Denali National Park and Preserve 

Geologic Resources Inventory Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2010/244 

National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 
THIS PAGE:

Mountaineering rangers on backcountry patrol in a land of giants. Ruth Glacier, Denali

National Park and Preserve. 

National Park Service photograph by Tucker Chenoweth, Denali National Park and Preserve. 

ON THE COVER:

View of the terminus of Buckskin Glacier with Mount McKinley (20,320 ft) in the background, Denali National Park and Preserve, Alaska, August 6, 2004. 

Photo courtesy of Ronald D. Karpilo, Jr., Colorado State University. 
Denali National Park and Preserve 

Geologic Resources Inventory Report 

Natural Resource Report NPS/NRPC/GRD/NRR—2010/244 

Geologic Resources Division 

Natural Resource Program Center 

P.O. Box 25287 

Denver, Colorado 80225 

September 2010 

U.S. Department of the Interior 

National Park Service 

Natural Resource Program Center 

Ft. Collins, Colorado
The National Park Service, Natural Resource Program Center publishes a range of reports that 

address natural resource topics of interest and applicability to a broad audience in the National 

Park Service and others in natural resource management, including scientists, conservation and 

environmental constituencies, and the public. 

The Natural Resource Report Series is used to disseminate 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. 

All manuscripts in the series receive the appropriate level of peer review to ensure that the 

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

intended audience, and designed and published in a professional manner. This report received 

informal peer review by subject-matter experts who were not directly involved in the 

collection, analysis, or reporting of the data. 

Views, statements, findings, conclusions, recommendations, and data in this report do not 

necessarily reflect views and policies of the National Park Service, U.S. Department of the 

Interior. Mention of trade names or commercial products does not constitute endorsement or 

recommendation for use by the U. S. Government. 

Printed copies of this report are produced in a limited quantity and they are only available as 

long as the supply lasts. This report is available from the Geologic Resources Inventory website 

(http://www.nature.nps.gov/geology/inventory/gre_publications.cfm) and the Natural 

Resource Publications Management website (http://www.nature.nps.gov/publications/

NRPM). 

Please cite this publication as: 

Thornberry-Ehrlich, T. 2010. Denali National Park and Preserve: geologic resources inventory 

report. Natural Resource Report NPS/NRPC/GRD/NRR—2010/244. National Park Service, 

Ft. Collins, Colorado. 

NPS 184/105592, September 2010 

ii NPS Geologic Resources Division 
DENA Geologic Resources Inventory Report iii

Contents

Lists of Figures and Tables ........................................................................................... iv

Executive Summary ....................................................................................................... v

Acknowledgements...................................................................................................... vi

Introduction ................................................................................................................... 1

Purpose of the Geologic Resources Inventory ...............................................................................................................1

Park Setting and Establishment ....................................................................................................................................1

Geologic Setting ..........................................................................................................................................................1

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

Introduction.................................................................................................................................................................5

Glacial Issues................................................................................................................................................................5

Earthquakes and Earthquake Hazards...........................................................................................................................6

Mining and Disturbed Lands.........................................................................................................................................8

Permafrost Issues.........................................................................................................................................................9

Surface Water Issues..................................................................................................................................................10

Paleontological Resources ..........................................................................................................................................11

Geothermal Activity ...................................................................................................................................................12

Slope Processes and Erosion.......................................................................................................................................12

General Geology Issues and Research Possibilities.......................................................................................................13

Geologic Features and Processes................................................................................ 20

Mt. McKinley (Denali).................................................................................................................................................20

Denali Fault System....................................................................................................................................................20

Kantishna Hills...........................................................................................................................................................21

Accreted Terranes......................................................................................................................................................22

Glacial Features..........................................................................................................................................................22

Glaciers .....................................................................................................................................................................24

Glacial Retreat and Surging Glaciers...........................................................................................................................25

Other Notable Geologic Features................................................................................................................................25

Map Unit Properties .................................................................................................... 31

Geologic Units of Denali National Park and Preserve...................................................................................................32

Geologic History .......................................................................................................... 51

Precambrian (prior to 542 million years ago)...............................................................................................................51

Paleozoic Era (542 to 251 million years ago)...............................................................................................................51

Mesozoic Era (251 to 65.5 million years ago)..............................................................................................................51

Cenozoic Era (the past 65.5 million years)...................................................................................................................52

Glossary........................................................................................................................ 58

Literature Cited............................................................................................................ 64

Appendix A: Overview of Digital Geologic Data....................................................... 69

Appendix B: Scoping Session Participants ................................................................. 73

Attachment 1: Geologic Resources Inventory Products CD
iv NPS Geologic Resources Division

List of Figures

Figure 1: Map of Alaska Showing major mountain ranges and rivers. ...............................................................................2

Figure 2: Generalized cross section through central Alaska showing the juxtaposition of accreted terranes.......................3

Figure 3: Map of Denali National Park and Preserve..........................................................................................................4

Figure 4: The Straightaway Glacier is one of many surge-type glaciers which issue from Mt McKinley.............................14

Figure 5: Glacial retreat photography pairing at the head of Hidden Creek.....................................................................15

Figure 6: Glacial retreat photography pairing in the Teklanika River valley.......................................................................16

Figure 7: Abandoned mined land resetoration ...............................................................................................................17

Figure 8: Thermokarst development...............................................................................................................................17

Figure 9: Toklat River.....................................................................................................................................................18

Figure 10: Theropod discovery in the Cantwell Formation...............................................................................................18

Figure 11: Plant fossils provide insight to the paleoecology of Denali..............................................................................18

Figure 12: View of landslide debris on Buckskin Glacier..................................................................................................19

Figure 13: Researchers investigate dinosaur fossils in Denali’s Cantwell Formation ..........................................................19

Figure 14: Denali (Mt. McKinley) dominates the ridgeline of the Alaska Range. ..............................................................26

Figure 15: Denali has a complex geologic history which includes active plate dynamics...................................................26

Figure 16: Map of Alaska showing major faults and other regional tectonic structures....................................................27

Figure 17: Cross section of subduction zone between the Talkeetna Superterrane and the Yukon-Tanana Terrane .........28

Figure 18: Diagrammatic view of a retreating glacier......................................................................................................29

Figure 19: Short-lived features occurring on the surface of glaciers.................................................................................29

Figure 20: Ice and crevasses of Eldridge Glacier..............................................................................................................30

Figure 21: Geologic timescale. .......................................................................................................................................54

Figure 22: Three-dimensional model of an active margin setting ....................................................................................55

Figure 23: Reversal of stream direction from southward to northward accompanying uplift of the Alaska Range. ...........55

Figure 24: Map of Alaska during the Paleocene and Eocene epochs...............................................................................56

List of Tables

Table 1: Summary diagram of geologic events in the Denali area ...................................................................................57
DENA Geologic Resources Inventory Report v

Executive Summary

This report accompanies the digital geologic map for Denali National Park and Preserve in 

Alaska, produced by the Geologic Resources Division in collaboration with its partners. It

contains information relevant to resource management and scientific research. This 

document incorporates preexisting geologic information and does not include new data or 

additional fieldwork.

Denali National Park and Preserve covers more than

6 million acres and features a vast and varied geological 

landscape. The park protects large portions of the long, 

arcuate Alaska Range—including Mount McKinley 

(known as “Denali” [“The High One”] in the native 

Athabaskan language), which has the greatest vertical 

relief of any mountain on Earth. The active tectonic 

processes of southern Alaska are still uplifting the 

mountains along the Denali fault system. Countering this 

uplift are weathering and erosion of the highlands by 

wind and water. Like much of Alaska, the whole of 

Denali National Park and Preserve is composed of 

accreted terranes—where the Pacific plate, acting like a 

conveyor belt, has been bringing bits of islands, the 

ocean floor, and slivers of other continents northward to 

for hundreds of millions of years forming a “jigsaw 

puzzle” of these terranes. The compositions, structures, 

metamorphic grades, and fossils of these terranes set 

them apart from neighboring rocks separated by discrete

faults. The terranes are covered with more recent 

sedimentary deposits, and are studded with igneous 

intrusive rocks. Glacial ice covers a significant amount of 

the surface area of Denali National Park and Preserve;

glaciers carve through thousands of meters of 

sedimentary, metamorphic, and igneous rocks exposed 

within the park, creating wide U-shaped valleys and 

transporting vast amounts of sediment. These glaciers 

flow over 40 km (25 mi), descending more than 4,500 

vertical meters (14,800 ft) from the highest peaks of the 

range to the lowland hills below. The size, climate, 

isolation, and complexity of the park’s geologic setting 

create both a challenge to scientists hoping to 

understand the environment and a valuable target for 

preservation of a pristine ecosystem.

Understanding the geology in south-central Alaska leads 

to an appreciation for the unique relationship between 

geology and the environment. Geologic processes give 

rise to rock formations, topographic expression, surface 

and subsurface fluid movement, and soils; thus, geologic 

units hold clues to the history of the area. Man-made 

disturbances at the park are also significant. River 

terraces and channel deposits were reworked during 

mining periods, locally altering the topographic 

expression of the landscape and threatening riparian 

zone health. Human developments may have altered the 

fragile permafrost regime; as well, glaciers are shrinking 

due to climate change.

Denali National Park and Preserve’s Resource 

Stewardship Strategy for 2008-2027 identified several

geologic processes, values, and components fundamental 

to achieving the park’s goals and maintaining its 

significance. The following are critical geologic issues for 

park management:

• Glacier Issues. Today, glacial ice covers approximately 

17% of the park. Glacier processes are incredibly 

dynamic and have far-reaching effects. Resource 

management concerns include interactions with the 

changing climate (manifested as glacial thinning or 

surging glaciers) to visitor safety on glacial surfaces 

and unstable glacial deposits. The aerial photographic 

record of glaciers at Denali is extensive, providing an 

important tool for evaluating glacial changes. Glaciers 

carved vast valleys and deposited thick mantles of 

unconsolidated sediment on park slopes, which are 

vulnerable to slope processes and susceptible to 

intense erosion. Continual monitoring of the “state of 

health” of the park’s glaciers would help resource 

managers understand both the past and future 

conditions of the glaciers.

• Seismicity. Active faults are prevalent on the park’s 

landscape. The large-scale Denali fault system runs 

through the entire park, extending more than

2,100 km (1,300 mi). Fault processes are active; many 

fresh fault scarps reveal recent movement, and more 

than 600 seismic events are measured in the area each 

year. More than 70% of these events are relatively 

small—magnitude 1.5 to 2.5—and lie beneath the 

Kantishna Hills, which is a growing anticline. 

However, even small-magnitude earthquakes can 

damage park infrastructure, including buildings and 

roads, and undermine slope stability throughout the 

park. On November 3, 2002, a magnitude 7.9 

earthquake centered east of the park caused severe 

local shaking. This event was followed by increased 

seismic activity, which will require close to 14 years 

for conditions to return to background level. Seismic 

and geodetic monitoring provides important 

knowledge of the tectonic setting, geologic structure, 

and activity throughout the area. Studies of ancient 

earthquake history on important faults can yield data 

on recurrence intervals and past magnitudes.
vi NPS Geologic Resources Division

• Mining and Disturbed Lands. Alaska has long been 

associated with vast mineral wealth. Gold was 

discovered in the park area in 1903. Most ore-bearing 

veins were intruded into brittle faults and fractures 

within metamorphosed pelitic rocks. Much mining 

activity focused on the placer gold deposits of the 

Kantishna Hills region in the northern foothills area 

of the park. Extensive terrace areas were processed 

during extraction efforts. Massive tailing piles remain, 

exposing heavy metal-laden material to weathering 

and causing acid mine drainage. Concerns include: 

water quality; long-term riparian zone health; channel 

and floodplain morphology; and visitor safety. 

Mining continues in the Kantishna Hills area with 

strict environmental protection regulations. Studies 

of the change in the chemistry of the waters near 

mined or disturbed areas should be considered.

Other geologic issues at the park include permafrost, 

surface water issues, paleontological resources, 

geothermal energy, and slope processes. Permafrost is 

present across the northern portion of the park. 

Permafrost in Alaska has been warming since the 1970s. 

Melting permafrost can have dramatic effects on the 

landscape of the park, including the development of 

thermokarst. Surface water quality in the park is 

influenced by the underlying geology. The significant 

paleontological resources of the park are diverse and 

span hundreds of millions of years. A Paleontology 

Management Plan is currently being developed by the 

park. Geothermal resources are present within the park; 

however a comprehensive inventory or monitoring plan 

has not yet been completed. Slope processes (mass 

wasting) present a geologic hazard in many areas of the 

park. Seismic activity increases the risk for mass wasting 

within the park.

The glossary contains definitions of many of the 

technical terms used in the report. A geologic timescale is 

provided as figure 21.

Acknowledgements

The Geologic Resources Inventory (GRI) is one of 12 inventories funded by the National Park Service Inventory 

and Monitoring Program. The GRI is administered by the Geologic Resources Division of the Natural Resource 

Program Center.

The Geologic Resources Division relies heavily on 

partnerships with institutions such as the U.S. 

Geological Survey, Colorado State University, state 

geologic surveys, local museums, and universities in 

developing GRI products.

Special thanks to: Guy Adema (Denali National Park 

and Preserve) for providing information and images 

for the report. John Burghardt (NPS Geologic 

Resources Division) provided substantial comments 

on the mining and disturbed lands section. Kerry 

Moss and Julia Brunner of the NPS Geologic 

Resources Division also provided information.

Credits

Author

Trista Thornberry-Ehrlich (Colorado State 

University)

Review

Peter Haeussler (U.S. Geological Survey)

Will Elder (National Park Service)

Tim Connors (NPS Geologic Resources Division)

Editing

Bonnie Dash (Envirocal)

Digital Geologic Data Production

Jim Chappell (Colorado State University)

Digital Geologic Data Overview Layout Design

Phil Reiker (NPS Geologic Resources Division)

Dedication

This report is dedicated to the memory of Phil Brease, 

Denali park geologist from 1986 until his death in 2010. His 

passion for geology and geology education continues to be

an inspiration to many. Photo courtesy Guy Adema (Denali 

National Park and Preserve).
DENA Geologic Resources Inventory Report 1

Introduction

The following section briefly describes the National Park Service Geologic Resources 

Inventory and the regional geologic setting of Denali National Park and Preserve.

Purpose of the Geologic Resources Inventory

The Geologic Resources Inventory (GRI) is one of 12 

inventories funded by the National Park Service (NPS) 

Inventory and Monitoring Program. The GRI, 

administered by the Geologic Resources Division of the 

Natural Resource Program Center, is designed to 

provide and enhance baseline information available to 

park managers. The GRI team relies heavily on 

partnerships with institutions such as the U.S. Geological 

Survey, Colorado State University, state geologic surveys, 

local museums, and universities in developing GRI 

products.

The goals of the GRI are to increase understanding of the 

geologic processes at work in parks and to provide sound 

geologic information for use in park decision making. 

Sound park stewardship requires an understanding of 

the natural resources and their role in the ecosystem. 

Park ecosystems are fundamentally shaped by geology.

The compilation and use of natural resource information 

by park managers is called for in section 204 of the 

National Parks Omnibus Management Act of 1998 and in 

NPS-75, Natural Resources Inventory and Monitoring 

Guideline. 

To realize these goals, the GRI team is systematically 

conducting a scoping meeting for each of the 270 

identified natural area parks and providing a parkspecific digital geologic map and geologic report. These 

products support the stewardship of park resources and 

are designed for nongeoscientists. Scoping meetings 

bring together park staff and geologic experts to review 

available geologic maps and discuss specific geologic

issues, features, and processes. 

The GRI mapping team converts the geologic maps 

identified for park use at the scoping meeting into digital 

geologic data in accordance with their Geographic 

Information Systems (GIS) Data Model. These digital 

data sets bring an interactive dimension to traditional 

paper maps. The digital data sets provide geologic data 

for use in park GIS and facilitate the incorporation of 

geologic considerations into a wide range of resource 

management applications. The newest maps contain 

interactive help files. This geologic report assists park 

managers in the use of the map and provides an overview 

of park geology and geologic resource management 

issues.

For additional information regarding the content of this 

report and current GRI contact information please refer 

to the Geologic Resources Inventory web site 

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

Park Setting and Establishment

Mount McKinley National Park was established on 

February 26, 1917 by an act of Congress. The park was 

intended as “... a public park for the benefit and 

enjoyment of the people... for recreation purposes by 

the public and for the preservation of animals, birds, and 

fish and for the preservation of the natural curiosities 

and scenic beauties thereof ...said park shall be, and is 

hereby established as a game refuge.” (39 Stat. 938). In 

1976, the area was declared an International Biosphere 

Reserve. In 1980, the Alaska National Interest Lands 

Conservation Act added approximately 3.8 million acres 

to Mount McKinley National Park (about 1.9 million 

acres of which were to become the Denali Wilderness); 

at this point, the park was renamed as Denali National 

Park and Preserve. Today, the park covers more than 6

million acres, preserving and protecting large portions of 

the Alaska Range, including the 6,194-m- (20,320- ft)-tall 

Mount McKinley—known as “Denali” (“The High 

One”)—in the native Athabaskan language). The park is

situated approximately 200 km (125 mi) north of 

Anchorage, Alaska (fig. 1).

Geologic Setting

Mount McKinley’s two peaks tower over neighboring 

summits, ultimately rising from 61 m (200 ft) at the 

lowest point in the park (on the Yentna River) to 6,194 m

(20,320 ft). The peaks form an east-west-trending 1,000-

km- (600-mi)-long line of mountains known as the 

Alaska Range. This major regional feature forms a 

topographic barrier and drainage divide between the 

coastal lowlands around Cook Inlet and the Yukon 

lowlands of the interior of Alaska (Brease 2004). The 

Denali fault runs parallel to the length of the central and 

eastern Alaska Range, and it crosses most of Alaska. 

Approximately 375 km of right-lateral offset have been 

documented along the fault since Cretaceous time 

(Lowey 1998), and the fault remains seismically active.

The Alaska Range has permanent snow cover on 

northern exposures above approximately 2,100 m

(7,000 ft). This snowpack supports several large glaciers. 

Over 17% of the park’s land (more than 1 million acres) 

is covered with glacial ice. The largest glacier is the 55-

km- (34–mi)-long Muldrow Glacier. This glacier flows 

northward toward the developed road corridor west of 

the Eielson Visitor Center. Kahiltna Glacier is the longest 

in the park, at 71 km (44 mi). Ruth Glacier has a 

thickness of up to 1,160 m (3,850 ft), and moves about 

0.95 m (3.1 ft) per day through the deepest gorge in 

North America (National Park Service 2009).

To the north of the Alaska Range is a series of east-westtrending foothill ridges ranging from approximately 610 

to 1,372 m (2,000 and 4,500 ft) in height; the widths of 

these foothills range from 5 to 11 km (3 to 7 mi). The
2 NPS Geologic Resources Division

parallel foothills extend eastward from the Kantishna 

Hills north of Wonder Lake. They are separated by 

broad, flat, sediment-filled glacial valleys that drain the 

region from south to north. Northward-draining rivers 

include the Foraker, Herron, McKinley, Bearpaw, 

Toklat, Savage, Teklanika, and Nenana Rivers. To the

south, across the divide posed by the Alaska Range, the 

Chulitna, Susitna, Tokositna, Kahiltna, Yentna, and 

Kichatna Rivers drain. 

Like most of Alaska, the Denali area is composed of a 

series of accreted terranes (fig. 2). These terranes include 

bits of islands, oceanic crust, flysch basin deposits, and 

continental fragments that have been transported from 

elsewhere by large strike-slip faults and ancient oceanic 

plates. Because the terranes were too thick to subduct 

beneath the North American continent into the Aleutian 

trench, they collided with the edge of the continent, 

squeezing ocean basins, island arcs, and miniterranes 

between them in a complex wedge of thickened crust.

Volcanism, mountain building, and orogenesis often 

accompany terrane accretion. The terranes typically 

follow an arching pattern that trends roughly east-west, 

paralleling the Gulf of Alaska coastline. In the park, the 

terranes are identified as packages of rocks bounded by 

faults, with distinctly different rock types, fossils, and 

other physical properties than surrounding terranes.

In the area of Denali, the oldest major accreted terrane is 

the Yukon-Tanana Terrane. This large mass was added 

to the continent about 225 million years ago. The 

Talkeetna Superterrane (Wrangellia, Alexander, and 

Peninsular Terranes)—also referred to as the Wrangellia 

composite terrane—slammed into the continent about 

110 to 85 million years ago. These two terranes, as well as 

several smaller terranes (such as the McKinley, Pingston, 

Windy, and Dillinger Terranes), compose the bulk of the 

landforms in Denali National Park and Preserve (fig. 3). 

Smaller accretionary prisms, such as the Chugach,

accreted about 67 million years ago; the Prince William 

accreted by 50 million years ago. The youngest regionalscale terrane, the Yakutat Terrane, is still attached to the 

Pacific Plate, traveling approximately 5 cm (2 in.) 

northward per year; thus, accretion is an ongoing process 

along the coast of southern Alaska. 

Figure 1: Map of Alaska Showing major mountain ranges and rivers. Graphic compiled by Phil Reiker (NPS Geologic Resources Division).
DENA Geologic Resources Inventory Report 3 Figure 2: Generalized cross section from north (south of the Brooks Range) to south (Gulf of Alaska) through central Alaska showing the juxtaposition of accreted terranes over the subduction zone between the Pacific and North American Plates. Note the location of Denali National Park and Preserve. Graphic by Trista L. Thornberry-Ehrlich (Colorado State University), adapted from Lillie (2005) fig. 11.7.
DENA Geologic Resources Inventory Report 4

Figure 3: Map of Denali National Park and Preserve. See yellow box on park map for location 

of detail map. NPS graphics.
DENA Geologic Resources Inventory Report 5

Geologic Issues

The Geologic Resources Division held a Geologic Resources Inventory scoping session for

Denali National Park and Preserve on February 24–26, 2004, to discuss geologic 

resources, address the status of geologic mapping, and assess resource management 

issues and needs. This section synthesizes the scoping results, in particular those issues 

that may require attention from resource managers. Contact the Geologic Resources 

Division for technical assistance.

Introduction

Resource management issues are discussed in relative 

order of significance, with the most critical listed first. 

Potential research projects and topics of scientific 

interest are presented at the end of this section.

Glacial Issues

Glaciers and Glacial Geology

Glaciers are a major feature of the Denali National Park 

and Preserve landscape. Over 1 million acres (17% of the 

park’s area) is covered with ice. This ice includes more 

than 400 glaciers, some 40 of which are named. Famed 

glaciers include the Kahiltna Glacier, which is 71 km

(44 mi) long, making it the longest glacier in the Alaska 

Range. Ruth Glacier is locally the thickest in the park, 

filling a deep gorge. Eldridge, Traleika, Tokositna, 

Yentna, and Muldrow Glaciers are among the other wellknown glaciers at Denali. Permanent snowpack above 

2,100 m (7,000 ft) supports the flow of glaciers from 

elevations above 6,100 m (20,000 ft) down glacial valleys 

to elevations as low as 300 m (1,000 ft). 

Some of the smaller glaciers at Denali display interesting 

characteristics. Most of the smaller valley or hanging 

glaciers in the park are unique because terminal areas are 

insulated by deep deposits of rock debris and dust. This 

lessens melting and allows the smaller glaciers to remain 

stagnant for longer periods of time than larger glaciers. 

Portions of the larger Muldrow, Ruth, Kahiltna, and 

Tokositna glaciers are also insulated by deep deposits of 

rock debris and dust (P. Haeussler, USGS, geologist, 

written communication, November 2009).

Glaciers have been, and continue to be, powerful agents 

of landscape change. They carve valleys and gorges out 

of solid bedrock much faster than rivers and streams. 

Glaciers leave vast deposits of till and moraines. Glaciers 

feed outwash flows and streams, and can dam streams to 

form temporary lakes. At Denali National Park and 

Preserve, glacially carved features include valley cirques, 

arête ridges, drumlins, expansive U-shaped valleys, and 

horns. The widespread glacial deposits include: lateral, 

medial, and terminal moraines (less than 100 m [325 ft] 

thick); ablation and lodgement till (less than 10 m [32 ft] 

thick); eskers and advance and recessional outwash; and 

rock glaciers (potentially 100s of meters thick). 

Rock glaciers are masses of talus that accumulate locally 

to the point where they retain moisture, freeze, and move 

slowly downslope (Brease 2004). Blocks of glacial ice left 

stranded by glacial retreat can become buried by 

outwash deposits. The ice then melts, forming small, 

round kettle lakes such as Chilchukabena Lake near the 

northwest boundary of the park. Wonder Lake, at over 

82 m (268 ft) deep, is the largest kettle lake at Denali. 

Pro-glacial Lake Moody, which formed by the damming 

action of ice and moraines in front of melting glacial ice,

is also a glacial remnant at Denali. 

Historical glacial activity in the area is recorded in the 

rocks, deposits, and vegetation patterns at Denali 

National Park and Preserve. Four distinct periods of 

widespread glaciation are recognized in the region of the 

park. Evidence of former glacial maxima exists on the 

north side of the Alaska Range, where, beyond the 

existing glaciers, moraine and outwash deposits extend 

into the foothills belt and cover large areas of bedrock, 

possibly filling vast areas underlying present-day river 

valleys through the unglaciated foothills section. The 

Wisconsin glaciation (Wisconsinan stage) was the last 

major advance of glacial ice in North America. Pork 

Chop Pond, a Wisconsinan kettle lake, contains thick 

layers of sediment (cored in 1996) that include aeolian 

sediments, peat, microlaminated muds, tephra (volcanic 

ash), and other organic deposits. These sediments record 

late Wisconsin-glacial and following interglacial climate 

(Axford and Werner 1997).

Glaciers and Climate Change

As stated by the Intergovernmental Panel on Climate 

Change: “Warming of the climate system is unequivocal, 

as is now evident from observations of increases in global 

average air and ocean temperatures, widespread melting 

of snow and ice, and rising global sea level.” (IPCC 2007).

This warming is very likely (more than 90% certain) 

related to anthropogenic greenhouse gas emissions

(IPCC 2007). 

Alaska has warmed at more than twice the rate of the 

continental United States. Alaska’s annual average 

temperature has increased 2.0°C (3.4°F) while winters 

have warmed by 3.5°C (6.3°F) over the past 50 years 

(Karl et al. 2009). Projections reported by Karl et al. 

(2009) suggest Alaska’s annual average temperature will 

rise between 2.8 and 7.2°C (5 and 13°F) by 2100, 

depending on emission scenarios. For more information 

regarding climate change effects and NPS response, visit 

the NPS Climate Change Response Program web site 

(http://www.nature.nps.gov/climatechange/index.cfm).
6 NPS Geologic Resources Division

In response to the warming climate, glaciers are 

shrinking at the park. Most of the glaciers are 

consistently thinning, and only about 10% are surging

(fig. 4) (P. Haeussler, USGS, geologist, written 

communication, November 2009). Surging refers to 

periods of relatively high-speed glacial flow following 

periods of slow flow. Most surging occurs on glaciers 

with northern exposure. The photographic record of the 

glaciers of Alaska spans more than 110 years. The earliest 

aerial photographs date from 1926 as part of a 

cooperative arrangement between the U.S. Geological 

Survey and the U.S. Navy. Systematic vertical aerial 

photography of Alaskan glaciers began in the 1940s and 

continues today (Molina and Sfraga 1999). These records 

provide a comprehensive data set and could be utilized

to determine fine-scale glacial changes at Denali. 

Glacial monitoring at the park began in earnest in 1991 as 

part of the National Park Service’s Long-term Ecological 

Monitoring Program. This program initially focused on 

an “index” method—i.e., single point mass balance 

monitoring—but has since been supplemented with 

more detailed mass balance measurements on smaller 

glaciers, terminus monitoring on multiple glaciers, 

selected movement monitoring, depth measurements, 

and extensive photo documentation. Two index 

monitoring sites exist on Kahiltna and Muldrow Glaciers 

(Adema et al. 2003)

In 2004, data from past survey and research expeditions 

were revisited, new digital photographs were taken, and 

new stations were established for future comparisons of 

glacial positions (figs. 5, 6). Geographic coordinates, 

elevation, modern analog aerial images (using 

helicopters), and other accurate geographic information 

were incorporated into a parkwide GIS coverage of 

glacial extent from surveys during the 1950s through

2000s. Information included bidecadal coverages for 

individual glaciers (Karpilo et al. 2004). Efforts such as 

this could be expanded on a parkwide scale,

incorporating more historic information, photographs, 

and modern technology to study glacial change at Denali 

National Park and Preserve. Karpilo (2009) suggested 

glacier monitoring techniques based on four “vital signs:” 

glacier mass balance, terminus position, area, and 

velocity.

Glacial Hazards

Glacial issues at the park extend to geologic hazards 

caused by glacial movement and glacial remnants. Relief 

in glaciated areas is often very steep and prone to erosion 

and mass movement depending on rock type. Glacial till 

often maintains very steep slopes (P. Haeussler, USGS, 

geologist, written communication, November 2009). 

Many deformed and altered rock units are present in 

glaciated areas of the park; these are prone to mass 

movements when exposed on slopes because of 

pervasive zones of weakness. When glaciers retreat up a 

valley, near-vertical walls are left with no structural 

support or stability. Deep, unstable, unconsolidated 

glacial deposits are also prone to mass wasting and 

intense erosion. Glacier terminal areas are attracting 

increasing numbers of visitors, and these areas could 

pose icefall and rockfall hazards, as well as unstable trail 

bases. The vast extent of glaciers and icefields affect the 

local climate. Glaciers produce microclimates that cause 

local temperature cells to push moisture-rich air upward, 

creating localized weather aberrations.

Resource Management Suggestions for Glacial Issues

• Perform comprehensive studies on the history of 

glaciation at Denali. Potential research targets could 

include glacial debris and deposits, lichen growth, 

vegetation patterns, striations, and glacial lakes and 

lake deposits. 

• Study glacial change at Denali by developing a glacier 

“state of health” program within the park (P. 

Haeussler, USGS, geologist, written communication, 

November 2009). 

• To understand climatic effects on glaciers, conduct 

glacier dynamics research and perform mass balance 

studies. Promote contracting with the University of 

Alaska Fairbanks glaciology group (contact Chris 

Larsen) for airborne laser altimetry studies on a select 

group of glaciers to quantify glacier mass balance (P. 

Haeussler, USGS, geologist, written communication, 

November 2009).

• Study stability and safety issues related to glacial areas 

(W. Elder, NPS, geologist, written communication, 

December 2009).

• Compare glacial response at Denali with other known 

concentrations of glaciers in Alaska and worldwide to 

compare and contrast glacial response to global 

climatic shifts.

• Perform mass balance studies to determine reasons 

behind glacial surging.

• Perform glacial movement studies to determine 

differences between glaciers influenced to varying 

degrees by nonclimatic factors such as rock and dust 

coverage.

• Cooperate with other government agencies to obtain 

complete records of historical and ongoing glacial 

photography and measurement.

• Determine quantitative relationships between glacier

size, orientation, location, depth, etc. and the degree 

of local microclimatic aberrations. 

• Study Late Quaternary pollen, plant macrofossils, and 

insect fossils to determine past glacial and interglacial 

conditions (climate, vegetation, etc.) (Elias et al.

1996).

• Inventory the named glaciers in the park using 1957 

and 1983 aerial and other photography and 

topographic maps to document spatial changes. 

• Increase glacier profiling efforts, including monitoring 

terminal fronts, glacier thickness, and surge activity.

Earthquakes and Earthquake Hazards

Faults are prevalent features of the geologic structure at 

Denali National Park and Preserve. The large-scale 

Denali fault system runs through the entire park, parallel 

to the Alaska Range, extending more than 2,100 km 
DENA Geologic Resources Inventory Report 7

(1,300 mi) from the Yukon-Alaska border to the Bering 

Sea. The system includes the Denali fault (locally split 

into the Hines Creek and McKinley strands) and 

numerous subsidiary faults. Faulting at the park is active,

with many fresh fault scarps showing evidence of recent 

movement. Fission track data indicate that Mt. McKinley 

is being uplifted along regional faults at rates of 

~1 mm/year. More than 600 earthquakes per year are 

measured in the park area. More than 70% of these 

events are of magnitude 1.5 to 2.5; they commonly occur 

at very shallow depths, within 0 to 14 km (0 to 9 mi) 

below ground surface. The Alaska regional seismic 

network consisted of approximately 400 monitoring sites 

operated by various agencies. Seismic waveform data are 

now recorded digitally. The Alaska Earthquake 

Information Center (AEIC) is upgrading existing sites 

with digital broadband sensors (Ratchkovski et al. 2004).

Most earthquakes at Denali are relatively small (too small 

to be noticed by humans); however, even minor shaking 

can pose hazards of mass wasting, landslides, and debris 

flows on undercut, weakened, or unconsolidated 

geologic units exposed on slopes. On November 3, 2002,

a magnitude 7.9 earthquake (consisting of multiple 

subevents), centered 48 km (30 mi) east of the park,

caused severe local shaking. Reports of shaking and 

“unusual effects” from this earthquake were received 

from distances up to 3,500 km (2,200 mi) across western 

Canada (Cassidy and Rogers 2004). For the 30 years

prior to this event, only four events greater than 

magnitude 3 were recorded. Leading up to and following 

this large earthquake, seismicity in the area increased. It 

is estimated that close to 14 years will be required for 

local seismicity rates to return to background level 

(Ratchkovski et al. 2004). According to the AEIC website

(http://www.aeic.alaska.edu/), its system of over 400 sites 

currently reports about 20,000 earthquakes each year 

(well over 100 earthquakes in a few days) across the 

network. The AEUC site lists the location, depth, 

distance from surrounding communities, and magnitude

for each event. The website frequently notes central 

Alaska for earthquake activity.

The fault rupture associated with the 2002 event was 

complex, beginning on variably dipping fault segments 

and continuing along vertical strike-slip segments 

(Eberhart-Phillips et al. 2003; Aochi et al. 2005). An

unusual pattern of landslides and liquefaction resulted 

from the earthquake. The landslides were concentrated 

as rockfalls and rockslides in a narrow (~30-km [19-mi]-

wide) zone that straddled the more than 340-km

(211-mi) rupture zone. This pattern is consistent with 

strong, low-frequency shaking with only moderate 

acceleration levels. These rockslides were most visible at 

Black Rapids Glacier, Gakona Glacier, West Fork 

Glacier, and McGinnis Glacier (Harp et al. 2003; 

Schwartz et al. 2005).

Conversely, liquefaction effects (sand blows, lateral 

spreads, and broad settlement) within alluvial deposits of 

streams in and adjacent to the central Alaska Range were 

much more widespread, extending for several hundred 

km east of Fairbanks (Harp et al. 2003). This pattern is 

consistent with a long duration of shaking. Most

structural damage was focused 160 km (100 mi) east of 

the park, but the Denali fault system is capable of 

producing a similar earthquake in or closer to the park. 

