology, respectively. Kevin C. “Casey” 

McKinney provided insight into the potentially 

fossiliferous outcrops of the Troublesome Formation in 

the park. Also, thanks to park staff members, Larry 

Frederick for the opportunity to review the park’s 

comprehensive interpretation plan with respect to 

geology, and Terry Terrill for providing information on 

the park’s research needs. 
 ROMO Geologic Resource Evaluation Report 3 

Introduction 

Geologic resources serve as the foundation of park ecosystems, as such an understanding 

of these resources is needed for informed decision making in parks. 

Purpose of the Geologic Resources Evaluation Program 

The 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. A geologic inventory is administered 

by the Geologic Resources Division through the 

Geologic Resource Evaluation (GRE) Program. The goal 

of the GRE Program is to provide each of the identified 

274 “natural area” parks with a digital geologic map, a 

geologic evaluation report, and a geologic bibliography. 

Each product is a tool to support the stewardship of park 

resources and each is designed to be user friendly to 

non- geoscientists. 

The GRE teams hold scoping meetings at parks to review 

available data on the geology of a particular park and to 

discuss the geologic issues in the park. During these 

meetings park staffs are afforded the opportunity to meet 

with experts on the geology of their park. Scoping 

meetings are usually held individually in each park, 

which permits a focused discussion and exploration of 

available information on a park’s resources. However, 

some scoping meetings involve multiple parks or an 

entire Vital Signs Monitoring Network to expedite the 

inventory process. 

Geologic Setting 

Looking west from Denver the Front Range rises from 

the plains in two giant steps: first the foothills that climb 

above the “Mile High City,” then the high alpine 

summits, 54 of which loom above 14,000 feet (4,267 m). 

The difference in elevation between the peaks and 

nearby lowlands is striking. The square- topped 

silhouette of Longs Peak (14,256 ft, 4,345 m), the highest 

mountain in Rocky Mountain National Park, is the 

northernmost “fourteener” (mountains that exceed 

14,000 feet above sea level) and towers 9,000 feet (2,743 

m) above the adjacent plain. Longs Peak, a mass of 

Precambrian Silver Plume Granite, has challenged 

climbers since 1868 when a small party, that included 

John Wesley Powell, made the first recorded ascent. The 

infamous Diamond of Longs Peak, which ranks as the 

largest, highest, and steepest wall in the Southern 

Rockies, remains alluring to technical rock climbers from 

around the world. 

The high country of the park consists of mountain peaks 

ranging in elevation from 11,000 to 14,000 feet (3,350 to 

4,270 m) above sea level that form the Continental 

Divide, Trail Ridge, the Mummy Range, and the Never 

Summer Mountains. In addition to their height, the age 

of the rocks that form the core of these mountains is 

impressive. Although not the oldest rock in the National 

Park System (Grand Teton National Park holds that 

honor), they are from the same geologic time span, the 

Precambrian, which contains the oldest rocks on Earth 

and harkens back to a time when Earth’s early crust and 

continents were forming. Volcanism formed much 

younger rocks (23 to 29 million years ago), which lie on 

the western slope of the park and constitute much of the 

Never Summer Mountains. 

Much of the high country consists of gently rolling 

topography into which glaciers have cut cirques and 

valleys. Although the rocks that comprise the range are 

ancient, the timing of its uplift makes the Southern 

Rockies geologic newcomers as compared to mountain 

ranges such as the Appalachians. Like the ranges that 

were here before them, the Rockies began their rise from 

the bed of an ancient sea, but in this case just 70 million 

years ago during a period of mountain building called the 

Laramide orogeny. The north- south trending Front 

Range is principally the result of Laramide mountain 

building, faulting, and subsequent erosion. Present- day 

relief was enhanced by additional uplift during Cenozoic 

time (the most recent geologic era). 

The Front Range contains some of the most accessible 

alpine scenery in the Southern Rockies. Rocky Mountain 

National Park preserves thousands of acres of mountain 

meadows, snow- fed streams, rolling alpine uplands, 

glacial moraines and valleys, volcanoes, lava, and ash. 

Trail Ridge Road traverses 50 miles (80 km) of rugged, 

mountain terrain between the resort communities of 

Estes Park and Grand Lake. The 11- mile (18- km) section 

of road that lies above tree line follows the Continental 

Divide and winds through periglacial environments 

covered by alpine tundra. More than 300 miles (483 km) 

of hiking trails provide access from roadways and 

trailheads to remote areas of the park. 

Rocks and deposits are the foundation of today’s scenery 

and record the geologic history and evolution of the 

park, which spans nearly two billion years. The evolution 

of the park’s landscape may be highlighted with these 

geologic events: 

Precambrian Time 

• Sediment deposited in an ancient sea (1,800 to 2,000 

million years ago) 

• Sedimentary and volcanic rocks metamorphosed into 

biotite schist and biotite gneiss (1,750 million years ago) 

• Intrusion of Boulder Creek Granordiorite (1,664 

million years ago) 
4 NPS Geologic Resources Division 

• Intrusion of granitic batholiths: Hagues Peak Granite 

(1,480 million years ago) and Silver Plume Granite 

(1,420 million years ago) 

• Intrusion of the Iron Dike (1,317 million years ago) 

• Erosion of mountains (1,300 to 500 million years ago) 

Paleozoic and Mesozoic Eras 

• Shallow sea covered the area (500 to 300 million years 

ago) 

• Accumulation of marine sediments on beveled 

Precambrian mountains 

• Intrusion of kimberlites (probably during the 

Devonian Period, 417 to 354 million years ago) 

• Formation of the Ancestral Rocky Mountains (300 

million years ago) and erosion of pre- Mississippianage cover 

• Intermittent inundation by seas (Permian to 

Cretaceous, 286 to 65 million years ago) 

• Deposition of marine, fluvial, and aeolian deposits 

• Beginning of Laramide orogeny (70 million years ago, 

Late Cretaceous) 

• Withdrawal of seas 

Cenozoic Era 

• Laramide orogeny continues (including uplift, 

volcanism, erosion, fluvial deposition) 

• Ongoing erosion (Mesozoic strata stripped away, 

exposing Precambrian rocks) 

• Intrusion of granitic magmas and eruption of lava 

flows and ash (29 to 23 million years ago) 

• Continued erosion; uplift, broad up- arching, and 

block faulting 

• Canyon cutting (continues to present) 

• Global climate cooling (beginning timing unknown, 

possibly about 2.5–2.6 million years ago; major climatic 

cooling by 800,000 years ago) 

• Glaciation: Bull Lake (beginning timing unknown to 

about 127,000 years ago) and Pinedale (beginning 

about 30,000 years ago; glacial maximum between 

23,500 and 20,000 years ago; 15,000 and 12,000 years 

ago deglaciation occurred; prior to 10,000 years ago, all 

Pinedale glaciers disappeared) 

• Neoglaciation (about 5,000 to 120 years ago) 

• Geomorphic processes continue to affect the present 

landscape 
 ROMO Geologic Resource Evaluation Report 5 

Geologic Issues 

This section identifies geologic issues that may warrant attention from resource 

managers in Rocky Mountain National Park. These issues are relevant for maintenance 

of facilities, mitigation of hazardous conditions, and protection of resources. 

Alpine Environments 

Frost Cracking 

Frost cracks are common features in alpine areas. They 

occur in turf- banked lobes and terraces. Frost cracking 

has the potential to create significant engineering and 

maintenance problems at high elevations. Investigators 

studied frost cracking at high elevations (approximately 

11,500 ft; 3,505 m) on Niwot Ridge, south of the park in 

the Indian Peaks Wilderness (Benedict, 1970). The mean 

annual air temperature during the study was 26°F (- 3°C), 

with 12- year temperature extremes of - 34°F (- 37°C) and 

67°F (19°C). Annual precipitation during this interval 

ranged from a minimum of 19 inches (48 cm) to a 

maximum of 32 inches (81 cm). Because of the close 

proximity and similar environment, information gained 

from this study may be useful for park managers in 

Rocky Mountain National Park. 

Frost cracks are variable both in size and appearance. 

Some are only hairline fissures in the turf, whereas others 

are 8 to 12 inches (20 to 30 cm) wide. The sides of frost 

cracks are generally free of vegetation and have been 

churned by needle ice and microsolifluction. Single 

cracks are most common, but sub- parallel and 

irregularly branching cracks also occur. The largest 

cracks are more than 150 feet (46 m) in length (Benedict, 

1970). 

Frost cracks occur only where heaving is intense and 

varies within short horizontal distances, such as on turfbanked lobes and terraces, frost boils, and areas that are 

temporarily domed upward by localized heaving. Frost 

cracks either cannot form, or else are not preserved, in 

areas where solifluction is intense (Benedict, 1970). 

In general, frost cracks are seasonal and begin to open as 

soon as soil starts to freeze and expand (in November 

during the study on Niwot Ridge). Cracks continue to 

expand as long as heaving continues. The cracks begin to 

close with the arrival of above- freezing temperatures, 

but may reopen during brief intervals of renewed 

freezing (mid- May). 

Solifluction 

Identifying high- elevation areas with active 

solifluction—slow soil movement in periglacial areas—

and incorporating that information into the park’s GIS 

would be useful to park managers, including 

maintenance staff. Periglacial landscapes with active soil 

flowage can create significant engineering and 

maintenance problems for facilities, roads, trails, and 

septic systems. Sections of Trail Ridge Road, which cross 

slopes with active soil flowage, have significant and 

recurring maintenance problems (Geoindicators report, 

unpublished data, 2001). The rates of flowage have 

fluctuated throughout geologic time, and some change is 

expected. However, the combination of building the 

road across this terrain and loading the slope with 

roadfill material may have changed the rate of movement 

in these areas. 

Flooding 

Flash flooding is extremely rare at high elevations (above 

about 7,500 ft, 2,286 m) (Jarrett, 1987), but storm- related 

flooding is not uncommon in the Front Range. Floods 

have produced marked geologic and geomorphic 

changes. 

Big Thompson Flood 

No previous historic flood involved as much erosion and 

material transport as the Big Thompson River flood of 

1976 (Shroba and others, 1979). Because of its close 

proximity to the park and the fact that the headwaters 

originate there, this flood warrants mention. 

Exceptionally heavy summer rainfall, due to a persistent 

weather system over a few days, caused this event. 

Damage caused by the flood largely occurred east of 

Rocky Mountain National Park and downstream from 

Lake Estes. 

The Big Thompson River initiates near timerline just 

below the Continental Divide at an altitude of about 

11,000 feet (3,350 m). Some of its tributaries arise even 

higher from small glaciers (Shroba and others, 1979). The 

headwaters are rimmed on the west, north, and south by 

peaks that stand more than 12,000 feet (3,660) in 

elevation. The Big Thompson River descends about 6,330 

feet (1,930 m) in 55 miles (88 km)—as the crow flies—

from its sources to its confluence with the South Platte 

River on the Great Plains at an altitude of about 4,670 

feet (1,420 m). The Big Thompson River descends about 

3,500 feet (1,065 m) in 17 miles (27 km) as it flows 

eastward from its source to the Town of Estes Park at the 

west edge of the downpour area of the Big Thompson 

River flood (Shroba and others, 1979). 

The Big Thompson storm and flood of 1976 were 

exceptional but not unique events. Comparable storms 

and floods have happened in the Front Range in the past 

and probably will happen in the future (Shroba and 

others, 1979). Intense rainfall from the Big Thompson 

thunderstorm complex on the evening of July 31, 1976, 

and the ensuing floods that evening and following day 
6 NPS Geologic Resources Division 

led to widespread erosion and deposition along the Big 

Thompson River and its tributaries. Because of the 

intensity of the rainfall and the steepness of the terrain, 

runoff quickly reached flood stage. 

The main channel was scoured throughout its length. 

Point bars formed where the gradient flattened at wide 

places on the floodplain and on the insides of bends. 

Large boulder- gravel bars diverted the river from its 

pre- flood channel, notably at the community of Drake. 

Where bridges, buildings, or vegetation impeded flow, 

deposition intensified. Boulders as large as 7 feet (2.1 m) 

in intermediate diameter were deposited in bars. The 

largest boulder apparently moved by the flood measured 

approximately 12- by- 12- by- 23 feet (4- by- 4- by- 7 m) 

and weighed an estimated 275 tons (250 t) (Shroba and 

others, 1979). 

Downstream from the mouth of the canyon, overbank 

deposition was the chief geologic effect of the flood, 

although scour was appreciable at the outsides of bends 

and in the main channel (Shroba and others, 1979). 

Sheetflooding on hillslopes locally removed as much as a 

foot (30 cm) of soil and left pebbly to boulderly lag 

deposits. Locally, sheetflooding transported boulders 

down slopes, which were deposited on gentler inclines 

(Shroba and others, 1979). Debris slides, debris flows, 

rockslides, and rockfalls were set off in the intensedownpour area. Saturation of the soil was the chief 

cause, but lateral undercutting did cause some landslides 

(Shroba and others, 1979). 

Lawn Lake Flood 

At approximately 0530 Mountain Daylight Time on the 

morning of July 15, 1982, Lawn Lake dam failed. The dam 

was a 79- year- old (Pitlick, 1993b), 26- foot (7.9- m) high 

earthen dam (Jarrett and Costa, 1986) near the head of 

the Roaring River valley. The dam released 674 acre- feet 

(831,716 m3

) of water and an estimated peak discharge of 

18,000 cubic feet (509,760 dm3) per second (Jarrett and 

Costa, 1986). By comparison, investigators estimate the 

“500 year flood” in this area to have peak discharges of 

only about 400 cubic feet (11,330 dm3

) per second (Hoyt, 

1987). Thus the hydrologic consequences of the Lawn 

Lake dam failure were truly exceptional, and peak 

discharges of the flood far exceeded naturally occurring 

flows (Pitlick, 1993a). 

The flood caused the death of three people and property 

damage totaling $31 million. The Colorado State 

Engineer determined that the probable cause of failure 

was deterioration of lead caulking used for the 

connection between the outlet pipe and the gate valve. 

The resulting leak eroded the earthfill of the dam. 

Continued erosion by percolating water led to 

progressive formation of narrow conduits or “pipes,” 

and ultimately to failure of the embankment (Jarrett and 

Costa, 1986). 

Floodwater from the Lawn Lake discharge overtopped 

Cascade Lake dam, located 6.7 miles (11 km) 

downstream. With 4.2 feet (1.3 m) of water flowing over 

its crest, Cascade Lake dam failed by toppling. The flood 

continued down Fall River into the Town of Estes Park, 

where overbank flow caused extensive damage (Jarrett 

and Costa, 1986). 

Geomorphic effects of the dam- failure flood are locally 

conspicuous but highly variable. For example, channels 

for several miles (kilometers) below the Lawn Lake dam 

were widened tens of feet (meters) and scoured from 5 to 

50 feet (1.5 to 15 m). An alluvial fan was deposited at the 

confluence of the Roaring River. The alluvial fan 

dammed the Fall River, forming a lake of 17 acres (6.9 ha) 

upstream from the fan (Jarrett and Costa, 1986). Few 

geomorphic changes occurred in the reach of the Fall 

River through Horseshoe Park because the gradient is 

very low, banks are well vegetated, and the floodwaters 

spread out over the entire valley floor (Pitlick, 1993b). 

