Explore Geology
geology fieldnotes title

Noatak

National Preserve

Alaska

cover of park brochure

park geology subheading
photo of mountain
Noatak National Preserve, Alaska

As one of North America's largest mountain-ringed river basins with an intact, unaltered ecosystem, the Noatak River environs feature some of the Arctic's finest arrays of plants and animals. The river offers equally superlative wilderness float-trip opportunities-from deep in the Brooks Range to tidewater of the Chukchi Sea. Noatak National Preserve lies almost completely enclosed by the Baird and De Long mountains of the Brooks Range. In this transition zone, the northern coniferous forest thins out and gradually gives way to the tundra that stretches northward to the Beaufort Sea. The Noatak basin is internationally recognized as a Biosphere Reserve. Under this United Nations scientific program the area's ecological and genetic components are monitored to establish baseline data for measuring changes in other ecosystems worldwide. Information can also be gathered here on sustainable uses of natural resources by humans, as exemplified by the Inupiat and other native peoples who have lived off the land of northwest Alaska for many thousands of years. The Noatak River is classified as a National Wild and Scenic River from its headwaters to the Kelly River.

The basic geological framework of the northwest region was set by the late Paleozoic era and included the Brooks Range geosyncline (a broad sedimentary trough), the Arctic Foothills, and the Arctic Coastal Plain. During the Triassic period (Mesozoic era), the site of the present Brooks Range was stabilized, and limestone and chert were formed. The process of mountain-building began during the mid Jurassic period. By the Cretaceous period the Brooks Range dominated the landscape, and volcanic activity from the Jurassic period continued in an area south of the range.

The sedimentary rocks of the Brooks Range and the DeLong Mountains were intensely folded and faulted during the late Cretaceous period. It was during this time that the existing east west fault trends within the area were established. A resurgent strong uplift during the early Tertiary period (Cenozoic era) was responsible for the present configuration of the Brooks Range. Volcanic activity produced intrusions and debris throughout the region during the Tertiary and Quaternary periods.

Bedrock geology of the DeLong Mountains includes faulted and folded sheets of sedimentary clastic rocks with intrusions of igneous rock. Shale, chert, and limestone of Paleozoic and Mesozoic eras are dominant. Graywacke and mafic rock of the Jurassic and Cretaceous periods are also found.

The lowland area of the Noatak drainage is underlain primarily by siltstone, sandstone, and limestone of the mid to late Paleozoic era. Also in evidence are graywacke, chert, and igneous rock of Mesozoic origin.

The Baird Mountains south of the lowland are composed of strongly folded sedimentary rocks with granitic intrusions. Known bedrock consists primarily of Paleozoic or older, highly metamorphosed rocks.

Permafrost plays an important role in the geologic processes and topographic development of the preserve. The Noatak drainage and adjacent lowland areas are underlain by discontinuous permafrost, and areas in the Baird and DeLong mountains are underlain by continuous permafrost. Permafrost can reach depths of 2,000 feet, but is generally between 15 and 260 feet in the Noatak area. Continental ice sheets did not cover all of northwest Alaska during the Pleistocene period, although glaciers did cover most upland areas. The last retreat of the glaciers, about 4,500 years ago, established the present sea level and the extensively glacially carved landscape that is in evidence today. This landscape is characterized by deep, U shaped valleys, rocky peaks, and braided streams. A portion of the Noatak valley lowland was glaciated during Wisconsin time and today is typified by such glacial features as kame, kettles, moraines, and alluvial till.

The three major soil types within the preserve include the upland or mountain slope soils of the lithosol type, tundra soils, and soils associated with the Noatak drainage and lowlands. Lithosol soils on the higher slopes of the DeLong and Baird mountains are limited and are mostly imperfectly weathered rock fragments and barren rock. The soil is without zonation and consists of a thin layer of highly gravelly and stony loam. Where this soil accumulates in protected pockets on mountain slopes, it supports mosses, lichens, and some dwarf shrubs. Below the upland soils on more gently rolling terrain, the tundra soils predominate. These are dark, humus rich, nonacid soils. Texture in the tundra soils varies from highly gravelly to sandy. The floodplains of the Noatak and its tributaries are characterized by silty and sandy sediments and gravel. These soils occur in association with the greatest proportions of organic material along the lower reaches of the Noatak. A fibrous peat extends to the permafrost layer in many areas.

Soil erosion along the Noatak riverbanks is considered severe. This occurs during spring breakup when high volumes and velocities of water scour the riverbanks and carry sediment downstream. In places where waters contact ground ice in adjacent riverbanks, thermal erosion can occur. As the ice melts, banks are undercut and sediments are swept downstream. Additional erosion can occur during high precipitation and storm periods in summer.



park maps subheading

A general park map is available on the park's map webpage.

For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.

photo album subheading

A geology photo album has not been prepared for this park.

For information on other photo collections featuring National Park geology, please see the Image Sources page.

books, videos, cds subheading

Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.

Please visit the Geology Books and Media webpage for additional sources such as text books, theme books, CD ROMs, and technical reports.

Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
ISBN 0-393-92407-6
9" x 10.75", paperback, 550 pages, full color throughout

The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!

Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.



geologic research subheading

For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.

The NPS maintains a searchable data base of research needs that have been identified by parks.

A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.



selected links subheading

NPS Geology and Soils Partners

NRCS logoAssociation of American State Geologists
NRCS logoGeological Society of America
NRCS logoNatural Resource Conservation Service - Soils
USGS logo U.S. Geological Survey

teacher feature subheading

Currently, we do not have a listing for any park-specific geology education programs or activities.

For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.
updated on 01/04/2005  I   http://nature.nps.gov/geology/parks/noat/index.cfm   I  Email: Webmaster
This site is best viewed in Internet Explorer 6.0 or Netscape 7.0