This could have catastrophic effects on visitor use 

facilities, park infrastructure, the Trans-Alaska pipeline, 

and geologic landforms. 

Widespread aftershocks from the large 2002 earthquake 

east of Denali increased the number of events recorded 

by the AEIC—from 1,000 to over 16,000—for a similar 

period (Ratchkovski et al. 2004). Thus, even if 

earthquakes are not focused within park boundaries, 

regional seismic episodes have far-reaching effects that 

could impact park resources. Future development plans 

should take into account the earthquake-related hazards 

of liquefaction, lateral spreading, rockfalls, landslides, 

and fault ruptures. In addition to these potential 

problems, the subgrade soils and permafrost (possibility 

of melting) in the Denali area pose further geotechnical 

design concerns in the event of an earthquake, so more 

detailed research is needed to understand their response 

to intense ground shaking (Adamczak et al. 2004). Braile 

(2009) suggested the following “vital signs” for seismic 

monitoring: monitoring earthquakes, analysis and 

statistics of earthquake activity, analysis of historical and 

prehistoric earthquake activity, earthquake risk 

estimation, geodetic monitoring and ground 

deformation, and geomorphic and geologic indications 

of active tectonics.

Resource Management Suggestions for Earthquakes

• Continue to collaborate on studies by Alaska 

Earthquake Information Center, universities and the 

U.S. Geological Survey regarding seismic activity in 

the region.

• Add seismometers in the park, to augment those put in 

place by the Geophysical Institute at the University of 

Alaska, Fairbanks. Present locations include 

Wickersham Dome in the Kantishna Hills, Thorofare 

Mountain near the Eielson Visitor Center, and Mount 

Healy. Cooperate with the AEIC to increase the 

number of digital broadband seismic stations within 

park boundaries. 

• Continue seismic and geodetic monitoring in the park,

as well as the study of ancient earthquakes on knonw 

important faults, to understand the implications of an 

event on a particular fault and to establish recurrence 

intervals (P. Haeussler, USGS, geologist, written 

communication, November 2009).

• Perform studies to determine the paleoearthquake 

history along the Denali fault in the ~161-km- (100-

mi)-long region west of the 2002 event.

• Perform detailed mapping of the Denali fault and

other active fault traces across the park to better 

understand deformation through time.

• Study paleoseismicity (most recent events) along 

sections of the park’s faults using samples of gouge 

and radiocarbon dating of offset organic material.

• Support efforts to determine fault slip rates (e.g.,

Matmon et al. 2006).
8 NPS Geologic Resources Division

• Study geomorphology, tectonic history, and fault 

orientation relationships, and perform 

thermochronology studies (apatite fission track, 

U-Th/He) to determine timing and characteristics of 

landform development.

• Perform vulnerability assessments of areas in which 

visitor health and safety are likely to be affected in the 

event of a large earthquake.

• Incorporate earthquake epicenter data into a GIS,

including geologic data, slope data, and trail data, to 

determine areas susceptible to failure during a 

moderate earthquake. 

• Promote a better GPS geodetic network in the park to 

provide information about seismic hazards, where 

active structures lie, and the larger-scale tectonic 

setting (P. Haeussler, USGS, geologist, written 

communication, November 2009). 

• Promote 3-D ionosphere tomography studies using 

GPS data to constrain source and propagation of 

seismic waves in the Denali area (Garcia et al. 2005).

Mining and Disturbed Lands

Since the gold rush era of the late 1800s, Alaska has been 

associated with vast mineral wealth, with approximately 

30 million ounces of gold recovered to date. Most orebearing veins were intruded into brittle faults and 

fractures within metamorphosed pelitic rocks, and are 

composed of quartz with minor chlorite, carbonate 

minerals, and white mica (Goldfarb et al. 1997). In 1903, 

gold was discovered in the area of what is now Denali 

National Park and Preserve (Norris 1998). Past mining 

activity was focused in the Dunkle Mine area in the 

Chulitna Terrane of the Alaska Range, the Mt. Eielson/

Copper Mountain district (in the 1940s), and the placer 

gold deposits of the Kantishna Hills region of the YukonTanana Terrane in the northern foothills area of the park 

(Van Maanen and Solin 1988; Metz et al. 1989; see 

summary at www.mindat.org). Mining interests included

precious metals such as gold and silver, base metals

(copper, lead, antimony, zinc, tungsten, arsenic) and coal 

(Metz et al. 1989). Abandoned cabins, debris, small 

tailing piles, assay trenches, adits, and small shafts are 

historical markers of the hard rock mining history in the 

region. Most of the historical underground mine features 

have been closed or have since collapsed (GRI scoping 

notes 2004).

No new claims have been made since the establishment 

of Denali National Park and Preserve in 1980. In 1985, 

litigation was intended to halt mining inside the park,

and no legal mining has occurred since (Burghardt 1997;

J. Burghardt, NPS Geologic Resources Division, 

geologist, written communication, May 2010). According 

to the NPS Abandoned Mine Lands database 

(maintained at the GRD in Denver, Colorado), as of May

2010, there were 28 patented claims and 9 unpatented 

claims within the park. The patented claims are 

underground mine and placer mine sites for 

commodities such as gold, copper, coal, limestone, and 

antimony. Many of the claims have been used to 

establish lodges and cabins rather than mines (J. 

Burghardt, NPS Geologic Resources Division, geologist, 

written communication, May 2010). The Abandoned 

Mineral Lands program also maintains a list of various 

identified mine-related features within the park, 

including adits, equipment, surface mines, tailings, 

buildings, and other structures. Currently (September 

2010), this database has 37 listed features, at 28 sites,

many of which require remediation. An online mineral 

database website, www.mindat.org, contains records of 

nearly 200 mine-related localities within or near the park.

Occasionally, legal disputes arise from the mining claims

within the park. The Stampede antimony mine is owned 

jointly with the University of Alaska, Fairbanks. Several 

mine areas (Gold King placer claims and Red Top mill) 

are CERCLA (Comprehensive Environmental Response, 

Compensation, and Liability Act; “Superfund”) sites. 

This designation involves assessing risks to human health 

and the environment posed by hazardous waste sites, 

identifying potentially responsible parties (PRPs), and 

seeks to find funding for remediation efforts (GRI 

scoping notes 2004). 

Denali National Park and Preserve also contains vast 

deposits of well-sorted sands and gravels. Small-scale 

quarries and gravel pits exist within park boundaries for 

construction and maintenance of park roads and other 

infrastructure and visitor use facilities. The park’s 

Resource Stewardship Strategy for 2008-2027 lists 

monitoring and mitigating impacts to fluvial morphology 

and water quality as a result of park gravel acquisition 

operations among its resource management goals (Denali 

National Park and Preserve 2009).

Negative effects from mining are far reaching and long 

lasting. Impacts include disturbed floodplain areas from 

extensive placer mining. Placer mining involved 

removing riparian zone vegetation and topsoil, then 

sieving valuable minerals from gravels in the stream 

channel, active floodplain, and old terraces. This process 

leaves behind barren gravel piles devoid of any soil that 

would promote natural revegetation. There are channels 

down to bedrock in some areas (Densmore 2005). A 

concern of park resource management is that past placer 

mining activity could result in changes in channel and 

floodplain morphology, streamflow, and streambed 

composition facilitated by erosion and/or deposition, 

that could affect aquatic and riparian ecosystem health 

(Van Maanen and Solin 1988). Recent regulations 

require that topsoil be stripped and stockpiled away 

from the placer mining area, then reincorporated with 

the sieved gravels so that planted material used in 

reclamation has a substrate in which to grow (J. 

Burghardt, NPS Geologic Resources Division, geologist, 

written communication May 2010). Remediation of old 

and/or abandoned mines is ongoing. Methods include 

rebuilding the floodplain areas, restructuring the stream 

channel (fig. 7), and recontouring terraces, as well as 

planting species such as Alnus viridis (green alder) for 

nitrogen fixation within new soils. Replanting along Glen 

Creek watershed (mined from 1906 to the mid 1970s) 

demonstrated the ability of the Alnus viridis species to 

accelerate the rate of succession by stimulating the 

growth of woody dominant riparian species such as Salix 

alaxensis (feltleaf willow) (Densmore 2005). For many
DENA Geologic Resources Inventory Report 9

areas, reclamation is limited by factors such as steep 

slopes, a lack of a local topsoil source from disturbed 

areas, an acid-generating sulfide substrate not amenable 

to revegetation, and remoteness (Burghardt 1997).

Preliminary studies suggest that differences in physical 

properties of mined and non-mined reaches of several 

streams were relatively minor; however, the streambed 

composition below mined areas tended to be enriched in 

fine-grained material (34 mm average mean particle size 

vs. 65 mm) and exhibited less variation in mean particle 

size (Van Maanen and Solin 1988). Along Eldorado 

Creek, mining and the operation of heavy equipment 

throughout the area, and particularly at the antimony 

mine at the headwaters of Slate Creek, have enhanced 

the flow of natural iron-rich springs (Burghardt 1997).

Placer mining forces larger particles to the streambed 

surface, which is contrary to natural settling. This could 

affect spawning habitat for fish as well as aquatic plant 

distributions. Along Rainy Creek in the Kantishna Hills 

region, the entire stream had been diverted from its 

natural channel during mining operations involving the 

construction of settling ponds. This resulted in extreme 

erosion of soil and fine-grained floodplain material as 

well as damage to pre-existing vegetation (Van Maanen 

and Solin 1988).

Associated with mining are exposures of hazardous 

materials in mine tailings. Mine tailings and other ground 

disturbances expose bedrock and crushed rock material 

to weathering. This leads to water and soil contamination 

by heavy metals and sulfides due to acid mine drainage. 

The Banjo Mine (a small-scale gold mine) has 500 cubic 

yards of mine tailings that contain leachable arsenic and 

lead, as well as antimony and cadmium that exceed 

drinking water standards and hazardous waste toxicity 

limits. Stampede Mine, a 20-acre site, maintains a finegrained mine tailings dump adjacent to Stampede Creek. 

This mine is associated with dissolved antimony 

concentrations in the creek that exceed federal drinking 

water standards (ADEC 2006).

The Slate Creek antimony deposit, associated with 

historical mining operations within the park between 

Moose Creek and McKinley River, has drainage with pH 

values of 2.7 to 5.8, as well as concentrations of sulfate 

ions, arsenic, iron, manganese, nickel, antimony, and 

total dissolved solids that exceed State of Alaska drinking

water standards. At the mouth of Slate Creek, some 3 km 

(2 mi) downstream, manganese and antimony contents 

exceeded drinking water standards. Stream sediment, 

soil, and rock samples around the mining area were 

enriched in arsenic, manganese, and antimony. In 

addition, sparse to no vegetation exists in the active 

stream channel and aquatic algae are conspicuously 

absent (Eppinger et al. 2000).

Mining operations introduce foreign objects and 

substances to the landscape, including petroleum drums, 

mercury, and other chemicals for gold extraction. 

Several areas in the Kantishna Hills region (Gold King 

#1-15-Area#1; Comstock #1-8-Area#5; Discovery #1-3-

Area#7; Trommel Wash Plant-Area#8; Antimony Lode 

Mining Area#9; Caribou Howtay #11b-24-Area#10;

Glacier Assoc.#1-5-Area#12; Caribou Howtay #1-6-

Area#13; Rainy Creek #1-3&6-8-Area#2; Liberty #53-

Area#3; and Stampede Mine) have petroleum 

hydrocarbon contamination arising from miscellaneous 

drums, spills, and soil stains associated with the 

operations. The Glen Creek area contains mercury and 

diesel contamination from placer mine operations 

(ADEC 2006). A project to close a hazardous mine 

opening within the park was included in the 2009 

American Recovery and Reinvestment Act (ARRA).

Resource Management Suggestions for Mining and Disturbed 

Lands

• Develop a mining history interpretive program 

focusing on the geology responsible for the valuable 

mineral resources in the Denali area. 

• Continue reclamation efforts, including revegetation 

and remediation of streams and riparian (floodplain) 

environments. Increase plantings of Alnus viridis, 

which accelerates the rate of succession by 

stimulating growth of woody dominants (Densmore

2005).

• Collect continuous records of streamflow that relate 

changes in channel configuration and bed elevation to 

sediment transport, erosion, and deposition in mined 

and non-mined stream reaches for comparison.

• Monitor suspended sediment concentrations and fine 

bed material in mined and non-mined streams to help 

determine ecological effects of placer mining. 

• Monitor water quality in mine-affected areas to 

determine degree of improvement, and target areas in 

need of further restoration. Tracking water chemistry 

changes through time would help resource managers 

understand the long-term effects of disturbed lands 

(P. Haeussler, USGS, geologist, written 

communication, November 2009).

• Continue to support environmental-geochemical 

studies of different mining areas, especially those 

located near springs and/or streams.

• Contact the NPS Geologic Resources Division

regarding the history of mining at the park; the 

current status of mining operations, ore contents, 

reclamation efforts, and claim litigation and 

acquisition; and other mine-related queries.

Permafrost Issues

Unique to high altitudes and latitudes, permafrost is 

present discontinuously in the arctic climate of Denali 

National Park and Preserve. This frozen layer can persist 

to depths of up to 610 m (2,000 ft) below the surface. At 

Denali, the permafrost is defined as containing soil and 

rock that have been at a temperature of 0°C (32°F) or 

colder for two or more years. 

Osterkamp and Jorgenson (2009) described the rationale 

for monitoring permafrost conditions and processes, 

including examples and case studies from Denali 

National Park and Preserve. Clark and Duffy (2003) 

mapped permafrost distribution within the park. Their
10 NPS Geologic Resources Division

map shows that permafrost is present across the entire 

northern side of the park, but only locally south of the 

Alaska Range. Presenting a more regional perspective, 

the International Permafrost Association has published a 

digital map that summarizes the distribution and 

properties of permafrost and ground ice in the circumArctic region (Zhang et al. 1999). Permafrost is a major 

controlling factor on surface water flow, and therefore 

on vegetation and habitat. Permafrost exerts an influence 

on the fluxes of carbon and nitrogen from terrestrial to 

aquatic ecosystems coincident with fire disturbances 

(Petrone et al. 1999). It appears that leaching of carbon 

and nutrients from the burned ash layer is greatest in the 

active layer over permafrost, and this is marked as 

increases in these chemical components within the 

watershed (Petrone et al. 1999). Abundant water is 

available in the active layer above the permafrost because 

it cannot seep into the impermeable permafrost below 

(Brease 2004).

Permafrost also acts as a natural barrier to the downward 

flow of water, as well as against potentially harmful 

contaminants such as oil or diesel spilled from fuel 

storage tanks. Industrial users are interested in this 

potential use of natural permafrost in lieu of synthetic 

secondary liners (McCauley et al. 1999). Contaminants

could pool atop the surface of the permafrost, causing a 

local long-standing concentration.

A delicate heat balance exists between permafrost and 

the layer above it, which freezes and thaws with seasonal 

temperature change. The balance of this system is 

sensitive to changes in the vegetative cover and mat and 

snow depth, and is dependent on the structural and 

compositional characteristics of the freeze-thaw layer 

(Brease 2004). These parameters can significantly affect 

the local thermal regime, resulting in changes at ground 

level such as frost heaving, polygonal ground patterns, 

and sags. Extreme conditions or anthropogenic 

alterations in the right geologic setting can cause melting 

of permafrost. Geologists are particularly concerned 

about the effects of global climate change (global 

warming) on permafrost in subarctic ecosystems. 

Permafrost is warming throughout Alaska; temperatures 

have increased throughout the state since the late 1970s 

as summarized by Karl et al. (2009). Ongoing monitoring 

is necessary to determine the extent to which this is 

occurring at the park. Osterkamp and Jorgenson (2009) 

suggested methods for monitoring permafrost 

conditions and processes utilizing thermal state and 

physical conditions “vital signs.”

Melting of permafrost can have dramatic effects on the 

landscape at Denali. The term “thermokarst” describes a 

specific landform that develops when permafrost is 

partially or totally melted. Thermokarst is a highly 

irregular surface expression that forms variously shaped 

polygonal depressions (patterned ground), altiplanation 

(long, smooth, flat ridges), and ice wedges (fig. 8). If 

melting of ice-rich permafrost (ground ice content 

greater than 20% by volume) occurs, widespread 

irregular subsidence of up to 2.0 m (6 ft) of the ground 

surface could result in significant impacts on the 

hydrological and ecosystem processes throughout the 

region. In areas of abundant ice, thawing would result in 

river bank collapse, creation of thaw lakes, and other 

thermokarst features (Zhang et al. 1999).

Permafrost is very sensitive to human disturbance. 

Thermokarst has been created by humans in other parts 

of Alaska during construction projects. Accompanying 

thermokarst development, increases in soliflucation, or 

soil movement, atop the frozen layer are more 

pronounced when permafrost is melted. This situation 

can cause heaving, sagging, slope creep, soil slumping, 

and deep erosion at the surface during successive periods 

of freeze-thaw heaving in the active layer (periglacial 

milieu) (Brease 2004). Hillslope stability becomes a safety 

concern. Like other subsurface movements or 

disturbances, soliflucation can be detrimental to buried 

cables, wastewater treatment pipes, sewers, septic 

systems, utility poles, paved surfaces, trails, buildings, 

and roadbed foundations. Five large areas of roadway 

have been affected. Extensive knowledge of permafrost 

extent, properties, and processes will help resource 

managers decide where to develop road areas in the 

future and how best to maintain existing roads.

Resource Management Suggestions for Permafrost Issues

• Increase monitoring and develop a soil temperature 

monitoring network.

• Work with the National Resource Conservation 

Service soils mapping program to create a derivative 

map that includes different types of permafrost. A soil 

survey geographic database has been completed for 

the park as part of the NPS Soil Resources Inventory 

program (National Park Service 2006). Clark and 

Duffy (2003) produced a permafrost distribution map 

for the park.

• Increase the installation of thermisters (installed 35 m

[115 ft] deep) along road corridors for permafrost 

monitoring.

• Investigate permafrost and ground ice conditions as 

well as their relation to the present climatic 

conditions and potential response to climatic change. 

Create a model of ground surface response to 

permafrost thaw to better predict ensuing ecosystem 

changes. 

• Install additional inclinometers and piezometers along 

roadway slopes, as well as on slope areas near visitor 

use facilities or other identified vulnerable reaches.

Surface Water Issues

Snow and rainfall are channeled into three major systems 

at Denali National Park and Preserve. The first system is 

the series of glaciers, ice, and perennial snowfields. The 

second is the groundwater aquifers. The third includes 

all the streams, rivers, creeks, lakes, and ponds present 

on the landscape in Denali, including surface ice on 

lakes, which is a significant ecosystem factor. 

There are approximately 400 streams and rivers in the 

park. Major waterways include the Foraker, McKinley, 

Kantishna, Toklat, and Teklanika Rivers on the northern 

slopes, and the Yentna, Kahiltna, and Chulitna Rivers 
DENA Geologic Resources Inventory Report 11

flowing south. The Nenana River marks the eastern 

boundary of the park. Due to continued regional uplift 

and plentiful water and sediment supply, these streams 

are aggrading in some areas and downcutting in the 

upland areas. 

Ecosystem processes on the river floodplains are closely 

linked to fluvial processes and controlled by climate. 

Fluvial processes include flooding, sedimentation, and 

erosion, which interact with biotic processes such as seed 

dispersal and seedling establishment, and thus determine 

temporal and spatial development of riparian zones 

(Adams 1999). Floodplains with regular influxes of finegrained silt and well-drained river terrace environments 

are rich ecosystems at Denali, supporting vast forests and 

lowland species. It is important that resource managers 

understand the fluvial processes that influence 

vegetation succession, including silt deposition, erosion, 

and fiver flow patterns that regulate flood events, as 

these processes are intimately linked with climate 

(Adams 1999).

Studies within the Rock Creek watershed targeted for 

long-term ecological monitoring revealed that 

streamwater chemical compositions, including elevated 

levels of Ca2+, Mg2+, and SO4

2-

, are directly influenced by 

underlying geology. In contrast, streamwater 

concentrations of nutrients and dissolved organic carbon

are regulated by biological activity. Vegetation patterns 

are controlled by soil development, which is strongly 

related to geologic processes of weathering and 

alteration in addition to fluvial processes such as erosion 

and flooding. The productivity of the Rock Creek 

watershed is limited by physical factors such as unstable 

channel morphology, increased stream discharge, and 

organic matter retention (Popovics et al. 1999). Studies of 

this nature could be applied to many other watersheds at 

Denali to begin to quantify geologic controls on 

streamwater quality and riparian zone ecosystem health. 

The park contains classic examples of braided streams

(fig. 9). These streams typically (but not always) flow 

from glaciers, and contain choking amounts of sediment,

causing them to split and crisscross the landscape. Not 

all streams at Denali are cloudy glacier-fed streams; clear 

streams that develop from springs and precipitation 

contain much lower levels of sediment. Turbidity and 

suspended sediment are greater in glacier-fed streams 

from the northern slope than from the southern slope. 

Levels of pH, alkalinity, conductivity, and ionic 

concentrations are also elevated in northern streams. 

These differences in chemical and sediment 

characteristics of streams at Denali are controlled by 

bedrock geology; marine sedimentary bedrock yields 

higher dissolved ion concentrations than resistant 

granitic bedrock (Edwards et al. 2000).

The wet northern slope area contains a unique wetland 

hydrology with shallow glacial lakes, bogs, ponds, and 

taiga. This flat, boggy, tundra area comprises 

approximately 20% of the park’s land area. Some areas 

developed over millennial timeframes (Mann 1999). 

Long-term peat development records climatic change 

over time through pollen, plant debris, and other 

remains. 

Resource Management Suggestions for Surface Water Issues

• Contact the NPS Water Resources Division for 

assistance with surface water issues. The USGS Water 

Resources Discipline is an additional source of 

technical assistance.

• Inventory lakes, ponds, and other small water bodies,

including bogs and wetlands. 

• Conduct a comprehensive survey determining a 

vulnerability index for flooding in areas used by 

backcountry campers, park infrastructure, and other 

visitor use facilities.

• Identify floodplain areas, such as those around 

Kantishna lodges, for remediation.

• Perform studies linking spatial variability, climate, and 

fluvial processes with vegetation patterns and 

succession.

• Perform studies combining soils characteristics and 

detailed geologic mapping, soil water flow rate and 

chemistry, stream retention of organic matter, and 

streamwater chemistry to understand the 

relationships between soil, underlying bedrock, 

channel morphology, and streamwater quality for 

various watersheds.

• Monitor stream morphology, focusing on areas near 

gravel mines and damaged floodplain areas (from 

placer mining). Lord et al. (2009) have suggested 

techniques for monitoring stream systems.

Paleontological Resources

According to the park’s Resource Stewardship Strategy

for 2008-2027, paleontological resources are important 

resources for park management and visitors, and the 

park has a legal mandate to protect such important, 

nonrenewable resources. The 2009 Paleontological 

Resources Preservation Act directs the Secretaries of 

Interior and Agriculture to implement comprehensive 

paleontological resource management programs. The 

NPS and other federal land managing agencies are 

developing joint regulations associated with the Act (J.

Brunner, NPS Geologic Resources Division, policy and 

regulatory specialist, personal communication, May 

2010). 

Denali National Park and Preserve contains many 

fossiliferous geologic units. Most of these are from the 

warm shallow seas present throughout much of the late 

Paleozoic and Mesozoic eras. Some of the accreted 

terranes traveled north from lower latitudes where 

marine life flourished. Fossils include invertebrates (as 

the dominant type), marine mollusks, insects, plant 

debris, and abundant trace fossils. A brachiopod, 

Myrospirifer breasei, was named after park geologist Phil 

Brease. Fossils found outside the park, in the same 

geologic units that exist in the park, that might also be 

present at Denali, include dinosaur remains of 

hadrosaurs, pachycephalosaurs, theropods,

tyrannosaurids, ceratopsians, and a variety of vertebrate 
12 NPS Geologic Resources Division

trace fossils (Gangloff 1999; W. Elder, written 

communication, December 2009). Paleontological work 

by Brease et al. (2009) revealed the presence of dinosaur, 

plants and trace fossils in abundance within certain 

geologic units in the park (figs. 10, 11). Thousands of 

trace fossils of fish, pterosaurs, theropods, hadrosaurs, 

birds, and terrestrial and aquatic invertebrates are 

preserved in the lower Cantwell Formation, making this 

one of the best-preserved Late Cretaceous polar 

continental ecosystems in the global paleontological 

record (Brease et al. 2009).

At Denali, fossils occur in rocks which span the 

Paleozoic, Mesozoic, and Cenozoic eras. The boundary 

between the Cretaceous and Tertiary periods, commonly 

referred to as the “K-T boundary,” is present in the park. 

This yields a unique opportunity to determine the highlatitude effects on the paleoecosystem during the mass 

extinction that occurred at the end of the Cretaceous 

Period.

Paleontology work in the park has been mostly limited to 

the Healy quadrangle, with some additional fossil finds 

in the Talkeetna quadrangle on the south side of the 

range crest by Reed and Nelson (1977) (P. Haeussler, 

USGS, geologist, written communication, November

2009). Much of the park area remains to be surveyed and 

inventoried for paleontological resources. Field-based 

inventories are ongoing. A literature-based 

paleontological resource summary for the central Alaska 

Inventory and Monitoring Network is currently 

underway with expected completion in late 2010 or early 

2011. The network summary is part of a national effort to 

systematically research fossil occurrences in NPS areas 

Servicewide. Conducting additional large-scale geologic

mapping would inevitably reveal additional fossils. The 

park is currently developing a Paleontology Management 

Plan to address this vast resource (Brease et al. 2009; G. 

Adema, NPS, Denali National Park and Preserve, 

personal communication, July 2010). Santucci et al.

(2009) identified “vital signs” for monitoring in situ 

paleontological resources: geologic and climatic variables 

affecting natural erosion rates, catastrophic geologic 

processes or geohazards, hydrology and bathymetry (i.e., 

changes in water level affecting resources near water 

bodies), and human impacts.

Resource Management Suggestions for Paleontological 

Resources

• Perform a comprehensive paleontological inventory at 

the park, including documented locations, 

abundance, ease of access, risk factors and 

disturbance, baseline conditions, fragility, and any 

necessary protection measures (Denali National Park 

and Preserve 2009).

• Study timing relationships of various deposits across 

the park using index fossils and locality studies. Focus 

on the Cantwell Formation for bio-stratigraphic 

work.

• Cooperate with researchers in creating a 

paleogeographic atlas of Alaska using invertebrate 

fossil records, for example.

• Perform palynology studies to research the 

Cretaceous-Tertiary stratigraphic boundary in the 

park area. 

• Use paleontology to understand the spatial and 

temporal relationships between the different terranes 

and subterranes present in the park region.

• Create paleontology interpretive programs to increase 

visitor awareness of the fossil resources at Denali.

• Increase efforts started by the geoscientist in the parks 

program to produce a comprehensive paleontological 

database (using Microsoft Access), expanding on the 

more than 200 sites already entered. Obtain GPS data 

for sites, as well as ground truthing, and further 

description and characterization. Information should 

be incorporated into the park’s GIS.

Geothermal Activity

Denali National Park and Preserve is located near an 

active plate margin, above a deep subduction zone, 

making it a prime area for geothermal activity. It was one 

of the original 22 national parks considered for 

geothermal resource management, but was not one of 

the 16 selected for extensive research (K. Moss, NPS 

Geologic Resources Division, environmental specialist, 

written communication, December 2009). Hot and warm

springs are present throughout the park area, including 

Windy Creek and Wigane Creek. Cold meteoric 

groundwater trickling through the subsurface is heated 

by rock deep below the earth’s surface. This heating 

causes the water to expand; it is then usually forced 

upward under intense pressure to emerge as heated 

pools. There is no inventory of, or monitoring plan for, 

geothermal features within the park. These are needed 

data sets for park resource managers.

Resource Management Suggestions for Geothermal Activity

• Obtain water chemistry data for geothermal features 

along the south side of the park, focusing on the 

Windy Creek area. 

• Inventory travertine deposits.

• Perform studies on the hydrogeology of Wigane 

Creek. This upwelling water feature could be 

geothermal, but the nature of the system is unknown.

• Inventory all hot spring features in the park. Map 

locations digitally for incorporation in the park’s GIS.

Slope Processes and Erosion

The geologic processes of erosion are prevalent at Denali 

National Park and Preserve. Glaciers are remarkable

agents of erosion, and sheet runoff, streams, and rivers 

all carve channels and valleys into the landscape. 

Topography provides opportunities for erosion (P. 

Haeussler, USGS, geologist, written communication, 

November 2009). When unconsolidated sediments—

such as slope deposits, glacial till and moraines, and 

alluvium, as well as altered and/or deformed bedrock—

are exposed on moderate slopes, the potential for 

erosion and mass wasting increases. Some volcanic and 

sedimentary units are quickly altered to shrink-and-swell 

clays (minerals that swell when water-saturated and 
DENA Geologic Resources Inventory Report 13

shrink upon drying). This constant change in volume 

undermines the integrity of the rocks. 

The area’s earthquake activity increases the risk of 

catastrophic failure on park slopes. As described above in 

the seismicity section, ground shaking related to a single 

large earthquake event can produce widespread effects,

including an increase in the intensity and quantity of 

smaller-scale seismic events that can induce slope failure.

An earthquake in 1912, located near the intersection of 

the Denali fault and the Richardson Highway, destroyed 

a climbing route on Mt. McKinley used in the 1910 

Sourdough Expedition that allowed quick ascension of 

the summit of North Peak (Carver et al. 2004; Brease

2004; P. Haeussler, USGS, geologist, written 

communication, November 2009). On steep, 

unconsolidated slopes, as well as slopes of deformed 

rocks with cleavage oriented parallel to the slope, large 

slumps and slides can be triggered by small seismic 

events. Vulnerable areas can be assessed and identified 

based on the composition of the slope forming material, 

degree of slope, and orientation to known active faults. 

Along the entrance road to the park, where it parallels 

the Hines Creek fault, landslides are relatively common 

after heavy rainfall. The water-saturated and heavy rocks 

and soil slide down the slope in slumps of ice-cored,

lobe-shaped masses called solifluction lobes (Gilbert

1979). Much of the park road is built on unconsolidated 

glacial and fluvial deposits that erode easily and slump.

Large landslides often display hummocky topography, 

which is a very irregular and hazardous trail base for 

visitor use. Several slides—one older and vegetated, and 

three younger and unvegetated (not visible on 1949 era 

aerial photographs)—exist along the trail to Triple Lakes. 

Another slide, only 1 km (0.6 mi) above the park road, 

pushed the course of Tattler Creek southward. In 1953, 

massive landslides of sheared basalt flows dammed Stony 

Creek, creating Bergh Lake (Gilbert 1979). These slides 

attest to longstanding and continuous slide activity in the 

area. 

Rockfalls are prominent components to mass wasting at 

the park. Large rockfalls exist on the south side of the 

upper Buckskin Glacier and off the east face of the Eye 

Tooth (fig. 12). Rockfall events are inherent in areas of 

steep topography, freeze-and-thaw cycles, bare slopes,

and rock faces (P. Haeussler, USGS, geologist, written 

communication, November 2009).

Snow and ice avalanches are a year-round threat to 

visitor safety, park infrastructure, and backcountry areas. 

Snow avalanches are a significant hazard at the park. 

Earthquakes can trigger snow avalanches, much in the 

same way as rockfalls or landslides. Larger avalanches 

with longer runouts can be generated with a larger 

trigger mechanism such as an earthquake (P. Haeussler, 

USGS, geologist, written communication, November

2009). 

Other features at risk for erosion and mass wasting 

include rock glaciers, glacier fronts, terminal moraine 

slopes, and eskers (figs. 4, 19). Park resource 

management attempts to mitigate the effects of erosion 

and mass wasting along the most vulnerable and exposed 

areas. Engineering along Lake Moody attempts to 

alleviate some of the geologic hazards in the area. Areas 

along park roads and trails subjected to repeated 

subsurface sliding are targeted for reinforcement. 

Wieczorek and Snyder (2009) suggested the following 

“vital signs” for monitoring slope processes: types of 

landslides, landslide triggers and causes, geologic 

materials in landslides, measurement of landslide 

movement, and assessing landslide hazards and risks.

Resource Management Suggestions for Slope Processes and 

Erosion

• Catalog mass failures. As new failures occur, their 

location and type should be noted and incorporated 

into the park’s GIS. Past mass failures should also be 

categorized, catalogued, and incorporated in the 

park’s GIS (P. Haeussler, USGS, geologist, written 

communication, November 2009). 

• Perform slope vulnerability studies to identify reaches 

within the park susceptible to massive landslides in 

the event of an earthquake. Target unconsolidated 

deposits and heavily deformed geologic units. 

• Determine what effects, if any, social trail development 

has had on erosion and seasonal runoff in the park. 

• Identify areas where park infrastructure is threatened 

by erosion and mass wasting.

• Incorporate spatial slope data into the park’s GIS to 

correlate with underlying geologic units and 

structure, as well as vegetation patterns and 

hydrologic information to determine areas vulnerable 

to extreme erosion and mass wasting. 

General Geology Issues and Research Possibilities 

The remoteness, arctic climate, ruggedness, and sheer

size of Denali National Park and Preserve poses 

significant challenges to geologists and other researchers 

seeking to study the landscape. However, these same 

characteristics also serve to preserve a living laboratory 

and a unique opportunity to study pristine alpine-arctic 

environments, active glaciers, active seismicity, 

permafrost, paleontology (fig. 13) and active margin 

terrane accretion.

Resource Management Suggestions for General Geology 

Issues and Research Possibilities

• Perform larger scale, detailed geologic mapping in a 

digital format for incorporation in the park’s GIS.

• Perform regular surveys and repeated monitoring of 

soil conditions to determine the lasting impacts of 

off-road vehicle and snowmobile use on soil 

compaction and wetland/bog ecosystem health. 

• Identify and photograph the park’s rare or unique 

geological features and type sections. Periodically 

monitor their condition (Denali National Park and 

Preserve 2009).

• Perform an air quality and visibility change analysis,

focusing on the introduction of industrial pollution, 
14 NPS Geologic Resources Division

arctic haze, and coal-fired electricity generation.

Contact the NPS Air Resources Division (Denver, 

CO) for technical assistance.

• Cooperate with federal and local agencies for 

continuing geologic mapping efforts. 

• Promote detailed studies of the geologic history and 

origin of the smaller terranes located along the Denali 

Fault and throughout the Kahiltna Glacier area. 

• Develop additional geologic-themed interpretive 

programs to increase visitor awareness of the role 

geology plays in the landscape evolution and 

ecosystem at the park.