Studies concluded that the complex history of erosion 

and deposition in this gravel- bed river illustrate that 

floods in small drainage basins may produce highly 

variable geomorphic responses (Pitlick, 1993a). 

Hydrogeology 

The Continental Divide forms a mountain chain that 

runs the length of the park north- to- south and divides 

the park hydrologically. Waters on the park’s west side 

form the headwaters of the Colorado River. East side 

streams and rivers are part of the Mississippi drainage. 

Precambrian crystalline rocks underlie 95% of Rocky 

Mountain National Park. The Precambrian rocks 

(granite, gneiss, and schist) may contain small amounts of 

water in their fractures. The crystalline rocks are 

relatively impermeable and are generally poor aquifers. 

Wells intercepting fractures and weathered zones in 

these rocks commonly yield as many as 5 to 10 gallons (19 

to 38 L) per minute from wells 100 to 200 feet (30 to 60 

m) deep. Greater yields may be possible where several 

fracture sets intersect (Larry Martin, written 

communication, 2002). 

Unconsolidated sedimentary deposits of Quaternary age 

underlie the large valleys in the park. These deposits, 

transported and deposited by glaciers and streams, may 

contain water in sand and gravel. The deposits contain 

sediments that range in size from clay to boulders and are 

generally poorly sorted. The deposits may be classified in 

two categories: moraines and outwash. Moraines 

generally form conspicuous ridges that border or 

terminate in flat- lying meadows. Because the moraines 

generally contain large amounts of clay and silt, and are 

poorly sorted, they yield only small amounts of water to 

wells (Larry Martin, written communication, 2002). 

Glacial outwash and alluvial deposits, consisting of sand, 

silt, and gravel, underlie large parks, such as Moraine 

Park and Horseshoe Park. Streams have reworked 

outwash sediments, generally resulting in a sedimentary 

deposit that has had most of the clay removed and 

carried downstream. Wells constructed in outwash 

deposits can be very productive, yielding several 
 ROMO Geologic Resource Evaluation Report 7 

hundred gallons (more than 1,000 L) per minute (Larry 

Martin, written communication, 2002). 

Water Quality 

Although quality is high in the park’s waters as compared 

to much of the country, threats do exist. Nitrogen 

deposition is a factor influencing waters and soils in the 

park. In lakes and streams, the impacts of nitrogen 

deposition grow worse over time as the natural buffering 

capability of the soil and rock is used up. Eventually, 

chronic acidification can lead to the loss of many aquatic 

organisms and entire fish populations (Rocky Mountain 

National Park). 

Surficial materials in the watersheds of Rocky Mountain 

National Park play a dominant role in evaluating 

sensitivity to acidification. Most soils in the area have 

formed from parent material of glacial or alluvial origin. 

The mineralogic composition of soils and overburden 

reflects parent rock type composition, susceptibility to 

chemical weathering, and climate. Investigators have 

determined that the rock types in the area (biotite gneiss, 

schist, and granite) have a statistically insignificant 

influence on the buffering capacity of soil tested. This 

resulted primarily from the low clay content of the soils 

which in turn was dependent on composition of parent 

rock type, rock weathering characteristics, and climate 

influence on rate and degree of weathering. 

Mineralogically, clay content is directly proportional to 

the buffering capacity of a soil. In the absence of clay, 

most of the buffering capacity of soils is attributed to 

decomposed organic matter and soil pH (Johnson and 

Herzog, 1982). 

Landform types are useful in estimating the buffering 

capacity of surficial materials as they imply the amount of 

organic matter and the thickness of soil present. 

Examples of two landform types implying minimum and 

maximum capacities are bare bedrock and wet meadows. 

Thus the bedrock geology of the area is an important 

factor influencing water chemistry, while not 

significantly influencing the buffering capacity of the 

soils (Johnson and Herzog, 1982). 

Wetlands 

Wetlands are areas of high biological productivity and 

diversity and provide important sites for wildlife habitat. 

They serve as flood buffers and as filters, sequestering 

and storing heavy metals and other pollutants. By storing 

organic carbon in waterlogged sediments, wetlands also 

act as sinks for carbon. They are also sources of carbon, 

releasing carbon via degassing during decay processes, or 

after drainage and cutting, as a result of oxidation or 

burning. Wetlands develop naturally in response to 

morphological and hydrological features of the 

landscape. External factors such as climate change, 

landscape processes, or human activities can affect their 

evolution. 

The meadows at the bottom of the Cache la Poudre 

Valley, with headwaters north of Fall River Pass, contain 

some of the park’s major wetlands. Springs flowing into 

the valley from both sides keep the ground so saturated 

with water that trees cannot grow (Raup, 1996). 

Diverting surface- water flow through the Grand Ditch 

has impacted wetlands, as well as groundwater level and 

spring activity, in the Kawuneeche Valley (Cooper and 

others, 2000). The impacts to wetlands include: (1) 

inhibiting geomorphic processes (e.g., frequency of 

flooding and channel- forming flows), (2) increasing 

exotic plant species, and (3) causing peatlands to lose 

carbon (Cooper and others, 2000). 

Mass Wasting 

Landslides 

The landslides that have occurred in the park are 

Holocene and late Pleistocene in age (Braddock and 

Cole, 1990). Investigators have not determined the cause 

and frequency of landslides but have prepared a 

preliminary map of landslide deposits (Colton and 

others, 1975). This map, however, is not a substitute for 

careful detailed large- scale site investigations by 

engineering geologists and soil engineers (Colton and 

others, 1975). Park managers should conduct careful 

studies of areas susceptible to landslide and related 

activity before any development begins. 

Landslides in the park include slumps and earth flows of 

glacial till along the sides of Kawuneeche Valley; large, 

nearly intact masses of volcanic rocks between Iron 

Mountain and Bald Mountain; and jumbled, hummocky 

masses of relatively intact blocks of Precambrian rocks 

(Braddock and Cole, 1990). Several areas of hummocky 

steps around Iceberg Lake are landslide deposits that slid 

down the steep slopes of the cirque (Raup, 1996). 

A major landslide area on the flanks of Jackstraw 

Mountain can be seen across the tributary valley to the 

east of Farview Curve. The large slide on Jackstraw 

Mountain is composed of biotite schist. The foliation 

(compositional layering) in the schist around the slide 

area dips to the north and northwest, nearly parallel to 

the direction of slide movement (Bradock and Cole, 

1990). The jumbled blocks in this landslide started 

moving after the tributary glacier in this valley melted 

between 15,000 and 12,000 years ago (Raup, 1996). 

Debris Flows 

On June 16, 1978, a mudflow deposited a lobate mass of 

mud, sand, and gravel on the west side of Kawuneeche 

Valley north of Baker Gulch. The so- called “Holzwarth 

debris flow” was initiated at an altitude of about 10,200 

feet (3,110 m) when about 110 cubic yards (85 m3

) of 

water- saturated debris occupying an area of about 300 

square feet (2,790 dm3

) suddenly began to slide. The 

sliding mass accelerated, incorporated more saturated 

debris, liquefied, and flowed to the base of the slope 

within a few minutes. The track of the debris flow varies 

from about 40 to 100 feet (12 to 30 m) wide. Within the 

track all the trees were removed, and in places a foot (30 

cm) of soil was scoured away. Trees were pushed to the 

edge of the track and piled into a windrow of debris. 
8 NPS Geologic Resources Division 

Surface flow of water down the track produced deep 

gullies. Tracks of a similar debris flow, which occurred 

between 1969 and 1974, are also present in Baker Gulch 

(Braddock and Cole, 1990). 

Investigators suspect that the cause of this debris flow 

may be linked to changes in water flow in the Grand 

Ditch. Investigators have not performed a conclusive 

study, however. 

Rockfalls 

Talus deposits are present at the base of all steep slopes 

in the park. Talus slopes form as angular blocks of rock 

and abundant interstitial smaller rock fragments both on 

steep slopes and at the base of cliffs (Braddock and Cole, 

1990). Researchers suggest that freeze- thaw processes 

cause rockfalls, which are also triggered by intense 

summer rainstorms (Caine, 1986). Rockfalls are the 

primary agents in the formation of talus, though some 

talus deposits were transported by debris flows and snow 

avalanches (Braddock and Cole, 1990). Most talus is 

Holocene in age (Braddock and Cole, 1990). 

In a 20- year period at least three rockfalls involving 

more than 6.5 cubic yards (5.0 m3

) of debris occurred in 

the upper Green Lakes valley in the Indian Peaks 

Wilderness south of the park. This study area is typical of 

high elevation environments on the east side of the Front 

Range [and in the park] (Caine, 1986). Each rockfall 

included clasts larger than 3 feet (nearly 1 m) that 

traversed the entire talus slope. In total they involved 

more than 200 cubic yards (150 m3

) of rock (Caine, 1986). 

The movement within talus slopes themselves is 

generally about an inch (25 mm) per year in the Green 

Lakes area (Caine, 1986). 

Investigators analyzed data during this study, which 

suggest that intervals of more active sediment production 

and transport have occurred since deglaciation of the 

alpine valleys at the end of the Pinedale glaciation (Caine, 

1986). More active sediment production and transport in 

the past accounts for the present volumes of talus in 

today’s alpine landscapes. 

Although rockfalls are not as active as they once were, 

they do occur. Hence, because of their areal extent, 

rockfalls are significant for planning and public safety. 

Park managers should include talus slopes in the park’s 

GIS because these data would be useful for planning or 

rerouting trails that cut across or below these slopes. 

Minerals and Mining 

Colorado Mineral Belt 

Rocky Mountain National Park lies just north of the 

Colorado Mineral Belt—an area that contains most of 

the mining districts in Colorado. The mineral belt is 10–15 

miles (16–24 km) wide and spans diagonally 

southwestward across the mountain ranges of Colorado 

from Jamestown in the Front Range to the San Juan 

Mountains in the southwestern part of the state. Igneous 

rocks of Laramide and younger ages and ore deposits of 

various types characterize the mineral belt (Pearson, 

1980). Its northwest boundary is generally drawn to 

include mineralized areas and the Laramide stocks of the 

eastern part of the Indian Peaks Wilderness, just south of 

the park (Pearson, 1980). 

The Jamestown, Ward, Gold Hill, and Caribou mining 

areas in the Boulder County tungsten district lie in the 

mineral belt within 6 miles (10 km) of the park. In 

addition, about 15 miles (24 km) south of the Indian 

Peaks Wilderness are the large disseminated 

molybdenum ore bodies at Urad and Henderson, and the 

base and precious metal veins in the Central City–

Blackhawk district. Geologists also consider the minor 

Lost Lake and Lake Albion districts, partly in the Indian 

Peaks, to be part of the Colorado Mineral Belt (Pearson, 

1980), as defined by the presence of Laramide intrusive 

bodies. 

Except for the Urad and Henderson districts, Front 

Range mineral deposits typically occur as veins that 

occupy faults of small displacement—largely of 

Precambrian rocks but partly in Laramide intrusive 

rocks. Most of the faults are only a few hundred feet 

(meters) long, and few exceed 1 mile (1.6 km). Tweto 

(1968) summarized the Laramide- age ore bodies in these 

and other districts in the mineral belt of the Front Range. 

The ore deposits in such veins [those in 

Precambrian rocks] are in ore shoots that have 

thicknesses of several inches to a few feet, stope 

lengths of a few tens to a few hundreds of feet, 

and pitch lengths from a few tens to 1,000 feet. 

The ore bodies thus are small in tonnage, and 

many of them could be worked only because of 

their rather high grade, which in many cases was 1 

to 10 ounces of gold or 50 to 500 ounces of silver 

per ton. Since the veins are discontinuous and the 

ore bodies are small, the outlook for future 

production from deposits of this kind is poor, 

primarily because the cost of discovery is high in 

proportion to the value of an ore body. 

Although exploration and mining activity continue 

sporadically, particularly during periods of relatively 

high metal prices, the outlook for mining these veins in 

the Front Range is still pessimistic (Pearson, 1980). A 

proposed southern extension of the park—54 square 

miles (140 km2

) of rugged mountain country to the east of 

Monarch Lake—would have included a portion of the 

now- Indian Peak Wilderness as part of the national park 

(Lovering and Goddard, 1938). Regarding the proposed 

southern extension of the park, investigators determined 

“mineral deposits throughout the area are not abundant” 

and “no deposits in the district are of commercial grade” 

(Lovering and Goddard, 1938). 

Minerals 

Pegmatites (see also Rock Units and Properties section of 

this report) and other sources of mineral specimens 

occur throughout the park, although not at commercial 

grades. However, these deposits may attract mineral 
 ROMO Geologic Resource Evaluation Report 9 

collectors. For example, Specimen Mountain, once 

thought to be a volcano, is a pile of volcanic rock that 

accumulated during the same series of eruptions that 

deposited the rocks at Lava Cliffs (Raup, 1996). Specimen 

Mountain lives up to its name: samples found there are 

said to be “suitable for cutting” (Seaman, 1934). Locally 

the jasper forms geodes, partially or completely filled 

with agate, onyx, opal, calcite, and minor amounts of 

allophane and chloropal (Wahlstrom, 1941). Frank Byers, 

son of William Byers who climbed Longs Peak with John 

Wesley Powell in 1868, remembered that when he was a 

boy at his father’s ranch in Hot Sulphur Springs, 

Specimen Mountain was called Geode Mountain (Arps 

and others, 1977). 

Mining History 

Most of the mining in the vicinity of Rocky Mountain 

National Park occurred outside the present- day 

boundary, but small workings at Eugenia Mine (on Battle 

Mountain near the Longs Peak Trail), North Star 

“Shipler” Mine (along the Colorado River Trail), and 

Prospect Canyon (in Glacier Gorge) attest to early 

prospecting and mining activity. Probably the most wellknown mining area in the park is Lulu City, in 

Kawuneeche Valley. In 1879 a small party of prospectors 

out of Ft. Collins discovered silver along the North Fork 

of the Grand River (now the Colorado River) and 

located several mines, two of which were the North Star 

and Iron Mines in Kawuneeche Valley. Hearing of the 

discoveries, prospectors flocked to the area in pursuit of 

quick riches. By 1880 Lulu City was “home” to as many as 

500 miners and had a butcher shop, a post office, a real 

estate agency, about 20 houses, and several mining 

companies. However, the riches did not materialize as 

fast as the town. By 1884 miners abandoned the town in 

search of other opportunities (U.S. Department of the 

Interior, National Park Service, Land Resources 

Division, Mining and Mineral Branch, 1993). 

One miner, however, remained in the district until 1914, 

the year before the park was established. Joseph Shipler 

worked a small prospect on side of Shipler Mountain. He 

created a sizeable pile of mine waste and gathered a little 

silver ore (Kaye, 1983). 