• Map, describe, and characterize the significant loess 

deposits (windblown, glacially-derived silt) at Denali.

• Determine if caves exist in the Devonian and Silurian 

age limestones. If caves are present, perform a 

comprehensive inventory, digitally mapping locations 

to incorporate into the park’s GIS. 

• If needed, develop a plan to protect any existing cave 

resources as well as ensure visitor safety. 

Figure 4: The Straightaway Glacier (shown) is one of many surge-type glaciers which issue from Mt. McKinley. Surging glaciers can move 10-

100 times the normal flow rates. NPS Photo/Adema.
DENA Geologic Resources Inventory Report 15 Figure 5: Repeat photography pair showing retreat of a glacier at the head of Hidden Creek in Denali National Park and Preserve. Upper photo was taken in 1911 by USGS geologist Steven R. Capps, lower image was taken on August 7, 2004 by Ronald D. Karpilo, Jr. Photos courtesy of Ronald D. Karpilo, Jr. (Colorado State University).
16 NPS Geologic Resources Division

Figure 6: Repeat photography pair showing retreat of a glacier in the Teklanika River valley in Denali National Park and Preserve, 

Alaska. Upper photo was taken in 1919 by USGS geologist Steven R. Capps, lower image was taken on August 9, 2004 by Ronald D. 

Karpilo, Jr. Photos courtesy of Ronald D. Karpilo, Jr. (Colorado State University).
DENA Geologic Resources Inventory Report 17

Figure 7: Denali has been steadily restoring abandoned mine lands like this project on Slate Creek. Encapsulated soil lifts guide a new 

channel away from exposed ore to improve water quality and aquatic habitat. NPS Photo/Adema.

Figure 8: Thermokarst development, like this example in the Toklat Basin on the north side of Denali, is an indicator of the dramatic and

quick change occurring on the base permafrost landscape. NPS Photo/Yocum.
18 NPS Geologic Resources Division

Figure 9: One of Denali’s most dramatic features are the large, braided rivers like the Toklat river. Not only geologically striking, the 

Toklat provides a renewable source of gravel for maintenance of the Denali Park Road. NPS Photo/Adema.

Figure 10: Theropod dinosaur discoveries in the 

Cantwell Formation have excited considerable 

paleontological research. A theropod footprint 

trace fossil is shown here. NPS Photo/Brease.

Figure 11: Plant fossils, such as this fern, provide insight to the paleoecology of 

Denali. NPS Photo/Brease.
DENA Geologic Resources Inventory Report 19

Figure 12: View of landslide debris on Buckskin Glacier with granite peak named The Moose's Tooth (3,150 m; 10,335 ft) visible in the 

background, Denali National Park and Preserve, Alaska, August 7, 2004. Photo courtesy of Ronald D. Karpilo, Jr. (Colorado State 

University).

Figure 13: Researchers investigate dinosaur fossils in Denali’s Cantwell Formation. NPS Photo/Brease.
20 NPS Geologic Resources Division

Geologic Features and Processes

This section describes the most prominent and distinctive geologic features and processes 

in Denali National Park and Preserve.

Mt. McKinley (Denali)

Mt. McKinley (known as “Denali” [“The Great One”] in 

the native Athabaska language) dominates the landscape 

of Denali National Park and Preserve, towering some

915 m (3,000 ft) above the neighboring peaks in the 

Alaska Range (figs. 1, 3, 14). Its highest point is 6,194 m 

(20,320 ft) above sea level, making it the tallest mountain 

on the North American continent. Mt. McKinley 

features greater relief than most mountains on Earth. For 

example, the Wickersham Wall on the northern slope of 

the mountain has approximately 5,500 m (18,000 ft) of 

vertical relief. This peak was first scaled in 1913 by a 

party led by Hudson Stuck. Today, features such as 

Browne Tower, Karstens Ridge, McGonagall Pass, and 

Denali Pass, not to mention the numerous icefalls and 

crevasses posed by the large glaciers in the area, still 

challenge climbers (Greenwood and Rowell 1980). The

American Alpine Journal frequently describes climbing 

endeavors and routes within Denali National Park and 

Preserve.

Uplift of the Alaska Range began during the Jurassic and 

culminated in the Tertiary, some 60 to 30 million years 

ago. Recent studies suggest that the modern mountain 

mass in the immediate area of Denali was uplifted rapidly 

(~1 km/million years [0.6 mi/million years]) beginning ~6 

million years ago (Plafker et al. 1989). This uplift was a

result of interactions between the right lateral Denali

fault (with a local morphology that includes a 22-degree 

bend) and a series of northeast-striking thrust faults, and 

changes in motion between the Pacific and North 

American plates (Haeussler 2005). This caused a space 

problem that forced crustal blocks upward (Fitzgerald et 

al. 1993).

Mt. McKinley is still rising approximately 1 mm (0.04 in) 

per year. Uplift of the range hinged on the convergence 

of several geologic factors, including subduction, 

faulting, terrane accretion, and plutonism (Fitzgerald et 

al. 1993). The emplacement of the Chugach and Prince 

William accretionary wedges and the Yakutat terranes, as 

well as assorted smaller terranes, involves extreme 

shortening (fig. 15) as well as thrust faulting, which 

thickens the crust and shoves large crustal blocks 

upward (Dumoulin et al. 1998). The buoyancy of this 

thickened crust leads to further uplift as it adjusts to 

approach isostatic equilibrium. 

Subduction of the Pacific Plate beneath southern Alaska 

introduces water into the mantle, which then leads to 

partial melting and generation of magmas. At Denali, this 

led to plutonism and volcanism until about 38 million 

years ago. Since that time, subduction has continued, but 

there is no magmatism in Denali National Park and 

Preserve (P. Haeussler, USGS, geologist, written 

communication, November 2009).

Relatively buoyant and resistant granitic plutons form 

much of the core of the Alaska Range. These rocks are 

not easily worn away by erosion and weathering, thus 

allowing elevations to remain relatively high compared 

with other mountains of similar ages. The dominant 

peaks of the range—Mt. McKinley, Mt. Foraker, and Mt. 

Hunter—are composed of resistant granites. Differential 

erosion of less competent metasedimentary rocks of the 

surrounding mountains accentuates the height of these 

peaks (Fitzgerald et al. 1993). The biotite granite of the 

so-called McKinley pluton comprises most of the Mt. 

McKinley massif. It contains quartz, plagioclase, 

potassium feldspar, biotite, white mica, tourmaline, and 

other accessory minerals. Nearly 4 km (2.5 mi) of this 

igneous intrusive body is exposed within Denali National 

Park and Preserve, rendering it an ideal research target 

for petrologic and geochemical variations within a large 

continuous intrusion (West and Swanson 1995).

Denali Fault System

The Denali fault system is a 2,100-km- (1,300-mi)-long 

structure, trending from the Yukon border southwest 

toward the Bering Sea. The entire system connects with 

the Queen Charlotte fault and the Fairweather fault of 

southeastern Alaska toward British Columbia, forming a 

significant piece of the transform fault boundary 

between the Pacific and North American plates. The 

great arcuate system of northward-convex transcurrent 

faults that sweeps across Alaska is one of the most 

distinctive geologic features within the state (Moore et al. 

1994). The Denali fault was first named and described by 

St. Amand in 1957. The surface trace of the fault is 

concave to the south, roughly paralleling the shape of the 

Gulf of Alaska. The curvature of the fault is about 70 

degrees between the eastern and western portions. It is 

one of the largest and topographically best-expressed 

geologic features of south-central Alaska (Csejtey et al.

1982). This system now accommodates counterclockwise rotation of accreting terranes by absorbing 

some of the relative motion between the Pacific and 

North American plates. The Tintina-Kaltag fault and 

Iditarod-Nixon Fork fault systems (fig. 16) (other largescale, right-lateral, strike-slip systems), located north of 

Denali, accommodate some of this motion; as well, some 

faults to the south accommodate offsets today (Miller et 

al. 2002; Ratchkovski et al. 2004; W. Elder, written 

communication, December 2009). These margin-parallel,

strike-slip faults have experienced multiple episodes of 

dextral motion since approximately 100 million years ago

(Miller et al. 2002).

Estimates of right lateral offset along the Denali fault 

system are as little as several tens of km to as much as

600 km (370 mi) (Csejtey et al. 1982; Redfield and 

Fitzgerald 1993; Csejtey et al. 1995; Redfield and 

Fitzgerald 2000). The fault splits into two strands within 
DENA Geologic Resources Inventory Report 21

the Denali region. This split might have been due to a 

change in relative plate direction during the last ~50 

million years from north-south to a more lateral eastwest (Gilbert 1979; Cole et al. 1996). The northern 

branch is the Hines Creek fault; the McKinley fault is the 

southern strand of the Denali fault. Both faults are rightlateral motion, near vertical strike-slip faults. The

northern side of each fault moves eastward relative to the 

southern block. 

The Hines Creek fault traverses the northern reaches of 

the park. It roughly separates 350-million year old schist, 

as well as lower and middle Paleozoic metasedimentary 

rocks of the Yukon-Tanana Terrane from the Pingston 

and McKinley Terranes. It also bisects portions of the 

Paleozoic Farewell Terrane (a name used for the 

combined Dillinger, Nixon Fork, and Mystic Terranes) 

as well as granites of Mt. McKinley to the south that are 

Tertiary age (56 million years ago) (Csjetey et al. 1995; 

Dumoulin et al. 1998; Brease 2004). This fault passes near 

park headquarters and crosses the Alaska Railroad, 

extending westward, usually forming valley floors, for 80 

km (50 mi). This fault is not considered to be active. 

The McKinley strand of the Denali fault is active, and it 

passes through the central section of the park. It enters 

the park near Cantwell and trends eastward toward 

Anderson Pass and then beneath the Muldrow Glacier. 

(St. Amand 1957). This fault has displaced a pluton of 38

million year old Foraker granite (named for the second 

highest peak in the park) that is horizontally more than 

40 km (25 mi). This corresponds to an average slip rate of 

1 mm (0.04 in.) per year for the past 38 million years. 

Both strands of the Denali fault are north of Mt. 

McKinley. The McKinley fault has significant reverse 

thrust motion associated with it—i.e., the fault surface 

dips slightly toward the south, with Mt. McKinley being 

thrust upward and northward along this surface (Ford et

al. 2003). The Wickersham Wall on the northwest side of 

Mt. McKinley reflects the recent vertical component of 

movement along the fault (Gilbert 1979). Fault scarps 

along the McKinley strand, as well as local features such 

as angular grabens, en echelon (overlapped or staggered) 

ruptures, and “mole tracks,” exhibit a reliable history of 

Holocene movement across the fault system (Redfield 

and Fitzgerald 1993; Schwartz et al. 2005). These features 

also demonstrate the partitioned nature of movement 

between normal, thrust, and lateral (strike-slip) sense 

throughout such a major structure. The two fault strands 

coalesce east and west of Denali National Park and 

Preserve. 

As the Alaska Range is being uplifted, reverse and 

transform motion is accommodated by the Denali fault 

system and smaller-scale normal faults and thrust faults. 

On the trail to Triple Lakes, several igneous dikes,

intruding the Cantwell Formation, have been offset along 

several small faults. The hike along Tattler Creek shows 

evidence of at least 450 m (1,500 ft) of uplift within the 

Cantwell Formation (Gilbert 1979).

The intensity of deformation within the rocks through 

which the Denali and other faults pass is variable, but 

penetrative foliations, well-developed lineations, and 

strained grains suggest extensive transposition along the 

strands of the Denali fault, in particular. Locally, the 

zone of observable fault deformation reaches a width of 

5 km (3 mi). Cataclasites and zones of fault gouge from 

brittle deformation regimes cut mylonitic fabrics,

recording earlier ductile deformation along the fault 

(White 1997). Rocks trapped between shifting fault 

blocks are pulverized, deformed, and crushed. This 

renders them easily eroded; thus, most faults are 

traceable on the surface as linear topographic 

depressions (Gilbert 1979). Much of the actual fault trace 

is covered in Quaternary age sediments and/or alpine 

tundra (White 1997), and is visible east of Anderson Pass 

(P. Haeussler, USGS, geologist, written communication, 

November 2009).

Kantishna Hills

The Kantishna Hills are tectonically active and among 

the most interesting geologic features of Alaska (P. 

Haeussler, USGS, geologist, written communication, 

November 2009). Precambrian to early Paleozoic 

crystalline metamorphic rocks (mica schist), intruded by 

swarms of Cretaceous to Tertiary dikes, underlie the hills 

(Prindle 1907; Ruppert et al. 2008). The northeasttrending Kantishna Anticline is a growing feature 

resulting from at least five deformational episodes. Highangle and thrust faults generally follow the trend of the 

anticlinorium, whereas conjugate folds and faults trend 

northwest (Bundtzen 1981; Salisbury and Dietz, Inc. 

1984; Burghardt 1997). The southern end of the 

Kantishna Hills anticlinorium marks one of the most 

prominent areas of seismic activity in all of interior 

Alaska (Ruppert et al. 2008). It is growing at such a rate as 

to force rivers to divert around it (P. Haeussler, USGS, 

geologist, written communication, November 2009). The 

McKinley River flows around the southern end of the 

anticlinorium and through the seismic zone. The channel 

of this river changes from a well-developed braided 

channel to an incised meander morphology as the river 

approaches the southwestern part of the structure. 

North of the Kantishna Hills anticlinorium, the river 

abruptly reverts to a braided channel morphology 

(Ruppert et al. 2008). Active deformation, as the 

structure is propagating southwestward, is also 

responsible for reaches of convexity along the 

longitudinal stream profiles of McKinley River and 

Moose Creek near the Kantishna Hills (Ruppert et al. 

2008).

The lode mineralization in the Kantishna Hills appears to 

be spatially related to the axis of the Kantishna Anticline. 

This happened where the structure (especially areas of 

brittle deformation) focused mineralization and the 

emplacement of locally high-grade mineralized veins 

(Bundtzen 1981; Salisbury and Dietz, Inc. 1984; 

Burghardt 1997). Superheated, saturated fluids 

preferentially flowed through the fracture zones, 

depositing mineralized veins that would later attract the 

interest of miners. 
22 NPS Geologic Resources Division

Accreted Terranes

As much as 90% of Alaska’s current land mass is not part 

of the original North American craton, but was instead 

transported as a series of exotic terranes conveyed atop 

tectonic plates and accreted onto the continent (Stone

1984). These terranes include bits of islands, volcanic 

arcs, marine sediments, oceanic crust, and slivers of 

other continents that either obducted onto the continent 

or were too thick to subduct into the Aleutian trench. 

The central part of the Alaska Range in Denali National 

Park and Preserve is composed of three major separate 

terranes of varying scale (P. Haeussler, USGS, geologist, 

written communication, November 2009).

The terranes form long linear belts, and typically follow 

an arching pattern trending roughly east-west, paralleling 

the Gulf of Alaska coastline. Each separate terrane is 

bounded by faults, and is distinguished by differing rock 

assemblages, metamorphic grade, structural fabric, 

fossils, etc. Volcanism and mountain building

(orogenesis) often accompany terrane accretion; at 

Denali, pervasive faulting (including strike-slip, thrust, 

and high-angle reverse faults) have jumbled the terranes, 

obscuring their chronologic order (Stone 1980). Several 

faults, including the West Fork, Talkeetna, Denali, 

Chitina Valley, Castle Mountain, and Totschunda faults,

separate terranes in the Denali area (Nokleberg et al.

1994). The contacts between the various accreted 

terranes are also gave rise to hydrothermal 

metamorphism and magmatism, which in turn led to the 

development of gold veins in brittle faults and fractures 

(Goldfarb et al. 1997). Geologists use stratigraphic 

correlations, radiometric dating, paleomagnetism, 

detailed mapping, and other techniques to determine the 

relative sequence of accretion tectonic history. At least 

nine widespread magmatic episodes are represented by 

plutonic rocks scattered across Alaska (Miller 1994).

The names, designations, and numbers of identified 

terranes in the central Alaska Range have changed with 

more detailed geologic understanding of the area. Moore 

et al. (1994) provides one view of the tectonic assembly 

of the terranes of Alaska (beyond the scope of this 

report, which presents only a summary). The oldest 

terrane is the Yukon-Tanana terrane (and the Nixon 

Fork terrane, located west of Denali) that is composed of 

sequences of Precambrian through Paleozoic 

metasedimentary and metavolcanic rocks (Csejtey et al.

1982). This terrane comprises much of central Alaska 

and is present within the northern areas of the park, 

north of the Hines Creek fault. Farther south, several 

smaller terranes were caught between the Yukon-Tanana 

terrane and the accreting Wrangellia composite terrane 

or Talkeetna superterrane (Wrangellia, Alexander, 

Maclaren, and Peninsular terranes) during the 

Cretaceous collision between the Talkeetna and the 

continent (figs. 2, 16, 17) (Csejtey et al. 1982).

Farthest north among these smaller “miniterranes” is the 

Pingston terrane, which contains isoclinally folded, deep 

water mid-Paleozoic through Mesozoic, silty limestone, 

slate, and phyllite. The neighboring McKinley, Dillinger, 

and Windy terranes contain mixed Mesozoic flysch 

rocks and pillow lavas (McKinley terrane), micaceous 

sandstone (turbidites), graptolitic shale, deep water 

limestone (Dillinger terrane), serpentinite, basalt, tuff, 

chert, limestone, and mixed flysch (Windy terrane). 

Farther south, the Mystic terrane is composed of 

Mesozoic graptolitic shale, pillow basalt, shallow water 

limestone, sandstone, and chert. The Chulitna Terrane 

contains Mesozoic ophiolite rocks (oceanic crust), chert, 

volcanic conglomerate, limestone, and mixed flysch. The 

ophiolites of this belt were altered to serpentinite and 

contain clues to crustal suture (Roeske et al. 2005). The

West Fork terrane contains chert, sandstone, 

conglomerate, and tuffaceous argillite. The nearby Broad 

Pass terrane contains chert, tuff, and blocks of limestone 

and serpentinite (Jones et al. 1980).

These small terranes are tectonically mixed with 

intervening Jurassic and Cretaceous flysch, deposited in 

deep basins that existed between the colliding terranes

that collapsed and deformed upon collision (Csejtey et 

al. 1982). The Kahiltna assemblage is one such flysch 

sequence. It likely depositionally overlapped the 

northern margin of the Wrangellia and Peninsular

terranes, and is exposed in the northern Talkeetna 

Mountains and southern Alaska Range (Ridgway et al.

2002). Another noteworthy flysch sequence is the 

Gravina-Nutzotin belt, which overlies the Wrangellia 

and Alexander terranes (Nokleberg et al. 1994). These 

sedimentary basins might record the progressive 

development of a suture zone between the Talkeetna 

Superterrane (Wrangellia composite terrane) with the 

North American continental margin (Ridgway et al.

2002).

Younger large terranes and accretionary prisms, located 

to the south of Denali National Park and Preserve,

include the Chugach and Prince William accretionary 

blocks and the Yakutat terrane (P. Haeussler, USGS, 

geologist, written communication, November 2009). The 

youngest regional-scale terrane, the Yakutat terrane, is 

still attached to the Pacific Plate, traveling approximately 

5 cm (2 in.) northward per year; thus, accretion is an 

ongoing process along the coast of southern Alaska. 

Glacial Features

Glacial processes carved much of the rugged topography 

at Denali National Park and Preserve. A glacier is a 

powerful agent of erosion, capable of profoundly altering 

the landscape over which it passes. Glaciers primarily 

erode by two distinct processes: plucking and abrasion 

(Dyson 1966). In plucking, the glacier actually quarries 

out distinct masses of rock, incorporates them within the 

ice, and carries them along; as the glacier moves forward,

these blocks of rock are dragged or carried along with it 

(Dyson 1966). Abrasion involves glacial ice mixed with 

bits of rock and debris that actually scours the 

underlying bedrock as it passes over.

Cirques

By quarrying headward and downward at its mountain 

source, the glacier ultimately carves a steep-sided, bowlshaped basin called a cirque or glacial amphitheatre. The 
DENA Geologic Resources Inventory Report 23

cirque is the first place that ice forms and the place from 

which it disappears last; thus, it is subjected to intense 

glacial erosion longer than any other part of the glacial 

valley. Once the glacial ice melts away, a body of water 

known as a cirque lake can form in the depression 

(Dyson 1966). Cirque lakes are not common at Denali 

because most of the glaciers are still active. 

U-Shaped Valleys

Rock fragments of various sizes frozen into the bottom 

and sides of the glacier form a huge file or rasp, which 

abrades or wears away the bottom and sides of the valley 

down which the glacier flows. The valley thus attains a 

characteristic U-shaped cross-section, with steep sides 

and a broad bottom. This is in contrast to a stream-cut 

valley and its characteristic narrow, V-shaped profile. 

Many valleys in the park, once devoid of glacier ice, will 

possess this distinct U-shaped cross-section. The upper 

valleys of the Savage, Sanctuary, and Teklanika Rivers are 

U-shaped (Gilbert 1979).

The topography of the valley floor is not necessarily 

smooth, as it is usually contoured from erosion 

controlled by geologic properties of the bedrock. Steep 

drops or “steps” can mark valleys, between which the 

valley floor has a comparatively gentle slope. Such a 

valley floor is called a glacial stairway (Dyson 1966). 

These features result from the differences of erosional 

resistance between different rock types of the underlying 

geologic formations. A glacier will scour more deeply 

into a weaker rock, such as shale, schist, or altered 

volcanic rock, forming a “tread” (in contrast to the cliffs 

or “risers” formed by the erosion of stronger rocks such 

as massive sandstones, quartzites, or granites).

Hanging Valleys

The “tributaries” of glacial valleys, filled with smaller 

glaciers that feed into the larger ones, are known as 

hanging valleys. They form as a result of differences in 

erosional power between the smaller glacier and the 

larger valley glacier. The thicker the stream of ice, the 

more capable it is of erosion. Thus, a main valley deepens 

greatly, while the tributary valleys, with their smaller 

glaciers, cut down more slowly, leaving them hanging 

high above the floor of the main valley once the glacier 

ice melts (Dyson 1966).

Arêtes

Conspicuous throughout the Alaska Range are long, 

sharp ridges forming much of the backbone of the 

mountains poking above valleys filled with glacial ice. 

These features are known as arêtes, and owe their origin 

to glacial processes. 

As the long valley glaciers enlarge their source cirques by 

cutting farther toward the axis of the mountain range, 

the mountain wall is finally reduced to a very narrow,

steep-sided ridge, an arête. In the absence of glacier ice, 

knife-like ridges separate deep valleys at the park.

In some places, glaciers on opposite sides of a ridge can 

cut through the ridge, creating a low area known as a col

(but usually called a pass) (Dyson 1966). At locations

where three or more glaciers have plucked their way 

back toward a common point, they leave at their heads a 

sharp-pointed peak known as a horn.

Braided Rivers

Most of the major rivers at Denali seem underfit for their 

valleys. An underfit stream appears to be too small to 

have eroded the valley in which it flows, commonly the 

result of drainage changes caused by glaciers. They flow, 

splitting and intertwining in wide, glacially eroded, 

U-shaped valleys. They are choked with excess sediment

and follow steep gradients. Toklat River, visible from the 

park road, is a textbook example of such a river (fig. 9) 

(Gilbert 1979). When one stream channel fills with 

sediment, other channels form nearby. As streams drop

vast piles of poorly sorted sediment, valley trains (long 

narrow accumulations of glacial outwash confined by 

valley walls) develop (Brease 2004). 

Glacial Lakes

Most lakes throughout the park owe their existence 

directly or indirectly to glaciers and glacial processes. 

They can be divided into several main types, depending 

on their origin: cirque lakes, other rock-basin lakes, lakes 

dammed by glaciers and/or glacial deposits, kettle lakes, 

or glacial valley lakes.

Cirque lakes fill the depression plucked out of solid rock 

by a glacier at its source. These are not as common at 

Denali as in other glaciated parks because glacial activity 

is still so prevalent at the uppermost parts of most of the 

river drainages (Gilbert 1979). Other rock-basin lakes fill 

depressions created where glaciers moved over areas of 

comparatively weak rock. In all cases of cirque or rockbasin lakes, a bedrock dam contains the water. 

Lakes held back by outwash deposits are dammed by 

mixed sediments and stratified gravel, which were 

contained in or washed out from glaciers when they 

advanced into the lower parts of the valleys. Moraine 

lakes are formed when a moraine deposit blocks a stream 

outlet. Some lakes at Denali are caused by glaciers acting 

as dams across pre-existing river valleys or outwash 

streams from another glacier. Glacial impoundment is 

recorded in the rock record as varved clay (distinctly 

laminated sediments including the upper, fine-grained 

“winter” layer reflecting quiet depositional setting) 

lacustrine deposits that formed in the transient glacial 

lakes. Glacial Lake Moody once existed in the Nenana 

River canyon when the river was dammed by glacial 

deposits following the Healy Glaciation and during the 

Riley Creek Glaciation (Gilbert 1979). Glacial valley lakes 

are often long and finger-like, filling the former 

U-shaped valleys once occupied by large glaciers. These 

are large-scale features that could be dammed by 

moraine deposits. 

Kettle lakes and ponds form in response to glacier 

advance and retreat. Large pieces of ice often calve from 

the head of a glacier. These pieces are left stranded when 

the glacier retreats up the valley. When outwash streams 

deposit sand, clay, gravel, and other sediments around 

the block of stranded ice, the block is insulated and, once 
24 NPS Geologic Resources Division

melted, forms a small, typically round, pond in the midst 

of new thick glacial outwash. West of the Eielson Visitor 

Center, as well as north of the Teklanika Campground, 

numerous small lakes and ponds formed by melted

blocks of ice in morainal deposits are visible (Gilbert

1979). Wonder Lake, near Kantishna, was formed by a 

combination of glacial erosion and ice block melting 

(Brease 2004). 

Glacial Deposits

As the glacier ice moves, rock fragments continually 

break loose and can entrain into the ice itself. Some of 

the fragments are ground into powder as they move 

against each other and scour against the bedrock under 

the glacier. Many types of rock yield a milky gray powder 

when finely ground. Melt-water streams issuing from 

present-day glaciers are cloudy or milky from their load 

of this finely ground “rock flour.” Much of this silt is 

deposited in lakes where light refracting off the particles 

imparts a milky turquoise color to the water. 

Glacial till is a term used to describe deposits of mixed 

rock left by glaciers. During glacier advance, huge 

amounts of rock debris are transported down glacial 

valleys. When the glacier stops advancing and begins 

melting and retreating up the valley, a large rock debris 

deposit, known as a terminal moraine, is dumped at the 

point of furthest advance (fig. 18). Terminal moraines 

help constrain the timing of glacial advance and retreat.

The McKinley River area contains one of the most 

complete glacial deposit sequences along the north flank 

of the Alaska Range at Denali National Park and 

Preserve. Included in this sequence are three pre-late 

Wisconsin age moraines. These are broad ridges formed 

when the Muldrow and Peters Glaciers coalesced and 

extended down the valley as a broad lobe approximately 

50 km (31 mi) from present margins. Local deposits 

include a four-fold late Wisconsin moraine sequence

(40 km [25 mi] down the valley) and four separate 

neoglacial moraines. The oldest of the neoglacial 

deposits is 3,000 years old; the most recent is dated 

within the past 100 years. These deposits display 

irregular topography, with some remnant ice present at 

depth within the deposit and little vegetation cover 

(Werner et al. 1990).

Terminal moraine deposits throughout the park are 

susceptible to intense erosion immediately following 

deposition, as well as the obscuring effects of a vegetative 

cover. Studies of moraine deposits at Denali reveal at 

least seven major periods of glacial advance beginning 

around 2 to 3 million years ago. Locally, these are called 

(from earliest to latest): the Teklanika (Late Tertiary, >2 

million years before present [ybp]); Browne (150,000+ 

ypb); Bear Creek (125,000 to 150,000 ybp); Dry-Lignite 

Creek (125,000 ypb); Healy-McLeod Creek (65,000 to 

75,000 ybp); and Riley Creek-Wonder Lake (9,000 to 

25,000 ybp) glaciations. They are followed by the Carlo 

Creek readvance of 8,000 ybp (Gilbert 1979; Thorson 

1986; Brease 2004). As the Alaska Range was uplifted, 

subsequent glaciations that did not extend out as far as 

the previous ones left a record of nested moraines 

(Gilbert 1979; P. Haeussler, USGS, geologist, written 

communication, November 2009). Similarly, the various 

types of rock blocks in glacial deposits can record the 

distance and direction of the glacial transport from the 

stone’s provenance to present position. 

Lateral moraines are the piles of loose fragments and 

blocks that fall from overhanging cliffs. These blocks 

accumulate as low ridges of glacial till riding along the 

edge of the glacier. If two glaciers intersect, adjacent 

lateral moraines join to form medial moraines (Brease

2004).

Glacier ice supporting large boulders and blocks of rock 

can be stranded or rafted on glacial lakes. When the ice 

melts, the largest blocks are known as glacial erratics. A 

remnant boulder, or erratic, left from the Browne 

Glaciation sits on a hillside at elevation 1,040 m (3,400 ft) 

south of park headquarters. A similar granitic erratic, 

pulled from the crest of the Alaska Range was stranded at 

1,280 m (4,200 ft) on the summit of Mt. Fellows, east of 

park headquarters (Gilbert 1979).

Glacial deposits are cause for resource management 

concern because of the large proportions of weak rock 

flour and clays that form the matrix for larger, irregular 

blocks of rock. In many glacial deposits, the loose 

material continually slumps, sometimes sliding over a 

road or trail surface. Knowledge of the location of such 

deposits is critical for maintenance of park infrastructure 

and facilities.

Bergschrunds

Usually a large crevasse, the bergschrund develops in the 

ice at the head of a glacier as a result of the glacier 

moving away from the headwall (fig. 19). The size of the 

bergschrund of many active glaciers in Denali depends 

on the mass and area of glacier ice. Bergschrunds consist 

of an arcuate opening between the head of the glacier 

and the mountain (cirque) wall. The trend of the 

bergschrund usually parallels the wall. It is at this site that 

plucking is most active and dominant because water 

enters the cracks by day and freezes in the rock crevices 

at night.

Glaciers

Glaciers are major features on the landscape of Denali 

National Park and Preserve, covering 17% (~1 million 

acres) of the total park area. More than 400 glaciers exist 

at the park, the largest and/or most visible 40 of which 

are named. The Kahiltna Glacier is 71 km (44 mi) long, 

making it the longest glacier in the Alaska Range. The 

Ruth Glacier is the thickest glacier in the park, filling the 

very deep Ruth Gorge. The Eldridge, Tokositna, Yentna, 

Peters, Harper, and Muldrow Glaciers are among the 

other named glaciers at Denali.

Permanent snowpack and abundant precipitation above 

2,100 m (7,000 ft) supports the flow of glaciers from 

elevations above 6,100 m (20,000 ft) down glacial valleys 

to ~305 m (1,000 ft). The most extensive glaciers and 

snowfields are concentrated on the southeastern side of 

the Alaska Range, due to the abundant snowfall from 
DENA Geologic Resources Inventory Report 25

moisture-bearing winds from the Gulf of Alaska. On the 

drier north side, glaciers are typically smaller and 

shorter, with the exception of Muldrow Glacier (Brease

2004). Ice within these glaciers moves at varying speeds

depending on several factors: glacier thickness, underlying topography, bedrock type and structure, and the 

presence of water beneath the ice. The average rate in the 

smallest glaciers is 1.8 to 2.4 m (6 to 8 ft) a year, while the 

average in the largest glaciers is greater than 70 m (230 ft) 

a year. Glaciers are never motionless; however, their 

movement is somewhat slower in winter than in summer. 

Despite slow speeds, over a period of years, glacial ice 

transports immense quantities of rock material and 

debris ultimately to the ends of the glaciers.

Short-lived Glacial Surface Features

Countless interesting, short-lived surface features can be 

seen at various times on any glacier. These include 

crevasses, moulins (glacier wells), debris cones, and 

glacier tables (fig. 19). Crevasses are cracks that occur in 

the ice of all glaciers due to tensions caused by 

differences in ice velocity throughout the body of the 

glacier (fig. 20). They can be hidden by skiffs of snow or 

debris, and thus can pose a hazard problem to visitors.

Debris cones result from the insulating effect of rock 

debris, usually deposited by a stream running over the 

glacier’s surface, which protects the ice underneath from 

the sun’s rays. As the surface of the glacier is lowered by 

melting, cones or mounds form beneath the rockinsulated area and grow gradually higher until the debris 

slides from them. They are seldom higher than 3 to 4 feet, 

but can pose a hazard to hikers on the glacier. A glacier 

table is a mound of ice that is capped and insulated by a 

large boulder. Its evolution is similar to that of the debris 

cone or mound (Dyson 1966).

Snow that fills crevasses and wells during the winter 

often melts out from below, leaving thin snowbridges 

over the cracks in early summer. These snowbridges 

pose a very real danger to those traveling on glaciers

because of their inherent weakness and instability.

Glacial Retreat and Surging Glaciers

As climate warms (Karl et al. 2009; IPCC 2007), glaciers 

are shrinking at Denali National Park and Preserve (figs. 

5, 6, 18). Most of the glaciers are consistently thinning

(see “Geologic Issues” section). Many glaciers appear 

underfit for their U-shaped valleys (Brease 2004). When

the yearly snow accumulation decreases, the ice front of 

the glaciers seems to retreat, whereas the mass of the 

glaciers is merely decreasing by melting on top and along 

the edges (analogous to an ice cube melting on a kitchen 

counter). 

Surging Glaciers

When a glacier advances faster than average in one or 

more seasons, it is said to be surging. The Muldrow 

Glacier, approaching the park visitor center from the 

west, has advanced rapidly several times (Brease 2004).

The last major surge occurred during the 1956-1957 

season. Glacial surging can be the result of periodic water 

buildup beneath the glacier, lubricating the base of the 

glacier and facilitating rapid and potentially catastrophic 

movements of ice (Gilbert 1979). A major tributary to the 

Muldrow Glacier is the Traleika Glacier. This glacier has 

flowed at rates of 20 to 70 m (66 to 230 ft) per year since 

1991 (Adema et al. 2003). 

Presently, only about 10% of glaciers are surging at any 

one time (fig. 4) (P. Haeussler, USGS, geologist, written 

communication, November 2009). Most of surging 

glaciers are located on glaciers of northern exposure 

along the Alaska Range.

Other Notable Geologic Features

• Polychrome overlook’s multi-colored rocks are the 

result of weathered rhyolite tuffs and interlayered 

flows of the Teklanika Formation, deposited 56 

million years ago. Similar, colorful volcanics are 

visible on Cathedral, Double, and Igloo Mountains 

(Cole 2004). This volcanism was contemporaneous 

with the formation of Mt. McKinley, suggesting that 

the volcanic vent source was to the southwest. 

• Evidence of more recent volcanism, ~38 million years

ago, is conspicuous from the Eielson Visitor Center,

and forms much of Mt. Galen with basalt, andesite, 

dacite, and rhyolite lava flows, tuffs, and breccias 

(Cole 2004).

• Near Teklanika Campground, the quartz-rich 

conglomerate of the Cantwell Formation rests atop 

much older metamorphic rocks, marking a 100- to 65-

million year gap (unconformity) in the geologic 

record. Elsewhere, in the Tolkat River gorge, the 

Cantwell sits atop pillow basalts that are 135 million 

years older (Gilbert 1979).

• “Badlands” topography is developed along the gorge 

of the East Fork River within rhyolite pebble 

conglomerates of the Nenana Gravel. 
26 NPS Geologic Resources Division

Figure 14: Denali (Mt. McKinley) dominates the ridgeline of the Alaska Range in Denali National Park and Preserve. Wonder Lake (note 

canoe for scale) is in the foreground. NPS photo.

Figure 15: Denali has a rich variety of deformed bedrock, a tribute to the complex geologic history which includes active plate dynamics. 

NPS Photo/Adema.
DENA Geologic Resources Inventory Report 27

Figure 16: Map of Alaska showing the Denali fault, Iditarod-Nixon fault (INF), Tintina-Kaltag fault, the Border Ranges fault (BRF -

Talkeetna fault), and other regional structures in relation to the southern coast of Alaska and the Aleutian trench subduction zone. Note 

the location of the Yakutat Terrane. An orocline is an orogenic belt with an imposed curvature or sharp bend. Graphic by Phil Reiker 

(NPS Geologic Resources Division) after fig 1. from Miller et al. (2002).
28 NPS Geologic Resources Division

Figure 17: Cross section of subduction zone between the Talkeetna Superterrane and the Yukon-Tanana Terrane of southern Alaska during early Cretaceous accretion events. Note the location of miniterranes and ocean basins between the two large terranes. Graphic by Trista L. Thornberry-Ehrlich (Colorado State University), adapted from Csejtey et al. (1982) fig. 9.
DENA Geologic Resources Inventory Report 29

Figure 18: Diagrammatic view of a retreating glacier with a recent terminal moraine and a broad space between the moraine and the 

glacier front. Note the variety of glacial deposits. Graphic by Trista L. Thornberry-Ehrlich (Colorado State University).

Figure 19: Short-lived features occurring on the surface of glaciers. Graphic by Trista L. Thornberry-Ehrlich (Colorado State University).
30 NPS Geologic Resources Division

Figure 20: Ice and crevasses of Eldridge Glacier in Denali National Park and Preserve, Alaska, August 7, 2004. Photo courtesy of Ronald D. 

Karpilo, Jr. (Colorado State University).
DENA Geologic Resources Inventory Report 31

Map Unit Properties

This section identifies characteristics of map units that appear on the Geologic Resources 

Inventory digital geologic map of Denali National Park and Preserve. The

accompanying table is highly generalized and for background purposes only. Grounddisturbing activities should not be permitted or denied on the basis of information in this

table. 

Geologic maps facilitate an understanding of Earth, its 

processes, and the geologic history responsible for its 

formation. Hence, the geologic map for Denali National 

Park and Preserve provided information for the 

“Geologic Issues,” “Geologic Features and Processes,” 

and “Geologic History” sections of this report. Geologic 

maps are two-dimensional representations of complex 

three-dimensional relationships; their color coding 

illustrates the distribution of rocks and unconsolidated 

deposits. Bold lines that cross or separate the color 

patterns mark structures such as faults and folds. Point 

symbols indicate features such as dipping strata, sample 

localities, mines, wells, and cave openings. 

Incorporation of geologic data into a Geographic 

Information System (GIS) increases the usefulness of 

geologic maps by revealing the spatial relationships 

among geologic features, other natural resources, and 

anthropogenic features. Geologic maps are indicators of 

water resources because they show which rock units are 

potential aquifers and are useful for finding seeps and 

springs. Geologic maps are not soil maps, and do not 

show soil types, but they do show parent material—a key 

factor in soil formation. Furthermore, resource managers 

have used geologic maps to make connections between 

geology and biology; for instance, geologic maps have 

served as tools for locating sensitive, threatened, and 

endangered plant species, which may prefer a particular 

rock unit. 

Although geologic maps do not show where earthquakes 

will occur, the presence of a fault indicates past 

movement and possible future seismic activity. Similarly, 

map units show areas that have been susceptible to 

hazards such as landslides, rockfalls, and volcanic 

eruptions . Geologic maps do not show archaeological or 

cultural resources, but past peoples may have inhabited 

or been influenced by depicted geomorphic features. For 

example, alluvial terraces may have been preferred use 

areas and formerly inhabited alcoves may occur at the 

contact between two rock units.

The geologic units listed in the following table 

correspond to the accompanying digital geologic data. 

Map units are listed in the table from youngest to oldest. 

Please refer to the geologic timescale (fig. 21) for the age 

associated with each time period. The table highlights 

characteristics of map units such as: susceptibility to 

erosion and hazards; the occurrence of paleontological 

resources (fossils), cultural resources, mineral resources, 

and caves or karst; and suitability as habitat or for 

recreational use. Some information on the table is

conjectural and meant to serve as suggestions for further 

investigation.

The GRI digital geologic maps reproduce essential 

elements of the source maps including the unit 

descriptions, legend, map notes, graphics, and report. 

The following references are source data for the GRI 

digital geologic data for Denali National Park and 

Preserve:

Clautice, K.H., Newberry, R.J., Blodgett, R.B., Bundtzen, 

T.K., Gage, B.G., Harris, E.E., Liss, S.A. Miller, M.L., 

Reifenstuhl, R.R., and D.S. Pinney. 2001. Bedrock 

Geologic Map of the Chulitna Region, Southcentral 

Alaska. Scale 1:63,360. Report of Investigations 

RI2001-1A. Fairbanks, Alaska: State of Alaska 

Department of Natural Resources, Division of 

Geological and Geophysical Surveys.

Pinney, D.S. 2001. Surficial-Geologic Map of the Chulitna 

Mining District, Southcentral Alaska. Scale 1:63,360. 

Report of Investigations RI2001-1C. Fairbanks, Alaska: 

State of Alaska Department of Natural Resources, 

Division of Geological and Geophysical Surveys.

Pinney, D.S. 2001. Engineering-Geologic Map of the 

Chulitna Mining District, Southcentral Alaska. Scale 

1:63,360. Report of Investigations RI2001-1D. 

Fairbanks, Alaska: State of Alaska Department of 

Natural Resources, Division of Geological and 

Geophysical Surveys.

Wahrhaftig, Clyde. 1970. Geologic Map of the Healy D-4 

Quadrangle, Alaska. Scale 1:63,360. Geological 

Quadrangle Map GQ-806. Reston, VA: U.S. Geological 

Survey.

Wahrhaftig, Clyde. 1970. Geologic Map of the Healy D-5 

Quadrangle, Alaska. Scale 1:63,360. Geological 

Quadrangle Map GQ-807. Reston, VA: U.S. Geological 

Survey.

Wahrhaftig, Clyde. 1952. Geologic Map of Part of Healy 

C-4 Quadrangle, Alaska, Showing Pleistocene Deposits 

along the Nenana River. Scale 1:63,360. Professional 

Paper 2933. Reston, VA: U.S. Geological Survey.

Wahrhaftig, Clyde, and R.E. Fellows. 1952. Geologic Map 

of Part of Healy B-4 Quadrangle, Alaska, Showing 

Quaternary Deposits along the Nenana River. Scale 

1:63,360. Professional Paper 2934. Reston, VA: U.S. 

Geological Survey.
32 NPS Geologic Resources Division

Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., 

Bundtzen, T.K., and P.J. Haeussler, compilers. 1998. 

Geologic Map of Central (Interior), Alaska. Open-File 

Report OF 98-133. Reston, VA: U.S. Geological 

Survey.

The Map Unit Properties Table is divided into units that 

are present on larger scale maps (1:63,360; Chulitna 

region and Healy quadrangle maps) and those on the 

smaller scale map (1:250,000; Wilson et al. 1998 

compilation). The overview of digital geologic data 

(Appendix A) illustrates the small scale digital geologic 

data.

The GRI team implements a geology-GIS data model 

that standardizes map deliverables. This data model 

dictates GIS data structure including data layer 

architecture, feature attribution, and data relationships 

within ESRI ArcGIS software, and increases the overall 

utility of the data. GRI digital geologic map products 

include data in ESRI personal geodatabase and shapefile 

GIS formats, layer files with feature symbology, Federal 

Geographic Data Committee (FGDC)-compliant 

metadata, a Windows help file that contains all of the 

ancillary map information and graphics, and an ESRI 

ArcMap map document file that easily displays the map 

and connects the help file directly to the map document.

GRI digital geologic data are included on the attached 

CD and are available through the NPS Data Store 

(http://science.nature.nps.gov/nrdata/). Data will be 

available on the Natural Resource Information Portal 

when the portal goes online. As of August 2010, access is 

limited to NPS computers at http://nrinfo/Home.mvc.

Geologic Units of Denali National Park and Preserve

The rock units at Denali National Park and Preserve 

represent a vast span of geologic history. Because 

juxtaposed slices of accreted terranes characterize the 

geology in the Denali area, different rock types and ages 

form a puzzle of units on the landscape. The oldest rocks 

are metamorphosed Proterozoic basement rocks of the 

Nixon Fork sequence. These rocks contain zircon grains 

dated using uranium-lead isotopes (U-Pb) at 1,250 ± 50 

million years ago (Wilson et al. 1998). 

Most of the oldest rocks are part of the Yukon-Tanana 

Terrane, north of the Hines Creek fault (Gilbert 1979). 

These Late Precambrian to Early Paleozoic age rocks 

include metamorphosed pelitic and quartzose schists, 

amphibolite, gritty quartzite, marble, greenstone, 

phyllitic layers, and other metasedimentary and 

metaigneous rocks (Gilbert 1979; Wilson et al. 1998).

Ordovician rocks include dark chert, slate, argillite, and 

some greenstone, limestone, and dolostone. Devonian 

limestone, chert, and volcanic ash fall and lava flows 

record prolific life and volcanic activity in a marine 

basin–island arc setting. The Mississippian Moose Creek 

Member contains metamorphosed basalts and other 

volcanic rocks (Clautice et al. 2001).

Pennsylvanian and Permian limestones, mudstones, and 

greywacke sandstones record marine deposition in open 

basins. During the Mesozoic, granitic magma formed 

irregular intrusive bodies throughout the region, and 

mixed schists and amphibolite of the MacLaren 

Metamorphic Belt underwent several grades of 

metamorphism and folding (Wilson et al. 1998; Clautice 

et al. 2001). Triassic greenstones, basalts flows, 

graywackes, tuffs, and limestones possibly record 

hotspot activity in a marine basin. These rocks record 

paleolatitudes of 5 degrees near the equator (Clautice et 

al. 2001).

Jurassic and Cretaceous age rocks in the map area range 

from calcareous sandstone and argillite to conglomerates 

and limestones to vast suites of volcanic rocks of varying 

compositions, granite-diabase-rhyolite intrusions, mixed 

mélanges, and mafic igneous rocks (Wilson et al. 1998; 

Clautice et al. 2001). The vast variety of rocks of this age

attests to the tectonic history of the area. Many terranes 

were accreted with accompanying metamorphism, 

sedimentation, deformation, and volcanism during this 

time. 

Tectonic processes continued throughout the Tertiary 

and Quaternary Periods. Tertiary age units include 

rhyolite, andesite, granite, granodiorite, tonalite, and 

monzonite intrusive igneous rocks. These units are 

mixed with fluviatile sedimentary rocks, carbonaceous 

mudstone, siltstone, conglomeratic sandstone, olivine 

basalts, volcanics, and coal beds. Named Tertiary units 

include the Suntrana, Sanctuary, Healy Creek, Lignite 

Creek, Grubstake, and Cantwell Formations (Wahrhaftig

1970; Wilson et al. 1998).

The intrusive igneous bodies and plutons of hornblende 

dacite of Jumbo Dome have a relatively young 

potassium-argon (K-Ar) radiometric date of 2.72 ± 0.25 

million years ago (Wahrhaftig 1970). Atop this and other 

map units at Denali National Park and Preserve are vast 

and varied unconsolidated Quaternary age rocks of 

fluvial, colluvial, glacial, lacustrine, and aeolian origin. 

Older deposits include: rubble from Jumbo Dome;

gravels of Late Wisconsin glaciations; high terraces and 

pediment gravels; rock glaciers; older alluvium (sands, 

gravels, and silts); glacial erratics up to 2 m (6 ft) in 

diameter; some varved clays deposited in glacial lakes;

and terminal glacial moraine deposits (Wahrhaftig 1970; 

Clautice et al. 2001).

Younger units include Holocene tills, alluvium, outwash, 

the end moraine of the Carlo Readvance, extensive 

terraces above current stream valleys, windblown loess, 

talus and landslide deposits, and other colluvium. The 

youngest units at Denali include: boggy peat; stream 

alluvium; alluvial fans; outwash gravel and drift; some 

localized debris flows; varved clay and silt in recently 

dried-up lakes and ponds; swamp deposits; and floodplain deposits of sand, gravel, silt, mud, and scattered 

boulders (Wahrhaftig 1970; Clautice et al. 2001).
DENA Geologic Resources Inventory Report 33

Map Unit Properties Table: Denali National Park and Preserve (Large Scale [1:63,360] Map Units)

Age Unit Name

(Symbol) Features and Description Erosion Resistance

Suitability for 

Infrastructure Hazards PaleontologicalResources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

QUATERNARY

Peat

(Qp)

Artificial Fill and 

Excavation Sites

(Qh)

Undifferentiated Stream 

Alluvium

(Qa)

Stream Gravel

(Qsg)

Alluvial Fan Deposits 

(Qaf)

Outwash Gravel

(Qo)

Floodplain Alluvium 

(Qfp)

Qp contains dense, dark organic material, 

often found in boggy areas. Qh is composed 

of pebbles, cobbles, gravels, sand, and silt 

beneath roads and former gravel pits. Unit 

is well- to poorly sorted. Qa includes stream 

gravel, pebbles, cobbles, sand, and silt, with 

some boulders in well-stratified and 

moderately sorted channels, floodplains, 

and low terraces. Stream gravel (Qsg) is 

present in active streambeds. Qaf contains 

fan-shaped, heterogeneous strata of gravels, 

sands, silts, and boulders. Some debris flow 

deposits present locally. Qo contains gravel 

in layers fluvially deposited and well sorted. 

Qfp consists of elongate deposits of fluvial 

sand, gravel, and silt with scattered 

boulders. Unit is well- to moderately sorted, 

well-stratified, often mantled by thin siltclay layers. Some terrace deposits locally.

Low to very 

low.

Hummocky 

topography and 

scarps make Qfp

unstable if water 

saturated.

Units are prone to 

rapid erosion 

during flood 

events, slope 

failure if 

undercut, and 

slope creep, 

especially when 

water saturated.

Modern remains 

possible; pollen, plant 

macrofossils, insects.

May contain 

campsites, 

settlements,

and other 

artifacts. 

Historic 

mining?

Gravel, sand, silt, 

and clay. Placer 

deposits?

Congeliturbate 

deposited along 

Alaska Railroad 

between Lagoon 

and Carlo. 

None.

Qa supports 

extensive 

willow-alder 

thickets and 

other riparian 

habitats. Qfp

supports bog 

environments 

and riparian 

zones.

Units are 

suitable for 

most 

recreation. 

Avoid 

development 

of use-areas 

on riparian 

zones and 

undercut 

floodplain 

areas.

Units record 

most recent 

geologic activity 

in the area.

Undifferentiated 

Colluvium

(Qc)

Landslide Deposits 

(Qcl)

Talus and Rubble 

Deposits

(Qct)

Rock Glacier Deposits 

(Qrg)

Units contain irregular masses, aprons, 

tongues, and fans of angular rock fragments, 

sand, and gravel. May include drift and 

outwash. Surface expression often mirrors 

underlying rock structure. Medium to 

thickly bedded layers of lobed and terraced 

deposits. Rubble includes blocks up to 15 m 

in diameter. Qct contains mostly large 

blocks, with little- to no matrix material 

such as silt and sand. Qrg includes mixtures 

of blocks, ice, gravel, sand, and silt in 

tongue- and fan-shaped masses with very 

irregular surfaces.

Low.

Units are often 

found at the base 

of unstable 

slopes. Surfaces 

are usually steep 

and irregular with 

large spaces 

between blocks;

unsuitable for 

most forms of 

infrastructure.

Units are 

associated with 

mass movement 

processes,

including sliding, 

rolling frost 

creep, 

gelifluction, and 

flowing. Open 

work rubble 

surfaces are 

dangerous. 

Extensive ground 

cracks present 

locally.

Modern remains 

possible; pollen, plant 

macrofossils, insects.

None 

documented.

Sand, gravel, and 

boulders. None.

Lichen 

communities 

help determine 

relative ages of 

deposits. Units 

may support 

large trees if 

old enough.

Avoid for 

recreational 

use;

dangerous 

surfaces 

associated 

with units.

Units record 

recent slope 

processes in the 

area; vegetation 

patterns can 

date slide 

activity.

Swamp Deposits

(Qs)

Outwash Alluvium 

(Qao)

Colluvial-Alluvial Valley 

Fill, Fan, and Apron 

Deposits

(Qcf)

Terrace Gravel

(Qtg)

Abandoned Channel 

Deposits

(Qac)

Terrace Alluvium

(Qat)

Qs includes water/ice-saturated layered 

peat, and organic silt and sand of variable 

thickness. Qao and Qcf contain elongate, 

apron, tongue- and fan-shaped 

heterogeneous mixtures of boulder, 

pebbles, and cobbles with matrices 

composed of sand and silt in thick beds. 

Terrace and channel gravels (Qtg, Qac, 

Qat) are typically more rounded than 

angular cobbles, and are well sorted with 

local crossbeds and smooth surfaces.

Low.

Slopes and scarps 

associated with 

Qao and Qtg may 

be too unstable 

for heavy 

infrastructure. 

High permeability 

of these units are 

probably not 

suitable for wastewater treatment 

facilities.

Qcf is associated 

with debris flow 

mechanisms, and 

may include 

avalanche 

deposits.

Peat, plant fragments.

May contain 

campsites, 

settlements 

and other 

artifacts. 

Historic 

mining?

Sand, silt, and gravel. 

Placer deposits? None.

Units contain 

bogs, wetlands, 

and riparian 

environments.

Fine for most 

light 

recreation. 

Avoid 

development 

of use-areas 

on riparian 

zones and 

undercut 

floodplain 

areas.

Units record 

Quaternary 

fluvial activity in 

the area.
Map Unit Properties Table: Denali National Park and Preserve (Large Scale [1:63,360] Map Units)

DENA Geologic Resources Inventory Report 34

Age Unit Name

(Symbol) Features and Description Erosion Resistance

Suitability for 

Infrastructure Hazards PaleontologicalResources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

QUATERNARY

Till of Latest Holocene 

Age

(Qt2)

Till of Early to Middle 

Holocene Age

(Qt1)

Alluvium

(Qca)

Outwash Gravel

(Qco)

Sand

(Qcls)

End Moraine of the 

Carlo Readvance

(Qcm)

Units contain heterogeneous mixtures of 

pebbles, cobbles, sand, silt, and clay with 

scant boulders. Some ice may exist locally. 

Surfaces of till units are often hummocky 

with morainal topography. Qcls is 

deposited in a dammed lake behind the end 

of the Carlo Readvance.

Low to very 

low for 

sand-rich 

units

Heterogeneous 

nature of these 

unconsolidated 

units renders 

them unstable on 

slopes and too 

permeable for 

waste treatment.

Units are 

associated with 

slumping and 

mass movements;

hummocky 

topography is 

difficult to 

traverse.

Modern remains 

possible; pollen, plant 

macrofossils, insects.

May contain 

campsites, 

settlements,

and other 

artifacts.

Sand, silt, and gravel. 

Placer deposits? None.

Qt1 supports 

some soil 

development 

with lichens, 

mosses, and 

tundra herbs.

Units are fine 

for most light 

recreation. 

Avoid areas of 

very large 

rubble.

Unit records 

latest glacial 

activity in the 

area.

Alluvium and Pediment 

Gravel

(Qra)

Younger Alluvium and 

Pediment Gravel

(Qra2)

Older Alluvium and 

Pediment Gravel

(Qra1)

Varved Clay

(Qrlc)

Outwash Gravel

(Qro)

Rubble of Jumbo Dome

(Qrr)

Glacial Moraine 

Deposits

(Qrm)

Units contain mixed pebbles, gravels, and 

sands in smooth surfaced lobes and 

pediments. Qrlc was deposited in glacial 

lakes prior to the Carlo Readvance. Qrr is

composed of inactive (non-flowing) rock 

glaciers and solifluction sheets cored with 

ice. Qrm contains till with extremely 

heterogeneous mixtures of boulders, 

pebbles, and clay with some outwash 

deposits interlayered.

Low.

Heterogeneous 

nature of these 

unconsolidated 

units renders 

them unstable,

especially if 

water-saturated 

and/or present on 

undercut slopes.

Units are 

susceptible to 

frost creep, 

erosion, and mass 

wasting. Open 

work rubble 

surfaces are 

dangerous. 

Extensive ground 

cracks present 

locally.

Modern remains 

possible; pollen, plant 

macrofossils, insects.

May contain 

campsites, 

settlements,

and other 

artifacts.

Gravel and sand; 

igneous stone 

rubble.

None.

Unit supports 

valley floor 

vegetation, 

some riparian 

zones.

Units are fine 

for most light 

recreation. 

Avoid areas of 

very large 

rubble.

Varved clays 

record seasonal 

cycles of 

deposition 

associated with 

glacial lakes.

Varved Clay and Silt

(Qhlc)

Alluvium and Pediment 

Gravel

(Qha)

Outwash Gravel

(Qho)

Rubble of Jumbo Dome

(Qhr)

Morainal Deposits

(Qhm)

Glacial Erratics

(Qhe)

Lacustrine Silt and Clay 

(Qhl)

Units contain layered clays, gravels, pebbles, 

and sands, as well as large boulders floated 

on ice rafts across glacial lakes (including 

Glacial Lake Moody). Morainal deposits 

include cobbles and boulders with a gravelsand-silt matrix. 

Low to very 

low for 

clay-rich 

units.

Heterogeneous 

nature of these 

unconsolidated 

units renders 

them unstable,

especially if 

water-saturated 

and/or present on 

undercut slopes.

Boulders and 

other large rocks 

may weather out 

of finer-grained 

matrix and pose 

rockfall hazard;

units are 

susceptible to 

erosion and 

gullying.

Plant fragments. None 

documented.

Clay, gravel, sand, 

and boulders. None. None documented.

Avoid areas of 

very large 

rubble for 

recreational 

opportunity 

development.

Units record 

glacial activity. 

Varved clays 

record seasonal 

cycles of 

deposition 

associated with 

glacial lakes.
Map Unit Properties Table: Denali National Park and Preserve (Large Scale [1:63,360] Map Units)

DENA Geologic Resources Inventory Report 35

Age Unit Name

(Symbol) Features and Description Erosion Resistance

Suitability for 

Infrastructure Hazards PaleontologicalResources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

QUATERNARY

Delta Gravel

(Qhd)

Drift of Late Wisconsin 

Age

(Qd)

Outwash Gravel

(Qdo)

Rubble of Jumbo Dome

(Qdr)

Morainal Deposits

(Qdm)

Lacustrine Silt and Clay

(Qdl)

Qhd is gravel contained in tongue- to lobeshaped layered deposits. Qd is composed of 

blanket deposits of heterogeneous pebble, 

gravel, cobble, sand, silt, and clay 

interlayers. Some large (2-m) boulders 

present locally. Sorting and bedding 

depends on degree of reworking by fluvial 

processes. Eskers present locally. Loess silt 

often blankets these units up to 1 m thick. 

Other units (Qdo, Qdr, Qdm, Qdl) range 

from scattered rubble, to layered 

heterogeneous lobes, to well-bedded silts 

and clays from lake deposits.

Low.

Eskers and 

diamictons may 

form steep slopes 

that would be 

unstable for 

infrastructure.

Scarps and slopes 

associated with 

these units are 

prone to mass 

movement and 

slope failures.

Modern remains 

possible; pollen, plant 

macrofossils, insects.

May contain 

campsites, 

settlements,

and other 

artifacts.

Gravel, sand, and

silt. None.

Units support 

vegetation that 

prefers strong 

drainage.

Avoid areas of 

very large 

rubble for 

recreational 

opportunity 

development.

Clay-rich 

diamictons and 

eskers showcase 

glacial 

landforms.

Glacial Erratics

(Qde)

Alluvium and Pediment 

Gravel

(Qba)

Outwash Gravel

(Qbo)

Glacial Erratics

(Qbe)

Colluvium

(Qpc)

Terrace and Pediment 

Gravel

(Qtp)

Dune Sand

(Qsd)

Rubble, Possibly Rock 

Glacier Origin

(Qrb)

Units contain large, scant boulders dropped 

from drifting glacial ice, as well as angular 

slope deposits in lobe- to fan shapes. 

Gravels and sands are better sorted than

heterogeneous rubble and boulders, 

possibly associated with an ice-cored rock 

glacier.

Low.

Colluvial units are 

often found at the 

base of unstable 

slopes. Surfaces 

are usually steep 

and irregular with 

large spaces 

between blocks.

Units are 

susceptible to 

frost creep, 

erosion, and mass 

wasting. Open 

work rubble 

surfaces are 

dangerous.

Modern remains 

possible; pollen, plant 

macrofossils, insects.

None 

documented.

Gravel, sand, and 

boulders. None. None 

documented.

Avoid areas of 

very large 

rubble for 

recreational 

opportunity 

development.

Glacial erratics 

are an 

interesting 

interpretive 

topic, and 

contain clues to 

glacial 

provenance.

QUATERNARY -

TERTIARY

Hornblende Dacite of 

Jumbo Dome

(QThj)

Unit contains hornblende-rich basaltic 

igneous intrusives. High.

Suitable for most 

forms of 

infrastructure

unless highly 

fractured and/or 

altered.

Unit associated 

with sheet-like 

exfoliation, which 

may lead to 

rockfall hazards.

None. None 

documented.

Hornblende 

phenocrysts. None.

Unit may alter 

to form 

calcium-, 

aluminum-, 

and 

magnesiumrich soils.

Unit is fine 

for most 

forms of 

recreation;

may attract 

climbers.

Isotopicallydetermined date 

on this unit of 

2.72 ± 0.25 

million years.

TERTIARY AND

OLDER

Thinly Covered 

Bedrock

(Ttcb)

Undifferentiated bedrock of various ages 

overlain by thin layers of unspecified 

surficial deposits.

Variable, depending on properties of underlying 

bedrock and surficial deposits. Unknown. Resources from bedrock units may be present.

Variable, depending on 

properties of underlying 

bedrock and surficial deposits.

Indicates where 

bedrock is 

located near the 

surface.
Map Unit Properties Table: Denali National Park and Preserve (Large Scale [1:63,360] Map Units)

DENA Geologic Resources Inventory Report 36

Age Unit Name

(Symbol) Features and Description Erosion Resistance

Suitability for 

Infrastructure Hazards PaleontologicalResources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

TERTIAR

Y

Nenana Gravel

(Tn)

Coal Bearing Group, 

Undivided

(Tcu)

Lignite Creek 

Formation

(Tlc)

Gravel and Sand

(Ts)

Grubstake and Lignite 

Creek Formations, 

Undivided

(Tgl)

Tn contains poorly consolidated layers of 

buff to reddish-brown pebble and boulder 

conglomerate with coarse sandstone, 

mudflow, and claystone interbeds. Some 

lignite present locally. Tlc contains 

crossbedded arkosic sandstone with pebble 

conglomeratic lenses and clay interbeds. 

Unit is mostly buff colored. Ts contains 

orangish- to buff colored sandy pebble, 

cobble, and gravel conglomeratic beds. Unit 

is typically well sorted and massively 

bedded with horizontal layering and 

crossbeds. Sands occur as broad lenses with 

total thickness ranges from 6 to 45 m. Tgl

contains greenish-gray siltstone and 

claystone with some interbedded pebbly 

arkosic sandstone and silt and clay layers.

Moderately 

low.

Ts is exposed as 

cliffs in streamincised areas, and 

may prove 

unstable on 

slopes. Units are 

permeable, but 

may be utilizable 

for waste water 

treatment. Avoid 

poorly 

consolidated 

areas for 

infrastructure.

Ts is prone to 

gullying and cliff 

formation, which 

may pose rockfall 

and mass 

movement 

hazards.

Pollen.

Chert pebbles 

may have 

provided tool 

material.

Lignite, sand, gravel, 

clay, and 

subbituminous coal.

None.

Units support 

wide range of 

habitats.

Units are fine 

for most 

recreation 

unless highly 

weathered,

rendering 

them unstable 

for trail base.

Chert, argillite, 

graywacke, 

volcanic rocks, 

Felsic to 

intermediate 

intrusive rocks, 

and Cantwell 

conglomeratic 

clasts indicate 

source area.

Suntrana Formation

(Tsn)

Sanctuary Formation

(Tsc)

Healy Creek Formation

(Thc)

Coal Bearing Sandstone

(Tcs)

Tsn contains crossbedded pebbly 

sandstone, poorly consolidated and 

interbedded with silty claystone and some 

coal lenses. Appears white on weathered

surfaces. Tsc is poorly consolidated and 

weathers brown- to gray with abundant 

banded (varved?) shale. Thc contains clayrich quartz and micaceous sandstone, some 

quartz-chert conglomerate, claystone, and 

coal interbeds. Unit is poorly consolidated. 

Tcs is pebbly sandstone and conglomerate 

with lignite, silty claystone, and 

carbonaceous claystone interbeds. 

Moderately 

low to low 

where 

consolidation is 

poor.

Most units are 

poorly 

consolidated,

which may render 

them unsuitable 

for heavy 

infrastructure.

Tsc is extremely 

susceptible to 

landslides and 

slope creep.

Potential plant fossils 

associated with coal 

beds.

Chert pebbles 

may have 

provided tool 

material.

Subbituminous coal 

lenses, 

conglomerate, sand, 

gravel, clay, and silt. 

Lignite 3 to 6 m 

thick are correlative 

with nearby Dunkle 

coal mine deposits.

Not enough 

carbonate 

present.

Units support 

wide range of 

habitats.

Poor 

consolidation 

of units may 

render them 

too unstable 

for heavy 

recreational 

use.

Contains 

Oligocene coal 

units.

Rhyolite

(Tr)

Latite

(Tl)

Andesite Plugs, 

Hypabyssal Intrusions, 

Plug-Domes and 

Associated Flows and 

Breccia

(Ti)

Vent Breccia

(Tvb)

Biotite Granite

(Tg)

Basaltic Composition 

Dikes

(Tb)

Diabase Sills

(Tdb)

Tr contains assorted felsic volcanic 

extrusive layers in widespread deposits. 

Units contain intermediate composition (Si 

content) igneous intrusive, as well as 

basaltic composition flows and intrusive 

dikes. Volcanic breccia indicating forceful 

eruptions present locally. Tg is fine-grained 

in dikes to coarser-grained irregular 

intrusions with alkali feldspar, biotite, 

ilmenite, and quartz. Unit is commonly 

intruded by basaltic or lamprophyric dikes. 

Tb are narrow (0.3- to 2-m) basaltic dikes 

cutting older granites with abundant 

phenocrysts. Tdb are intrusive into the 

Cantwell Formation (Tc)

Moderately 

high to 

high.

Units may contain 

radon emitting 

materials. Avoid 

for basements and 

foundations.

Blockfall and 

exfoliation of 

large sheets of 

rock associated 

with several units.

None.

Phenocrysts 

may have 

provided 

trade 

material.

Geodes; Tb contains 

clinopyroxene 

phenocrysts. 

Tourmaline, 

zinnwaldite, topaz, 

zircon, apatite, and 

fluorite.

None.

Unit may 

weather to 

enriched soils.

Phenocrysts 

and other 

sharp 

fragments

associated 

with 

unweathered 

portions of 

these units 

may prove 

undesirable 

for trail base.

Tg is dated by 

argon isotopes

at 46 to 55 

million years

(composition 

indicates felsic 

magma source). 

Tb is dated by 

argon isotopes 

at 52 million 

years, with 

magnetic

signature 

indicating early 

Tertiary 

paleolatitude?

Cantwell Formation

(Tc)

Cantwell Formation, 

Tuff Bed

(Tct)

Unit contains buff- to light gray sandstone 

and pebble conglomerate with some darker 

layers, siltstone, and shale interbedded. 

Several volcanic tuff layers are present 

locally (Tct). Unit is moderately- to well 

consolidated and provides bedrock source 

material for colluvial deposits. 

Moderate.

Units are fine for 

most 

infrastructure

unless highly 

heterogeneous 

and/or fractured

Unit is associated 

with slope 

processes,

including 

landslides.

None documented in 

large scale source 

maps. See Kcs on 

small scale data table, 

below.

Abundant 

chert pebbles 

may have 

provided tool 

material.

Building stone.

Not enough 

carbonate 

present.

Units support 

slope 

preferring 

vegetation.

Units are fine 

for most 

recreation.

Source rocks 

well 

documented 

from volcanic 

rocks to the 

south.
Map Unit Properties Table: Denali National Park and Preserve (Large Scale [1:63,360] Map Units)

DENA Geologic Resources Inventory Report 37

Age Unit Name

(Symbol) Features and Description Erosion Resistance

Suitability for 

Infrastructure Hazards PaleontologicalResources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

MESOZOIC

Granite

(MZgr)

Undifferentiated granite found in irregular 

bodies with no clear crosscutting 

relationships to place in an age bracket. 

Granite contains quartz, feldspar, biotite, 

and hornblende with various accessory 

minerals. 

High.

Unit may alter 

into materials 

known to cause 

radon problems.

Sheet-like 

exfoliation of unit 

may pose 

blockfall hazard.

None.

Phenocrysts 

may have 

been used for 

trade 

materials.

Accessory minerals 

and phenocrysts. 

Building material.

None. None 

documented.

Fine for most 

recreation 

unless highly 

fractured 

and/or 

altered.

Unit is 

widespread.