Colorado’s mining history is full of scams, and Rocky 

Mountain National Park can boast of a scam as well. The 

Triumph Mine, part of the Lulu City district, was part of 

a mining scandal. The tailings were reportedly salted 

with high- grade ore from silver mines in Georgetown. 

Unwitting investors bought the claims but ended up 

owning nothing of economic value (Robert Higgins, 

National Park Service, Geologic Resources Division, 

Mining and Mineral Branch, memorandum, February 28, 

1991). 

Abandoned Mine Lands 

In 1988, resource managers in Rocky Mountain National 

Park requested assistance from the NPS Mining and 

Minerals Branch to conduct an inventory and field 

inspections of abandoned mine lands (AML) in the park 

(RMP database, project number #ROMON550000). Staff 

from the Mining and Minerals Branch assisted park 

resource managers with inventorying abandoned mine 

lands in the park. Staff identified and inventoried four 

AML sites: Meeker Park, Eugenia Mine (off the Longs 

Peak Trail), Miner Bill’s Mine (Mount Chapin), North 

Star “Shipler” Mine (Lulu City area), and Aspen Brook 

site (Lily Lake area). Staff identified more than 20 mine 

openings (adits), with some posing moderate safety 

hazards. 

After staff completed the inventory in 1993, park 

managers implemented mitigation at several sites. They 

sealed the Iron Mine and an unnamed mine next to the 

Iron Mine with rock and mortar. Managers closed the 

North Star “Shipler” Mine, along the Colorado River 

Trail, to human entry using a gate that still allows bats to 

enter and exit. The objective of the mitigation was to 

prevent park visitors from entering the mines, and 

potentially endangering themselves, while preserving the 

historic integrity of the area (U.S. Department of the 

Interior, National Park Service, Land Resources 

Division, Mining and Minerals Branch, 1993). 

Seismicity 

The Uniform Building Code Seismic Map (1979) 

designates Rocky Mountain National Park as a zone of 

minor seismic hazard, similar to most Colorado 

mountain areas. Since earliest records beginning in 1867, 

historical earthquake activity has affected the park. The 

largest historical earthquake in Colorado occurred on 

November 7, 1882, in the vicinity of Estes Park. This 

earthquake predates seismographs, so an estimated 

magnitude of 6.5 is based on the size of the area over 

which the earthquake was felt (Colorado Geological 

Survey, unpublished data, 1999). A large earthquake near 

the park could cause rockfalls and landslides, and 

changes in springs and streamflow (Geoindicators 

report, unpublished data, 2001). 

Geologists have divided Colorado into seven 

seismotectonic provinces and estimated maximum 

credible earthquakes (MCE) for each province (Kirkham 

and Rogers, 1981). This subdivision places the park in the 

area called Eastern Mountain Province for which the 

estimated MCE is in the range of magnitude 6.0 to 6.75 

on the Richter scale. In addition to seismic provinces, 

engineers include significant faults in seismotectonic 

evaluations: Laramie River, Frontal (Blue River), and 

Derby (U.S. Department of the Interior, Bureau of 

Reclamation, Division of Dam and Structural Safety, 

1982). The Laramie River and the Frontal (Blue River) 

faults have MCE values of 7.0; the Derby fault has MCE 

of 6.25 (U.S. Department of the Interior, Bureau of 

Reclamation, Division of Dam and Structural Safety, 

1982). 

The Lawn Lake flood provided the impetus to remove 

four of the park’s dams at high reservoirs: Lawn, 

Sandbeach, Pear, and Bluebird lakes. Lily and Sprague 

lakes have reservoirs (and dams) remaining. Although 

earthen dams are generally very stable in earthquakes 

(Jim Cole, written communication, 2003), determining 

the volumes of these remaining reservoirs and preparing 
10 NPS Geologic Resources Division 

an inundation map—including downstream hazards for 

camping and picnic areas—may provide valuable 

information for park planning and mitigation in the 

event of seismic activity and dam failure. 

Water Diversion Projects 

By the time Congress passed the bill that established 

Rocky Mountain National Park, 19 reservoirs and three 

water diversion projects had been approved within its 

boundaries for power and irrigation to the towns of 

Boulder, Longmont, and Loveland, among others. In all, 

more water developments were proposed or executed 

within today’s park boundaries, than in all other national 

parks combined (U.S. Department of the Interior, 

National Park Service, Division of Interpretive Planning, 

Harpers Ferry Center, 1985). 

Colorado–Big Thompson Project 

The most ambitious trans- mountain water project to 

exist within the park is the Colorado–Big Thompson 

Project, which began in 1938 and was completed in the 

1959 (Merriman, 1960). An important feature of this 

project is the 13.1- mile- long Alva B. Adams tunnel, which 

carries water underneath Rocky Mountain National Park 

from the wetter west side to the drier east side. The 

principal engineering structures of the entire project 

include: 13 reservoirs, 23 dams and [water] dikes, six 

power plants, 36 substations and seven switchyards, 

three pumping plants, 19 tunnels (34 mi, 55 km), more 

than 100 miles (160 km) of supply and feeder canals, and 

785 miles (1,263 km) of transmission lines (Merriman, 

1960). 

Grand Ditch 

Even at its headwaters, water from the tributaries to the 

Colorado River is diverted for use on the east side of the 

Continental Divide. The Grand Ditch transports water 

from the west side of the Continental Divide to the east 

side, across 13 miles (21 km) of the east slope of the Never 

Summer Mountains. The Grand River Ditch Company 

owns the Grand Ditch. The company established senior 

water rights prior to congressional designation of Rocky 

Mountain National Park. In 1894 the Water Supply and 

Storage Company began construction of an irrigation 

ditch about 1,000 feet (305 m) above the then- Grand 

River valley. According to the park’s Web site, by 1934 

water was flowing to farmers on the eastern plains 

(Rocky Mountain National Park). The Grand Ditch 

intercepts approximately one- third of the surface water 

runoff from the east side of the Never Summer 

Mountains. Research indicates that this disruption in the 

hydrology affects plant and animal life in the 

Kawuneeche Valley (Cooper and others, 2000). Because 

of the importance of the ditch to farmers and 

communities on the northern Colorado plains, park 

managers have not acquired additional water rights. 

Hidden Valley 

On a smaller scale than both the Colorado–Big 

Thompson Project and the Grand Ditch is the diversion 

of the stream in Hidden Valley. Workers buried the 

stream channel and installed culverts during 

construction of the Hidden Valley Ski Area. The ski area 

opened for business in 1952, although winter 

recreationists had used the area since the 1920s. A ski lift 

was installed in 1971. The ski area was closed permanently 

in 1992. For decades, the entire streamflow in the small 

watershed was diverted for making artificial snow. Park 

managers are in the process of restoring the stream 

channel and natural flow (Geoindicators report, 

unpublished data, 2001). 

Removal of Dams 

The Lawn Lake flood provided the impetus to remove 

four of the park’s high mountain reservoirs in the park. 

After acquiring the water rights, park managers removed 

what remained of the earthen dam at Lawn Lake, some 

5,300 cubic yards (4,050 m3

) or 450 [vertical] feet (140 m) 

of earthen embankment (Rocky Mountain National 

Park). 

Park managers have removed three other high mountain 

dams. In 1988 they removed rock and dirt dams at 

Sandbeach Lake and Pear Lake, and then regraded the 

land to the original slope. In 1989 and 1990 they removed 

five million pounds (2,268,000 kg) of concrete and rebar 

from the Bluebird Lake dam. Park managers recycled the 

materials near Lily Lake. About 67 acres (27 ha) of 

shoreline around all three lakes were reexposed, and 

park managers are currently allowing the shores to 

restore naturally (Rocky Mountain National Park). 

Remaining Reservoirs 

Rocky Mountain National Park has two remaining water 

reservoirs: Lily Lake and Sprague Lake. Each of these 

lakes supports recreational fishing activity and hosts 

handicap accessible fishing areas. Park managers have no 

plans to remove the impoundment structures at these 

popular areas. 

Wind-Blown Sediment 

Wind- blown detritus is the dominant sediment source 

for alpine lakes in Colorado (Caine, 1974). Aeolian dust is 

transported through alpine hillslope systems and is 

stored in alpine lakes and tundra soils (Caine, 1986). In 

the context of the park’s close proximity to metropolitan 

areas of the Front Range, this information is significant 

with respect to incoming pollutants. 

Cumulative evidence from multiple studies in Rocky 

Mountain National Park (Loch Vale) and adjacent areas 

along the Colorado Front Range (Niwot Ridge) strongly 

suggest that present levels of nitrogen deposition are 

currently altering terrestrial and aquatic ecosystems on 

the eastern side of the mountains (Rocky Mountain 

National Park). Hence, the information provided in this 

report may simply be putting a geologic spin on an 

already- identified concern. Nevertheless, park managers 

are encouraged to study the wind- blown sediment in 

alpine systems and identify sources of the sediment. 

Furthermore, park managers are encouraged to include 

aeolian processes in the park’s inventory and monitoring 

program. The information gained from this study may 
 ROMO Geologic Resource Evaluation Report 11 

assist with future management decisions, as well as 

setting air- quality standards in the Front Range. 

Potential Research, Inventory, and Monitoring Projects 

This information addresses the desire of park managers 

to identify relevant geologic research projects (Terry 

Terrell, oral communication, 2002). It also highlights the 

range of possibilities for research in the park, the use of 

data for interpretive purposes, and the importance of 

identifying resources in order to protect them. The list is 

not prioritized. 

Geologic research is useful for gaining information and 

understanding of natural resources beyond what is 

typically thought of as geology. For example, assistance 

with the identification of already- mapped rhyolite 

exposures on the west side of the park would help 

pinpoint the locations for certain rare mosses that exist 

in the park and need to be protected. Also, dryas, an 

alpine flower that grows on limestone in Europe, grows 

in tundra areas of the park, which are not underlain by 

limestone. Analyzing the sources of soil components and 

geomorphic processes that allow this rare plant to 

unexpectedly grow in the park would aid in 

understanding the alpine tundra environment. 

Research in Rocky Mountain National Park can have 

international significance. For example, at a site in Loch 

Vale, near Sky Pond, investigators linked a glacial deposit 

with the European Younger Dryas (interval of lateglacial time about 10,500 years ago). This Santanta Peak 

moraine was deposited at the end of the Pleistocene ice 

age. The Satanta Peak advance began between 11,000 and 

12,000 years ago and ended about 10,000 years ago. This 

finding is important because understanding the 

worldwide extent, timing, and relative magnitude of the 

Younger Dryas event is scientifically significant for 

understanding the mechanism responsible for abrupt 

climate change (Menounos and Reasoner, 1997). 

Determine extent of landslide hazards in the park 

Staff at the U.S. Geological Survey (USGS) proposed that 

the western part of Rocky Mountain National Park be a 

study site for a project entitled “Landslide recurrence 

and slope evolution in the western United States” (1993–

1997). Because of retiring personnel, this particular 

project ended before any work was done in the park. 

Later, other USGS personnel initiated and executed a 

study at one of the proposed sites—the Interstate 70 

corridor. 

Nevertheless, work on the western slope in the park is 

still significant. For example, the upper parts of the 

Colorado and Laramie Rivers, including the beheaded 

part of the Laramie River now known as Joe Wright 

Creek, are in a fault zone that contains weak rocks of 

Mesozoic and Cenozoic ages that are susceptible to 

landslides. A large landslide beheaded the Laramie River 

and dammed the valley at what is now the upvalley end 

of Chambers Lake. Water impounded by this landslide 

eventually cut an outlet that allowed the lake to drain 

into the Cache la Poudre River (Rich Madole, written 

communication, 1998). 

Without further study, investigators cannot assess the 

extent of slope- failure risk to the park’s infrastructure. 

The risk does not appear to be great on the east slope of 

the Front Range, but some does exist (Rich Madole, 

written communication, 1998). Specific aspects of 

landslides to be studied are: (1) susceptibility of Tertiary 

volcanic rocks to landslides and (2) relationship between 

metamorphic foliation and landslide potential (Jim Cole, 

written communication, 1998). 

Determine potential for debris flows below the Grand Ditch 

The Holzwarth debris flow was deposited on June 16, 

1978, on the west side of Kawuneeche Valley north of 

Baker Gulch. Tracks of a similar debris flow, which 

occurred between 1969 and 1974, are also present in 

Baker Gulch (Braddock and Cole, 1990). Investigators 

suspect that the debris flows in this area are linked to 

diversion of water into the Grand Ditch but do not have 

conclusive information regarding the cause or the 

potential for future debris- flow events. 

Study early history of Colorado (Grand) River drainage 

The field area would consist of the landscape preserved 

below the Never Summer–Specimen Mountain 

volcanics. The study would look at the relationship 

between the Troublesome Formation and the 

paleogeography of the upper Colorado River drainage. 

Conduct a detailed study of high-grade metamorphic rocks 

Many aspects of metamorphic rocks in and surrounding 

the park are not well understood. Examples of potential 

research projects include: (1) the chemical reactions 

involved in partial melting of the metamorphic rocks, (2) 

geochemical changes in mineral compositions, (3) 

pressure- temperature- time relations between the lowgrade rocks in the lower Big Thompson canyon and the 

zone of melting, and (4) origin and significance of 

retrograde minerals in the metamorphic rocks (e.g., 

muscovite, tourmaline, and topaz). 

Examine Troublesome Formation for paleontological 

resources 

The park is not known for its paleontological resources 

however, one unit is of interest with respect to fossils. 

Most of the rocks in the park are Precambrian gneisses 

and schists, with some volcanic rocks of Tertiary age. 

The Troublesome Formation—sedimentary rock of early 

Miocene and late Oligocene time—in the vicinity of the 

park, primarily Middle Park, has yielded various fossil 

mammals (Lovering, 1930; Izett, 1974), such as rodents 

similar to pocket gophers (Lewis, 1969; Kron, 1988). 

Outcrops of the Troublesome Formation on the west 

side of the park are probably fossiliferous (Casey 

McKinney, written communication, 2003). 

Determine geomorphic history of Black Canyon drainage 

Glacial processes are expected to have played a role in 

the development of the Black Canyon drainage in the 

northeast portion of the park. However, evidence of 

glacial activity is not readily apparent (Jim Cole, written 
12 NPS Geologic Resources Division 

communication, 1998). This puzzle has long intrigued 

geologists working in the area. 

Determine the origin of the flat lands in Estes Park 

Understanding the origin of the flat lands in Estes Park is 

significant for interpreting the evolution of the area’s 

landscape and the drainage on the east side of Rocky 

Mountain National Park (Jim Cole, written 

communication, 1998). 

Expand study of emplacement mechanisms of Longs Peak–

St Vrain batholith 

Researchers have not fully studied the area that hosts the 

Longs Peak–St. Vrain batholith (Jim Cole, written 

communication, 1998). A potential research project could 

include the area beyond that which was covered by Cole 

(1977). 