CRETACEOUS

Hornblende Biotite 

Granite

(Kg)

Intermediate 

Composition Plutonic 

Rocks

(Km)

Rhyolite Intrusive into 

the Cantwell Formation

(Kr)

Diabase Intrusive into 

the Cantwell Formation 

and Basalt Intrusive into 

the Birch Creek Schist

(Kdb)

Andesite Intrusive into 

the Cantwell Formation

(Ka)

Kg is present in narrow dikes and small 

stocks with granitic porphyry textures of 

monzogranite to syenogranite 

compositions. Grain size ranges from less 

than 2 mm to 2 cm. Unit grades into Km,

which contains northeast/southwestoriented stocks and dikes with textures 

ranging from fine-grained porphyritic to 

medium grained. Unit is generally quartz 

poor with monzodiorite, monzonite, and 

diorite compositions, and alters to chlorite, 

carbonate, sericite, albite, epidote, and 

pyrite. Intrusions into Tc indicate a younger 

age for the unit than previously thought, 

additional investigation is needed to 

resolve. Compositions range from felsic to 

intermediate to mafic (basaltic), and most 

are present as narrow dikes.

Moderately 

high to high 

depending 

on degree 

of 

weathering.

Units may contain 

radon producing 

materials. Avoid 

for basements;

avoid heavily 

fractured areas.

Units are 

susceptible to 

rockfall hazards 

on slopes.

None.

Pyrite may 

have been 

used for 

starting fires.

Hornblende 

phenocrysts, zircon, 

apatite, ilmenite, 

muscovite, and 

rutile. Hydrothermal 

alteration minerals 

include chlorite, 

calcite, and white 

mica.

None.

Units may give 

rise to fertile 

soils.

Suitable for 

most 

recreation;

may be 

attractive to 

climbers.

Kg has

minimum age of 

61.4 to 71 

million years 

(determined by 

argon isotopes)

origin is likely 

volcanic island 

arc-related. Km

is dated at 67 to 

71 million years. 

Associated with 

gold-related 

Kuskokwim 

Mountains

magmatic belt 

event.

CRETACEOUS -

DEVONIAN

Undifferentiated 

Sedimentary Rocks of 

Devonian to Cretaceous 

Age

(KDu)

Heterogeneous mix of sedimentary rocks,

including sandstone, claystone, shale, 

limestone, conglomerate, and tuff (volcanic 

ash fall).

Moderate;

variable 

among 

units.

Units are fine for 

most 

infrastructure

unless highly 

heterogeneous 

and/or fractured.

Heterogeneous 

layers of these 

units may be 

prone to mass 

wasting; shrinkand-swell clays 

may be present in 

volcanic ash units.

Various fossils, none 

specified.

None 

documented. Building stone.

Possible in 

limestonerich units.

Units support 

wide range of 

habitats.

Units are fine 

for most 

recreation.

Records eras of 

sedimentary 

deposition 

settings.

CRETACEOUS - JURASSIC

Calcareous Sandstone 

and Argillite, with 

Coquinoid Limestone

(KJs)

Argillite and Sandstone

(KJas)

Sandstone and Argillite

(KJsa)

Conglomerate

(KJc)

Units are rich in gray, poorly sorted subangular to sub-rounded lithic sandstones 

mixed with argillite layers and coquinoids 

locally. Some of the sandstone is calcareous

(e.g., KJs). In outcrop, units weather to an 

orangish-brown color. Bedding is 

predominantly thin, parallel, and sheet-like. 

Some isoclinal folding is present, leaving 

cleavage in the argillaceous lithologies. KJas

contains dark gray and black argillite and 

sandstone. Unit weathers orangish-brown 

with prominent cleavage parallel to 

bedding. Some white quartz veining is 

present locally. Argillite accounts for a 

smaller percentage in the lower units (e.g., 

KJsa), with massive sandstone beds 

becoming more prominent. Lowermost unit 

(KJc) is conglomerate with sandstone 

matrix. Clasts are mostly quartz, chert, and 

argillite.

Moderate 

to 

moderately 

high,

depending 

on degree 

of 

weathering.

Prominent 

cleavage, thin 

bedding, 

heterogeneous 

composition, and 

minor dissolution 

in these units may 

render them weak 

on slopes for 

heavy 

infrastructure.

Slaty layers are 

prone to slides,

and 

conglomeratic 

blocks may pose 

rockfall hazard if 

underlain by 

weaker claystone 

units.

Coquinoid beds with 

Buchia sublaevis shells 

in 2-m-thick layer 

(Lower Cretaceous 

age).

Chert 

nodules may 

have 

provided tool 

material;

pyrite may 

have been 

used to start 

fires.

KJas contains white 

quartz veins, 

sulfides, crystal filled 

vugs, and fractures;

KJsa contains rare 

tripolitic chert and 

white mica. Building 

stones.

Minor 

carbonate 

dissolution 

is possible 

in 

coquinoid 

layers.

Units support 

wide range of 

habitats.

Units are fine 

for most 

recreation.

Unit records 

orogenic 

provenance of 

sediments in a 

shallow 

(<125 m) shelf

environment.
Map Unit Properties Table: Denali National Park and Preserve (Large Scale [1:63,360] Map Units)

DENA Geologic Resources Inventory Report 38

Age Unit Name

(Symbol) Features and Description Erosion Resistance

Suitability for 

Infrastructure Hazards PaleontologicalResources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

JURASSIC

Argillite, Cherty 

Argillite, and Minor 

Cherty Tuff and Basaltic 

Tuff

(Jac)

Calcareous Sandstone, 

Sandy Limestone, and 

Argillite

(Js)

Jac is mostly deformed and slightly 

metamorphosed argillite with some minor 

chert-rich layers and tuff layers. Chert is 

light gray to black. Sheared areas are 

phyllitic. Js is thin to medium bedded, 

calcareous sandstone, with minor interbeds 

of limestone and argillite. 

Moderate.

Suitable for most 

infrastructure

unless highly 

altered and/or 

fractured. Avoid 

phosphatic areas.

Altered tuff layers

may contain 

shrink-and-swell 

clays.

Radiolaria, 

ammonites, other 

Jurassic fossils.

Chert 

nodules may 

have 

provided tool 

material.

Phyllite. Phosphates 

in Js.

Not enough 

carbonate 

present.

Unit may 

produce soils 

rich in 

phosphorus.

Unit is fine 

for most light 

recreation. 

Avoid finely 

bedded areas 

for stability.

Radiolarians 

restrict Jac to 

Late Jurassic 

age. Ammonites

in Js are Early 

Jurassic age 

(Sinemurian).

TRIASSIC

Redbed Sandstone and 

Conglomerate

(TRrb)

Brown Sandstone and 

Argillite

(TRs)

Limestone

(TRul)

TRrb contains calcareous sandstone, 

siltstone, and conglomerate layers that

weather to reddish-maroon colors. 

Hematite lends color to this unit; clasts are 

mostly well-rounded quartz, basalt, and 

volcaniclastics. TRs contains thick-bedded 

yellowish-brown sandstone, argillite, and 

minor calcareous sandstone and limestone. 

TRul contains thick-bedded limestone, 

with shale, siltstone, and mudstone 

interbeds. Lithologies include 300 m of 

mudstone, wackestone, packstone, and 

rudstone. 

Moderate 

to 

moderately 

high.

Units may contain 

shrink-and-swell 

clays;

heterogeneous 

layering may be 

unstable on 

slopes. Fine for 

most 

infrastructure

unless highly 

fractured.

If massive layers 

are underlain by 

weaker layers 

locally, rockfall 

hazard may result.

TRs contains 

Heterastridium (4-cm 

diameter), snails, and 

bivalves. TRul

contains scleractinian 

thicket reefs, 

brachiopods, corals, 

bivalves, and 

gastropods.

Caves 

possible in 

this unit; may 

have been 

settlement 

areas.

Building stones.

Karst 

features 

such as 

dissolution 

holes and 

caves are

possible for 

lower unit.

Units weather 

to calciumand iron-rich 

soils locally.

Fine for most 

recreation; if 

caves are 

present, may 

attract 

speleologists.

Fossils record 

Late Triassic 

age; near-shore 

environment 

grading 

offshore in 

lower units.

Basalt, Basaltic Tuff, and 

Limestone

(TRlb)

Basaltic Dikes and Sills

(TRb)

Intrusive Greenstone

(TRgn)

Red Colored Tuff, 

Andesite, Basalt, 

Graywacke, 

Conglomerate

(TRvs)

Limestone

(TRll)

TRlb is a massive stack of basalt and basaltic 

tuff layers, 50 to 100 m thick, with finegrained gray limestone interbeds. Basalt is 

tholeiitic and strongly magnetic. Alteration 

minerals include chlorite, albite, carbonate, 

and hematite. Unit is commonly intruded by 

fine-grained equigranular to porphyritic 

basaltic dikes and sills (TRb). TRgn is an 

intrusive greenstone unit. TRvs contains a 

red-weathered stack of volcanic and 

volcaniclastics, including lithic tuff, 

conglomerate, graywacke, tuffaceous 

siltstone, and mudstone with some basalt 

and dacite flows. Calcareous cements and 

clasts are present. Lithic fragments include 

quartz, felsic volcanics, and plutonic and 

metamorphic rocks. Unit was exposed to 

contact metamorphism near Cretaceous

plutons. TRll is thin-bedded, light gray to 

brown on weathered surfaces composed of 

carbonaceous mudstone and packstone 

present in fault-bounded slivers.

Moderate.

Calcareous layers 

and cements may 

dissolve,

rendering unit 

unstable in some 

areas; units may 

contain shrinkand-swell clays. 

Avoid for heavy 

infrastructure.

If carbonate 

layers and 

cements are 

dissolved, rockfall 

hazards exist;

heavily altered 

layers may fail 

when water 

saturated on 

slopes.

Limestone layers 

include colonial 

scleractinian corals,

megalodontid 

bivalves, and 

brachiopod 

Spondylospira 

lewesensis; TRll

contains at least 13 

species of ammonites.

None 

documented.

Chlorite, albite, 

clinopyroxene, and 

hornblende. Tintype mineralization;

gold, silver, 

beryllium, uranium, 

rubidium, boron, 

cobalt, and nickel

resources.

Dissolution 

possible for 

limestone 

interbeds.

Units weather 

to produce 

iron-, 

magnesium-, 

and aluminumrich soils.

Fine for most 

recreation 

unless heavily 

altered and/or 

dissolved 

locally; may 

interfere with 

compass 

readings

(TRb is 

strongly 

magnetic).

Basalts contain 

magnetite 

recording 

paleolatitudes 

of 5 degrees, 

possibly of 

hotspot origin 

correlative with 

Nikolai 

Greenstone 

flood basalts? 

TRb has argon 

isotope date of 

179 million 

years. TRvs

correlates with 

Tangle 

subterrane.

TRll contains 

fossils found in 

northern 

Washington.

PERMIAN

Limestone

(Pl)

Unit is approximately 100 m thick with a 

succession of limestone. Lower beds are 

medium- to thick-bedded limestone 

(packstone to grainstone). Upper unit 

contains light gray silicified mudstone, 

packstone, and grainstone. Unit weathers to 

orange-yellow-brown color.

Moderate.

Unit may be 

friable and too 

permeable for 

wastewater 

treatment 

infrastructure.

Dissolution may 

pose sinkhole 

hazard;

susceptible to 

rockfall if highly 

dissolved on 

slopes.

Horridonid 

brachiopods, 

bryozoans, 

pelmatozoan debris, 

solitary rugose corals, 

ostracodes, and 

trilobites.

Caves 

possible in 

this unit; may 

have been 

settlement 

areas.

None documented.

Karst 

features 

such as 

dissolution 

holes and 

caves are 

possible.

Unit weathers 

to basic 

calcium- and

magnesiumrich soils.

Avoid heavily 

dissolved 

areas for 

recreation;

any caves may 

attract 

speleologists.

Unit contains 

megafauna of 

“Arctic 

Permian” type.
Map Unit Properties Table: Denali National Park and Preserve (Large Scale [1:63,360] Map Units)

DENA Geologic Resources Inventory Report 39

Age Unit Name

(Symbol) Features and Description Erosion Resistance

Suitability for 

Infrastructure Hazards PaleontologicalResources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

PERMIAN -

PENNSYLVANIAN

Permian Mudstone and 

Graywacke

(PPNs)

Unit is at least 200 m thick with thinly 

bedded mudstone and graywacke. Lower 

beds are gray-green graywacke turbidites 

that weather to yellow-brown, composed of 

lithic sandstones with thin intervals of 

mudstones. Thin-bedded, medium to dark 

gray and yellow-brown mudstone and 

siltstone comprise upper beds.

Moderate.

Unit is relatively 

weak and 

unstable for most 

heavy 

infrastructure, 

especially if 

exposed on slope.

Unit is prone to 

mass wasting 

hazards, including 

slumping, slope 

creep, and 

possibly debris 

flows if 

unvegetated 

slopes are water 

saturated.

Trace fossils of 

ichnogenera 

Chondrites and 

Scalarituba; some 

brachiopods, bivalves, 

and bryozoans.

None 

documented. None documented.

Not enough 

carbonate 

present.

None 

documented.

Unstable on 

slopes. Avoid 

for most use.

Unit records 

transition from 

Pennsylvanian 

to Permian in 

the area with 

conformable 

contacts.

PALEOZOIC

Tuff

(PZt)

Argillite and Tuff

(PZst)

Chert, Argillite, and 

Graywacke

(PZs)

Rhyolite Schist

(PZr)

Greenstone and 

Metamorphosed Basic 

to Intermediate 

Agglomerate

(PZga)

Marble

(PZm)

Schist of Sedimentary 

Origin

(PZss)

PZt contains a mélange of dark gray-green 

andesitic to rhyodacitic composition ash 

and crystal tuff, subordinate argillite, and 

cherty argillite, siltstone, and graywacke, 

and minor volcanic flows. Bedding ranges 

from fine and flinty to more massive and 

crystalline. PZst contains similar 

assemblages with more siltstone and chert. 

PZs contains bedded chert, carbonaceous, 

fissile black argillite with yellow- and 

orange-weathering salts, basalt, cherty tuff, 

green volcaniclastic rock, siltstone, 

greywacke, and white quartz–pebble and 

black argillite conglomerate. PZr is 

metamorphosed silica-rich volcanic 

deposits. Units become less volcanic to 

more sedimentary, including 

metamorphosed limestone (marble) (PZm)

and other mixed, slightly metamorphosed 

schists (PZss).

Moderately 

high.

Heterogeneous 

nature of units 

may render them 

unstable on 

slopes. Some 

units may contain 

radon-emitting 

materials and 

shrink-and-swell 

clays if altered.

Unit is susceptible 

to slope 

processes,

including 

blockfall, 

landslides, 

slumping, and 

slope creep for 

finer grained 

units.

Radiolaria.

Massive chert 

deposits may 

have 

provided tool 

material.

Volcanic breccia, 

red argillite, and 

marble. Building 

material.

Some 

dissolution 

possible in 

limestone 

interbeds.

None 

documented.

Units fine for 

most 

recreation 

unless heavily 

altered.

Records 

basinwide 

volcanism and 

coincident 

sedimentary 

deposition as 

part of “West 

Fork terrane.”

MISSISSIPPIAN

Moose Creek Member

(Mtmg)

Unit is composed of slightly 

metamorphosed basaltic to intermediate 

composition volcanic rocks. Green 

metavolcanic schists dominate this unit.

Moderately 

high.

Unit is fine for 

most 

infrastructure

unless heavily 

altered and/or 

fractured.

Rockfall hazard 

when unit is 

exposed on slope.

None. None 

documented.

Chlorite, epidote, 

and green micas. None.

Unit weathers 

to iron- and

magnesiumrich soils.

Units fine for 

most 

recreation 

unless heavily 

altered.

Unit records 

Mississippianage volcanism.

DEVONIAN

Andesitic Tuff and 

Flows

(Dv)

Red and Brown Chert

(Dc)

Limestone

(Dl)

Dv contains green-weathering, pyroxene 

andesite tuff and flows, with compositions 

ranging from island-arc tholeiitic basalt 

(locally pillowed) to dacitic tuff. The lower 

contact is interlayered with massive red and 

brown ferruginous and manganiferous 

radiolarian chert (Dc). Slight greenschist 

metamorphism is prevalent with alteration 

minerals, including chlorite, albite, 

carbonate, and epidote. Dl contains

medium- to thick-bedded, medium to dark 

gray lime mudstone to wackestone that is 

locally fossiliferous.

Moderately 

high 

depending 

on degree 

of 

weathering.

Unit may contain 

radon-emitting 

materials and 

shrink-and-swell 

clays if altered.

Shrink-and-swell 

clays may buckle 

trail bases and 

may be slippery 

when water 

saturated; rockfall 

hazard associated 

with resistant 

units underlain by 

weaker units.

Radiolaria; Dl

contains rugose and 

tabulate corals, 

brachiopods, 

conodonts, and 

assorted megafossils.

Massive chert 

deposits may 

have 

provided tool 

material.

Manganese- and 

iron-rich cherts.

Karst 

features 

such as 

dissolution 

holes and 

caves are 

possibly 

found in Dl.

Unit weathers 

to iron- and

magnesiumrich soils.

Units fine for 

most 

recreation 

unless heavily 

altered.

Dv correlates 

with Dc and 

UNKsp as part 

of an island arc 

complex; units 

record 

Devonian island 

arc and basin 

depositional 

setting.
Map Unit Properties Table: Denali National Park and Preserve (Large Scale [1:63,360] Map Units)

DENA Geologic Resources Inventory Report 40

Age Unit Name

(Symbol) Features and Description Erosion Resistance

Suitability for 

Infrastructure Hazards PaleontologicalResources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

PRECAMBRIAN OR PALEOZOIC

Keevy Peak Formation

(PZPCkp)

Birch Creek Black 

Carbonaceous Schist

(PZPCbcb)

Schist and Slate

(PZPCss)

Gneiss and Schist

(PZPCgs)

Schist, Quartzite, and 

Marble

(PZPCsqm)

Stretched Conglomerate

(PZPCscg)

Schist

(PZPCsch)

Birch Creek Schist

(PZPCbc)

PZPCkp contains a heterogeneous mixture 

of quartz-sericite schist, quartzite, and 

purple and green schist interlayered with 

slate arkosic gritlike schist, marble, and 

scant limy schist. PZPCcb contains a similar 

assemblage with local layers of green 

chloritic and epidotic schist and impure 

marble. PZPCss contains fine-grained 

yellow, pale-green, and maroon schist and 

slate with some quartz-sericite schist and 

meta-chert. PZPCgs contains microcline 

and quartz gneiss with interlayered lenses of 

black carbonaceous schist. Lower units 

contain brown to gray cataclastic and 

crystalloblastic textures of interlayered 

quartz-sericite schist (PZPCsqm, PZPCbc, 

PZPCsch), chloritic to epidotic schist with 

some calcite (PZPCbc), stretched 

conglomerate (PZPCscg), quartzite, and 

marble present locally.

Moderately 

high.

Altered schist 

layers, as well as 

brittlely deformed 

layers, render 

these units locally 

unstable for heavy 

infrastructure.

Unit is susceptible 

to slope 

processes,

including 

blockfall, 

landslides, 

slumping, and 

slope creep for 

altered, 

deformed, and 

fine-grained units.

None documented;

deformation and 

metamorphism likely 

obscures any 

preexisting fossil 

remains.

Pyrite may 

have been 

used for fire 

starting.

Disseminated pyrite, 

marble, chlorite, and

epidote.

Not enough 

carbonate 

or marble 

present.

Quartzite may 

form spires 

attractive to 

goats and 

birds.

Altered and 

deformed 

areas of units 

should be 

avoided for 

most forms of 

recreation.

PZPCss and 

PCPZgs may 

correlate with 

Nilkoka Group 

or Totatlanika 

Schist; units 

record 

deformation 

and 

metamorphic 

conditions of 

terrane 

formation.

UNKNOWN

Serpentine Gabbro and 

Silica-Carbonate Rocks

(UNKsp)

Aeromagnetic High, 

Probably Serpentine 

and Gabbro

(UNKsp*)

Units are heterogeneous stacks of 

serpentinized, chromite-bearing dunite to 

altered, layered gabbro. Gabbro ranges 

from fine- to coarse-grained leucocratic to 

melanocratic altered clinopyroxene–

plagioclase-bearing. Unit is altered locally to 

silica-carbonate magnetic rock. 

Moderately 

high.

Avoid areas of 

heavy alteration 

and pervasive 

fracturing for 

infrastructure.

Highly altered 

nature of unit 

renders it weak 

on slope; rockfall 

hazards.

None. None 

documented.

Clinozoisite, albite, 

sericite, chlorite, and 

epidote; 

magnetite(?).

None.

Unit contains 

abundant iron

and 

magnesium for 

basic soil 

compositions.

Strong 

magnetic 

signature may 

interfere with 

compass 

readings.

Possibly part of 

feeder dike 

complex for Dv

island arc 

complex.
DENA Geologic Resources Inventory Report 41

Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

QUATERNARY

Surficial Deposits, 

Undifferentiated

(Qs)

Unit includes unconsolidated and 

interlayered silt, sand, and fluvial gravel, as 

well as glacial deposits—including moraines, 

till, and outwash. Unit also includes slope 

colluvium in fan-shaped lobes at the bases 

of slopes. Some terrace deposits and 

floodplain deposits present along rivers. 

Very low.

High 

permeability of 

these units likely 

not suitable for 

wastewater 

treatment 

facilities.

Units are 

associated with 

heavy erosion and 

mass wasting,

including frost 

creep along 

moderate slopes.

Modern remains 

possible; pollen, plant 

macrofossils, insects.

May contain 

campsites, 

settlements 

and other 

artifacts, and

historic 

mining areas.

Gravel, sand, silt, 

placer gold deposits, 

and other heavy 

metal sediments.

None.

Units support 

riparian zones 

and valley floor 

vegetation and 

forests.

Units are fine 

for most light 

recreation. 

Avoid 

riparian areas 

and large 

rubble zones.

Units record 

surficial 

landscape 

evolution 

throughout the 

area.

TERTIARY

Kenai Group, 

Undivided

(Tk)

Sterling Formation

(Tsf)

Hornblende Dacite

(Thd)

Nenana Gravel

(Tn)

Sedimentary Rocks, 

Undivided

(Tsu)

Tsadaka, West 

Foreland, and 

Wishbone Formations,

Undivided

(Ttw)

Tk contains pebble and cobble 

conglomerate interlayered with mediumgrained sandstone, some clay layers, and 

coal seams. Tsf contains massively bedded, 

coarse conglomerate that appears orangetan to light gray in outcrop. Thd contains 

intrusive igneous hornblende dacite 

(intermediate silica content) of Jumbo 

Dome. Tn is more than 1,300 m thick 

containing conglomerate and sandstone 

with mudstone, claystone, and lignite 

interbeds. Unit is well sorted, but poorly 

consolidated, and appears yellowish to 

brownish in outcrop. Tsu and Ttw contain 

mixtures of dark gray shales, yellowish 

sandstones, multi-colored siltstone, pebble 

conglomerate, and some claystone and 

lignite beds locally. Ttw contains cobble to 

boulder conglomerate with other 

sedimentary lenses and some tuffaceous 

beds.

Tn and other 

sedimentary 

units are 

moderately 

low to 

moderate;

igneous unit 

is high.

Heterogeneous 

nature of units 

renders them 

less stable on 

slopes. Avoid 

highly fractured 

areas for 

infrastructure.

Unit is prone to 

rockfall, especially 

in boulder 

conglomerates 

underlain by 

poorly 

consolidated 

units.

None documented. None 

documented.

Plutonic 

conglomerate clasts 

in Ttw. Coal seams 

up to 5 m thick in 

Tk, lignite.

Not enough 

carbonate 

present.

Units support 

wide range of 

habitats.

Units are fine 

for most 

recreation. 

Avoid slope 

toes and 

highly 

fractured 

zones.

Thd has an 

isotopicallydetermined age 

of 2.79 ± 0.25 

million years. 

Tk records 

estuarine and 

fluvial 

depositional 

environments 

during the 

Pliocene to 

Oligocene.

Volcanic Rocks, 

Undivided

(Tvu)

Tyonek Formation

(Tty)

Coal-Bearing Rocks

(Tcb)

Hypabyssal Felsic and 

Intermediate Intrusive 

Rocks

(Thf)

Hypabyssal Mafic 

Intrusive Rocks

(Thm)

Andesite and Basalt

(Tvb)

Granitic and Volcanic 

Rocks, Undivided

(Tiv)

Granodiorite to 

Tonalite

(Toem)

Tvu consists of interlayered volcanic flows 

of compositions ranging from basalt to 

rhyolite, some pyroclastic rocks, and 

intrusive rocks present locally. Tty is a 

mixture of sandstone, siltstone, shale, and 

claystone with various carbonaceous 

cements. Locally divided into sandstone 

member and conglomerate member. Tcb

contains cyclic sequences of siltstone, 

claystone, mudstone, shale, sandstone, 

subbituminous coal and lignite, quartz, and 

pebble conglomerates. Thf comprises small 

stocks, sills, and dikes of rhyolitic to dacitic 

intrusive rocks. Thm is widely exposed,

containing small stocks and irregularly

shaped bodies of diorite porphyry, diabase, 

basalt, and lamprophyre. Tvb contains 

andesitic breccia and tuff layers with some 

local basalts and pyroclastic layers. Tiv

contains portions of a granitic batholith and 

erosional remnants of rhyolitic flows. Toem

contains biotite, biotite-hornblende, and 

hornblende granodiorite, quartz diorite, and 

quartz monzodiorite.

Moderate to 

high for 

intrusive 

igneous 

bodies; lower 

for poorly 

consolidated 

tuffs and 

breccias, 

heterogeneous 

units, and 

sedimentary 

units.

Units are very 

heterogeneous 

and may be 

slightly unstable 

on slopes; may 

also contain 

radon-emitting 

materials. Avoid 

for basements 

and foundations. 

Shrink-andswell clays may 

be present,

which could 

undermine 

roads and 

foundations.

Unit is prone to 

rockfall, 

particularly in 

areas where 

resistant igneous 

intrusive rocks are 

underlain by 

friable, weathered 

sedimentary 

rocks.

Scant shell fragments, 

bioturbation, plant 

fragments(?).

Chert pebbles 

in Tcb may 

have 

provided tool 

material.

Geodes; vesicles in 

Tvb may contain 

secondary minerals. 

Subbituminous coal 

and lignite.

Dissolution 

of 

carbonate 

cements 

may lead to 

unit 

instability.

Units support 

wide range of 

habitats and 

may weather to 

nutrient-rich 

soils.

Units are fine 

for most 

forms of 

recreation.

Records 

deposition 

environment in 

Tertiary basins.
Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

DENA Geologic Resources Inventory Report 42

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

TERTIARY

Fluviatile Sedimentary 

Rocks and Subordinate 

Volcanic Rocks

(Tfv)

Arkose Ridge 

Formation

(Tar)

Granite and 

Granodiorite

(Tegr)

Chickaloon Formation

(Tch)

Basalt

(Tb)

Volcanic Rocks of the 

Cantwell Formation

(Tcv)

Granitic Rocks

(Tpgr)

Granodiorite and Other 

Intermediate Plutonic 

Rocks

(Thgd)

Tfv contains interlayered sequences of 

conglomerate, sandstone, siltstone, and 

mudstone with a few basalt-andesite flows. 

Tar is as much as 700 m thick of fluvially

deposited feldspathic and biotitic 

sandstone, conglomerate, siltstone, and 

shale layers in coarsening upward 

sequences. Tegr contains biotitehornblende granite and granodiorite 

present in irregular bodies. Some altered 

biotite and hornblende tonalite present 

locally. Tch contains a heterogeneous 

mixture more than 1,500 m thick of 

carbonaceous mudstone, siltstone, 

conglomeratic sandstone, and conglomerate 

with interbedded bituminous coal beds. Tb

contains vesicular olivine basalt that appears 

brownish-black in outcrop. Tcv contains 

deformed sequences of andesite, altered 

basalt, rhyolite and interlayered dacite 

flows, felsic pyroclastic rocks, and minor 

sandstone and mudstone. Some calcareous 

rocks present locally. Tpgr is widespread 

unit of biotite-muscovite granite and quartz 

monzonite present generally in plutonic 

bodies. Thgd is biotite and biotitehornblende granodiorite, with some smaller 

quartz diorite, monzonite, and 

monzodiorite plutons present locally. 

Moderate to 

moderately 

high for 

sedimentary 

rocks; high 

for intrusive 

igneous 

rocks.

Heterogeneous 

nature of 

sedimentary 

layers may be 

unstable on 

slopes. Units 

may contain 

radon-emitting 

materials. Avoid 

for basements 

and foundations;

fine for most 

infrastructure

unless highly 

fractured.

Heterogeneous 

layers of these 

units may be 

prone to mass 

wasting and 

landslides on 

steep slopes;

shrink-and-swell 

clays may be 

present in 

volcanic ash units.

Carbonized plant 

fragments (may 

correlate with 

Cantwell Formation).

Crystallized 

vesicles may 

have 

provided 

trade 

material.

Geodes; vesicles 

may contain 

secondary mineral 

crystallization, 

pillow lavas, and 

muscovite. 

Bituminous coal;

may contain copperbearing mineral 

ores.

Minor 

dissolution 

of 

carbonate 

cements.

Units may 

degrade into 

relatively 

magnesium-, 

iron-, and 

calcium-rich

soils.

Units are fine 

for most 

recreation 

unless 

unaltered 

crystalline or 

glassy areas 

persist in 

basalt flows,

rendering 

them unsafe 

for foot 

traffic.

Tar records 

deposition on 

alluvial fans 

overlain by 

braided stream 

deposits 

throughout the 

Tertiary and 

Cretaceous 

transition. Tegr

dated at 45, 44, 

48, and 52.8 

million years. 

Tcv dated at 49 

million years 

using 

potassiumargon isotopes

of tuffs. Tpgr

has dates 

between 52 and 

65 million 

years. Thgd

dated at 58 to

66 million 

years.

CRETACEOUS–TERTIARY

Rhyolite and Related 

Rocks

(TKvr)

Andesite and Related 

Rocks

(TKvi)

Intrusive Rocks

(TKi)

Granitic Rocks

(TKg)

Granodiorite, Tonalite, 

and Monzonite Dikes, 

and Stocks

(TKgd)

Gabbro and 

Leucogabbro

(TKgb)

Gneissose Granitic 

Rocks

(TKgg)

TKvr consists of light gray to pink rhyolitic 

volcanic rocks with minor dacite, including 

flows, tuff, welded(?) tuff, and volcanic 

breccias. TKvi is predominantly andesitic, 

but has some minor dacite and basalt flows, 

tuffs, and breccias present locally. TKi

contains intrusive rocks ranging from 

granite to diorite in composition, mostly 

intermediate silica contents. TKg is a 

widespread unit containing biotite and 

biotite-hornblende granite and lesser 

amounts of Granodiorite, quartz monzonite, 

and alkali granite locally. TKgd contains 

monzonite bodies and other intermediate 

silica composition dikes, stocks, and 

irregular intrusions. TKgb is present in 

small plutons of hypidiomorphic granular 

textured gabbro and leucogabbro. TKgg

contains gneissose granodiorite, quartz 

diorite, and local granite in small plutonic 

bodies, structural grain strikes northeastsouthwest and dips vertically to 80°

northwest.

Moderately 

high to high.

Units may 

contain radonemitting 

materials. Avoid 

for basements 

and foundations;

fine for most 

infrastructure

unless highly 

fractured.

Units are 

associated with 

blockfall and 

landslides if 

present on an 

undercut slope. 

Bulbous plutons 

may be subject to 

exfoliation 

(sloughing) of 

large blocks of 

rock.

None. None 

documented.

Migmatite and 

mylonite layers. 

Building material.

None.

Portions of 

these units 

follow valley 

floors and 

support low 

forests.

Units are 

suitable for 

most 

recreation 

unless highly 

fractured 

and/or 

altered,

rendering 

them unstable 

for trails and 

other uses.

TKvr age 

ranges from 70 

to 50 million 

years. TKgd has 

dates from 59 to 

75 million years 

from 

potassiumargon isotopes. 

TKgg has dates 

from uraniumlead isotopes in

zircon and 

sphene, as well 

as dates from 

potassiumargon isotopes 

in mica, from 70 

to 29 million 

years; youngest 

ages may relate 

to unroofing of 

Denali fault 

system.
Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

DENA Geologic Resources Inventory Report 43

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

PALEOCENE(?) - CRETACEOUS

Cantwell Formation, 

Sedimentary Rocks 

Subunit

(Kcs)

Matanuska Formation

(Km)

Wilber Creek Flysch

(Kwcf)

Nelchina Limestone

(Knl)

Kcs contains a 4,000-m-thick interlayered 

sequence of polymictic conglomerate, 

sandstone, arkosic sandstone, siltstone, 

argillite, and shale, and a few thin coal beds. 

Km contains shallow marine shales with 

calcareous concretions. Unit appears wellindurated, dark gray, and thinly bedded. 

Some volcanic-lithic siltstone, sandstone, 

graywacke, and subordinate conglomerate 

present locally. Kwcf is a mixture of 

massively bedded siltstone, shale, 

sandstone, and conglomerate of clasts 

derived from quartzite, limestone, mafic and 

felsic igneous rocks, greenstone, diorite, 

sandstone, siltstone, phyllite, chert, rare grit, 

shale rip-ups, and very rare carbonatite. 

Units appear dark gray to greenish in 

outcrop and are well-sorted. Knl is shallowwater calcareous sandstone, siltstone, 

claystone, and thick-bedded to massive 

clastic limestone. Some conglomerate beds 

present locally.

Moderate.

Units are fine for 

most 

infrastructure

unless highly 

heterogeneous 

and/or 

fractured; units 

may contain 

radon-emitting 

materials and/or 

shrink-and-swell 

clays from 

altered volcanic

ash.

Unit is associated 

with slope 

processes,

including 

landslides.

Paleocene(?) plant 

fossils;

Paragastroplites 

flexicostatus of Albian 

age. Regionally, 

concretions in Km can 

be highly fossiliferous. 

Kcs contains dinosaur 

foot prints and other 

plants and traces.

None 

documented.

Calcareous 

concretions;

carbonatite. Thin 

coal beds.

Knl may 

contain 

karst 

features 

such as 

dissolution 

holes and 

caves; some 

areas may 

be too 

clastic for 

extensive 

dissolution.

Unit may 

weather into 

calcium-, iron-, 

magnesium-, 

and aluminumrich soils.

Units are 

suitable for 

most 

recreation 

unless highly 

fractured 

and/or altered

Kcs contains 

tuffs with 

potassiumargon isotope

dates from

Cretaceous. Km

records shallow 

marine 

deposition 

environment 

during the 

Cretaceous 

between 

volcanic arcs.