Refine petrologic studies of granitic rocks of Silver Plume 

intrusive event 

Researchers need to refine the origin and significance of 

unusual aluminous minerals (e.g., garnet, sillimanite) in 

some parts of the Silver Plume Granite. For example, a 

research project that quantifies the volatile content in the 

granite magmas and late- stage evolution of volatile (gas) 

phase and brecciation needs to be completed. 

Clarify geologic details of Never Summer Mountains 

Researchers have not studied in detail the timing and 

kinematics of the Never Summer thrust or the 

emplacement and subsequent deformation by the Never 

Summer intrusions (Jim Cole, written communication, 

1998). Research would provide important information 

about the Cenozoic depositional and tectonic history of 

the park. 

Monitor mass balance of glaciers 

Investigators do not know whether the masses of ice in 

the park are shrinking or growing over long periods of 

time (Braddock and Cole, 1990). Knowledge of seasonal 

mass balances (e.g., summer and winter) would shed light 

on glacier fluctuations in the park. For example, it would 

help answer questions such as: is glacier contraction 

caused primarily by less nourishment in winter or by 

more melt in summer? Monitoring of mass balance 

would also assist in the interpretation of streamflow 

records. 

Data from the park’s glaciers could be shared with the 

Global Terrestrial Network- Glacier (GTN- G) of World 

Meteorological Organization’s (WMO) Global Climate 

Observing Network (GCOS). In addition, Rocky 

Mountain National Park could be part of the Global 

Terrestrial Observing Systems (GTOS), Terrestrial 

Monitoring System (TEMS). 

Conduct comprehensive study of structural geology of the 

park 

A comprehensive study of the structural geology specific 

to the park is needed. Such a study could include a map 

of faults and their maximum credible earthquake 

potentials, evidence for the park’s structure fitting into 

the theory of plate tectonics, and data regarding the 

uplifted erosion surface in the park’s high country (see 

“Uplifted Erosion Surface” in “Geologic Features and 

Processes”). Researchers could also study the 

relationship between regional uplift and climate change 

(e.g., cooling during glaciations). Such a study, and the 

accompanying manuscript, would be useful for resource 

managers and interpreters alike. 

Promote the park as a laboratory for mountain 

geomorphology 

Landforms and processes related to all four major 

geologic agents—the work of water, ice, mass movement 

(gravity), and wind—exist in the alpine environments 

within the park (Rich Madole, written communication, 

1998). These landforms and processes further relate to 

studies of Pleistocene and Holocene deposits and 

sedimentary records of climate in ice- marginal and 

post- glacial settings (Jim Cole, written communication, 

1998). 

The recognition by park managers that Rocky Mountain 

National Park is a laboratory for mountain 

geomorphology can be used to their advantage. 

Advertising this fact to the scientific community would 

result in data and information that could be used in 

making management decisions regarding the park’s 

natural resources, as well as in preparing interpretive 

materials and exhibits. 

Gather information on regional alpine studies 

Several agencies conducting regional alpine studies are 

located in the Front Range near Rocky Mountain 

National Park. These studies may provide local baseline 

data and long- term trends associated with glacial 

fluctuations and frozen- ground activity. Agencies and 

programs to consider the Niwot Ridge Long Term 

Ecological Research Program, monitoring programs in 

the Indian Peaks Wilderness (University of Colorado) 

and Loch Vale (U.S. Geological Survey), and research at 

the Institute for Alpine and Arctic Research (INSTAAR) 

in Boulder. These agencies and programs also can 

provide standardized techniques and established 

protocols for monitoring alpine processes. 

Develop snow avalanche maps for visitor safety and 

environmental studies 

For the reason of visitor safety, park managers should 

determine whether the Colorado Avalanche Information 

Center or INSTAAR have mapped snow- avalanche areas 

in the park. 

In addition to visitor safety, snow avalanches are 

landscape disturbances that help shape ecosystems. 

Avalanche paths are generally productive environments 

and provide habitats that serve as migration paths for 

large mammals, fuel breaks for fire, and conduits for 

carbon and sediment from higher to lower elevations. 
 ROMO Geologic Resource Evaluation Report 13 

Determine former locations of tree line–tundra interface 

The tree line–tundra interface is an important marker for 

understanding paleoclimates. Tree line position may be a 

better indicator of climate change than monitoring 

glacier fluctuations in the park. A possible study is to 

determine the location of the former tree line–tundra 

ecotone and evaluate what controls its position. 

Determine the depth and thickness of the permafrost and 

monitor the rate of creep 

Knowing rates of creep would be useful for park 

planning and to the park’s maintenance staff. Staff could 

be trained to use frost tubes to monitor rates of 

movement, which can be calibrated with monitoring 

studies at INSTAAR. 

Monitor dust deposition in the park 

The U.S. Geological Survey has developed standardized 

protocols for monitoring dust deposition. Park managers 

could incorporate dust monitoring into the existing airquality monitoring program, thereby quantifying the dust 

component of the airborne particulate matter and 

identifying source areas of the particulate matter. This 

data will help determine whether there is a relationship 

between dust deposition and nitrate concentrations. 

Establish a lake-level monitoring program 

Historical fluctuations in lake levels provide a detailed 

record of climate changes on a scale of 10 years to 1 

million years. Lakes are dynamic systems that are 

sensitive to local climate and to land- use changes in the 

surrounding landscape. Some lakes receive their water 

mainly from precipitation, some are dominated by 

rainfall and snowmelt runoff from drainage networks, 

and others are controlled by groundwater systems. The 

areal extent and depth of water in lakes are indicators of 

changes in climatic parameters such as precipitation, 

radiation, temperature, and wind speed. Where not 

directly affected by human actions, lake level fluctuations 

are excellent indicators of drought conditions. Lakes can 

also be valuable indicators of near- surface groundwater 

conditions. 

In general, park staff could observe and record seasonal 

variability of lake levels. Park managers could also select 

particular lakes for more formal monitoring. 

Monitor lake ice phrenology 

Global climate change occurs naturally, but human 

activities can accelerate the process. Monitoring the first 

thaw–first freeze of lakes in the park provides an early 

warning of global warming. While park managers cannot 

directly address global warming issues through their 

management of park resources, knowing when impacts 

are occurring is useful. One approach would be to 

monitor ice phrenology, i.e., determine the date of first 

freeze and first thaw for alpine lakes; thereby, providing 

baseline data of long- term climate change. 

Determine fire history, ecotones, and paleoclimate 

information from sediment cores 

The chemical, physical, and biological character of 

aquatic sediments can provide a finely resolvable record 

of environmental change, in which natural events may be 

clearly distinguishable from human inputs. Information 

recorded in wetlands, lakes, and marshes would provide 

a perspective of fire history, ecotones, and paleoecology 

in the park. Investigators could obtain and analyze 

sediment cores from selected lakes, marshes, and 

wetlands in the park. 

Develop strategies for restoration and monitoring of stream 

and wetlands at Hidden Valley 

Park managers should consult personnel in the NPS 

Water Resources Division regarding restoration 

strategies of the stream and wetland at Hidden Valley. 

Replicating channel gradient and channel dimension is 

more important than the exact location of the original 

stream. The Water Resources Division could also assist 

in developing a monitoring program to quantify the 

response of the stream channel and wetlands restoration. 

Monitor channel changes in response to removal of check 

dams 

Park managers have inventoried 210 check dams in the 

park, and the park has an active program of removing old 

or failed check dams. Removal of check dams will alter 

streamflow and sediment transport and may change 

channel morphology downstream. The channels 

downstream should be monitored, including quantifying 

channel changes and stream response to the removal of 

check dams on park streams. 
14 NPS Geologic Resources Division 

Geologic Features and Processes 

Rocky Mountain National Park abounds in geologic features that may be of concern for 

park planning, public safety, or resource protection. Geologic features (or landforms) and 

processes have scientific and aesthetic significance, as well as continually affecting human 

beings and other living things. These features and processes may not be readily apparent on 

the park’s geologic map. 

Colorado River 

The Colorado River originates in Kawuneeche Valley in 

Rocky Mountain National Park. Here it is very narrow, 

contrasting greatly with the segment of the river that 

flows through Grand Canyon National Park. The river 

flows 1,400 miles (2,253 km) from its birthplace in the 

park to the Gulf of California. 

Columnar Jointing 

High above the floor on the east side of Kawuneeche 

Valley in the vicinity of the Bowen- Baker Trailhead, a 

lava flow of rhyolite displays a peculiar type of jointing. 

This ornate rock feature, called columnar jointing, is not 

caused by weathering or erosion but by contraction of 

molten rock as it cools. This process produces parallel, 

prismatic columns that are polygonal in cross section. 

The lava flowed from one of the volcanoes in the Never 

Summer Mountains about 26 million years ago (Raup, 

1996). The position of the lava flow high above the valley 

floor indicates that this valley was filled to that level with 

volcanic ash and lava at the time of the eruption. Erosion 

by water and ice in the ensuing years has removed most 

of the volcanic rocks and cut the valley to its present level 

(Raup, 1996). 

Exfoliation Domes and Ornate Erosion Features 

The rounded knobs on McGregor Mountain and Lumpy 

Ridge are homogeneous masses of granite with very 

uniform structure. As erosion of overlying rocks—

presumably thousands of feet of sedimentary rock—

slowly released pressure from the granite, exfoliation 

domes were formed. The granite responded by 

expanding and cracking into concentric slabs that 

resemble the rings of an onion. 

Fractures that form in response to the removal of 

overlying rock may be quite prominent, in which case 

they often result in “sheeting” and sometimes form 

bizarre landforms. Helped along by frost action, sheeting 

produced the Keyhole on the popular route to the 

summit of Longs Peak. 

Over millions of years, wind erosion and freeze- thaw 

action have sculpted the rocks in the park into many 

ornate forms. On Lumpy Ridge, for example, 

fantastically shaped rocks include balanced rock and 

clusters of oddly shaped boulders, such as “hen and 

chicks.” 

Glacial Features 

Cirques and Tarns 

Few landforms have caught the imagination of 

geomorphologists more than the glacial cirque: a bowlshaped, amphitheater- like hollow or basin eroded into a 

mountain 

mass. The small glaciers that exist in the park occupy 

cirques once excavated by their large predecessors. After 

the glacier that created the cirque melts, a small lake, 

called a tarn, may occupy the basin. One of the most 

spectacular cirques is the area below the East Face of 

Longs Peak. Chasm Lake (a tarn) fills the basin. Other 

distinctive cirques in the park are located on Terra 

Tomah and Ypsilon Mountains. 

Glacial Erratics 

In many glaciated areas, large boulders end up stranded 

when glaciers recede. These out- of- place rocks are 

called erratics. Erratics testify to the effectiveness of 

glacial erosion and transport, and may have glacial 

striations. They also testify to glacial deposition and lie 

scattered on bedrock surfaces different from their own 

compositions. Visitors can see nice examples of erratics 

along the Cub Lake trail. 

Glacial Polish, Striations, and Grooves 

Rocks and sediment frozen to the base and sides of 

glaciers act like sandpaper and grind, scratch, and polish 

the rocks over which they pass. Transported rocks also 

become smoothed and rounded themselves. Glacial 

polish, striations, and grooves line Old Fall River Road, 

which leads to the head of the glacial valley at Fall River 

Pass. 

Glacial Till and Moraines 

A glacier carries all sizes of debris at its base, sides, and 

surface, and deposits this material along the sides and 

floor of the valley down which it flows. Till is the general 

term for the poorly sorted mixture of fine to coarse rock 

debris deposited directly from glacier ice. The most 

obvious landforms composed of till are moraines. 

Moraines can be undulating mounds or sharp ridges 

depending on how long a glacier remained stable in a 

particular position or how much erosion and weathering 

have taken place in the intervening time between 

deposition and the present. 
 ROMO Geologic Resource Evaluation Report 15 

Lateral moraines form on the sides of glaciers and merge 

with an end or terminal moraine, an arc- like ridge that 

forms at the terminus of glaciers. Excellent examples of 

lateral moraines are on the north and south sides of 

Moraine Park. The south lateral moraine is nearly 1,000 

feet (305 m) high. An end (terminal) moraine forms when 

ice stabilizes for a time prior to retreat. An end moraine 

may dam meltwater to create a lake on its upvalley side. 

Moraine Park Museum sits on an end moraine, which 

also happens to be the terminal moraine, and represents 

the furthest point of glacial advance. A good viewing 

point of moraines is Many Parks Curve. 

Hanging Valleys 

Few landscape features are aesthetically more beautiful 

than a hanging valley with a high cascade or waterfall. A 

hanging valley that is formed by glacial erosion (there are 

other kinds of hanging valleys) is a side valley with its 

mouth at a relatively high level above the main glacial 

valley; it is smaller than the main valley. A “trunk” glacier 

eroded the larger, main valley, and a tributary glacier 

eroded the smaller hanging valley. The discordance of 

the levels of the valley floors, as well as their difference in 

size, is due to the greater erosive power of the main, 

trunk glacier. Some lakes, such as Nanita and Nokoni, lie 

in hanging valleys. Streams that occupy hanging valleys 

are Roaring River, Chiquita Creek, and Fern Creek. 

Horns, Arêtes, and Cols 

Mountains that are, or have been, surrounded by glaciers 

tend to have characteristic forms caused by the 

fracturing action of ice, leading to steep rockwalls at the 

heads of cirques that flank peaks. Where isolated, such 

mountains may form upstanding horns with three or four 

distinct faces. The most famous horn is the Matterhorn 

in the Swiss Alps. The Little Matterhorn, tucked away in 

Glacier Gorge, is less spectacular than its Swiss namesake 

but it still possesses distinctly carved faces. Sometimes 

steep, straight ridges, called arêtes, may link horns and 

cols—open, U- shaped passes. A good example of a col 

lies above Andrews Glacier in Loch Vale. This particular 

col directs wind- blown snow, carried over the 

Continental Divide, onto the surface of this “wind drift” 

glacier. 

Outwash Deposits, Kettles, and Kettle Ponds 

During a warming trend as a glacier recedes, a stream 

laden with sediment is “washed out” from the glacier 

(hence the term “outwash”) and deposited in a flat area 

below. In mountainous areas, these deposits are called 

valley trains. Depressions, known as kettles, often 

pockmark outwash and moraines. Kettles form when a 

block of stagnant ice becomes wholly or partially buried 

in sediment and ultimately melts, leaving a pit behind. 

Kettles can be feet or miles long but are usually shallow. 

In many cases, water eventually fills the depression and 

forms a pond or lake, called a kettle pond or kettle lake. 

Sheep Lakes are kettle ponds that lie in the outwash on 

the floor of Horseshoe Park. These small ponds are 

intermittent and usually dry up late in the summer. 

Bighorn sheep visit these kettle ponds, primarily during 

their lambing season in May and June, to drink the water 

and eat the mud, which is rich in nutrients for lactating 

ewes. We have the glaciers to thank for this prime 

wildlife- viewing area. 

Roches Moutonnées 

Roches moutonnées are characteristic of glacial erosion 

on massive rocks. Roches moutonnées are asymmetrical, 

elongate knobs or hillocks of resilient bedrock that have 

been smoothed and scoured by moving ice on the 

upglacier (stoss) side. On the down (lee) side, the rock is 

steep and hackly from glacial quarrying. Moutonnées are 

the wigs—with smooth bangs and curly backs—that 

barristers and judges wore in early European and British 

courts and resemble this glacial form. People have also 

interpreted roches moutonnées as “rock sheep,” as they 

are thought to resemble grazing sheep. The knob in the 

middle of Moraine Park is a fair example of a roche 

moutonnée. 

U-shaped Valleys 

Prior to the appearance of glaciers, alpine valleys are 

characteristically V- shaped, as is typical for valleys cut 

by streams. As a glacier moves down a valley, it makes the 

valley wider, steeper, and straighter, so that the previous 

V- shaped valley is transformed into a U- shaped one. 

Good examples of U- shaped valleys are abundant in the 

park, for instance, the valley of Fall River and 

Kawuneeche Valley. When glaciers retreat, the bottoms 

of U- shaped valleys may become flat, as sediment 

deposited in lakes impounded by the terminal moraines 

fills them. 

Glaciers 

Today, the park’s small glaciers are restricted to high 

elevations above 11,000 feet (3,350 m) and north- and 

east- facing cirques, where they are sheltered from the 

Sun’s direct rays. Local topography helps to shelter the 

glaciers and directs wind- blown snow onto their 

surfaces. In general, during the winter blowing snow 

occurs over 50% of the time, with 95% of the days in 

January having blowing snow. On average, over 30 

blowing snow events occur each winter, with each event 

averaging 36- hours long (Berg, 1986). Hence, glaciers in 

the Front Range are referred to as “wind- drift glaciers” 

because they receive most of their snow as wind- blown 

snow, which falls predominantly on the western slope 

and is transported to the eastern slope. Notably, these 

glaciers have been able to form well below regional 

snowline because of wind drift. A fine example of a 

wind- drift glacier in the park is Andrews Glacier. 

Braddock and Cole (1990) identified 34 snow banks and 

ice masses in the vicinity of Rocky Mountain National 

Park. These include the snow and ice bodies shown on 

1:24,000- scale topographic maps published between 1957 

and 1962. Fourteen of the ice masses have been named: 

Rowe Glacier (between Rowe Peak and Hagues Peak), 

Sprague Glacier (at Irene Lake in Spruce Canyon), 

Tyndall Glacier (at the head of Tyndall Creek), Andrews 

Glacier (east of Andrews Pass), Taylor Glacier (at the 

head of Icy Brook), Chiefs Head Peak Glacier (above 

Frozen Lake), Mills Glacier (on the east side of Longs 
16 NPS Geologic Resources Division 

Peak), Moomaw Glacier (south of The Cleaver), and the 

six St. Vrain Glaciers (outside of the park at the head of 

Middle St. Vrain Creek). 

All but one of these snow banks or ice masses are on the 

east side of the Continental Divide; the exception is the 

mass above Murphy Lake (near Snowdrift Peak). All but 

one occur at the heads of cirques: north- , northeast- , or 

east- facing; the exception is the large snowbank 

northeast of Rowe Mountain, which is in a northeastfacing gully. Some of the ice masses, such as Andrews 

Glacier, are actively moving and can be considered actual 

glaciers; others are stagnant. Over long periods of time, it 

is not known whether these masses are growing or 

shrinking (Braddock and Cole, 1990). 

Rock Glaciers 

Rock glaciers are distinctive from ice glaciers in that their 

movement is characterized by a large amount of 

embedded and overlying rock material. A rock glacier 

may be composed of (1) ice- cemented rock formed in 

talus that is subject to permafrost, (2) ice- cemented rock 

debris formed from avalanching snow and rock, or (3) 

rock debris that has a core of ice, either a debris- covered 

glacier or a remnant moraine. Two types of rock glaciers 

occur in the Front Range. The first type forms on the 

floors of modern cirques and closely resembles the 

tongues of small valley glaciers. They are referred to as 

cirque- floor rock glaciers (Outcalt and Benedict, 1965) 

or tongue- shaped rock glaciers (Madole, 1972). Because 

they contain cores of banded glacial ice and grade 

upvalley into lateral moraines, investigators determine 

rock glaciers of this type to represent the debris- covered 

tongues of former glaciers in the Front Range. This may 

not be true everywhere, however (Madole, 1972). Most 

cirque- floor rock glaciers consist of two or more 

superimposed lobes, bounded by longitudinal furrows, 

resulting from independent ice advances. Despite their 

compound nature, the complexes now appear to be 

moving downslope as single units (Outcalt and Benedict, 

1965). 

Rock glaciers of an entirely different character occur 

beneath steep valley walls, where they are supplied with 

debris from avalanche couloirs. Interstitial ice, 

responsible for the movement of the “valley- wall” rock 

glaciers, probably results from the metamorphism of 

snow buried beneath rockfall debris or supplied by 

winter avalanching (Outcalt and Benedict, 1965). 

Geologists also refer to this type of rock glacier as a 

lobate- shaped rock glacier (Madole, 1972). 

In Rocky Mountain National Park, rock glaciers either 

accumulate at heads of cirques and flow down the length 

of the main valley or accumulate along the sides of 

valleys and flow outward toward the center. Rock 

glaciers are abundant on both sides of the Continental 

Divide and both sides of the Never Summer Mountains, 

and have flowed down slopes that face all compass 

directions (Braddock and Cole, 1990). Rock glaciers 

occur on Ships Prow, Pagoda Mountain, and Storm Peak 

on the east side of the park, and near Azure, Julian, and 

Hayden lakes on the west side of the park (Braddock and 

Cole, 1990). 

Lakes 

Numerous lakes—nearly 150—punctuate the landscape 

of Rocky Mountain National Park. They come in many 

shapes and sizes, and their origins vary. 

As the large valley glaciers retreated, they left basins in 

their paths. Today, chains of glacial lakes are found in 

these deprressions and appear as treads of a rising 

staircase. The term paternoster, i.e., “Our Father,” is an 

apt description for these chains of lakes, as they resemble 

the beads on a rosary. An example of paternoster lakes is 

the linked Fifth–Fourth–Spirit–Verna–Lone Pine lakes 

on the west side of the park. Some, such as Gorge Lakes 

(seen from Trail Ridge looking across Forest Canyon), 

fill glacially carved but do not form chains. Others, such 

as Forest Lake and Bierstadt Lake—additional examples 

of kettle ponds—formed behind dams of glacial moraine 

(Emerick, 1995). 

A number of small pothole ponds, formed by weathering 

of exposed bedrock, lie among the granite outcrops 

along Lumpy Ridge. The largest of these is Gem Lake, a 

rain- fed pond with no inlet or outlet (Emerick, 1995). 

Ponds and lakes are among the most temporary features 

of the landscape. Though they may seem long- lived in 

terms of human generations, lakes gradually fill with 

sediment and become shallower and smaller (Emerick, 

1995). 

Meandering Streams 

Streams constantly erode their banks and deposit new 

sediment; hence, riparian zones change more than any 

other type of ecosystem in the park. In flat valleys, 

streams tend to meander, widening their bends and 

occasionally short- circuiting them, leaving the 

abandoned meanders to form oxbow lakes, which over 

time fill in with sediment. Floods that result from snowy 

winters and wet springs may scour channels or form new 

stream courses. 

Meandering streams are typical of streams in the park 

because gradients are low behind the Pleistocene 

moraine dams. In many cases, meandering streams 

represent lake floors of past glacial lakes or outwash 

deposits. Good examples of meandering streams are in 

the area surrounding the Bowen- Baker Trailhead, where 

the Colorado River meanders across the valley, and 

Horseshoe Park. Horseshoe Park earned its name 

through this geomorphic process: loops in the 

meandering stream that have been cut off and left behind 

as isolated sections, resemble horseshoes. 

Patterned Ground 

Today the term periglacial is used to describe processes 

and landforms associated with very cold climates in areas 

not permanently covered with snow and ice. Periglacial 

features are distinctive from glacial features and in many 

cases are located far from glaciers. One particular 
 ROMO Geologic Resource Evaluation Report 17 

periglacial features in Rocky Mountain National Park is 

patterned ground, which forms at high elevations, above 

about 11,500 feet (3,505 m) in the Front Range (Ives and 

Fahey, 1971). An interesting effect of ice- crystal growth in 

soils (ground ice) is the moving of soil and rock 

fragments upward toward the surface to form mounds 

and rows of soil or rock. Rock fragments lying close to 

the surface conduct heat causing a cycle of freezing and 

thawing and growth of ice under rocks. Continued 

thickening of ice layers heaves rocks upward, causing 

them to rise to the surface. Frost action moves rocks 

both sideways and upward. Heaved rocks form patterns 

of bands, circles, nets, and polygons called patterned 

ground. 

Large angular blocks of rock in an accumulation known 

as felsenmeer (German for “rock sea”) are a conspicuous 

display of frost action above treeline. People have also 

described them as “tombstone rocks” (Kiver and Harris, 

1999). A popular stopping point along Trail Ridge Road is 

Rock Cut. Tundra Communities Trail leading from the 

road provides easy access through felsenmeer and 

patterned ground. 

Sackung 

Many geologic features do not fit nicely into just one 

category; sackung features are a case in point being both 

glacial and structural. As thick, mountain glaciers carved 

their way down preexisting valleys, they caused two 

changes: they steepened the valley walls, and to a lesser 

degree, they deepened the valleys. When the ice filled 

these valleys, the glaciers provided lateral support to the 

valley walls. When the ice melted, the steep valley walls 

lost their support. Gravity caused the mountains between 

the over- steepened valleys to actually spread laterally 

into the valleys. Small faults along the tops and sides of 

ridge crests were created that commonly have uphillfacing scarps called sackung features. In the past, 

geologists have thought these faults were caused by 

mountain- building processes; they now know they were 

caused by mountain “falling” processes. 

Solifluction 

The term solifluction was proposed by Andersson (1906) 

as “the slow flowing from higher to lower ground of 

masses of waste saturated with water.” Because 

Andersson did not state explicitly that it referred to flow 

over frozen ground, some geomorphologists have 

extended the term to include similar movement in 

temperate and tropical regions. It is preferable to restrict 

the term to slow soil movement in periglacial areas, 

however (Bates and Jackson, 1987). (See also Geologic 

Issues section of this report.) 

The term solifluction implies the presence of permafrost. 

Permafrost (i.e., permanently frozen ground) has no 

doubt existed over most of the alpine zone in the past, 

but it is discontinuous today (Rich Madole, written 

communication, 2003). 

During the summer season in the high country, water is 

unable to percolate into an impervious layer of frozen 

ground below the surface. As a result an “active layer” of 

soil becomes supersaturated and flows. Flowage can 

occur on slopes as gentle as two or three degrees. Where 

there is a well- developed mat of vegetation, a sheet may 

move downward in a series of well- defined lobes and 

form terrace- like features. Features formed by soil 

flowage appear as wavy slopes and are quite prominent 

along Trail Ridge Road, for example, between Forest 

Canyon Overlook and Rock Cut. 

Tors 

Tors are isolated rock towers rising prominently above 

otherwise level terrain. They are typically composed of 

granite, which is very jointed and made more so by sheer 

jointing that develops because of dilation as rock is 

unloaded. Tors may assume peculiar or fantastic shapes. 

Visitors can see excellent examples along the nature walk 

above Rock Cut on Trail Ridge Road. Investigators think 

that periglacial processes may be important in the 

formation of tors (Bates and Jackson, 1987). Investigators 

have identified tors as indicators of non- glaciation 

(Street, 1973). Tors remain in areas that were beyond the 

limit of glaciation, otherwise glaciers would have 

modified or destroyed them. 

Uplifted Erosion Surface 

The so- called “Roof of the Rockies” is a remnant of an 

ancient rolling plain that has survived despite being 

broken by faults, uplifted several thousand feet, 

intersected by great canyons, and subjected to the 

vicissitudes of the Ice Age (Richmond, 1974). Big Horn 

Flats and the flat, plain- like surface that spans across the 

landscape between 11,000 and 12,000 feet (3,350 to 3,660 

m) on Trail Ridge are parts of this uplifted erosion 

surface. 

Since the erosion surface was first recognized and 

reported (Marvine, 1874), it has caught the attention of 

geologists and visitors alike, but not without controversy. 

Questions still remain regarding: (1) the number of 

surfaces—investigators have recognized as few as one to 

as many as 11 surfaces; (2) the age—early or late Tertiary, 

that is 5 million or 50 million years old; and (3) the 

genesis—peneplain (forming at low elevations and with 

low river gradients) vs. pediment (forming under arid 

conditions along mountain fronts or plateaus). 

Geologists have paid so much attention to erosion 

surfaces because of the structural implications. For 

decades, geologists used erosion surfaces as a clue to the 

post- Laramide deformational history of the middle and 

southern Rocky Mountains. Because peneplains were 

believed to form at low elevations and with low river 

gradients, substantial uplift was required to bring them to 

their present elevations. Using this kind of evidence, 

investigators estimated late Cenozoic uplift to between 

5,000 and 9,000 feet (1,524 and 2,743 m) (Davis, 1911; 

Chamberlain, 1919). Reclassifying peneplains as 

pediments greatly reduced the amount of uplift required 

(Johnson, 1931, 1932; Mackin, 1947). Uplift was then 

estimated from displaced flora and fauna, for example 

using fossils from Florissant, Colorado (Epis and Chapin, 
18 NPS Geologic Resources Division 

1975). The curious irony is that the magnitude of uplift 

based on paleontology is approximately the same as it 

was when based on peneplains (Bradley, 1987). 

The most recent theory regarding erosion surfaces 

identifies one major subsummit (lower) surface and a 

second (higher) summit surface. The lower surface 

formed in late Tertiary time when conditions were arid 

to semi- arid, classifying it as a pediment. The higher 

surface is much less extensive than the lower subsummit 

surface. Studies have concentrated on the lower erosion 

surface that has been called “Rocky Mountain,” 

“Sherman,” “Late Eocene,” and “Subsummit,” which 

leaves the full significance of the higher surface, which 

has been called “Flattop” and “Summit,” inconclusive 

(Bradley, 1987). Terra Tomah Mountain, Flattop 

Mountain, and Longs Peak are all part of the higher 

summit surface. 
 ROMO Geologic Resource Evaluation Report 19 

Formation Properties 

This section serves as the critical link between resource managers and the geologic map 

of the park. Formation Tables are highly generalized and for informational purposes 

only. Ground disturbing activities should not be permitted or denied on the basis of 

information contained in these tables. More detailed unit descriptions can be found in 

the help files accompanying the digital geologic map or by contacting the Geologic 

Resources Division at 303- 969- 2090. 