CRETACEOUS

Mélanges of the Alaska 

Ridge

(Kmar)

Volcanic Rocks

(Kvl)

Granitic Rocks

(Kg)

Mafic and Ultramafic 

Rocks

(Kmum)

Kmar contains four major suites: (1) cherty 

tuff, chert, argillite, and volcaniclastic 

sandstone; (2) dark gray to black argillite, 

slate, shale, graywacke, and subordinate 

chert, chert-pebble conglomerate, and 

polymict conglomerate; (3) limestone; and 

(4) mixed ultramafic rocks. Kvl includes 

dacite, andesite, basalt and assorted flows, 

tuffs, and dikes and sills locally; alteration of 

most units is widespread. Kg contains 

granitic to dioritic dikes, sills, and plutons. 

Kmum contains mixtures of gabbro, diorite, 

serpentinite, and mafic volcaniclastics. Most 

layers are altered and deformed to varying 

degrees present in lenses and dikes.

Moderate to 

high for 

granitic 

rocks.

Units may 

contain radonemitting 

materials and/or 

shrink-and-swell 

clays from 

altered 

volcanics;

heterogeneous 

layering may be 

unstable for 

foundations.

Heavy alteration 

associated with 

units render them 

likely to fail on 

slopes and if 

water saturated.

Buchia bivalves of Late 

Cretaceous to Jurassic 

age; Radiolaria and 

conodonts fragments.

Chert may 

have 

provided 

early tool 

material.

Tourmaline in Kg. 

Abrasives and

building materials.

Kmar suite 

3 is subject 

to karst 

dissolution.

None 

documented.

Highly altered 

units are 

unstable base.

Kmar records a 

nearshore 

environment 

caught up in a 

narrow belt 

during 

orogenesis. Kg

has dates from 

120 to 65 

million years.

CRETACEOUS AND JURASSIC

Argillite, Chert, 

Sandstone, and 

Limestone

(KJs)

Kahlitna Flysch 

Sequence

(KJf)

Flysch Sequence 1

(KJfk)

Flysch Sequence 2

(KJfn)

Conglomerate, 

Sandstone, Siltstone, 

Shale, and Volcanic 

Rocks

(KJcg)

KJs contains dark gray to greenish argillite 

interlayered with chert, sandstone, and thin 

shelly limestone layers. KJf, KJfk, and KJfn

contain intensely deformed and 

metamorphosed turbidites. Units include 

dark gray to black argillite, graywacke, 

pebble conglomerate, black chert, and dark 

gray impure limestone beds. Units are 

tightly folded and faulted. KJcg is 

interbedded pebble and cobble 

conglomerate with sandstone, siltstone, 

shale, and volcanic flows and dikes 

(andesite to latite).

Moderate.

Units are fine for 

most 

infrastructure

unless highly 

fractured, 

altered, and/or 

heterogeneous.

Intense 

deformation of 

unit renders it 

susceptible to fail 

if slope intersects 

predominant 

structural fabric.

Ammonites; bivalves 

Inoceramus, Buchia 

sublaevis, B. keyserlingi

in coquina, 

Inoceramus 

hobetsensis; broadleaf 

plant fossils.

None 

documented.

Feldspar porphyry 

in KJcg.

Some 

dissolution 

of limestone 

in KJs.

None 

documented.

Units can be 

too friable for 

climbing.

Argon isotopes 

of hornblende 

clast dates at 

94.6 ± 1.5 to 

101.0 ± 0.7 

million years.
Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

DENA Geologic Resources Inventory Report 44

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

JURASSIC

Trondhjemite

(Jtr)

Naknek Formation

(Jn)

Chinitna Formation, 

Tuxedni Group, and 

Coeval Sedimentary 

Rocks

(Jct)

Mafic and Ultramafic 

Rocks

(Jmu)

Alaska-Aleutian and 

Chitina Valley 

Batholiths, 

Undifferentiated

(Ji)

Jtr is foliated, altered, and deformed 

trondhjemite in northeast-trending plutons. 

Jn includes more than 1,400 m of thin- to 

thick-bedded gray siltstone, shale, 

sandstone, and conglomerate. Jct is a 

mixture of shallow marine clastic rocks 

ranging from conglomerate to siltstone to 

shale. All beds contain some volcanic 

elements, likely from nearby island arcs. 

Jmu contains dunite, harzburgitic dunite, 

wehrlite, websterite, alkali gabbro 

(monzogabbro), and clinopyroxenite in 

discontinuous belts, dikes, and sills. Ji

contains widespread batholithic rocks of 

granite, granodiorite, quartz diorite, and 

tonalite as part of the Alaska-Aleutian Range 

batholith.

Moderate to 

high for 

granitic 

batholith 

units.

Heterogeneous 

nature of 

sedimentary 

layers may be 

unstable on 

slopes. Units 

may contain 

radon-emitting 

materials. Avoid 

for basements 

and foundations.

Sheet-like 

exfoliation 

weathering of 

plutonic units 

render them 

susceptible to 

large blockfall.

Megafossils; Buchia 

bivalves, ammonites.

None 

documented.

Olivine, phlogopite, 

and clinopyroxene. 

Abrasives and

building materials.

Not enough 

carbonate 

present.

None 

documented.

Fine for most 

recreation 

unless highly 

fractured 

and/or 

altered.

Jtr potassiumargon isotope 

ages range from 

129 to 149 

million years. Jn

constrains the 

age of uplift of 

the AlaskaAleutian Range 

batholiths.

JURASSIC OR TRIASSIC?

Limestone and Marble

(JTRlm)

Talkeetna Formation

(JTRtk)

JTRlm is fine- to medium-grained, gray 

metamorphosed limestone in discontinuous 

lenses as much as 30 m thick. Limestone is 

massive to poorly bedded. JTRtk contains 

greenstone and tuff layers. Greenstone is 

altered equivalent of basaltic lava, 

agglomerate, breccias, and tuff. Some 

interlayered sandstone and shale present 

locally.

Moderate.

Calcareous 

layers and 

cements may 

dissolve,

rendering unit 

unstable in some 

areas. Tuff units 

may contain 

shrink-and-swell 

clays; avoid for 

heavy 

infrastructure.

If carbonate layers 

and cements are 

dissolved, rockfall 

hazards exist;

heavily altered 

layers may fail 

when water 

saturated on 

slopes.

Shallow marine fossils.

Caves 

possible in 

this unit; may 

have been 

settlement 

areas.

Marble.

JTRlm is 

subject to 

karst 

dissolution.

Units may 

weather to 

produce 

calcium-, iron-, 

and 

magnesiumrich soils.

Fine for most 

recreation 

unless heavily 

altered and/or 

deformed.

JTRtk is 

extrusive 

product of an 

early Jurassic 

island arc 

setting.

JURASSIC - TRIASSIC

Red and Brown 

Sedimentary Rocks and 

Basalt

(JTRsu)

Crystal Tuff, Argillite, 

Chert, Graywacke, and 

Limestone

(JTRct)

Tatina River Volcanic 

and Equivalent Units

(JTRtv)

JTRsu contains a redbed sequence of 

sandstone, siltstone, argillite, and 

conglomerates more than 2,000 m thick. 

Limestone and basalt interbeds present 

locally. JTRct is a deep marine sequence of 

tuff, minor chert, argillite, greywacke, and 

limestone that is heavily faulted and tightly 

folded. JTRtv consists of three distinct 

members: (1) upper green medium-grained, 

concretion-rich volcaniclastic sandstone, 

with gray, phosphatic shale, and minor tan 

chert-pebble conglomerate interbeds;

(2) lower volcanic rocks, including greenishgray pillow basalts interlayered with lenses 

of mudstone, shale, and siltstone gabbro 

bodies; and (3) brown silty shale and light

gray, green, and black chert with some 

coarse volcanic sandstone and 

conglomerate.

Moderate.

Heterogeneous 

nature of units 

may render 

them unstable 

on slopes. Some 

units may 

contain shrinkand-swell clays 

from altered

volcanics.

Unit is susceptible 

to slope 

processes,

including 

blockfall, 

landslides, 

slumping, and 

slope creep for 

finer-grained 

units.

Radiolaria, other Late 

Triassic and Early 

Jurassic fossils, bivalve

Monotis subcircularis, 

ammonites.

None 

documented.

Red chert pebbles. 

Phosphates and

copper ore.

Dissolution 

is possible 

within 

limestone 

interbeds;

may render 

units 

unstable.

None 

documented.

Fine for most 

recreation 

unless highly 

fractured;

clay-rich 

layers may 

pose hazards 

to hikers if 

water 

saturated.

Records 

Jurassic –

Triassic 

transition in 

marine and 

continental 

deposition 

settings.

JURASSIC? 

AND/OR PERMIAN

Ultramafic Rocks

(JPsu)

Unit is a mixture of serpentinized (altered) 

peridotite, harzburgite, and dunite. Unit is 

highly folded and contains some low-grade 

metasedimentary rocks and chert layers 

locally.

Moderate due 

to high degree 

of alteration.

Avoid areas of 

heavy alteration 

and pervasive 

fracturing for 

infrastructure.

Highly altered 

nature of unit 

renders it weak on 

slope; rockfall 

hazards.

None.

Chert layers 

may have 

provided tool 

material.

Olivine, chlorite, and 

actinolite. Abrasives. None.

Unit may 

weather to 

produce ironand

magnesium-rich 

soils.

Unit may 

interfere with 

compass 

readings.

Unit contains 

oceanic crust 

caught up 

during 

orogenesis.
Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

DENA Geologic Resources Inventory Report 45

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

JURASSIC AND 

PENNSYLVANIAN

Uranatina Metaplutonic 

Complex

(JPNaur)

The complex contains a greenschist facies 

(locally amphibolite facies) metamorphosed 

belt of schistose quartz diorite, quartz 

monzonite, granodiorite, hornblende diorite, 

amphibolite, and orthogneiss.

Moderately 

high.

Suitable for most 

infrastructure. 

Avoid schistose 

units and altered 

areas for heavy 

infrastructure.

Pervasive foliation 

and sheet-like 

exfoliation 

weathering of 

metaplutonic units 

render them 

susceptible to large 

blockfall.

None. None 

documented. Building materials. None. None documented.

Fine for most 

recreation 

unless heavily 

altered and/or 

deformed.

Jurassic 

potassium-argon 

isotope dates;

uranium-lead 

isotope ages of 

309 ± 11 to 153 ±

4 million years.

JURASSIC -

CAMBRIAN

Mystic and Dillinger 

Stratigraphic 

Sequences, Undivided

(JCmd)

Unit is a folded, structurally complex 

assemblage of siliciclastic turbidites, cherty 

pelagite, pillow basalt, wildflysch, chert, 

shale, reefoid limestone, and conglomerate 

and sandstone representing a mixture of 

depositional environments.

Moderate.

Heterogeneous 

nature of units 

renders them 

less stable on 

slopes. Avoid 

highly fractured 

areas for 

infrastructure.

Unit is prone to 

rockfall, especially 

in massive beds 

underlain by 

deformed units.

Permian- to Silurianage marine fossils, 

conodonts.

Chert may 

have been 

useful for 

early tool 

making.

Basalt alteration 

minerals and 

amygdules. Basalts 

may contain copperbearing minerals.

Some 

dissolution 

is possible 

in limestone 

layers.

None 

documented.

Deformed 

nature of unit 

renders it 

unstable on 

slopes.

Unit records 

deposition in 

deep marine, 

slope and shelf, 

and nonmarine 

settings over 

millions of 

years.

TRIASSIC

Calcareous Sedimentary 

Rocks

(TRcs)

Conglomerate and 

Volcanic Sandstone

(TRcg)

Nikolai Greenstone and 

Related Rocks

(TRn)

Gabbro, Diabase, and 

Metagabbro

(TRgb)

Metavolcanic and 

Associated 

Metasedimentary Rocks

(TRnm)

Limestone and Basalt 

Sequence

(TRlb)

Red Beds

(TRr)

TRcs contains thinly bedded, gray 

calcareous shale, argillite, sandstone, 

siltstone, and sandy to silty and argillaceous 

limestone. Unit is intensely deformed. 

Cherty limestone is present locally, as well 

as associated dikes, sills, and plugs of altered 

diabase and gabbro. TRcg is only present 

locally, and contains cobble to boulder 

conglomerate with clasts of green volcanic 

rocks and red radiolarian chert overlain by 

massive volcanic sandstone. TRn contains 

greenschist facies metamorphosed subaerial 

and submarine basalt flows with minor 

volcaniclastic layers. Unit appears dark 

gray-green to brown and is more than 2,000 

m thick. TRgb is predominantly altered 

hornblende-clinopyroxene gabbros with 

quartz gabbro and quartz diorite present in 

lenses. TRnm contains metabasalt, slate, 

and other metamorphosed sedimentary and 

igneous rocks. TRlb is interlayered 

limestone and amygdaloidal basalt flows. 

The limestone is massive and gray with local 

marbleized areas. TRr contains redbeds of 

sandstone, argillite, siltstone, and 

conglomerate with clasts of gabbro, 

serpentinite, and limestone (fossils).

Moderate to 

moderately 

high for 

metamorphic 

rocks.

Units are highly 

heterogeneous 

which may 

render the rock 

column 

relatively 

unstable. Units 

may contain 

radon emitting 

materials as well 

as shrink-andswell clays 

(altered 

volcanics). 

Avoid highly 

fractured and/or 

altered areas for 

infrastructure.

If present on 

slopes, rockfall, 

blockfall hazards 

exist for massive 

units, whereas 

slope creep, 

slumping, and 

debris flow 

potential exists 

for fine-grained, 

deformed, and/or 

altered units.

conodonts 

Negondolella 

polynathiformis and 

Epigondolella primitia, 

bivalve Monotis 

subcircularis, 

radiolaria, 

Heterastridium sp.

None 

documented.

Red radiolarian 

chert nodules and

mineralized 

amygdules in basalt 

flows. Slate, building 

materials, and 

marble.

Some 

dissolution 

possible in 

limestonemarble 

layers.

Units weather 

into nutrientrich soils. 

Dissolution in 

limestone 

layers may 

provide 

burrow habitat.

Units are 

suitable for 

most 

recreation 

unless heavily 

altered, 

deformed, 

and/or 

undercut on 

slopes.

TRcs records 

turbidite 

environment 

during midTriassic. TRn is 

a diagnostic 

unit of the 

Wrangellia 

terrane. TRlb

suggests 

shallow water 

deposition in an 

ocean island 

shield volcano 

environment.

TRIASSIC -

PENNSYLVANIAN

Flysch-like Sedimentary 

Rocks

(TRPNas)

Unit is pervasively deformed and folded 

with dark massive to thin-bedded marine 

Flysch-like layers, including conglomerate, 

sandstone, siltstone, argillite, limestone, and 

chert. Unit is several hundred meters thick. 

Unit is fault-bounded.

Moderate.

Deformed 

nature of unit 

may weaken its 

ability to 

support heavy 

infrastructure.

Fractured rocks 

are susceptible to 

blockfall and 

landslides.

Triassic Radiolaria, 

conodonts, 

Pennsylvanian 

brachiopods.

Chert may 

have been 

useful for 

early tool 

making.

Building material.

Some 

dissolution 

is possible 

in limestone 

layers.

None 

documented.

Avoid heavily 

deformed 

areas for 

recreation 

development.

Fault-bounded 

unit records 

structural 

evolution of the 

area.
Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

DENA Geologic Resources Inventory Report 46

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

TRIASSIC -

DEVONIAN

Volcanic and 

Sedimentary Rocks

(TRDv)

Unit contains interlayered greenish-gray to 

black chert, tuffs, volcanic conglomerate, 

with some maroon-colored volcanic 

mudstone, basaltic breccia, and graywackeshale beds with lenses of limestone, and 

ammonite-bearing limestone present 

locally. Unit was metamorphosed to 

greenschist facies.

Moderate.

Unit may 

contain shrinkand-swell clays 

as well as radonemitting 

material. Avoid 

for basements 

and foundations.

Mudstone-rich 

units are prone to 

failure on slopes, 

especially if water 

saturated.

Permian brachiopods, 

ammonites, 

conodonts. Devonian 

and Carboniferous 

fossils in the chert.

None 

documented.

Attractive maroon 

mudstone.

Some 

dissolution 

possible in 

limestone 

layers.

None 

documented.

Avoid 

particularly 

shaly areas for 

recreation 

development.

Unit is lower 

portion of 

Chulitna 

sequence.

SILURIAN -

TRIASSIC

Limestone Blocks

(TRSl)

Unit contains lenses and lozenge-shaped 

blocks of medium-bedded to massive gray 

limestone. Limestone is fine- to mediumgrained and fossiliferous.

Moderately 

high.

Unit may be 

friable and too 

permeable for 

wastewater 

treatment 

infrastructure.

Dissolution may 

pose sinkhole 

hazard;

susceptible to 

rockfall if highly 

dissolved on 

slopes.

Megafossils, 

conodonts.

Caves 

possible in 

this unit; may 

have been 

settlement 

areas.

None documented.

May 

contain 

karst 

features 

such as 

dissolution 

holes and 

caves.

If caves are 

present, unit 

may provide 

bat and other 

cave dweller 

habitat.

Any caves will 

attract caving 

interest.

Unit records 

marine basin 

conditions 

during a 

longstanding 

depositional 

setting.

MESOZOIC

Phyllite, Pelitic Schist, 

Calc-Schist, and 

Amphibolite of the 

MacLaren 

Metamorphic Belt

(MZpca)

Schist and Amphibolite

(MZsa)

MZpca is a metamorphosed (amphibolite 

facies, then retrograde greenschist facies) 

belt of mainly phyllite, quartz-mica schist, 

calc-schist, amphibolite, and subordinate 

marble and meta-andesite, derived from 

mixed deposits of siltstone, graywacke, 

marl, andesite, and gabbro. Unit was folded 

extensively at least twice during orogenesis. 

MZsa contains fine- to medium-grained 

schist and hornblende amphibolites, with 

some irregular bodies of calc-silicate schist 

and quartzite and local gneissose granitic to 

gabbroic metaigneous rocks. 

High; may be 

lower with 

increased 

degree of 

weathering.

Altered schist 

layers, as well as 

brittlelyductilely 

deformed layers,

render these 

units locally 

unstable for 

heavy 

infrastructure.

Unit is susceptible 

to slope 

processes,

including 

blockfall, 

landslides, 

slumping, and 

slope creep for 

altered, deformed, 

and fine-grained 

units.

None documented;

deformation and 

metamorphism likely 

obscures any 

preexisting fossil 

remains.

Garnets may 

have been 

used for early 

trade.

Garnets; abrasives.

Not enough 

carbonate 

present.

None 

documented.

Avoid 

schistose 

layers for 

recreation 

development.

MZpca has 

potassiumargon isotope 

dates from 

mica 48.0 to 

30.6 million 

years and 

amphibole ages 

of 69.6 million 

years. Unit 

contains 

Meteor Peak 

fault. MZsa has 

potassiumargon isotope

dates ranging 

from 65.9 to 

31.9 million 

years with 

biotite ages 

youngest.

MESOZOIC OR 

PALEOZOIC

Intrusive and Volcanic 

Rocks, Undivided

(MZPZi)

Units composition ranges spatially from 

granodiorite of Rainbow Mountain, diorite, 

and gabbro and quartz diorite, with dark 

gray to greenish dikes of basalt and 

granodiorite and some volcanics 

interlayered locally.

High; lower 

for less 

consolidated 

volcanic 

units.

Altered 

volcanics may 

contain shrinkand-swell clays,

which could 

undermine road 

and building 

foundations. 

Avoid fractured 

areas.

Sheet-like 

exfoliation of 

plutonic areas 

poses blockfall 

hazard.

None. None 

documented. Building material. None.

Unit may 

weather to 

produce 

calcium- and 

aluminum-rich 

soils.

Suitable for 

most 

recreation;

may attract 

climbers. 

Avoid 

fractured 

areas.

Units are 

widespread and 

provide unique 

dating 

opportunity 

through isotope 

dating and 

cross cutting 

relationships.
Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

DENA Geologic Resources Inventory Report 47

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

MESOZOIC?, PALEOZOIC?, AND (OR) 

LATE PROTEROZOIC?

Ultramafic and Mafic 

Rocks, Undivided

(MZZum)

Unit is widespread containing a 

heterogeneous mix of serpentinite, 

peridotite, dunite, gabbro, diorite, 

metabasite, and minor talc schist and 

roddingite. Textures of the different rock 

types range from intrusive to metamorphic. 

Devonian-age dikes present north of the 

Denali fault system.

Moderately 

high.

Avoid areas of 

heavy alteration 

such as 

serpentinite and 

talc schist and 

pervasive 

fracturing for 

infrastructure.

Highly schistose 

and altered nature 

of unit renders it 

weak on slope;

rockfall hazards.

None. None 

documented.

Talc, olivine, and 

roddingite; 

abrasives.

None.

Unit may 

weather to 

produce ironand

magnesiumrich soils.

Unit unstable 

on slopes. 

Avoid for trail 

development.

Argon isotopes 

from 

hornblende 

dates from 465 

to 536 ± 2.6 

million years.

PERMIAN

Eagle Creek Formation

(Pe)

Unit contains as much as 1,000 m of 

alternating sequences of marine dark gray,

thin-bedded argillite, and fine- to mediumgrained limestone beds. Minor lenses of 

gray siltstone, bioclastic limestone, 

calcareous siltstone, radiolarian chert, shale, 

limestone, and pyritic sandstone are present 

locally.

Moderate.

Dissolved and 

fractured 

limestones may 

render unit too 

permeable for

wastewater 

treatment.

Limestone 

dissolution may 

render units 

friable with 

increased fracture 

diameter, 

rendering unit 

weak on slopes.

Corals, bryozoans, 

brachiopods, 

echinoids, crinoids, 

fusulinids, and algal(?) 

fragments; Radiolaria.

Pyrite may 

have been 

used to start 

early fires.

Pyrite-bearing

sandstone.

Limestones 

may contain

karst 

features 

such as 

dissolution 

holes.

Small holes 

and cavities 

may provide 

burrow habitat.

Avoid areas of 

dissolution 

and fracture.

Unit records 

environmental 

conditions 

during the 

Permian; may 

contain 

extinction 

information.

PERMIAN - PENNSYLVANIAN

Station Creek and Slana 

Spur Formations, and 

Equivalent Rocks

(PPNasc)

Strelna Metamorphic 

Complex

(PPNast)

Marble

(PPNaskm)

PPNasc contains a lower volcanic member 

of submarine andesite and basalt flows with 

breccias and pillows, and an upper 

volcaniclastic member of graywacke and 

volcanilutite grading upwards. PPNast is 

composed of folded, faulted, and 

metamorphosed metasedimentary and 

metavolcanic rocks, including 

quartzofeldspathic and quartz-mica schist 

with lenses of marble, metachert, and 

orthogneiss. Volcanic layers are now 

greenstones. PPNaskm occurs as 30-mthick lenses of white, medium- to coarsegrained marble.

Moderately 

high.

Heterogeneous 

and deformed 

nature of units 

may render 

them unstable 

on slopes. Some 

units may 

contain radonemitting 

materials and 

shrink-and-swell 

clays if altered.

Units are 

susceptible to 

slope processes,

including 

blockfall, 

landslides, 

slumping, and 

slope creep for 

finer-grained 

units.

Late Paleozoic 

bryozoans?

None 

documented.

Migmatite and

greenstones; marble.

Marble may 

be 

susceptible 

to minor 

dissolution.

None 

documented.

Units are fine 

for most 

recreation 

unless highly 

fractured, 

altered, 

and/or 

deformed.

Unit records 

seafloor 

volcanism and 

conditions from 

Permian and 

Pennsylvanian.

PERMIAN -

DEVONIAN

Sheep Creek Formation 

and Correlative 

Siliciclastic Units

(PDsc)

Unit is heterogeneous mixture of sandstone, 

conglomerate, siltstone, and argillite with 

local beds of chert and limestone. Unit 

contains clasts of Devonian limestone. 

Moderate.

Units are fine for 

most 

infrastructure

unless highly 

heterogeneous 

and/or 

fractured.

Heterogeneous 

layers of these 

units may be 

prone to mass 

wasting.

Conodonts, fusilinids, 

brachiopods, corals, 

plant remains.

None 

documented. Building material.

Some 

dissolution 

is possible 

in limestone 

layers

None 

documented.

Units are fine 

for most 

recreation.

Unit records 

deposition 

spanning from 

Permian to 

Devonian.

PENNSYLVANIAN

Tetelna Volcanics

(PNat)

Unit appears greenish in outcrop composed 

of volcanic flows, mud, and debris flows, 

with lapilli-tuff interbedded with 

volcaniclastic rocks. Composition is mostly 

andesitic, and the entire unit was 

metamorphosed at lower greenschist facies.

Moderately 

high.

Unit may 

contain radonemitting 

materials and 

shrink-and-swell 

clays if altered.

Sedimentary 

rocks may 

weather out 

differentially,

posing a rockfall 

hazard.

None. None 

documented. Lapilli. None.

May weather 

to produce 

aluminum- and

calcium-rich

soils.

Units are fine 

for most 

recreation.

Unit records 

widespread 

Pennsylvanian 

volcanism and 

later 

metamorphicdeformation 

conditions.
Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

DENA Geologic Resources Inventory Report 48

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

MISSISSIPPIAN -

DEVONIAN

Totatlanika Schist

(MDt)

Unit is a mylonite assemblage of gritty 

semischist with intense deformation and 

low-grade metamorphic minerals and 

textures. Some chloritic quartzo-feldspathic 

schist and augen gneiss, phyllitic schist and 

semischist, phyllite, metavolcanic rocks, 

quartzite, marble, and greenstone are 

present locally with original textures often 

evident.

Moderate.

Altered schists 

and phyllite 

layers render 

these units 

locally unstable 

for heavy 

infrastructure.

Unit is susceptible 

to blockfall, 

landslides, 

slumping, and 

slope creep for 

altered, deformed, 

and fine-grained 

units.

None documented;

deformation and 

metamorphism likely 

obscures any 

preexisting fossil 

remains.

Augen may 

have been 

valuable 

trade 

material.

Clear to bluish gray 

quartz augen 

(“eyes”). Marble and

abrasives.

Some minor 

dissolution 

possible in 

marble.

None 

documented.

Avoid 

schistose 

areas for 

recreation 

development.

Uranium-lead 

isotopes in 

zircon provide 

an age of 375 

million years;

dates extrusive 

protolith.

MISSISSIPPIAN? –

DEVONIAN?

Keevy Peak Formation

(PZk)

Unit is a heterogeneous mixture of phyllite, 

meta-argillite, quartzite, metachert(?), and 

lesser amounts of calcareous phyllite, 

marble, and mafic and felsic metavolcanic 

rocks. Unit is multiply deformed and 

metamorphosed at greenschist facies.

Moderate.

Altered schist 

layers, as well as 

brittlely 

deformed layers,

render these 

units locally 

unstable for 

heavy 

infrastructure.

Unit is susceptible 

to blockfall, 

landslides, 

slumping, and 

slope creep for 

altered, deformed, 

and fine-grained 

units.

None documented;

deformation and 

metamorphism likely 

obscures any 

preexisting fossil 

remains.

None 

documented. Phyllite; marble.

Some minor 

dissolution 

possible in 

marble.

None 

documented.

Altered and 

deformed 

areas of units 

should be 

avoided for 

most forms of 

recreation.

Uranium-leab 

isotopes in 

zircon dates 

extrusion age at 

346 ± 1 million 

years.

DEVONIAN

Serpentinite, Basalt, 

Chert, and Gabbro

(Dsb)

Phyllite, Slate, Siliceous 

Siltstone, and Argillite

(Dps)

Yanert Fork Sequence 

and Correlative Rocks

(Dy)

Dsb contains sheared and altered 

serpentinite, chert, and pillow basalt 

forming lenticular blocks. Dps contains gray 

to silvery phyllite, slate, siliceous siltstone, 

and argillite with some thin limestone and 

calcareous siltstone interbeds. Dy contains 

metasedimentary and metavolcanic rocks of 

varying grade and fabric, including argillite, 

slate, phyllite, phyllonite, semischist, impure 

quartzite, schistose stretched-pebble 

conglomerate, banded metachert, felsic 

metatuff, and metabasalt. Some original 

pillows and layering present locally. 

Moderate.

Sheared and 

altered areas 

should be 

avoided for 

heavy 

infrastructure;

heterogeneous 

nature of units 

render them 

locally unstable.

Large blocks of 

massive to intact 

rock surrounded 

by sheared and/or 

altered rock pose 

blockfall hazards. 

Schistose cleavage 

may cause large 

slides locally, 

depending on 

orientation with 

slope.

Radiolaria. None 

documented.

Blocky building 

material and

copper-bearing 

minerals.

Some 

dissolution 

possible in 

limestone 

layers.

Limestone 

dissolution 

holes may 

provide 

burrow habitat. 

Units may 

weather into 

nutrient-rich 

soils.

Units are fine 

for most 

recreation 

unless highly 

fractured.

Dsb was part of 

a dismembered 

ophiolite 

assemblage. Dy

records a 

volcanicbearing 

turbiditic 

marine 

sequence on a 

continental 

slope.

DEVONIAN AND SILURIAN

Unnamed Limestone

(DSmdl)

Whirlwind Creek 

Formation and 

Unnamed Correlative 

Units

(DSwc)

Limestone

(DSl)

Tolovana Limestone

(DSt)

DSmdl contains light gray to brown 

limestone, some meta-limestone locally. 

DSwc is shallow marine limestone and 

dolostone with minor fossils. DSl contains 

gray, massive recrystallized limestone with 

sandy, silicified limestone and dolostone 

interbeds. Some brecciated and micritic 

limestones present locally. DSt contains 

alternating green and maroon limey 

mudstone grading upward into yellowishbrown silty and shaly lime mudstone and 

wackestone, grading into gray peloid and 

ooid-rich lime packstone and grainstone 

and scant dolostones present locally.

Moderate, 

depending 

on degree of 

alteration 

and 

dissolution of 

carbonate 

layers.

Unit may be 

friable and too 

permeable for 

wastewater 

treatment 

infrastructure.

Dissolution may 

pose sinkhole 

hazard;

susceptible to 

rockfall if highly 

dissolved on 

slopes.

Graptolites, 

dasclydacean algae, 

corals, 

stromatoporoids, 

brachiopods, 

conodonts, 

Ostracodes.

Caves 

possible in 

this unit; may 

have been 

settlement 

areas.

Ooids; limestone 

building material.

Karst 

features 

such as 

dissolution 

holes and 

caves are 

possible for 

DSwc and 

DSt.

If caves are 

present, they 

may provide 

habitat for bats 

and other cave 

dwellers.

Caves if 

present may 

attract 

speleologists.

Unit records 

Silurian deepwater 

conditions and 

Late Devonian 

shallow-water 

depositional 

environment.

DEVONIAN -

CAMBRIAN

Dillinger Sequence, 

Undivided

(DCd)

Unit contains mixtures of shales, siltstones, 

cherts, and silty limestones as slope or 

basinal deposits

Moderate;

lower for 

very heterogeneous 

areas.

Heterogeneous 

nature of unit 

may render it 

unstable on 

slopes.

If carbonate 

cements are 

dissolved, 

integrity of unit 

may be 

compromised;

possible slope 

processes hazards.

Conodonts, 

graptolites, corals.

Chert layers 

may have 

provided tool 

material.

None documented.

Some 

dissolution 

possible in 

limestone 

layers.

Unit supports 

wide variety of 

habitats.

Unit is fine 

for most 

recreation.

Unit contains 

turbidites from 

an ancient 

marine slope 

environment.
Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

DENA Geologic Resources Inventory Report 49

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

SILURIAN -

CAMBRIAN

Post River Sandstone, 

Lyman Hills Formation, 

and Correlative Units

(SCpl)

Unit contains sequences of shale, siltstone 

and chert, grading into silty limestone and 

shale with cross lamination textures.

Moderate.

Suitable for most 

infrastructure

unless highly 

fractured.

If massive units 

are underlain by 

shale units, a 

hazardous 

rockfall situation 

can exist.

Cambrian conodonts, 

Ordovician and 

Silurian graptolites.

Chert layers 

may have 

provided tool 

material.

None documented.

Minor 

dissolution 

possible in 

limestone 

layers.

None 

documented.

Unit is fine 

for most 

recreation.

Unit records 

basinal – slope 

depositional 

setting with 

turbidity 

currents.

ORDOVICIAN

Chert

(Oc)

Unit contains dark gray to black chert 

layered with siliceous slate, argillite, and 

some greenstone, impure limestone, and 

dolostone. 

Moderately 

high.

Suitable for most 

infrastructure

unless highly 

fractured.

Slate layers may 

undermine unit 

stability on a slope 

causing a blockfall 

hazard. If 

carbonate 

cements are 

dissolved, unit 

may be prone to 

failure.

Graptolites.

Chert layers 

may have 

provided tool 

material.

Slate.

Minor 

dissolution 

possible in

limestone 

layers.

None 

documented.

Avoid slaterich layers 

due to sharp 

surfaces.

Unit records 

Ordovician 

depositional 

setting in open 

basin.

CAMBRIAN? AND 

PROTEROZOIC

Wickersham Grit, 

Undivided

(CZw)

Argillaceous Upper Unit

(CZwa)

CZw is a poorly sorted sequence of 

quartzite, feldspathic quartzite, grit, 

calcareous siltstone, and fine-grained 

sandstone, and some scant dark limestone 

and chert layers. Unit is brittlely deformed 

and recrystallized with imbricate structures. 

CZwa is argillaceous with tan-weathering 

calcareous siltstone and sandstone, with 

some quartzite and chert present locally. 

Some dark limestone thin beds interlayered 

locally. 

Moderate;

deformed 

areas are 

more 

susceptible to 

erosion.

Pervasive 

deformation 

compromises 

stability of unit 

for heavy 

infrastructure. 

Avoid fractured 

areas for 

wastewater 

treatment 

facilities.

Pervasive 

fracturing incites 

a likely blockfall 

hazard.

None documented;

deformation and 

metamorphism likely 

obscures any 

preexisting fossil 

remains.

None 

documented.

Cataclasite. 

Quartzite building 

materials.

Minor 

dissolution 

possible in 

limestone 

layers.

None 

documented.

Avoid unit for 

most 

recreation 

due to high 

fracture 

density.

Unit records 

deposition in 

nearshore 

environments 

as well as nature 

of deformation 

during 

orogenesis and 

uplift.

PALEOZOIC

Spruce Creek Sequence 

and Correlative Rocks

(PZsc)

Volcanic and 

Sedimentary Rocks

(PZvs)

Calcareous and Phyllitic 

Rocks

(PZkcp)

PZsc contains mafic to felsic metavolcanic 

rocks, some minor greenstone (altered 

basalt) sills. Mafic layers are dark, massive;

and schistose with metabasalt, andesitic, and 

amphibolitic layers with minor quartz to 

mafic schist, pelitic schist, phyllite, 

metasiltstone, metatuff, and minor chert 

and marble. Felsic layers contain 

blastoporphyritic metarhyolite and felsic 

schist. PZvs contains dark, greenish-gray 

mafic volcanic rocks and black phyllite, 

chert pebble conglomerates, tuffs, and 

graywackes. Basalt pillows, breccias, and

flows present in volcanic rocks. PZkcp

contains greenschist facies calc-phyllite, 

marble, and phyllite.