This section provides readily available information about 

the rock units (deposits and formations—lithologically 

distinct, mappable bodies of rock) in Rocky Mountain 

National Park, including age, unit name, map symbol, 

locations within the park, description, local and global 

significance, geologic hazards within the unit, suitability 

for development and recreation, and resource potential 

and protection. 

Not all the rock units identified on Geologic Map of 

Rocky Mountain National Park and Vicinity, Colorado

(Braddock and Cole, 1990) are addressed. Only the rocks 

that occur within the park’s boundary and illustrate 

significant geologic events or processes are listed. Rock 

units are organized from youngest to oldest. 

Although none of the units contain mineral deposits of 

commercial values, many units contain specimens that 

may be temptations to casual collectors, and therefore, 

are notable for resource protection. Some of the units are 

mined for building stone and sand and gravel elsewhere. 

In the table, found on the following pages, “Ma” 

represents “millions of years.” In addition, although 

some of the units should be evaluated for flooding 

potential prior to development, intense mountain floods, 

on the scale of the Big Thompson Flood of 1976, are 

statistically unlikely above 8,000 feet (2,438 m). 


 ROMO Geologic Resource Evaluation Report 23 

Geologic History 

Precambrian Time 

Ancient rocks form the core of the mountains in Rocky 

Mountain National Park. These rocks are more than 

1,700 million years old and are from Precambrian time. In 

areas less exposed to the forces of heat and pressure (and 

accompanying recrystallization of rocks) sedimentary 

features still exist and display original sedimentary 

structures, which aid in interpretation of ancient 

environments. Most of the sedimentary rocks, however, 

metamorphosed into biotite schist and biotite gneiss. 

About 1,664 million years ago, a massive igneous 

intrusion occurred, today preserved as Boulder Creek 

Granodiorite and related pegmatites. The Boulder Creek 

batholith was the heat source for regional 

metamorphism. In a separate widespread intrusive 

episode, the granite of Hagues Peak (about 1,480 million 

years ago), mafic dikes (about 1,430 million years ago), 

and Silver Plume Granite and minor pegmatite (about 

1,420 million years ago) were emplaced into the older 

biotite gneisses and schists throughout the Front Range. 

Deformation around these younger intrusions was 

localized but significant. For example, the near 

horizontal layering of banded schists and sheets of gray 

granite exposed in cirques east of the Continental Divide 

formed as Silver Plume Granite intruded into the older 

rocks and spread out laterally. Metamorphic effects 

related to the intrusions of Silver Plume Granite were 

relatively minor because the biotite gneisses and schists 

had already been recrystallized at high temperature and 

pressure. 

Scientists do not know much about the Precambrian 

mountain ranges in which these rocks formed because 

they were worn away by erosion at the end of 

Precambrian time. The convoluted gneisses and schists, 

however, do tell us that Precambrian tectonic activity 

occurred repeatedly. Major faults produced during 

Precambrian events were later reactivated and play 

important roles in localizing mountain building in both 

Pennsylvanian and Laramide times. 

Paleozoic and Mesozoic Eras 

A long interval of erosion followed the metamorphic and 

igneous events of Precambrian time. Many thousands of 

feet of rock were removed, producing a major 

unconformity. Paleozoic seas crept across the area 

burying the ancient erosion surface with sediment. Little 

evidence remains in Rocky Mountain National Park of 

the more than 500 million years that comprise the 

Paleozoic and Mesozoic eras. Because of the lack of 

geologic clues within the park, geologists rely on 

upturned layers of sedimentary rock that lie outside the 

park’s boundaries to learn what happened during this 

time. 

Late Paleozoic mountain building (Pennsylvanian 

Period, about 300 million years ago) formed the 

Ancestral Rocky Mountains, which were elevated along 

some of the faults in the crystalline (Precambrian) 

basement. In general, the Paleozoic structures are not 

well preserved or are covered by later strata. 

Furthermore, in many areas where they are exposed, the 

possibility that later deformation reactivated and rotated 

these earlier structures cannot be completely ruled out 

(Kluth, 1997). Interpretation of the Ancestral Rocky 

Mountains, therefore, is based on thickness, facies, and 

contact information within the sedimentary rocks 

deposited near the uplift during the orogeny (Kluth, 

1997). The position of mountain uplift during 

Pennsylvanian time is coincident with the present- day 

Wet Mountains, Front Range, Medicine Bows, North 

Park Basin, Gore Range, and Park Range (Sonnenberg 

and Bolyard, 1997). As such, they extended from Boulder 

to Steamboat and were longer than the Front Range of 

today. 

The area remained above sea level well into the Jurassic 

Period (about 150 million years ago). During this time, 

sediment deposition occurred in rivers, swamps, and 

dunes. These deposits are preserved outside of the park. 

By Cretaceous time, however, seas once again spread 

across the land. Evidence of the Cretaceous Interior 

Seaway is preserved in Rocky Mountain National Park in 

the form of Pierre Shale. The summits of Howard 

Mountain and Mount Cirrus in the Never Summer 

Mountains consist of this marine shale that was once 

mud at the bottom of the Late Cretaceous sea. 

By the end of the Cretaceous Period and beginning of 

Tertiary Period (70 million years ago), the land was once 

again rising from the sea during a time of mountain 

building known as the Laramide orogeny. The events to 

follow consisted of a long series of repeated uplifts, 

periods of volcanism, and episodes of erosion 

(Richmond, 1974). 

Cenozoic Era 

The Laramide orogeny continued into the Cenozoic Era. 

The orogeny was a time of active tectonism and blockfault mountain building in Colorado (Sonnenberg and 

Bolyard, 1997). The deformation and uplift of the 

Laramide orogeny affected an area that had already been 

the site of large block uplift that formed the Ancestral 

Rocky Mountains (Kluth, 1997). Preexisting faults and 

shear zones largely controlled Laramide deformation 

(Sonnenberg and Bolyard, 1997). North- northwesttrending Precambrian faults control the northnorthwest grain of the Front Range (Sonnenberg and 

Bolyard, 1997). 
24 NPS Geologic Resources Division 

In addition to deformation expressed in the mountain 

uplifts, substantial Laramide deformation occurred in 

the bordering basins (Tweto, 1980a). These basins 

subsided concurrently with the uplift of the adjoining 

mountains. Each basin, e.g., the Denver, Raton, San Juan, 

Piceance, and Sand Wash, received Laramide orogenic 

sediments that constitute the principal record of events 

in the uplifts (Tweto, 1980b). Prior to uplift, thousands of 

feet of Paleozoic and Mesozoic sedimentary rocks 

overlay Precambrian crystalline rocks. Erosion, during 

and after the Laramide orogeny, removed the 

sedimentary rocks and some of the crystalline rocks from 

the range. The sedimentary rocks survive, however, in 

the flanking basins where they are commonly covered by 

Cenozoic rocks (Bradley, 1987). 

Widespread volcanism affected most of the Southern 

Rocky Mountains in Oligocene time (Steven, 1975). The 

lava flows at Mount Richthofen mark an episode 

occurred 29.5 million years ago. Near Specimen 

Mountain, mudflows, lava flows, and obsidian are 

indicators of more recent activity (27.5 million years ago). 

In the Troublesome Formation (lower Miocene and 

upper Oligocene), lava flows in the lower units and ash 

beds in the upper units record volcanic activity 23 to 29 

million years ago (Braddock and Cole, 1990). Volcanic 

ash is preserved as rhyolite welded tuff (late Oligocene) 

near Iceberg Lake along Trail Ridge Road. Volcanism 

was accompanied by igneous intrusion (Steven, 1975). 

The granite of Mount Cumulus stock (28.5 million years 

ago) is evidence of this. 

A period of erosion continued after widespread 

Oligocene volcanism and eventually removed many of 

the volcanoes that formed in the Front Range area. 

Widespread fluvial deposition of volcanic and 

Precambrian clasts started in middle Miocene (14 to 11.5 

million years ago); beds in the upper Troublesome 

Formation are evidence of this (Steven and others, 1997). 

Broad uplift, block faulting, and erosion characterize 

Neogene (Miocene and Pliocene) time. Considerable 

scientific debate continues concerning the origin of the 

topographic difference between the mountains and 

flanking lowlands that formed during this time. Does the 

escarpment indicate Neogene faulting along the 

mountain front or is it caused by differential erosion of 

the rocks on opposite sides of the Laramide- age faults? 

Some evidence shows that nearly all of the modern relief 

along the eastern escarpment of the Front Range is due 

to differential erosion (Leonard and Langford, 1993). 

Other evidence, from the White River Plateau and 

Elkhead Mountains, suggests that there was nearly 2,000 

feet (610 m) of offset during Neogene time (Tweto, 

1980a). The debate continues, and new concepts and 

evidence are fueling the dialogue (e.g., Pederson and 

others, 2002). 

The elevation of present- day mountains attests to 

Neogene events, as does a deposit in the park: a 

diamicton—unsorted, unstratified deposit—near Meeker 

Campground. This deposit is evidence of the Tertiary 

tectonic history in the area. The diamicton was deposited 

on a surface developed during Tertiary time that was 

later uplifted and deeply dissected (Wahlstrom, 1947; 

Madole, 1982). 

The diamicton also played a role in interpreting the 

Quaternary glacial history of the area. The diamicton 

resembles till, but investigators have interpreted it as a 

fan deposit of Neogene or Quaternary age (Braddock 

and Cole, 1990), thereby having an alluvial origin, not a 

glacial one. This distinction is important because of the 

implications it has on Cenozoic climatic history. With 

respect to the location of this diamicton, if it were of 

glacial origin, early Pleistocene (i.e., pre- Bull Lake) 

glaciers must have been much larger than glaciers during 

later Bull Lake and Pinedale advances. A glacial 

interpretation of this diamicton goes against the overall 

pattern of glaciation documented thus far in the Front 

Range and neighboring ranges; that is, the extent of early 

and late Pleistocene glaciation was not notably different 

(Madole, 1976b). 

The most recent regional tectonic event that influenced 

the Front Range was general uplift of the entire Southern 

Rocky Mountains, western Great Plains, and Colorado 

Plateau during the late Miocene and Pliocene, and 

possibly Quaternary time. Fault movement diminished 

after Pliocene time but continued on a minor scale 

through the Pleistocene and into the Holocene (Kirkham 

and Rodgers, 1981; Widmann and others, 1998). Uplift 

rejuvenated erosion and caused the long recognized 

“canyon cycle” (Lee, 1923) that cut deep canyons in the 

mountains. Canyon cutting probably continues today 

(Tweto, 1980a). 

Uplift of nearly a mile (1.6 km) and worldwide cooling 

during the last few million years caused a profound 

transformation of climates. At times, winter snow at high 

elevations no longer completely melted during the 

summer but piled up in favorable locations, ultimately 

forming large valley glaciers. Although several glaciations 

occurred during Pleistocene time, geologists distinguish 

deposits of only three ages within or in close proximity 

to the boundaries of Rocky Mountain National Park. 

These glaciations are referred to as pre- Bull Lake, Bull 

Lake, and Pinedale. Investigators have identified deposits 

of Bull Lake and Pinedale glaciations in the park. 

The glacial chronology of Rocky Mountain National 

Park is a work in progress. The beginning of the Bull 

Lake glaciation is based on correlations to marine 

isotope stage 6, which began about 180,000 years ago 

(Imbrie and others, 1984). Researchers estimated the 

timing using sea- surface temperature recorded in the 

oxygen- isotope compositions of the shells of 

foraminifera. Using oxygen isotopes, investigators date 

the end of the Bull Lake glaciation at 127,000 years ago 

(Bassinot and others, 1994). An interglacial (warm) 

period followed the Bull Lake glaciation, during which 

time Bull Lake glaciers completely melted away. Another 

glaciation followed for which there are good estimates of 

the timing of events. Using radiocarbon ages of organic-
 ROMO Geologic Resource Evaluation Report 25 

rich sediments at several high- elevation sites (Nelson 

and others, 1979; Madole, 1976b, 1980, 1986), investigators 

have estimated the timing of Pinedale glacial advances 

and retreats. Pinedale glaciation began about 30,000 

years ago and was at its maximum between 23,500 and 

21,000 years ago. Final deglaciation occurred between 

15,000 and 12,000 years ago. Prior to 10,000 years ago, all 

Pinedale glaciers disappeared from the area. Pinedale 

glaciation was the last true valley glaciation to affect the 

Front Range. 

Another glacial advance that occurred in late Pleistocene 

time is referred to as the Satanta Peak advance. This 

cirque- glacier advance was the most extensive to occur 

after the large valley glaciers disappeared. Researchers 

have documented this advance at Sky Pond in the park 

(Menounos and Reasoner, 1997). The Satanta Peak 

advance began prior to about 14,400 years ago and ended 

about 10,000 years ago (Rich Madole, written 

communication, 2003). The deposition of the Satanta 

Peak moraine in Loch Vale appears to be coeval with the 

European Younger Dryas event (Menounos and 

Reasoner, 1997). 

Ice accumulation during Holocene time was not 

extensive enough to be considered an ice age. Some 

investigators have applied the term “Neoglaciation” to 

ice accumulation during the Holocene, but 

Neoglaciation may be a misnomer for the Front Range 

(Benedict, 1981). Post- Pleistocene ice accumulation is 

limited to within cirques. Investigators have identified 

many deposits in Rocky Mountain National Park, and 

deposits record four intervals of ice accumulation in the 

vicinity of the park. From oldest to youngest, they are 

referred to as Ptarmigan (7,250–6,380 BP), Triple Lakes 

(5,200–3,000 BP), Audubon (2,400–950 BP), and Arapaho 

Peak (350–100 BP) (Benedict, 1985). The Ptarmigan 

advance represents a brief reversal of the warming trend 

that had begun about 10,000 years ago (Benedict, 1985). 

The Triple Lakes accumulation was the most extensive. 

Arapaho Peak deposits are the Front Range equivalent of 

Little Ice Age moraines (Davis, 1988). Like modern 

glaciers, Audubon and Arapaho Peak glaciers depended 

on wind- drifted snow for their existence (Benedict, 

1985). 

Braddock and Cole (1990) identified 34 snow banks and 

ice masses in the vicinity of Rocky Mountain National 

Park. These include the snow and ice bodies shown on 

1:24,000- scale topographic maps published between 1957 

and 1962. Fourteen of the ice masses have been named: 

Rowe Glacier (between Rowe Peak and Hagues Peak), 

Sprague Glacier (at Irene Lake in Spruce Canyon), 

Tyndall Glacier (at the head of Tyndall Creek), Andrews 

Glacier (east of Andrews Pass), Taylor Glacier (at the 

head of Icy Brook), Chiefs Head Peak Glacier (above 

Frozen Lake), Mills Glacier (on the east side of Longs 

Peak), Moomaw Glacier (south of The Cleaver), and the 

six St. Vrain Glaciers (outside of the park at the head of 

Middle St. Vrain Creek). 

All but one of these snow banks or ice masses are on the 

east side of the Continental Divide; the exception is the 

mass above Murphy Lake (near Snowdrift Peak). All but 

one occur at the heads of cirques: north- , northeast- , or 

east- facing; the exception is the large snowbank 

northeast of Rowe Mountain, which is in a northeastfacing gully. Some of the ice masses, such as Andrews 

Glacier, are actively moving and can be considered actual 

glaciers; others are stagnant. Winter winds—sometimes 

at velocities that exceed 200 miles (320 km) per hour—

blow snow over the Continental Divide where it drifts 

into the Pleistocene- age cirques and nourishes some 

small glaciers. The process of snow deposition gives 

these “wind- drift glaciers” their name. It is not known 

whether, over a long period of time, these masses are 

growing or shrinking (Braddock and Cole, 1990). 

The periglacial features that exist today are relicts of 

previous climatic conditions. Most of these features are 

not active today (Rich Madole, written communication, 

2003). Features include patterned ground and other 

periglacial deposits on ridgetops and upland surfaces, 

tongue- shaped and lobate rock glaciers, and colluvium 

(e.g., talus and scree), alluvium (e.g., deposits at the 

margin of lateral moraines). 
26 NPS Geologic Resources Division 

References Cited 

Allen, T.J., 1936, Noteworthy geologic features in Rocky 

Mountain National Park, Colorado [unpublished 

memorandum to the Director (October 31, 1936), list of 

features, and appended bibliography]: U.S. 

Department of the Interior, National Park Service, 9 p. 

Arps, L.W., and Kingery, E.E., assisted by Kingery, H.E., 

1977, High country names—Rocky Mountain National 

Park and Indian Peaks: Boulder, Colorado, Johnson 

Books, published in cooperation with the Rocky 

Mountain Nature Association, 198 p. (Reprinted 1994.) 

Bassinot, F.C., Labeyrie, L.D., Vincent, E., Quidelleur, X., 

and Shackleton, N.J., 1994, The astronomical theory of 

climate and the age of the Brunhes- Matuyama 

magnetic reversal: Earth and Planetary Science Letters, 

v. 126, p. 91–108. 

Bates, R.L., and Jackson, J.A., eds., 1987, Glossary of 

geology (3rd ed.): Alexandria, Virginia, American 

Geological Institute, 788 p. 

Benedict, J.B., 1970, Frost cracking in the Colorado Front 

Range: Geografiska Annaler, v. 52A, p. 87–93. 

Benedict, J.B., 1981, The Fourth of July valley—glacial 

geology and archeology of the timberline ecotone: 

Ward, Colorado, Center for Mountain Archeology, 

Research Report No. 2, 139 p. 

Benedict, J.B., 1985, Arapahoe Pass—glacial geology and 

archeology at the crest of the Colorado Front Range: 

Ward, Colorado, Center for Mountain Archeology, 197 

p. 

Berg, N.H., 1986, Blowing snow at a Colorado alpine 

site—measurement and implications: Arctic and 

Alpine Research, v. 18, p. 147–161. 

Boos, C.M., and Boos, M.F., 1934, Granites of the Front 

Range—Longs Peak–St. Vrain batholith: Geological 

Society of America Bulletin, v. 45, p. 303–332. 

Boos, M.F., and Boos, C.M., 1933, Iron Dike [abs.]: 

Geological Society of America Bulletin, v. 44, p. 73. 

Braddock, W.A., and Cole, J.C., 1990, Geologic map of 

Rocky Mountain National Park and vicinity, 

Colorado: U.S. Geological Survey Map I- 1973, scale 

1:50,000. 

Braddock, W.A., and Peterman, Z.E, 1989, The age of the 

Iron Dike—a distinctive Middle Proterozoic intrusion 

in the northern Front Range of Colorado: The 

Mountain Geologist, v. 26, no. 4, p. 97–99. 

Bradley, W.C., 1987, Erosion surfaces of the Colorado 

Front Range—a review, in Graf, W.L., ed., 

Geomorphic systems of North America: Boulder, 

Colorado, Geological Society of America, Centennial 

Special Volume 2, p. 215–220. 

Caine, T.N., 1974, The geomorphic processes of the 

alpine environment, in Ives, J. D., and Barry, R.G., eds., 

Arctic and Alpine Environments: London, Methuen, p. 

721–748. 

Caine, T.N., 1986, Sediment and movement and storage 

on alpine slopes in the Colorado Rocky Mountains, in

Abrahams, A.D., ed., Hillslope processes, The 

Binghamton Symposia in Geomorphology Series 16: 

Boston, Massachusetts, George Allen and Unwin, p. 

115–137. 

Chamberlain, R.T., 1919, The building of the Colorado 

Rockies: Journal of Geology, v. 27, p. 145–164, 225–251. 

Cole, J.C., 1977, Geology of east- central Rocky Mountain 

National Park and vicinity, with emphasis on the 

emplacement of the Precambrian Silver Plume Granite 

in the Longs Peak–St. Vrain batholith [Ph.D. thesis]: 

Boulder, University of Colorado, 344 p. 

Colorado Geological Survey, 1999, Where do diamonds 

come from?: RockTalk, v. 2, no. 3, p. 2–3. 

Colton, R.B., Holligan, J.A., and Anderson, L.W., 1975, 

Preliminary map of landslide deposits, Greeley 1° X 2° 

quadrangle, Colorado: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 704, scale 

1:250,000. 

Cooper, D.J., Woods, S.W., Chimner, R.A., and 

MacDonald, L.H., 2000, Effects of the Grand Ditch on 

wetlands of the Kawuneeche Valley, Rocky Mountain 

National Park, Colorado: U.S. Department of the 

Interior, National Park Service, 373 p. 

Davis, P.T., 1988, Holocene glacier fluctuations in the 

American Cordillera: Quaternary Science Reviews, v. 

7, p. 21–38. 

Davis, W.M., 1911, The Colorado Front Range—as study 

in physiographic presentation: Association of 

American Geographers Annals, v. 11, p. 21–83. 

Effinger, W.L., 1934, A report on the geology of Rocky 

Mountain National Park: Berkeley, California, 

Department of the Interior, National Park Service, 

Field Division of Education, 27 p. 

Emerick, J.C., 1995, Rocky Mountain National Park 

natural history handbook: Niwot, Colorado, Roberts 

Rinehart Publishers, 158 p. 
 ROMO Geologic Resource Evaluation Report 27 

Epis, R.C., and Chapin, C.E., 1975, Geomorphic and 

tectonic implications of the post- Laramide, late 

Eocene erosion surface in the Southern Rocky 

Mountains, in Curtis, B.F., ed., Cenozoic history of the 

Southern Rocky Mountains: Geological Society of 

America Memoir 144, p. 45–74. 

Fuller, M.B., 1924, General features of pre- Cambrian 

structure along the Big Thompson River in Colorado: 

The Journal of Geology, v. 32, no. 1, p. 49–63. 

Fuller, M.B. 1926, Contact metamorphism in the Big 

Thompson schist in northcentral Colorado: American 

Journal of Science, v. 211, p. 194–200. 

Gamble, B.M., 1979, Petrography and petrology of the 

Mount Cumulus Stock, Never Summer Mountains, 

Colorado [M.S. thesis]: Boulder, University of 

Colorado, 75 p. 

Hopkins, R.L., and Hopkins, L.B., 2000, Hiking 

Colorado’s geology: Seattle, The Mountaineers, 240 p. 

Hoyt, W.H., 1987, A geologist’s perspective of the 1982 

Estes Park flood, in Gruntfest, E.C., ed., What we have 

learned since the Big Thompson Flood: Natural 

Hazards Research and Applications Information 

Center, Special Publication 16, p. 213–219. 

Imbrie, J., Hays, J.D., Martinson, D.G., McIntyre, A., 

Mix, A.C., Morley, J.J., Pisias, N.G., Prell, W.L., and 

Shackleton, N.J., 1984, The orbital theory of 

Pleistocene climate—support from a revised 

chronology of the marine ä18O record, in Berger, A., 

Imbrie, J., Hayes, J., Kukla, G., and Saltzman, B., eds., 

Milankovitch and climate: Dordrecht, D. Reidel 

Publishing Co., pt. 1, p. 269–305. 

International Conference of Building Officials, 1979, 

Uniform building codes (1979 edition). 

Ives, J.D., and Fahey, B.D., 1971, Permafrost occurrence 

in the Front Range Colorado Rocky Mountains, 

U.S.A.: Journal of Glaciology, v. 10, p. 105–111. 

Izett, G.A., 1974, Geologic map of the Trail Mountain 

quadrangle, Grand County, Colorado: U.S. Geological 

Survey Map GQ- 1156, scale 1:24,000. 

Izett, G.A., 1975, Late Cenozoic sedimentation and 

deformation in northern Colorado and adjoining 

areas, in Curtis, B.F., ed., Cenozoic history of the 

Southern Rocky Mountains: Geological Society of 

America Memoir 144, p. 179–209. 

Jarrett, R.D., 1987, Hydrologic research related to the 

1976 Big Thompson River flood, Colorado, in

Gruntfest, E.C., ed., What we have learned since the 

Big Thompson Flood: Natural Hazards Research and 

Applications Information Center, Special Publication 

16, p. 203–212. 

Jarrett, R.D., and Costa, J.E., 1986, Hydrology, 

geomorphology, and dam- break modeling of the July 

15, 1982, Lawn Lake dam and Cascade Lake dam 

failures, Larimer County, Colorado: U.S. Geological 

Survey Professional Paper 1369, 78 p., 2 pls. in pocket. 

Johnson, D., 1931, Planes and lateral corrosion: Science, v. 

73, p. 174–177. 

Johnson, D., 1932, Rock fans of arid regions: American 

Journal of Science, v. 23, p. 389–416. 

Johnson, R.B., and Herzog, D.J., 1982, Summary of 

geologic factors that may influence the sensitivity of 

selected watersheds in Rocky Mountain National 

Park, Colorado, to atmospheric deposition: National 

Park Service, Water Resources Field Support 

Laboratory Report 82- 6, 23 p. 

Kaye, G., 1983, Lulu City—Colorado River trail: Estes 

Park, Colorado, Rocky Mountain Nature Association, 

14 p. 

Kirkham, R.M., and Rogers, W.P., 1981, Earthquake 

potential in Colorado—a preliminary evaluation: 

Colorado Geological Survey Bulletin 43, 175 p. 

Kiver, E.P., and Harris, D.V., 1999, Rocky Mountain 

National Park (Colorado), in Geology of U.S. 

Parklands (5th ed.): New York, John Wiley & Sons, 

chapt. 11, p. 630–644. 

Kluth, C.F., 1997, Comparison of the location and 

structure of the Late Paleozoic and later Cretaceous–

early Tertiary Front Range uplift, in Bolyard, D.W., 

and Sonnenberg, S.A., eds., Geologic history of the 

Colorado Front Range: Denver, Rocky Mountain 

Association of Geologists, p. 31–42. 

Kron, D.G., 1988, Miocene mammals from the central 

Colorado Rocky Mountains [Ph.D. thesis]: Boulder, 

University of Colorado, 377 p. 

Lee, W.T., 1923, Contributions to the geography of the 

United States, 1922—peneplains of the Front Range 

and Rocky Mountain National Park, Colorado: U.S. 

Geological Survey Bulletin 730, 17 p. 

Leonard, E.M., and Langford, R.P., 1994, Post- Laramide 

deformation along the eastern margin of the Colorado 

Front Range—a case against significant faulting: The 

Mountain Geologist, v. 31, no. 2, p. 45–52. 

Lewis, G.E., 1969, Larger fossil mammals and 

mylangaulid rodents from the Troublesome Formation 

(Miocene) of Colorado [Geological Survey Research 

1969]: U.S. Geological Survey Professional Paper 650-

B, p. B53–B56. 

Lovering, T.S., 1930, The Granby anticline, Grand 

County, Colorado: U.S. Geological Survey Bulletin 

822- B, p. 71–76. 
28 NPS Geologic Resources Division 

Lovering, T.S., and Goddard, E.N., 1938, Mineralization 

and geology of proposed southern extension of Rocky 

Mountain National Park, Colorado [unpublished 

report]: U.S. Department of the Interior, National Park 

Service, 25 p. 

Mackin, J.H., 1947, Altitude and local relief of the 

Bighorn area during the Cenozoic: Wyoming 

Geological Association, 2nd annual field conference, 

Guidebook, p. 103–120. 

Madole, R.F., 1972, Neoglacial facies in the Colorado 

Front Range: Arctic and Alpine Research, v. 4, no. 2, p. 

119–130. 

Madole, R.F., 1976, Glacial geology of the Front Range, 

Colorado, in Mahaney, W.C., ed., Quaternary 

stratigraphy of North America: Stroudsburg, 

Pennsylvania, Dowden, Hutchinson, & Ross, Inc., p. 

297–318. 

Madole, R.F., 1980, Time of Pinedale deglaciation in 

north- central Colorado—further considerations: 

Geology, v. 8, p. 118–122. 

Madole, R.F., 1982, Possible origins of till- like deposits 

near the summit of the Front Range in north- central 

Colorado: U.S. Geological Survey Professional Paper 

1243, p. 1–31. 

Madole, R.F., 1986, Lake Devlin and Pinedale glacial 

history, Front Range, Colorado: Quaternary Research, 

v. 25, p. 43–54. 

Madole, R.F., VanSistine, D.P., and Michael, J.A., 1998, 

Pleistocene glaciation in the Upper Platte River 

drainage basin, Colorado: U.S. Geological Survey 

Geologic Investigations Series I- 2644, 1 pl. 

Marvine, A.R., 1874, Report for the year 1873, in 7th 

annual report of the United States Geological and 

Geographical Survey of the Territories (Hayden’s 

Survey): Washington, D.C., p. 83–192. 

Matthews, V., KellerLynn, K., and Fox, B., 2003, 

Messages in stone—Colorado’s colorful geology: 

Denver, Colorado Geological Survey, 157 p. 

Meierding, T.C., and Birkeland, P.W., 1980, Quaternary 

glaciation of Colorado, in Kent, H.C. and Porter, K.W., 

eds., Colorado Geology: Denver, Rocky Mountain 

Association of Geologists, p. 165–173. 

Menounos, B., and Reasoner, M.A., 1997, Evidence for 

cirque glaciation in the Colorado Front Range during 

Younger Dryas chronozone: Quaternary Research, v. 

48, p. 38–47. 

Merriman, M., 1960, Engineering geology—distribution 

system of the Colorado–Big Thompson Project, in

Weimer, R.J., and Haun, J.D., eds., Guide to the 

geology of Colorado: Denver, Rocky Mountain 

Association of Geologists, p. 257–273. 

Nelson, A.R., Millington, A.C., Andrews, J.T., and 

Nichols, H., 1979, Radiocarbon- dated upper 

Pleistocene glacial sequences, Fraser Valley, Colorado 

Front Range: Geology, v. 7, p. 410–414. 

Outcalt, S.I., and Benedict, J.B., 1965, Photointerpretation of two types of rock glacier in the 

Colorado Front Range, U.S.A.: Journal of Glaciology, 

v. 5, p. 849–856. 