Moderate.

Units contain 

heterogeneous 

assemblages that 

may weaken 

rock columns on 

slopes; altered 

volcanic units 

may contain 

shrink–andswell clays.

Mass wasting, 

blockfall, and 

landslides are a 

potential hazard 

associated with 

these 

heterogeneous 

units.

None.

Phenocrysts 

may have 

attracted 

trade interest

and historic 

mining 

activity.

Quartz, orthoclase, 

and plagioclase 

phenocrysts;

stibiconite;

kermesite; stibnite;

pyrite; boulangerite;

cervantite; and

arsenopyrite. 

Marble, building 

materials, copperbearing minerals, 

polymetallic vein 

deposits, tactite, and 

stratiform 

occurrences;

support placer gold 

deposits.

Some minor 

dissolution 

is possible 

in marble.

Units may 

weather to 

produce 

nutrient-rich 

soils.

Units are fine 

for most 

recreation 

unless altered 

and/or heavily 

fractured.

Uranium-lead 

isotopes 

provide dates 

between 364 

and 375 million 

years.
Map Unit Properties Table: Denali National Park and Preserve (Small Scale [1:250,000] Map Units)

DENA Geologic Resources Inventory Report 50

Age Map Unit

(Symbol) Unit Description Erosion Resistance

Suitability for 

Infrastructure Hazards Paleontological Resources

Cultural 

Resources Mineral Occurrence Karst Issues Habitat Recreation GeologicSignificance

PALEOZOIC AND(OR) PROTEROZOIC?

Quartz and Pelitic Schist 

of the Yukon-Tanana 

Upland

(PZZYqs)

Schist and Amphibolite

(PZZYsa)

PZZYqs contains multiply metamorphosed 

quartzite, schistose quartzite, and quartzmica schist with minor gritty quartzite, 

chlorite schist, calc-silicate schist, marble, 

magnetite-biotite schist, amphibolite, and 

greenstone. PZZYsa contains pelitic schist 

containing subordinate quartzite, quartzschist, calc-silicate rocks and calc-schist, 

marble, amphibolite, graphitic schist, and 

augen gneiss interlayers. Unit is largely 

fault-bounded. Unit contains local augen 

gneiss.

Moderately 

high.

Avoid schistose 

layers for heavy 

infrastructure.

Schistose nature 

of units renders 

them friable,

and—when 

combined with 

layers of more 

resistant, hard 

rock—a 

dangerous 

rockfall situation 

occurs.

None.

Augen may 

have 

provided 

valuable 

trade 

materials;

historic 

mining

activity.

Augen gneiss. 

Marble, magnetite, 

graphite, and 

polymetallic mineral 

deposits.

Some minor 

dissolution 

possible in 

marble.

Some high 

calcium soils 

could be 

derived from 

these units.

Avoid friable 

schistose 

layers for 

heavy 

recreation.

Uranium-lead

isotopes in

zircon provide 

dates of 365 

million years

for protolith, 

potassiumargon isotopes 

providing dates 

ranging from 

105 to 120 

million years 

for 

metamorphic 

event timing.

PALEOZOIC OR 

PRECAMBRIAN

Pelitic and Quartzose

Schist of the Alaska 

Range

(PZZaqs)

Pelitic and Quarzitic 

Schist

(PZZrqs)

PZZaqs contains pelitic and quartzose 

schist with local calc-schist and feldspathic 

layers at greenschist to amphibolite facies 

metamorphic grade. PZZrqs is composed 

mostly of muscovite- and quartz-rich schist, 

and lesser calc-schist, quartzofeldspathic 

schist, gneiss, amphibolite, and quartzite, 

with scant marble interbeds. Metamorphic 

history includes greenschist, blueschist, 

granulite, and amphibolite facies conditions 

overprinting each other.

Moderate.

Avoid schistose 

layers for heavy 

infrastructure.

Schistose nature 

of units renders 

them friable and 

prone to rockfall 

and failure on a 

slope.

None. None 

documented.

High temperature 

and pressure 

metamorphic 

minerals. Thin 

marbles and 

abrasives.

Some minor 

dissolution 

possible in 

thin marble 

interbeds.

Quartzite may 

form spires 

attractive to 

goats and 

birds.

Avoid friable 

schistose 

layers for 

heavy 

recreation.

PZZrqs records 

conditions 

during extreme 

pressure and 

temperature of 

orogenesis.

PROTEROZOIC

Gritty Lower Unit

(Zwg)

Metamorphic Basement 

Rocks of the Nixon 

Fork Sequence, 

Undivided

(ZYnm)

Zwg contains poorly sorted quartzite and 

gritty quartzite with conspicuous granule 

conglomerate (contains white to blue quartz 

augen in a cherty, quartzofeldspathic-wacke 

matrix). ZYnm is metamorphosed 

(greenschist facies) quartz and pelitic schists 

with some heterogeneous pods, lenses, and 

layers of calc-schist, quartzofeldspathic 

schist, marble, schistose felsic metavolcanic 

rocks, greenstone, and gneissic and 

schistose plutonic rocks.

High to 

moderately 

high for 

schistose 

layers.

Avoid highly 

fractured areas 

for 

infrastructure;

fine for most 

light 

infrastructure.

Blockfall and 

landslides are a 

potential hazard 

associated with 

these 

heterogeneous 

units.

None documented;

deformation and 

metamorphism likely 

obscures any 

preexisting fossil 

remains.

Augen may 

have 

provided 

valuable 

trade 

materials.

Single-crystal milky 

white to blue quartz 

augen. Marble, 

abrasives and 

attractive building 

stones.

Some minor 

dissolution 

possible in 

marble.

None 

documented.

Units are fine 

for most 

recreation. 

Avoid 

micaceous

areas for 

climbing.

Unit records 

beach deposits? 

Potassiumargon isotope

ages date 

metamorphism 

at 296 to 291 

million years;

Uranium-lead 

isotopes in

zircon provide 

ages of 1,250 ±

50 million 

years.

UNKNOWN

Bedrock of Unknown 

Type or Age

(UNKbu)

Ultramafic and 

Associated Rocks

(UNKmlu)

UNKmlu contains serpentinized (altered) 

ultramafic rocks, as well as altered basalts, 

tuffs, and recrystallized chert. Unit appears 

green to maroon in a small sliver of outcrop.

UNKbu contains a mixed rubble of 

metasiltstone and chert, as well as unknown 

bedrock areas. 

Moderate.

Avoid areas of 

heavy alteration 

and/or a high 

concentration of 

fractures and 

joints.

Units are altered 

and poorly 

consolidated in 

areas, rendering 

them susceptible 

to rockfall and 

mass wasting.

Fossils possible, but 

none were specified.

None 

documented.

Secondary 

mineralization in 

basalt vesicles. 

Attractive green and 

red stones.

Unknown.

Unit supports 

development 

of iron- and 

magnesiumrich soils.

Units are fine 

for most 

recreation, 

although high 

iron content 

may interfere 

with compass 

reading.

Unit presents 

future research 

possibilities to 

determine 

precise timing 

and 

provenance.
DENA Geologic Resources Inventory Report 51

Geologic History

This section describes the rocks and unconsolidated deposits that appear on the digital 

geologic map of Denali National Park and Preserve, the environment in which those 

units were deposited, and the timing of geologic events that created the present 

landscape.

Ongoing research continues to yield new interpretations 

of the complex geologic history of Alaska and the Denali 

National Park and Preserve area.

Precambrian (prior to 542 million years ago)

The geologic story of Denali National Park and Preserve 

begins in Precambrian time (fig. 21). The oldest rocks in 

the park are the metamorphosed and deformed 

remnants of near shore beach, shallow to deep marine, 

and volcanic deposits. These rocks were deposited in an 

ancient ocean basin off the coast of the North American 

craton. Approximately 1 billion years ago, during the 

Proterozoic Eon, quartz-rich sands and muds were being 

shed from the ancient craton and deposited in a shallow 

sea. During this time, North America was part of a large 

supercontinent known as Rodinia (Condie and Sloan

1998).

Paleozoic Era (542 to 251 million years ago)

During the early Paleozoic, volcanic activity began in the 

marine basin, possibly accompanying the breakup of 

Rodinia, spreading basaltic lava and erupting volcanic 

ash to mix with the terrigenous sediments. In shallow sea 

areas, during the Cambrian, Silurian, and Devonian 

periods, marine animals (including corals) thrived, 

creating layers of limy muds mixed with the quartz-rich

sands and volcanic layers in the park (Gilbert 1979).

Following deposition, these early deposits experienced

several episodes of folding deformation and 

metamorphism under extreme temperature and pressure 

conditions. Metamorphism is bracketed between the 

middle Paleozoic age of the youngest protoliths and the 

widespread mid-Cretaceous granitic intrusions (DuselBacon et al. 1993). Deformation under conditions that 

produce greenschist and amphibolite rocks resulted in 

northwest-trending folds. A second episode at lower 

greenschist-facies conditions overprinted these folds 

with northeast trending folds during the Cretaceous 

(Dusel-Bacon et al. 1993). During greenschist to 

amphibolite-facies conditions, quartz sand deposits were 

hardened into quartzites; mixed sand, mud, and volcanic 

layers were converted to micaceous schists, gneisses, and 

phyllites; and limy mud deposits were metamorphosed 

into marble. 

This assemblage of rocks forms much of the widespread 

Yukon-Tanana terrane, which creates the basement 

complex of much of interior Alaska (Gilbert 1979; Moore 

et al. 1994). It is separated from younger terranes toward 

the south within the park by the Hines Creek fault, the 

northern branch of the Denali fault system. Timing of 

deformation for the rocks north of the Hines Creek fault 

is poorly constrained between fossil ages from the 

middle Paleozoic protoliths and undeformed Mesozoic 

age granitic igneous intrusions (Dusel-Bacon et al. 1993).

As early as the Middle Silurian, intermittent periods of 

tectonic collision and subduction of oceanic crust and 

occasional island arcs were occurring west of the North 

American continent, slowly adding pieces to the 

continental land mass. At least two subduction zones 

were present during the Mississippian, Pennsylvanian, 

and Permian periods. There is no evidence of significant 

mountain building (orogenesis) during this time in the 

Denali area. In the western conterminous United States, 

however, the Antler terrane was accreted during the 

Mississippian Antler orogeny (Condie and Sloan 1998). 

Mesozoic Era (251 to 65.5 million years ago)

The Antler orogeny started a long sequence of accretions 

along the western edge of the continent as the plates 

(Kula-Farallon-Pacific and North American plates) 

collided and slid past each other. The accretion of the 

metamorphosed and deformed ocean basin and volcanic 

flows of the Yukon-Tanana terrane onto the North 

American craton in the Denali area was possibly 

completed by about 225 million years ago in the early 

Triassic or prior to the Jurassic (Moore et al. 1994). 

Several large terranes, including Sonomia (Middle 

Triassic) and Stikinia (Late Triassic), were added to 

western Canada. 

South of the Hines Creek fault, part of other tectonic 

terranes (Pingston, Windy, Dillinger, and McKinley 

terranes) are belts of metamorphic rocks containing gray 

slate, marble, metamorphosed intrusive mafic rocks 

(gabbros), and greenstones (altered basalts) (Gilbert

1979; Lillie 2005). These rocks are part of a complex 

suture zone disrupted by strike-slip faulting along the 

Denali fault system (described below) and thrust or

normal bounding faults (Coney et al. 1980). These rocks 

were deposited in the latter half of the Paleozoic and 

beginning of the Mesozoic Era as muds, sand, and fossil 

debris in a deep ocean basin at tropical latitudes. Marine 

environments dominated the area for hundreds of 

millions of years. Some early minor deformation created 

fissures, allowing basaltic magma to intrude as plutons 

and extrude as flows (Gilbert 1979).

As the Peninsular and Wrangellia segments of the 

composite Talkeetna superterrane (elsewhere called the 

southern Alaska or Wrangellia composite terrane) were 

being dragged toward the southern boundary of the 

continent, the sediments trapped between the 

approaching terrane and the continent were squeezed, 
52 NPS Geologic Resources Division

metamorphosed, and deformed to form a northeastward 

tapering wedge of rocks (Farewell terrane?) called flysch. 

This accompanied an eastward-increasing metamorphic 

grade sequence during the Late Mesozoic (Dusel-Bacon 

et al. 1993). The Upper Jurassic-Cretaceous Kahiltna 

assemblage records a basin that persisted between the 

terranes and now contains flysch (Ridgway et al. 2002).

Some portions of the flysch wedge are exposed in 

mountains of the eastern portion of the park, such as Mt. 

Pendelton and Scott Peak. Masses of accreted island 

arcs, forming portions of the Pingston and McKinley 

terranes, were also caught between southern Alaska and 

the Talkeetna superterrane about 200 million years ago. 

The culmination of this event involved the emplacement 

of structurally interleaved tectonic fragments and low- to 

medium-grade metamorphism, creating the Maclaren 

metamorphic belt.

In the Jurassic, the block of rocks that eventually became 

the Brooks Range in northern Alaska collided with 

North America, producing high-pressure 

metamorphism, deformation, and thrusting along the 

southern margin of the continental terranes (Moore et al. 

1994). In the Early Jurassic, northward thrusting off the 

coast of central Alaska caused terranes to “telescope”

together. Large nappes and thrusts were forced onto the 

southern and western edges of the older accreted 

terranes (Condie and Sloan 1998). The Nevadan orogeny 

of the western conterminous United States also occurred 

during this time. Extreme crustal thickening along the 

plate margins led to partial melting at depth and the 

emplacement of Jurassic age igneous batholiths (granite, 

granodiorite, quartz diorite, and tonalite) of the AlaskaAleutian Range (Wilson et al. 1998). Between the Denali 

fault system and the Border Ranges to the south, a 

medium-grade metamorphic event occurred across most 

of the southern Peninsular and Wrangellia terranes prior 

to final accretion onto the continent. This 

metamorphism accompanied local intrusions of tonalitic 

to granodioritic plutons of Early to Middle Jurassic age 

in the Peninsular terrane and of Late Jurassic age in the 

Wrangellia terrane (Dusel-Bacon et al. 1993). Jurassic age 

plutons are present in the Talkeetna Mountains (Miller

1994).

Metamorphism within the Chugach accretionary wedge, 

south of the park, was associated with north-directed 

underthrusting beneath the Peninsular and Wrangellia 

terranes beginning in the Early to Middle Jurassic. This 

event created metabasalts, metachert, and other 

metasedimentary rocks under greenschist to highpressure blueschist metamorphic facies conditions

(Dusel-Bacon et al. 1993).

Starting in the Jurassic, strong orogenic activity began the 

formation of the Alaska Range. This was in response to 

subduction of the Kula Plate beneath southern Alaska. 

Accompanying subduction was terrane accretion, thrust 

faulting, crustal thickening, isostatic adjustment, and 

plutonism (Dumoulin et al. 1998). As the subducting 

Kula Plate (described below) descended farther into the 

crust beneath southern Alaska, dewatering of the oceanic 

crust as well as increasing heat caused local melting. This 

melting created magma plumes that rose to form 

relatively buoyant granitic plutons that now compose the 

core of the Alaska Range. Some of the oldest plutons are 

dated at 149 million years ago, whereas the younger 

plutons are 29 million years old (Wilson et al. 1998).

Intense deformation, plutonism, metamorphism, and 

volcanism continued in the Denali area in response to 

subduction and subsequent terrane accretion during the 

Cretaceous (fig. 22) (Condie and Sloan 1998). During

most of the accretion events, rising crustal temperatures 

led to massive gold vein formation (Goldfarb et al. 1997).

Movement along the Denali fault might have started 

during this time. Accretion of the Talkeetna superterrane—transported from the south along the margin of 

western Canada by dextral strike-slip movement—was 

complete by 110 to 85 million years ago during the 

Cretaceous (Hickman et al. 1990; Miller et al. 2002).

Prior to regional uplift, much of the Denali area was 

composed of continental lowlands, similar to the areas 

north of the Alaska Range today. Streams flowed 

predominantly south toward the coast, depositing 

alluvial sand, gravel, and silt. During the early stages of 

uplift, streams began diverting to northerly courses

(fig. 23). A pull-apart asymmetrical basin graben 

developed in the area between the Hines Creek and 

southern fault strands of the Denali fault system. This socalled Cantwell Basin filled with as much as 4,000 m 

(13,000 ft) of southward thickening sediments (Hickman 

et al. 1990).

Cenozoic Era (the past 65.5 million years)

Intense regional volcanism peaked around 56 and 38 

million years ago, leading to vast igneous intrusions and 

deposits of red, yellow, and brown basalts, rhyolites, 

andesites, and other volcanic rocks (Teklanika 

Formation). Some of these extrusive rocks are present at 

Polychrome Pass (older event) and Mt. Galen (younger 

event) (Cole 2004). Contemporaneous granitic igneous 

intrusions formed Mt. Eielson and Mt. Foraker (Gilbert

1979). Hydrothermal activity increased as well, leading to 

the development of gold-bearing quartz vein systems

(fig. 24) (Goldfarb et al. 1997). Extensive volcanic flows

covered the stream sediments that ultimately became the 

shale, sandstone, coal beds, and pebble conglomerate of 

the Tertiary lower Cantwell Formation (Wahrhaftig

1970; Gilbert 1979; Hickman et al. 1990).

During the Jurassic and Cretaceous, three major plates 

existed west of the North American continent separated 

by mid ocean spreading ridges: the Kula, Farallon, and 

Pacific plates. Most remnants of the Kula and Farallon 

plates were lost to subduction beneath northeastern Asia 

and western North America, respectively.The Juan de 

Fuca and Cocos plates in the eastern Pacific basin are 

remnants of the otherwise subducted Farallon plate. 

Subduction of the Farallon plate drove the Laramide 

orogeny spanning from Mexico to Canada from the Late 

Cretaceous into the Tertiary. 

By the mid-Tertiary, the Pacific plate dominated the 

basin. Dated volcanic layers (53.9 ± 1.6 million years ago

based on argon isotopes [40Ar/39Ar]) in the upper 
DENA Geologic Resources Inventory Report 53

Cantwell Formation are cut by younger high angle, 

northwest-trending, right-lateral shear zones, suggesting 

that the once collisional boundary between Alaska and 

the Pacific plate was changing to a more translational 

(“side-swiping”) boundary by this time (Cole et al. 1996). 

Once the Farallon spreading ridge (East Pacific Rise) was 

consumed, the margin between the Pacific and western 

North American plates became more transform in 

nature, around 30 million years ago (creating the San 

Andreas fault), and the Pacific plate continued to travel 

northwestward, subducting beneath Alaska, and 

dragging terranes with it (Condie and Sloan 1998).

From the Cretaceous to early Tertiary, accompanying the 

accretion of the Chugach accretionary prism to the 

south, the southern edge of the Talkeetna superterrane 

was exposed to further deformation and overprinting of 

a lower-grade metamorphic event (Dusel-Bacon et al.

1993). The Chugach split into a sequence of accretionary 

prisms and mélange complexes that underthrust each 

other sequentially from south to north, each 

accompanied by pervasive deformation and metamorphism throughout the Cretaceous into the early 

Tertiary. The accretionary wedge in its entirety was part 

of southern Alaska by about 67 million years ago, 

followed by the accretion of the Prince William 

accretionary prism at approximately 50 million years ago

(Lillie 2005). Between these large terranes, forearc 

basins, narrow volcanic arcs, and small-scale marine 

basins received alluvial, volcanic, and shallow marine 

sediments that record uplift to the north and subsequent 

erosion of vast amounts of sediments, as well as thrust 

faulting to the south associated with continued accretion 

in the Talkeetna area (Trop et al. 2003).

As accretion of the Yakutat Terrane that started ~20 

million years ago persists today, low-pressure, 

amphibolite facies metamorphism and deformation is 

occurring on the southern coast of Alaska (Dusel-Bacon 

et al. 1993; Lillie 2005). The Pacific plate continues to 

move northwestward at a rate of approximately 5 cm (2 

in.) per year. This active margin has lead to extensive 

faulting throughout the region over the past 100 million 

years. Some of this deformation is accommodated along 

the right-lateral Denali fault system running parallel to 

the Alaska Range. Fresh fault scarps and offset stream 

gravels attest to recent movement along the fault 

(Wahrhaftig 1970), as well as the magnitude 7.9 Denali 

fault earthquake in 2002 (Eberhart-Phillips et al. 2003). 

Maximum local uplift rates in Denali are estimated at ~1 

km/million years (0.6 mi/million years) beginning in the 

late Tertiary as a result of changes in motion of the 

Pacific plate relative to North America. This, in 

conjunction with the geometry (bend) along the Denali 

fault, caused local crustal blocks to be rapidly forced 

upward (Fitzgerald et al. 1993).

Block faulting during the mid-Tertiary created 

downfaulted inland basins, which collected vast deposits 

of sediments, including the coal-bearing Suntrana Group 

(30 to 5 million years ago) (Wahrhaftig 1970; Gilbert

1979). The Tertiary basin coal-bearing rocks record 

terrestrial cyclic sequences of siltstone, claystone, 

mudstone, shale, pebbly sandstone, subbituminous coal 

and lignite, and minor amounts of pebble conglomerate 

(Wilson et al. 1998). These basins supported vast forests 

and swampy bog environments (Gilbert 1979). The coalbearing rocks were covered by sand and gravel shed 

from erosion of further uplift of the Alaska Range during 

the Pliocene Epoch (5.3 to 2.6 million years ago). These 

thick sediments comprise the poorly consolidated 

Nenana Gravel (Gilbert 1979; Wilson et al. 1998).

Erosion kept pace with exhumation of the Alaska Range 

until the beginning of Pliocene time. Around 6 million 

years ago, the Alaska Range began to uplift rapidly,

causing most major streams of the central portions of the 

range to flow north (Gilbert 1979). During the Pliocene–

Pleistocene, several global ice age events also occurred. 

Glacial ice covered vast extents of the Alaska Range, 

carving U-shaped valleys. Interglacial period climates 

supported the growth of open boreal woodland, dense 

alder shrub vegetation, open taiga, graminoid tundra, 

and birch shrub tundra through at least the past 50,000 

years. Holocene coniferous forests only became 

established after 6,500 years before present (Elias et al.

1996). This vegetation is recorded in recent peat, swamp, 

bog, and other organic deposits in the Quaternary 

unconsolidated sediments in the foothills north of the 

Alaska Range in the park.

Between four and seven major glacial advances altered 

the landscape at Denali between 2 million and 10,000 

years ago (Gilbert 1979; Brease 2004), starting with the 

Teklanika glacial advance, which began possibly in the 

late Pliocene to early Pleistocene. Other advances,

including the Browne, Bear Creek, Dry-Lignite Creek, 

Healy-McLeod Creek, and Riley Creek, are also locally 

recorded in the glacial deposits at Denali. The Carlo 

Creek Readvance began in the early Holocene, 8,000 

years ago (Brease 2004). End units from this advance 

form lakes that trap fine-grained sands and other 

lacustrine deposits today (Wahrhaftig 1952). The past

glacial advances left ice erosional and glacial depositional 

features in most of the river valleys within the park. Ushaped valleys are present in the Savage, Toklat, 

Thorofare, Sanctuary, Teklanika, and McKinley Rivers’ 

drainages. Large glacial erratic deposits are located 

throughout lower areas of the park (Brease 2004). Glacial 

processes continue today as smaller glaciers cover more 

than 1 million acres within Denali National Park and 

Preserve. Table 1 summarizes the geologic history in the 

Denali area of Alaska.
54 NPS Geologic Resources Division

Figure 21: Geologic timescale. Included are major life history and tectonic events occurring on the North American continent with an emphasis 

on events affecting Alaska. Red lines indicate major unconformities between eras. Isotopic ages shown are in Ma. Compass directions in 

parentheses indicate the regional location of individual geologic events. Adapted from the U.S. Geological Survey, http://pubs.usgs.gov/fs/

2007/3015/, with additional information from the International Commission on Stratigraphy, http://www.stratigraphy.org/view.php?id=25.
DENA Geologic Resources Inventory Report 55

Figure 22: Three-dimensional model of an active margin setting with successive terrane accretion, uplift, volcanism, and subduction. Graphic 

by Trista L. Thornberry-Ehrlich (Colorado State University), adapted from Lillie (2005) fig. 11.8.

Figure 23: Reversal of stream direction from southward to northward accompanying uplift of the Alaska Range in the early Cenozoic. Graphic 

is by Trista L. Thornberry-Ehrlich (Colorado State University), adapted from Gilbert (1979) fig. 13.
56 NPS Geologic Resources Division

Figure 24: Map of Alaska during the Paleocene and Eocene epochs showing generalized locations of major terranes, faults, as well as 

significant gold districts (black circles). Graphic by Trista L. Thornberry-Ehrlich (Colorado State University), adapted from Goldfarb et al. (1997) 

fig. 7.
DENA Geologic Resources Inventory Report 57

Table 1: Summary of geologic events in the Denali area. Ma = million years ago; ybp = years before present. Colors (also used on the Map 

Unit Properties Table) according to the Commission for the Geological Map of the World. Table modeled after Brease (2004) table 34.1. Eon Era

Period Epoch Geologic Events

PHANEROZOIC

CENOZOIC

QUATERNARY

HOLOCENE Cantwell ash fall with volcanism from southerly source (~3,700 ybp) 

and multiple glaciation events.

PLEISTOCENE Multiple glacial advances starting ~2 Ma to 8,000 ybp; intense glacial 

erosion of rapidly uplifting Alaska Range.

TERTIARY

NEOGENE

PLIOCENE

Deposition of Nenana Gravel shed from uplifting Alaska Range; 

units include sandstone, conglomerates, claystone, and lignite. 

Uplift and exhumation of Mt. McKinley. Movement along Denali 

fault system likely resumes. 

MIOCENE

Deformation and thrust faulting cause a surge in uplift of the Alaska 

Range; beginning of Yakutat terrane accretion. Regional subsidence 

due to crustal thickening and continued sedimentation and coal 

deposits of the Tanana foreland.

PALEOGENE

OLIGOCENE Deposition in subsidence basins north and south of the Alaska 

Range; several phases of igneous intrusion and volcanism at 38 Ma.

EOCENE

Cantwell volcanism and McKinley intrusive sequence from 41 to 57 

Ma results in flows, breccias, and tuffs, as well as granodiorite 

intrusion with some sulfide mineralization; Prince William wedge 

accretes.

PALEOCENE

Emergent Alaska Range continues to shed sediments into foreland 

pull-apart basin, leading to piles of sandstone, siltstone, shale, tuff 

layers, coal, and conglomerates of the Cantwell Formation; strikeslip movement along Denali fault. Continued intrusion of granites in 

the Alaska Range, including the McKinley and Ruth plutons. 

MESOZOIC

CRETACEOUS

Multiple phases of igneous intrusive activity (granites and granodiorites), volcanism, and 

orogenesis as the Chugach wedge accretes to the continent; continued flysch deposition 

in shallow basins; pervasive deformation and metamorphism at 115 to 106 Ma, 74 Ma, and 

65 to 60 Ma; uplift of Alaska Range continues. Final closer of ocean between Talkeetna 

Superterrane, and previously accreted terranes to the north. 

JURASSIC

Orogenic activity increases as Talkeetna superterrane is accreting, pushing miniterranes 

within the intervening basin toward the continent; intense deformation and metamorphism; continued deposition of Mesozoic flysch in segmented, forearc, and backarc 

basins

TRIASSIC

Final accretion of Yukon-Tanana terrane; abundant submarine basalt flows form Nikolai 

Greenstones; continued deposition of redbed sandstones, conglomerates, tuffs, argillites, 

and limestones; Pingston, McKinley, and Chulitna terranes are pushed toward the margin 

of North America.

PALEOZOIC

PERMIAN Deposition of alternating limestone and argillite beds of the Eagle Creek Formation, as 

well as massive marine limestone, mudstone, and greywacke.

PENNSYLVANIAN

Widespread volcanism forms andesitic Tetelna Volcanics, later metamorphosed to 

greenschist; continued marine deposition of cherts, pillow basalts, shales, fossiliferous 

limestones, sandstones, and argillites.

MISSISSIPPIAN Moose Creek Member basaltic to intermediate volcanism, later metamorphosed to 

greenschists (Totatlanika Schist).

DEVONIAN Andesitic tuff from island arc volcanism, red and brown chert deposits, and shallow 

marine basin limestone.

SILURIAN Marine deposition and coral growth; intermittent volcanic activity. Continued deposition 

of turbidites, sandstones, argillites, dolomitic limestones, cherts, volcanic flows and ash 

falls, shales, and conglomerates; intermittent igneous activity, including mafic dike 

intrusions; multiple phases of deformation and metamorphism change sediments to 

quartzites, phyllites, slates, marbles, gneisses, meta-volcaniclastic schists, and greenstones.

ORDOVICIAN

CAMBRIAN

PRECAMBRIAN

Shallow marine basins covered large area south of ancient North American continent; 

resulted in deposition of quartz-rich sediments interlayered with volcanic flows and ash 

and limestone. Formations include Keavy Peak Formation and Birch Creek Schist.
58 NPS Geologic Resources Division

Glossary

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

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

here please visit: http://geomaps.wr.usgs.gov/parks/misc/glossarya.html. Definitions are 

based on those in the American Geological Institute Glossary of Geology (fifth edition; 2005).

accretionary prism. A wedge-shaped body of rock 

consisting of rocks scraped off of subducting oceanic 

crust at a subduction zone. Rocks consist of trench-fill 

turbidites, seamounts and surrounding reefs. 

Accretionary prisms form in the same manner as a pile 

of snow in front of a snowplow. 

active margin. A tectonically active margin where 

lithospheric plates converge, diverge or slide past one 

another (also see “passive margin”). Typically 

associated with earthquakes and, in the case of 

convergent and divergent boundaries, volcanism. 

alluvial fan. A fan-shaped deposit of sediment that 

accumulates where a hydraulically confined stream 

flows to a hydraulically unconfined area. Commonly 

out of a mountain front into an area such as a valley or 

plain.

alluvium. Stream-deposited sediment.

alpine glacier. A glacier occurring in a mountainous 

region on the sides of a mountain. 

altiplanation. Soliflucation and related mass movements 

that tend to produce flat or terrace-like surfaces, 

especially at high elevation and latitudes where 

periglacial processes predominate. 

andesite. A dark-colored, fine-grained extrusive rock 

that, when porphyritic, contains phenocrysts 

composed primarily of zoned sodic plagioclase and 

one or more of the mafic minerals with a groundmass 

composed generally of the same minerals as the 

phenocrysts. 

angular unconformity. An unconformity where the strata 

above and below are oriented differently; generally 

caused by structural deformation and erosion prior to 

deposition of the upper bed.

anticline. A convex-upward (“A” shaped) fold. Older 

rocks are found in the center.

anticlinorium. A large, regional feature with an overall 

shape of an anticline. Composed of many smaller 

folds.

aquifer. A rock or sedimentary unit that is sufficiently 

porous that it has a capacity to hold water, sufficiently 

permeable to allow water to move through it, and 

currently saturated to some level.

arête. A rocky sharp-edged ridge or spur, commonly 

present above the snowline in rugged mountains 

sculptured by glaciers, and resulting from the 

continued backward growth of the walls of adjoining 

cirques. 

argillite. A compact rock, derived from mudstone or 

shale, more highly cememted than either of those 

rocks. It lacks the fissility (easily split) of shale or the 

cleavage of slate. It is regarded as a product of lowtemperature metamorphism.

ash (volcanic). Fine pyroclastic material ejected from a 

volcano (also see “tuff”).

asthenosphere. Earth’s relatively weak layer or shell 

below the lithosphere.

axis (fold). A straight line approximation of the trend of a 

fold, that divides the two limbs of the fold.

base flow. Stream flow supported by groundwater flow 

from adjacent rock, sediment, or soil.

base level. The lowest level to which a stream can erode 

its channel. The ultimate base level for the land surface 

is sea level, but temporary base levels may exist. 

basement. The undifferentiated rocks, commonly 

igneous and metamorphic, that underlie the rocks 

exposed at the surface.

basin (sedimentary). Any depression, from continental to 

local scales, into which sediments are deposited.