Pederson, J.L., Mackley, R.D., and Eddleman, J.L., 2002, 

Colorado Plateau uplift and erosion evaluated using 

GIS: GSA Today, v. 12, no. 8, p. 4–10. 

Pearson, R.C., 1980, Mineral resources of the Indian 

Peaks study area, Boulder and Grand counties, 

Colorado: U.S. Geological Survey Bulletin 1463, 109 p. 

Pitlick, J., 1993a, Geomorphic response of the Fall River, 

Rocky Mountain National Park, Colorado, in

McCutchen, H.E., and Herrmann, R., eds., Ecological 

effects of the Lawn Lake flood of 1982, Rocky 

Mountain National Park, Scientific Monograph 

NPS/NRROMO/NRSM- 93/21: U.S. Department of 

the Interior, National Park Service, p. 18–32. 

Pitlick, J., 1993b, Response and recovery of a subalpine 

stream following a catastrophic flood: Geological 

Society of America Bulletin, v. 105, p. 657–670. 

Raup, O.B., 1996, Geology along Trail Ridge Road, Rocky 

Mountain National Park, Colorado: Helena and 

Billings, Montana, Falcon Press Publishing Company, 

73 p. 

Richmond, G.M., 1974, Raising the roof of the Rockies: 

Estes Park, Colorado, Rocky Mountain Nature 

Association, 81 p., 1 pl. in pocket. 

Rocky Mountain National Park, Natural and cultural 

resources—environmental landscape, 

http://www.nps.gov/romo/resources/environment.ht

ml (accessed May 2004). 

Seaman, D.M., 1934, Opal found at Specimen Mountain, 

Colorado: Portland, Oregon Mineralogist, v. 2, p. 12. 

Shroba, R.R., Schmidt, P.W., Crosby, E.J., and Hansen, 

W.R., 1979, Geologic and geomorphic effects in the Big 

Thompson Canyon area, Larimer County, in Storm 

and flood of July 31–August 1, 1976, in the Big 

Thompson River and Cache La Poudre River basins, 

Larimer and Weld counties, Colorado: U.S. Geological 

Survey Professional Paper 1115, p. 87–148. 

Sonnenberg, S.A., and Bolyard, D.W., 1997, Tectonic 

history of the Front Range of Colorado, in Bolyard, 

D.W., and Sonnenberg, S.A., eds., Geologic history of 

the Colorado Front Range: Denver, Rocky Mountain 

Association of Geologists, p. 1–7. 
 ROMO Geologic Resource Evaluation Report 29 

Steven, T.A., 1975, Middle Tertiary volcanic field in the 

Southern Rocky Mountains, in Curtis, B.F., ed., 

Cenozic history of the Southern Rocky Mountains: 

Geological Society of America Memoir 144, p. 75–94. 

Steven, T.A., Evanoff, E., and Yuhas, R.H., 1997, Middle 

and late Cenozoic tectonic and geomorphic 

development of the Front Range of Colorado, in

Bolyard, D.W., and Sonnenberg, S.A., eds., Geologic 

history of the Colorado Front Range: Denver, Rocky 

Mountain Association of Geologists, p. 115–124. 

Street, F.A., 1973, A study of tors in the Front Range of 

the Rocky Mountains in Colorado, with special 

reference to their value as an indicator of nonglaciation [M.S. thesis]: Boulder, University of 

Colorado, 241 p. 

Tweto, O., 1968, Geologic setting and interrelationships 

of mineral deposits in the mountain province of 

Colorado and south- central Wyoming, in Ore 

deposits of the United States, 1933–1967 (Graton Sales 

Volume): American Institute of Mining, Metallurgy, 

and Petroleum Engineers, no. 1, p. 551–588. 

Tweto, O., 1980a, Tectonic history of Colorado, in Kent, 

H.C., and Porter, K.W., eds., Colorado Geology: 

Denver, Rocky Mountain Association of Geologists, p. 

5–9. 

Tweto, O., 1980b, Summary of Laramide orogeny in 

Colorado, in Kent, H.C., and Porter, K.W., eds., 

Colorado Geology: Denver, Rocky Mountain 

Association of Geologists, p. 129–134. 

U.S. Department of the Interior, Bureau of Reclamation, 

Division of Dam and Structural Safety, 1982, SEED 

report on Bluebird dam, Pear dam, Sandbeach dam, 

Glacier No. 1 dam, Sprague Lake dam located within 

the boundary of Rocky Mountain National Park, 

Colorado: Denver, U.S. Department of the Interior, 103 

p. 

U.S. Department of the Interior, National Park Service, 

Division of Interpretive Planning, Harpers Ferry 

Center, 1985, Interpretive prospectus—Rocky 

Mountain National Park, Colorado: Rocky Mountain 

Regional Office, 67 p. 

U.S. Department of the Interior, National Park Service, 

Land Resources Division, Mining and Minerals 

Branch, 1993, Lulu City area, Rocky Mountain 

National Park: [Lakewood, Colorado], Abandoned 

Mineral Lands Reclamation Program information 

sheet, 1 p. 

Voynick, S.M., 1994, Colorado rockhounding—a guide to 

minerals, gemstones, and fossils: Missoula, Montana, 

Mountain Press Publishing Company, 372 p. 

Wahlstrom, E.E., 1941, Hydrothermal deposits in the 

Specimen Mountain volcanics, Rocky Mountain 

National Park, Colorado: American Mineralogist, v. 

26, p. 551–561. 

Wahlstrom, E.E., 1947, Cenozoic physiographic history 

of the Front Range, Colorado: Geological Society of 

America Bulletin, v. 58, p. 551–572. 

Wahlstrom, E.E., 1956, Petrology and weathering of the 

Iron Dike, Boulder and Larimer counties, Colorado: 

Geological Society of America Bulletin, v. 67, p. 147–

163. 

Wegemann, C.H., 1955, A guide to the geology of Rocky 

Mountain National Park [Colorado]: Washington, 

D.C, U.S. Department of the Interior, National Park 

Service, 32 p. 

Widmann, B.L., Kirkham, R.M., and Rogers, W.P., 1998, 

Preliminary Quaternary fault and fold map and 

database of Colorado: Colorado Geological Survey 

Open File Report 98- 8, 331 p. 
Appendix A: Geologic Map Graphic 

This image provides a preview or "snapshot" of the digital geologic map for Rocky 

Mountain National Park which can be found on the included CD. 

The original map digitized by NPS staff to create this product was: Braddock, W.A. and Cole, J.C., 1990, Geologic map of Rocky 

Mountain National Park and vicinity, Colorado, U.S. Geological Survey Miscellaneous Investigations Series Map I-1973, 1:50,000 scale. 

For a detailed digital geologic map and cross sections, see included CD. 

30 NPS Geologic Resources Division 
 ROMO Geologic Resource Evaluation Report 31 

Appendix B: Evaluation of Comprehensive Interpretive 

Plan (2001) 

The geology of Rocky Mountain National Park is spectacular and readily accessible. 

“Geologic origins” and “glacial landscapes” have been repeatedly identified as 

important interpretive themes throughout the history of the park (e.g., Effinger, 1934; 

Allen, 1936; Wegemann, 1955; Interpretive prospectus [1985]). 

General Comments 

“Natural systems and processes” are mentioned in the 

Primary Interpretive Theme A of the draft of the 

comprehensive interpretive plan (CIP) for Rocky 

Mountain National Park (2001). It is assumed that this 

includes geology and geologic processes, but these 

important and primary themes have not received 

sufficient emphasis in this recent plan. 

In addition, geology—the foundation for all other 

resources—is not directly identified in the section of the 

CIP listing resource- based issues that have been 

identified as important to interpret. Nitrate deposition is 

identified and is obviously geologically related with 

respect to wind- blown (aeolian) sediments. Water 

quality is also listed, and the interactions of both 

groundwater and surface water (i.e., rivers and streams, 

lakes and ponds, and wetlands) with soil and water- rock 

reactions (weathering) are well known. Nevertheless, 

these relationships may not be readily apparent to 

interpreters without a background in geology. 

During a workshop that addressed the CIP, stakeholders 

identified “the Woman’s ROMO” as an important topic 

to interpret. With respect to geology, a woman was the 

first person to conduct a systematic study of the area’s 

structure and metamorphism. Margaret Bradley Fuller, 

who later changed her name to Boos after marriage, 

studied the metasedimentary rocks east of Estes Park in 

the Big Thompson Canyon (1924, 1926). She also did 

work on the Iron Dike (1933), after which she and her 

husband published the results of a reconnaissance on the 

granites of the Front Range (Boos and Boos, 1934). 

Interpreting geology is challenging, particularly for those 

interpreters who have not been trained in the subject. It 

takes an awareness of the importance of geology to the 

park setting, human history, present landscape, and 

present species to insist on doing it, but it can be done. 

Publications, the park’s Web site, interpretive facilities, 

and interdivisional communication are areas that could 

benefit from the inclusion of geology. 

Publications 

Use portions of this report for interpretive materials 

The CIP for Rocky Mountain National Park identified 

the need to update interpretive publications, specifically 

on geology (p. 10). The Geologic Features and Processes 

section of this report could be adapted for a site bulletin. 

This report (or portions of it) could be reformatted for 

general audience and published through the Rocky 

Mountain Nature Association. 

Insure the availability of geologic publications in cooperating 

association bookstores 

Many national parks have publications available for 

visitors on their park’s geology. On October 16, 2002, this 

was not the case for Beaver Meadows Visitor Center in 

Rocky Mountain National Park. Some suggested 

publications for distribution to the general public are: 

Braddock, W.A., and Cole, J.C., 1990, Geologic map of 

Rocky Mountain National Park and vicinity, 

Colorado: U.S. Geological Survey Map I- 1973, scale 

1:50,000. 

Hopkins, R.L. and Hopkins, L.B., 2000, Hiking 

Colorado’s geology: Seattle, The Mountaineers, 240 p. 

Matthews, V., KellerLynn, K., and Fox, B. 2003. 

Messages in stone—Colorado’s colorful geology: 

Denver, Colorado Geological Survey, 157 p. 

Consider reprinting certain geologic publications 

Other good publications on the geology of the park have 

gone out of print. Two books in particular are worth 

consideration for reprinting: 

Raup, O.B., 1996, Geology along Trail Ridge Road, Rocky 

Mountain National Park, Colorado: Helena and 

Billings, Montana, Falcon Press Publishing Company, 

73 p., 1 pl. 

Richmond, G.M., 1974, Raising the roof of the Rockies: 

Estes Park, Colorado, Rocky Mountain Nature 

Association, 81 p., 1 pl. in pocket. 

Web site 

Use NPS “Views” as a model for park’s Web site 

The CIP identified a needed upgrade of the park’s Web 

site (p. 17). The Internet is a wonderful place to post 

information about the park’s natural resources, including 

geologic resources. “Views of the National Park Service, 

Virtual Experiences, and Knowledge Centers” could 

serve as a model for Rocky Mountain National Park. 
32 NPS Geologic Resources Division 

Interpretive Facilities 

Incorporate geology into Alpine Visitor Center exhibit 

The exhibit at the Alpine Visitor Center that needs to be 

renovated could include a geology theme. The 

geomorphic processes and geologic features that occur at 

high elevations in the park are readily visible and easily 

interpreted. They are distinctive and visited by millions 

of people each year. They include: potential hazards such 

as solifluction and frost cracking, solifluction terraces, 

patterned ground (e.g., rock polygons, rock stripes, rock 

circles, felsenmeer), uplifted erosion surfaces (an 

interesting and yet not fully explained geologic story), 

tors, and sackung features. (Please refer to the Geologic 

Features and Processes section and Geologic Issues 

section of this report for explanations.) 

Incorporate geology into Hidden Valley nature trail 

As the Hidden Valley area is redeveloped, a nature trail 

should to be planned. An interesting story links human 

influences and geologic processes. Workers buried the 

stream channel in Hidden Valley and placed culverts 

during construction of the lodge at the ski area. 

Diversion of streamflow for winter recreation also 

impacted this small watershed. For several decades, 

streamflow was diverted for making artificial snow at the 

ski resort. Human alteration of streamflow in this 

watershed may have caused significant impacts to the 

aquatic habitat, including the stream channel and 

wetlands, and may have affected many lifecycles, 

including that of the threatened greenback cutthroat 

trout (Oncorhynchus clarki stomias). Evaluation and 

documentation of human alteration and its effects could 

be developed into an interpretive message. The story to 

be told is that of impact and restoration of the natural 

(geologic) system. 

Hidden Valley is also a site where the Iron Dike 

outcrops. The accessibility of the Iron Dike provides the 

opportunity to tell an ancient story about the 

Precambrian history of the park. It also provides an 

opportunity to educate visitors about the role of bedrock 

composition on soil chemistry and its influence on 

vegetation and animal species. 

Interdivisional Communication 

Insist on peer review of scientific information prior to 

dissemination 

“Given the new emphasis on research in Rocky 

Mountain National Park, it is critical that the interpretive 

program be infused with the latest information on 

current issues and research” (CIP, p. 19). Also critical is 

that park staff develops a process that insures that the 

information gained from scientific research is “good 

science.” The process should include peer review by 

appropriate scientists to verify the accuracy of the 

information before being released to the public (or 

media) in either oral or written form. The NPS Geologic 

Resources Division could facilitate outside reviews by 

appropriate organizations and individuals. 

Get needed geologic expertise 

The transfer of information from researchers to park 

staff and the public is necessary for making sound 

decisions and to enhance the understanding (and 

enjoyment) of park resources. The CIP identified 

“geologic topics” as research needs for the park (p. 15), 

specifically the need for high- quality research on the 

formation of the Rockies. 

Because the park does not have a geologist on staff, the 

Interpretation Division is encouraged to submit a 

proposal for the Geoscientists- in- the- Parks (GIP) 

program. Geoscientists at all points in their careers 

participate in this program, and all levels of expertise 

may be requested. Rocky Mountain National Park 

received funding for a GIP in 2001. This project and the 

media attention that it received increased interest of the 

geoscience community to conduct research in the park 

(Terry Terrell, oral communication, 2002). A lesson 

learned from this is that interesting geologic research is 

waiting to be conducted in Rocky Mountain National 

Park; park managers simply need assistance in identifying 

projects. The GIP program manager can assist in drafting 

the short proposal. The potential project to be 

completed may simply be to identify needed geologic 

research for making management decisions or a review 

of current interpretive materials on the park’s geology.

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. 

Rocky Mountain National Park 

Geologic Resource Evaluation Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2004/004 

NPS D-307, September 2004 

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 • Katie KellerLynn

Editing • Sid Covington 

Digital Map Production • Stephanie O’Meara and Jenny Adams 

Map Layout Design • Melanie Ransmeier
Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, CO 80225 

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

(303) 969-2090 

EXPERIENCE YOUR AMERICATM 

National Park Service 

U.S. Department of the Interior