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

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

batholith. A massive, discordant pluton, greater than 100 

km2

, (40 mi2) often formed from multiple intrusions.

bed. The smallest sedimentary strata unit, commonly 

ranging in thickness from one centimeter to a meter or 

two and distinguishable from beds above and below.

bedding. Depositional layering or stratification of 

sediments.

bedrock geology. The geology of underlying solid rock 

as it would appear with the sediment, soil, and 

vegetative cover stripped away.

bergschrund. The crevasse occurring at the head of an 

alpine glacier, which separates the moving snow and 

ice of the glacier from the relatively immobile snow 

and ice adhering to the headwall of a cirque.

block (fault). A crustal unit bounded by faults, either 

completely or in part.

blueschist. A schistose metamorphic rock with a blue 

color due to the presence of sodic amphibole, e.g. the 

minerals glaucophane or crosstie, and commonly 

mottled bluish-gray lawsonite. Often associated with 

high pressure, relatively low temperature metamorphic 

conditions.

braided stream. A stream, clogged with sediment that 

forms multiple channels that divide and rejoin.

breccia. A coarse-grained, generally unsorted 

sedimentary rock consisting of cemented angular 

clasts greater than 2 mm (0.08 in).

brittle. Describes a rock that fractures before sustaining 

deformation.

calcareous. Describes rock or sediment that contains 

calcium carbonate (CaCO3).

carbonaceous. Describes a rock or sediment with 

considerable carbon, especially organics, 

hydrocarbons, or coal.
DENA Geologic Resources Inventory Report 59

cataclasite. A fine-grained rock formed by pervasive 

fracturing, milling, crushing, and grinding by brittle 

deformation, typically under conditions of elevated 

pressure.

cementation. Chemical precipitation of material into 

pores between grains that bind the grains into rock.

chemical sediment. A sediment precipitated directly from 

solution (also called nonclastic).

chemical weathering. Chemical breakdown of minerals 

at Earth’s surface via reaction with water, air, or 

dissolved substances; commonly results in a change in 

chemical composition more stable in the current 

environment.

chert. A extremely hard sedimentary rock with 

conchoidal (smooth curved surface) fracturing. It 

consists chiefly of interlocking crystals of quartz (syn: 

flint).

cirque. A deep, steep-walled, half-bowl-like recess or 

hollow located high on the side of a mountain and 

commonly at the head of a glacial valley. Produced by 

the erosive activity of a mountain glacier. It often 

contains a small round lake.

clastic. Describes rock or sediment made of fragments of 

pre-existing rocks.

clay. Can be used to refer to clay minerals or as a 

sedimentary fragment size classification (less than 

1/256 mm [0.00015 in]).

cleavage. The tendency of a rock to split along parallel, 

closely spaced planar surfaces. It is independent of 

bedding and is produced by deformation or 

metamorphism.

concordant. Strata with contacts parallel to the attitude 

of adjacent strata.

congeliturbate. Mass of soil or other unconsolidated 

material moved or disturbed by frost action.

conglomerate. A coarse-grained, generally unsorted, 

sedimentary rock consisting of cemented rounded 

clasts larger than 2 mm (0.08 in).

continental crust. The crustal rocks rich in silica and 

alumina that underlie the continents; ranging in 

thickness from 35 km (22 mi) to 60 km (37 mi) under 

mountain ranges.

continental shield. A continental block of Earth’s crust 

that has remained relatively stable over a long period 

of time and has undergone only gentle warping 

compared to the intense deformation of bordering 

crust

convergent boundary. A plate boundary where two 

tectonic plates are colliding.

cordillera. A Spanish term for an extensive mountain 

range that is used in North America to refer to all of 

the western mountain ranges of the continent.

craton. The relatively old and geologically stable interior 

of a continent (also see “continental shield”).

crevasse. A deep fissure or crack in a glacier, caused by 

stresses resulting from differential movement over an 

uneven surface. Crevasses may be as much as 100 m 

(330 ft) deep. 

cross section. A graphical interpretation of geology, 

structure, and/or stratigraphy in the third (vertical) 

dimension based on mapped and measured geological 

extents and attitudes depicted in a vertically oriented 

plane.

cross-bedding. Uniform to highly varied sets of inclined 

sedimentary beds deposited by wind or water that 

indicate distinctive flow conditions (e.g., direction and 

depth).

crust. Earth’s outermost compositional shell, 10 to 40 km 

(6 to 25 mi) thick, consisting predominantly of 

relatively low-density silicate minerals (also see 

“oceanic crust” and “continental crust”).

crystalline. Describes a regular, orderly, repeating 

geometric structural arrangement of atoms.

dacite. A fine-grained extrusive rock with the same 

general composition as andesite, but having a less 

calcic plagioclase and more quartz.

debris cone. A cone or mound of ice or snow on a glacier, 

covered with a veneer of debris thick enough to 

protect the underlying material from ablation.

debris flow. A rapid and often sudden flow or slide of 

rock and soil material involving a wide range of types 

and sizes.

deformation. A general term for the process of faulting, 

folding, and shearing of rocks as a result of various 

Earth forces such as compression (pushing together) 

and extension (pulling apart).

dike. A tabular, discordant igneous intrusion.

dip. The angle between a bed or other geologic surface 

and horizontal.

dip-slip fault. A fault with measurable offset where the 

relative movement is parallel to the dip of the fault.

disconformity. An unconformity at which the bedding of 

the strata above and below are parallel.

discordant. Having contacts that cut across or are set an 

angle to the orientation of adjacent rocks.

divergent boundary. An active boundary where tectonic 

plates are moving apart (e.g., a spreading ridge or 

continental rift zone).

drainage basin. The total area from which a stream 

system receives or drains precipitation runoff.

drift. All rock material (clay, silt, sand, gravel, boulders) 

transported by a glacier and deposited directly by or 

from the ice, or by running water emanating from a 

glacier.

ductile. Describes a rock that is able to sustain 

deformation before fracturing.

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

action of the wind.

extrusive. Of or pertaining to the eruption of igneous 

material onto the surface of Earth.

facies (metamorphic). The pressure-temperature regime 

that results in a particular, distinctive metamorphic 

mineralogy (i.e., a suite of index minerals).

facies (sedimentary). The depositional or environmental 

conditions reflected in the sedimentary structures, 

textures, mineralogy, fossils, etc. of a sedimentary 

rock.

fan delta. An alluvial fan that builds into a standing body 

of water. This landform differs from a delta in that a 

fan delta is next to a highland and typically forms at an 

active margin.

fault. A break in rock along which relative movement 

occurs between the two sides.

fault gouge. Soft, uncemented, pulverized, clay-like 

material found along some faults formed by friction as 

the fault moves.
60 NPS Geologic Resources Division

felsic. Describes an igneous rock having abundant lightcolored minerals such as quartz, feldspars, or 

muscovite. Compare to “mafic.”

flysch. A marine sedimentary facies characterized by a 

thick sequence of poorly fossiliferous, thinly bedded, 

graded marls and sandy and calcareous shales and 

muds, rhythmically interbedded with conglomerates

(rare), coarse sandstones, and graywackes. Typically 

deposited in deep ocean basins near convergent plate 

boundaries and rising mountains.

footwall. The mass of rock beneath a fault surface (also 

see “hanging wall”).

formation. Fundamental rock-stratigraphic unit that is 

mappable, lithologically distinct from adjoining strata, 

and has definable upper and lower contacts.

fracture. Irregular breakage of a mineral. Any break in a 

rock (e.g., crack, joint, fault).

frost wedging. The breakup of rock due to the 

expansion of water freezing in fractures.

gelifluction. Progressive lateral flow of earth material 

under periglacial conditions.

geology. The study of Earth, including its origin, history, 

physical processes, components, and morphology.

graben. A down-dropped structural block bounded by 

steeply dipping, normal faults (also see “horst”).

granodiorite. A group of plutonic rocks containing 

quartz, plagioclase, and potassium feldspar with 

biotite, hornblende, or, more rarely, pyroxene, as the 

mafic components.

graywacke. A term commonly used in the field for a dark 

gray to dark green, very hard, dense sandstone of any 

composition but with a chlorite-rich matrix; these 

rocks have undergone deep burial.

greenschist. A schistose metamorphic rock, whose green 

color is due to the presence of the minerals chlorite, 

epidote, or actinolite, corresponds with 

metamorphism at temperatures in the 300–500°C

(570–930°F) range. 

hanging valley. A tributary glacial valley whose mouth is 

high above the floor of the main valley, which was 

eroded by the main body of the glacier. 

hanging wall. The mass of rock above a fault surface 

(also see “footwall”).

horn. A high pyramidal peak with steep sides formed by 

the intersection walls of three or more cirques.

horst. Areas of relative “up” between grabens, 

representing the geologic surface left behind as 

grabens drop. The best example is the Basin-andRange province of Nevada. The basins are grabens and 

the ranges are weathered horsts. Grabens become a 

locus for sedimentary deposition (also see “graben”).

igneous. Refers to a rock or mineral that originated from 

molten material; one of the three main classes of 

rocks—igneous, metamorphic, and sedimentary.

intrusion. A body of igneous rock that invades (pushes 

into) older rock. The invading rock may be a plastic 

solid or magma.

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

and parallel to a subduction zone.

isostasy. The process by which the crust “floats” at an 

elevation compatible with the density and thickness of

the crustal rocks relative to underlying mantle.

isostatic adjustment. The shift of the lithosphere to 

maintain equilibrium between units of varying mass 

and density; excess mass above is balanced by a deficit 

of density below, and vice versa.

joint. A semi-planar break in rock without relative 

movement of rocks on either side of the fracture 

surface.

laccolith. A mushroom- or arcuate-shaped pluton that 

has intruded sedimentary strata and domed up the 

overlying sedimentary layers. Common on the 

Colorado Plateau.

lacustrine. Pertaining to, produced by, or inhabiting a 

lake or lakes.

lamination. Very thin, parallel layers.

landslide. Any process or landform resulting from rapid, 

gravity-driven mass movement.

lava. Still-molten or solidified magma that has been 

extruded onto Earth’s surface though a volcano or 

fissure.

lignite. A brownish-black coal that is intermediate in 

coalification between peat and subbituminous coal.

limbs. Either side of a structural fold.

lithification. The conversion of sediment into solid rock.

lithology. The physical description or classification of a 

rock or rock unit based on characters such as its color, 

mineral composition, and grain size.

lithosphere. The relatively rigid outmost shell of Earth’s 

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

encompasses the crust and uppermost mantle.

loess. Windblown silt-sized sediment, generally of glacial 

origin.

mafic. Describes dark-colored rock, magma, or minerals 

rich in magnesium and iron. Compare to “felsic.”

magma. Molten rock beneath Earth’s surface capable of 

intrusion and extrusion.

mantle. The zone of Earth’s interior between crust and 

core.

matrix. The fine grained material between coarse (larger) 

grains in igneous rocks or poorly sorted clastic 

sediments or rocks. Also refers to rock or sediment in 

which a fossil is embedded.

meander. Sinuous lateral curve or bend in a stream 

channel.

mechanical weathering. The physical breakup of rocks 

without change in composition.

mélange. A mappable body of jumbled rock that includes 

fragments and blocks of all sizes, both exotic and 

native, embedded in a fragmented and generally 

sheared matrix.

member. A lithostratigraphic unit with definable 

contacts; a member subdivides a formation.

meta–. A prefix used with the name of a sedimentary or 

igneous rock, indicating that the rock has been 

metamorphosed.

metamorphic. Describes the process of metamorphism 

or its results. One of the three main classes of rocks—

igneous, metamorphic, and sedimentary.

metamorphism. Literally, a change in form.

Metamorphism occurs in rocks through mineral 

alteration, genesis, and/or recrystallization from 

increased heat and pressure.
DENA Geologic Resources Inventory Report 61

mid-ocean ridge. The continuous, generally submarine, 

seismic, median mountain range that marks the 

divergent tectonic margin(s) in Earth’s oceans.

migmatite. Literally, “mixed rock” with both igneous 

and metamorphic characteristics due to partial melting 

during metamorphism.

mineral. A naturally occurring, inorganic crystalline solid 

with a definite chemical composition or compositional 

range.

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

usually flat-lying except in the flexure itself.

monzonite. A group of plutonic rocks containing 

approximately equal amounts of alkali feldspar and 

plagioclase, little or no quartz, and commonly augite as 

the main mafic mineral. Intrusive equivalent of latite.

moraine. A mound, ridge, or other distinct accumulation 

of unsorted, unstratified glacial drift, predominantly 

till, deposited chiefly by direct action of glacial ice.

mole track. A small, geologically short-lived ridge, 

formed by the humping up and cracking of the ground 

where movement along a large strike-slip fault 

occurred in heavily alluviated terrain.

moulin. A roughly cylindrical, nearly vertical hole or 

shaft in the ice of a glacier, scoured out by swirling 

meltwater as it pours down from the surface. 

mylonite. A fine-grained, foliated rock typically found in 

localized zones of ductile deformation, often formed at 

great depths under high temperature and pressure.

nappe. A sheetlike, allochthonous (manufactured 

elsewhere) rock unit that has moved in a 

predominantly horizontal surface. The mechanism 

may be thrust faulting, recumbent folding, or gravity 

sliding.

nonconformity. An erosional surface preserved in strata 

in which crystalline igneous or metamorphic rocks 

underlie sedimentary rocks.

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

moves down relative to the footwall.

obduction. The process by which the crust is thickened 

by thrust faulting at a convergent margin.

oceanic crust. Earth’s crust formed at spreading ridges 

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

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

composition.

orogeny. A mountain-building event.

outcrop. Any part of a rock mass or formation that is 

exposed or “crops out” at Earth’s surface.

outwash. Glacial sediment transported and deposited by 

meltwater streams.

overbank deposits. Alluvium deposited outside a stream 

channel during flooding.

overburden. Non-economic, often unconsolidated, rock 

and sediment overlying an ore, fuel, or sedimentary 

deposit.

paleogeography. The study, description, and 

reconstruction of the physical landscape from past 

geologic periods.

paleontology. The study of the life and chronology of 

Earth’s geologic past based on the fossil record.

Pangaea. A theoretical, single supercontinent that 

existed during the Permian and Triassic periods (also 

see Laurasia and Gondwana).

parent (rock). The original rock from which a 

metamorphic rock was formed. Can also refer to the 

rock from which a soil was formed.

passive margin. A margin where no plate-scale tectonism 

is taking place; plates are not converging, diverging, or 

sliding past one another. An example is the east coast 

of North America. (also see “active margin”).

pebble. Generally, small rounded rock particles from 4 to 

64 mm (0.16 to 2.52 in) in diameter.

periglacial. Describes processes, climates, and features at 

the margin of former or existing glaciers or icesheets 

influenced by the cold temperatures of the ice.

permeability. A measure of the relative ease with which 

fluids move through the pore spaces of rocks or 

sediments.

phenocryst. A coarse crystal in a porphyritic igneous 

rock.

placer. A surficial mineral deposit formed by mechanical 

concentration of mineral particles from weathered 

debris. The mineral concentrated is usually a heavy 

mineral such as gold, cassiterite, or rutile. 

plate tectonics. The concept that the lithosphere is 

broken up into a series of rigid plates that move over 

Earth’s surface above a more fluid asthenosphere.

pluton. A body of intrusive igneous rock that crystallized 

at some depth beneath Earth’s surface.

plutonic. Describes igneous rock intruded and 

crystallized at some depth beneath Earth’s surface.

porosity. The proportion of void space (e.g., pores or 

voids) in a volume of rock or sediment deposit.

porphyry. An igneous rock consisting of abundant coarse 

crystals in a fine-grained matrix.

potassium feldspar. An alkali feldspar rich in potassium 

(e.g., orthoclase, microcline, sanidine, adularia).

Principal of Original Horizontality. The concept that 

sediments are originally deposited in horizontal layers 

and that deviations from the horizontal indicate postdepositional deformation.

Principle of Superposition. The concept that sediments 

are deposited in layers, one atop another, i.e., the rocks 

on the bottom are oldest with the overlying rocks 

progressively younger toward the top.

progradation. The seaward building of land area due to 

sedimentary deposition.

protolith. The parent or unweathered and/or 

unmetamorphosed rock from with regolith or 

metamorphosed rock is formed.

provenance. A place of origin. The area from which the 

constituent materials of a sedimentary rock were 

derived.

radioactivity. The spontaneous decay or breakdown of 

unstable atomic nuclei.

radiometric age. An age in years determined from 

radioisotopes and their decay products.

red beds. Sedimentary strata composed largely of 

sandstone, siltstone, and shale that are predominantly 

red due to the presence of ferric oxide (hematite) 

coating individual grains.

regolith. General term for the layer of rock debris, 

organic matter, and soil that commonly forms the land 

surface and overlies most bedrock.

regression. A long-term seaward retreat of the shoreline 

or relative fall of sea level.
62 NPS Geologic Resources Division

relative dating. Determining the chronological 

placement of rocks, events, or fossils with respect to 

the geologic time scale and without reference to their 

numerical age.

reverse fault. A contractional high-angle (greater than 

45°) dip-slip fault in which the hanging wall moves up 

relative to the footwall (also see “thrust fault”).

rhyolite. A group of igneous rocks, typically porphyritic 

and commonly exhibiting flow texture, with 

phenocrysts of quartz and alkali feldspar in a glassy to 

cryptocrystalline groundmass. The fine-grained 

extrusive equivalent of granite.

rift valley. A depression formed by grabens along the 

crest of an oceanic spreading ridge or in a continental 

rift zone.

rock. A solid, cohesive aggregate of one or more minerals.

roundness. The relative amount of curvature of the 

“corners” of a sediment grain, especially with respect 

to the maximum radius of curvature of the particle.

sand. A clastic particle smaller than a granule and larger 

than a silt grain, having a diameter in the range of 1/16 

mm (0.0025 in) to 2 mm (0.08 in).

sandstone. Clastic sedimentary rock of predominantly 

sand-sized grains.

scarp. A steep cliff or topographic step resulting from 

displacement on a fault, or by mass movement, or 

erosion. Also called an “escarpment.”

seafloor spreading. The process in which tectonic plates 

diverge and new lithosphere is created at oceanic 

ridges.

seamount. An elevated portion of the sea floor, 1,000 m 

(3,300 ft)or higher, either flat-topped or peaked.

sediment. An eroded and deposited, unconsolidated 

accumulation of rock and mineral fragments.

sedimentary rock. A consolidated and lithified rock 

consisting of clastic and/or chemical sediment(s). One 

of the three main classes of rocks—igneous, 

metamorphic, and sedimentary.

sequence. An informal rock-stratigraphic unit that is 

traceable over large areas and defined by a major sea 

level transgression-regression sediment package.

serpentinite. A rock consisting almost wholly of 

serpentine-group minerals, e.g. antigorite and 

chrysotile, commonly derived from the alteration of 

peridotite. Accessory chlorite, talc, and magnetite may 

be present.

shale. A clastic sedimentary rock made of clay-sized 

particles that exhibit parallel splitting properties.

sill. A tabular, igneous intrusion that is concordant with 

the surrounding rock.

silt. Clastic sedimentary material intermediate in size 

between fine-grained sand and coarse clay (1/256 to 

1/16 mm [0.00015 to 0.002 in]).

siltstone. A variable-lithified sedimentary rock with siltsized grains.

slickenside. A smoothly polished and often striated 

surface representing deformation of a fault plane.

slope. The inclined surface of any geomorphic feature or 

measurement thereof. Synonymous with gradient.

slump. A generally large, coherent mass movement with a 

concave-up failure surface and subsequent backward 

rotation relative to the slope.

soil. Surface accumulation of weathered rock and 

organic matter capable of supporting plant growth and 

often overlying the parent material from which it 

formed.

soliflucation. The slow downslope movement of 

waterlogged soil, normally at 0.5–5.0 cm/year (0.2–2 

in/year), especially the flow occurring at high 

elevations in regions underlain by frozen ground that 

acts as a downward barrier to water percolation, 

initiated by frost action and augmented by meltwater 

resulting from alternate freezing and thawing of snow 

and ground ice. 

spring. A site where water issues from the surface due to 

the intersection of the water table with the ground 

surface.

strata. Tabular or sheet-like masses or distinct layers of 

rock.

stratigraphy. The geologic study of the origin, 

occurrence, distribution, classification, correlation, 

and age of rock layers, especially sedimentary rocks.

stream. Any body of water moving under gravity flow in 

a clearly confined channel.

strike. The compass direction of the line of intersection 

of an inclined surface with a horizontal plane.

strike-slip fault. A fault with measurable offset where the 

relative movement is parallel to the strike of the fault. 

Said to be “sinistral” (left-lateral) if relative motion of 

the block opposite the observer appears to be to the 

left. “Dextral” (right-lateral) describes relative motion 

to the right.

subduction zone. A convergent plate boundary where 

oceanic lithosphere descends beneath a continental or 

oceanic plate and is carried down into the mantle.

subbituminous. A black coal, intermediate in rank 

between lignite and bituminous coal. It is distinguished 

from lignite by higher carbon and lower moisture 

content. 

subsidence. The gradual sinking or depression of part of 

Earth’s surface.

suture. The linear zone where two continental 

landmasses become joined due to obduction.

system (stratigraphy). The group of rocks formed during 

a period of geologic time.

tectonic. Relating to large-scale movement and 

deformation of Earth’s crust.

terraces (stream). Step-like benches surrounding the 

present floodplain of a stream due to dissection of 

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

floor(s).

terrane. A large region or group of rocks with similar 

geology, age, or structural style.

terrestrial. Relating to land, Earth, or its inhabitants.

terrigenous. Derived from the land or a continent.

theory. A hypothesis that has been rigorously tested 

against further observations or experiments to become 

a generally-accepted tenet of science.

thermokarst topography. An irregular land surface 

containing cave-in lakes, bogs, caverns, pits, and other 

small depressions formed in a permafrost region by the 

melting of ground ice.

thrust fault. A contractional dip-slip fault with a 

shallowly dipping fault surface (less than 45°

) where 
DENA Geologic Resources Inventory Report 63

the hanging wall moves up and over relative to the 

footwall.

till. Unstratified drift, deposited directly by a glacier 

without reworking by meltwater, and consisting of a 

mixture of clay, silt, sand, gravel, and boulders ranging 

widely in size and shape.

tonalite. A plutonic rock with the composition of diorite, 

but with an appreciable amount of quartz (between 5 

and 20 percent of the light-colored constituents).

topography. The general morphology of Earth’s surface, 

including relief and locations of natural and 

anthropogenic features.

trace (fault). The exposed intersection of a fault with 

Earth’s surface.

trace fossils. Sedimentary structures, such as tracks, 

trails, burrows, coprolites (dung), etc., that preserve 

evidence of organisms’ life activities, rather than the 

organisms themselves.

transgression. Landward migration of the sea as a result 

of a relative rise in sea level.

travertine. A limestone deposit or crust, often banded, 

formed from precipitation of calcium carbonate from 

saturated waters, especially near hot springs and in 

caves.

trend. The direction or azimuth of elongation or a linear 

geological feature.

tuff. Generally fine-grained, igneous rock formed of 

consolidated volcanic ash.

unconformity. An erosional or non-depositional surface 

bounded on one or both sides by sedimentary strata 

that marks a period of missing time.

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

movement that raises the rocks.

vent. An opening at Earth’s surface where volcanic 

materials emerge.

volcanic. Related to volcanoes. Igneous rock crystallized 

at or near the Earth’s surface (e.g., lava).

water table. T The upper surface of the saturated zone; 

the zone of rock in an aquifer saturated with water.

weathering. The set of physical, chemical, and biological 

processes by which rock is broken down.

xenolith. A foreign rock entrained in magma as an 

inclusion.
64 NPS Geologic Resources Division

Literature Cited

This section lists references cited in this report. A more complete geologic bibliography is 

available from the National Park Service Geologic Resources Division.

Adamczak, S., Jr., R. D. Abbott, and F. J. Wuttig. 2004. 

“Earthquake Hazards: Geotechnical Design Concerns. 

A Review Based on the November 3, 2002 Alaska 

Earthquake.” In It's a Cool World, eds. Daniel W.

Smith, David C. Sego, and Charles A. Lendzion. 

Proceedings of the International Symposium on Cold 

Regions Engineering 12: unpaginated.

Adams, P. C. 1999. “Fluvial Geomorphic Processes and 

Succession on the Tanana River Floodplain.” In Arctic 

Science Conference Program and Abstracts 50: 161.

Adema, G. W., P. Brease, and A. Bucki. 2003. “Glacier 

Monitoring in Denali National Park and Preserve.” In 

Geological Society of America Abstracts With Programs 

35 (6): 132.

Alaska Department of Environmental Conservation 

(ADEC). 2006. Contaminated Sites Program – Database 

Results. Division of Spill Prevention and Response, 

Contaminated Sites Program http://www.dec.state.

ak.us/SPAR/csp/ (accessed August 30, 2006).

Aochi, H., O. Scotti, and C. Berge-Thierry. 2005. 

“Dynamic Transfer of Rupture Across Differently 

Oriented Segments in a Complex 3-D Fault System.” In

Geophysical Research Letters 32 (21): 4 pp.

Axford, Y. L. and A. Werner. 1997. “A Lacustrine Record 

of Late-Glacial/Holocene Environmental Change:

Pork Chop Pond, Denali National Park, AK.” In

Geological Society of America Abstracts With Programs 

29 (6): 35, 1997

Braile, L. W. 2009. Seismic monitoring. In Geological 

Monitoring, eds. R. Young and L. Norby, 229-244, 

Boulder, CO: Geological Society of America.

Brease, P. 2004. “Denali National Park and Preserve: 

South Central Alaska.” In Geology of National Parks, 

eds. A. G. Harris, E. Tuttle, and S. D. Tuttle: 477-504. 

Brease, P., L. Stromquist, A. Fiorillo, and S. T. Hasiotis. 

2009. “Cretaceous Dinosaurs in Denali—A Newly 

Discovered Resource Requires a New Management 

Plan.” In Geological Society of America Abstracts With 

Programs 41 (7): 150.

Bucki, A. K. and V.B. Valentine. 2003. “Thickness 

Changes of the Muldrow Glacier Near the Traleika 

Confluence, Denali National Park, Alaska.” In Arctic 

Science Conference Program and Abstracts 54: 199.

Bundtzen, T. K. 1981. Geology and Mineral Deposits of 

the Kantishna Hills, Mt. McKinley Quadrangle, 

Alaska. MS Thesis. Anchorage, AK: University of 

Alaska.

Burghardt, J. E. 1997. Mineral Report: Validity Examination of the Comstock #1 Lode, Comstock #2 Lode, 

Comstock #5 Lode, and Comstock #6 Lode Mining 

Claims. Unpublished report. Denver, CO: Geologic 

Resources Division, National Park Service.

Capps, S. R. 1933. The Eastern Portion of Mount McKinley 

National Park [Alaska]. Bulletin B 0836-D: 219-300. 

Reston, VA: U. S. Geological Survey.

Carver, G., G. Plafker, M. Metz, L. Cluff, B. Slemmons, E. 

Johnson, J. Roddick, and S. Sorensen. 2004. “Surface 

Rupture on the Denali Fault Interpreted From Tree 

Damage During the 1912 Delta River Mw 7.2-7.4 

Earthquake: Implications for the 2002 Denali Fault 

Earthquake Slip Distribution.” In Bulletin of the 

Seismological Society of America 94 (6B): S58-S71.

Cassidy, J. F. and G. C. Rogers. 2004. “The M (sub w) 7.9 

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DENA Geologic Resources Inventory Report 69

Appendix A: Overview of Digital Geologic Data

The following page is an overview of the digital geologic data for Denali National Park 

and Preserve. For a poster-size PDF of this map and complete digital data, please see the

included CD or visit the Geologic Resources Inventory publications web site 

(http://www.nature.nps.gov/geology/inventory/gre_publications.cfm).

The overview incorporates the small scale (1:250,000) data set that encompasses the entire park and preserve. 

Larger scale (1:63,360) data is available for Chulitna region and Healy quadrangle.


Overview of Digital Geologic Data 

for Denali National Park and Preserve 

Extent of Digital Data, Area of Detail from Map Sheet 1 in Red I 

1 Major Highwap - DENA - Faults 

-. thrust fault, known or certaln 

--. thrust fault, appmxlmate 

--. thrust fault, mncealed 

-+-* thrust fault. ~nfe:.ed and quer~ed 

- normal fault, known or certaln 

---- normal fault, appmxlmate 

-- normal fault, concealed 

--^-- normal fault, Inferred and quer~ed 

- r~ght-lateral dr~ke-sl~p fault, known or certaln 

---- r~ght-lateral dr~ke-sl~p fault, approximate 

----- r~ght-lateral str~ke-sl~p fault, Inferred and quer~ed 

---- normal r~ght-lateral str~ke-sl~p fault, appmxlmate 

-- normal r~ght-lateral str~ke-sl~p fault, concealed 

--^-A normal r~ght-lateral str~ke-sl~p fault, Inferred and quer~ed 

- unknown offdd~splacernent, known or certaln 

---- unknown offdd~splacernent. appmx~mate 

- h~gh-angle reverne fault, known or cerlaln 

---- h~gh-angle reverne fault, approximate 

- h~gh-angle reverne fault, concealed 

h~gh-angle reverne fault, Inferred 

DEHA - Gpologit Con- 

- known or certaln 

---- approxlrnate 

- concealed 

- - - - - - - Inferred 

...L-L Inferred and quer~ed 

- quadrangle boundary 

water or shorel~ne 

Tegr - Grarite ard granojlorce 

Tm - Vdmrlr rock ~t ti.e Carmll Formallon 

Twr - Grant:mr rmkr 

ITh - ChulPna wquence. .aJ and bm d~mentary r& ard Mwlt 

1% - Ctul~t-a requerre. rta: tutf. arg~ll~re, chen.grawacke.and lhrnertolr 

ITRW - Mystl: qdence. Tanna Rmr Votan~c and equrvalert ~nla 

ICmd - Myjtr and D#ll,n+r nra'lgraph~r wquencrr. dndvlw 

TRa - Calcamur redmrrertav mcrr 

TRcg - Colglorrerate and 'mlcarc rardrtore 

TRr - N~lola~ Grmnore and related mh 

TRrv - Maarolmneand amaid rnet&~mentarj dr 

TRlb - Ch~lnra quence. lhrnertore and baran querce 

TRr - Chulnna reqwnrm. red bdr 

TRPk - Flywhl~ke d~memarl mh 

TRDU- Cbul~tra querce. mlcanlc ard redmemaw rdr 

TRSI - Melarger d the Alarka Rarge. lhrnenm bkkr 

MZPZI - lntrur~w and mlcanlc mk urdlvlded 

Mnum - Ukrarnaf~c and watr &. ~ndrrlded 

PPNarc- Skola~ Group. Sta~on Creek and Slana Spur Forrnatlonr, and eq~walent mkr 

PPNa - Skolal Gmup. Strelna w&worphemplex 

PPNarkw - Skolal Gro~p, warble 

FC%c - Mplc requerce. Sheep Creek iormar~on and cormlam uer~nclan~c uru 

MDT-TD~~~~~I~~SC~IP~ 

Drb - Ch~sPrd rquence. krpeniiwte. &It, rrert ard gabbro 

TKw - Rhyolne and mlaed rocrr DSrrdl- Mys;~ and D8llhnger reqm.wce. ~nnamed lhmenore 

Te - Kwal Gmup. und~dd 

Tn - Kera. Group. Sterl~rg Fwmanon 

Tkd - H~nblerde date 

Tr - krm Grawl 

TKvl- Ander~te and mlaed rockr 

TKI -Irtrur,w rdr. undnM 

TKg - Grarnlc rocks 

TKgd- Grandarm. toralne, and mnzonm dlker, anddr 

DCd - D:lllrger?qdence. undwlM 

SCpl- D~ll~npr reqLerce. Pon Rrrer 5andnore. Lvan Hllk Formalor. and mrrelatlw Lnfi 

k-chen 

Ch - W~berrharn Gr~t. urdraulbd 

PZk - Keq Peak Formalon 

Tru - Sed~memarl dr. urdluded 

Tvu - mlmne rock, undvldd 

TV - Kenal Gro~p. Tyonek hrmatlon 

Tcb - Coalkarmg mckr 

Vt - H~pabynal felre and ~rtemd~ate ~ntrurw rku 

Vw -Hypabyiralwat~ lntrurlw rocks 

T*b - Ankm and halt 

TK* - Gatbro and le~cqbbro 

TKg3- GWI- grarnlcrah 

KG - Cdrwll Formalon, d~rnertarj mir abur n 

Kwar - Melanger d the Alarka Rarge 

k-Arg~llne. +en, randiron*, ard lh~mne 

M - Kablkra fwh reqwnce. undvldd 

Mk-Kahlkna tt@ -Len-, tbxh requencel 

P&c-Spr~ce Creek qwnce and mrrelatlw rock 

Ph - mlcanlc and redlrnertary rob5 

FZ!aqr - Pelnr and qLamme hln ot *e Ab*a Ranp 

UNK~IL - Melanger d the Alarka Rarge. ~kramaf~cand amaid mkr 

Tv - Grann~c ard volmre rock, undvldd 

Mn - Kahllma tbxh requence. flywh q~ence2 

Tmrn - Grandmrne to toralne 

n Cblnma Formalon. T~xrdn~ Gmup. and -a1 redlrnertaw rmkr 

Th - Flu~atlle redlwertaw rock and rubord~rate mlcarr & 

AlarkbAleutlar Range and Cbnlra Vallq baholnhr, undltterem~ated 

UNKbu - Bedrock d ~nknm P,~E or ap 

Produced by the Geologic Resources Inventory September 2010 
DENA Geologic Resources Inventory Report 73

Appendix B: Scoping Session Participants

The following is a list of participants from the GRI scoping session for Denali National 

Park and Preserve, held on February 24–26, 2004. The contact information and email 

addresses in this appendix may be outdated; please contact the Geologic Resources 

Division for current information. The scoping meeting summary was used as the 

foundation for this GRI report. The original scoping summary document is available on 

the GRI web site: http://www.nature.nps.gov/geology/inventory/gre_publications.cfm.

LAST

NAME

FIRST

NAME AFFILIATION TITLE PHONE E-MAIL

Adema Guy Denali National Park and Preserve physical scientist 907-683-6356 guy_adema@nps.gov

Blodgett Robert U.S. Geological Survey paleontologist 907-786-7416 rblodgett@usgs.gov

Brease Phil Denali National Park and Preserve geologist phil_brease@nps.gov

Claudice Karen Alaska Division of Geological and 

Geophysical Surveys

geologist 907-451-5023 karen@dnr.state.ak.us

Connors Tim NPS, Geologic Resources Division geologist 303-969-2093 tim_connors@nps.gov

Dickison George NPS, Alaska Regional Office GIS coordinator 907-644-3546 george_dickison@nps.gov

Fiorillo Tony Dallas Museum of

Natural History

paleontologist 214-421-3466

x 234

tfiorillo@dmnhnet.org

Gamble Bruce U.S. Geological Survey geologist 907-786-7479 bgamble@usgs.gov

Giffen Bruce NPS, Alaska Regional Office geologist 907-644-3572 bruce_giffen@nps.gov

Halloran Jim NPS, Alaska Regional Office geologist 907-644-3574 jim_halloran@nps.gov

Heise Bruce NPS, Geologic Resources Division geologist 303-969-2017 bruce_heise@nps.gov

Kucinski Russell NPS, Alaska Regional Office geologist 907-644-3571 russ_kucinski@nps.gov

Liebsher Tom Yukon-Charley Rivers

National Preserve

chief, natural resources 907-455-0620 thomas_liebsher@nps.gov

Norby Lisa NPS, Geologic Resources Division geologist 303-969-2318 lisa_norby@nps.gov

Rosenkrans Danny Wrangell-St. Elias National Park and 

Preserve

geologist 907-823-7240 danny_rosenkrans@nps.g

ov

Sharp Devi Wrangell-St. Elias National Park and 

Preserve

chief, natural resources 907-822-7212 devi_sharp@nps.gov

Spencer Page NPS, Alaska Regional Office ecologist 907-644-3448 page_spencer@nps.gov

Stevens Deanne Alaska Division of Geological and 

Geophysical surveys

geologist 907-451-5014 deanne@dnr.state.ak.us

Stromquist Linda NPS, Alaska Regional Office geologist 907-644-3576 linda_stromquist@nps.gov

Wesser Sara NPS, Central Alaska Network network coordinator 907-644-3558 sara_wesser@nps.gov

Wilder Doug NPS, Central Alaska Network data manager 907-455-0661 doug_wilder@nps.gov

Wilson Ric U.S. Geological Survey geologist 907-786-7448 fwilson@usgs.gov

The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides scientific and other 

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

Communities. 

NPS 184/105592, September 2010 
National Park Service 

U.S. Department of the Interior 

Natural Resource Program Center 

1201 Oakridge Drive, Suite 150 

Fort Collins, CO 80525 

www.nature.nps.gov 

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