The Geology of Noatak National Preserve

The lower Noatak basin. Image from the National Park Service's page.

Noatak National Preserve in Arctic Alaska is almost entirely enclosed by the Baird and DeLong Mountains of the Brooks Range, in the North Slope and Northwest Arctic Boroughs. This summary draws on the National Park Service's Geodiversity Atlas, part of the Geologic Resources Inventory.

The preserve

• First established as a national monument on December 1, 1978, and redesignated a national preserve on December 2, 1980.
• About 2,665,693 hectares (6,587,071 acres).
• Created to protect the nation's largest unaltered river basin and watershed, protect habitat for a wide variety of plants and animals, preserve archeological sites, and provide for subsistence and scientific study.
• The Noatak River is a national wild and scenic river, and archeologists surveying its tributaries have found a cultural history reaching back more than 11,000 years.
• The area was designated a Biosphere Reserve in 1976.

The rocks

Most of the preserve's bedrock belongs to three groups of formations:

Other units include:

• schists and quartzites of Ordovician–Devonian age and the Devonian Beaucoup Formation, in the south;
• exposures of the Brooks Range's Jurassic ophiolite — a displaced slab of ocean crust and upper mantle — in the west and northwest;
• some of the youngest bedrock, the Cretaceous Okpikruak and Fortress Mountain Formations, along the northwestern and north-central boundaries.

On the surface lie Pleistocene–Holocene glacial deposits, along with dune, terrace and landslide deposits, colluvium and alluvium.

Copter Peak. Image from the National Park Service's page.

Further data

The Geologic Resources Inventory has produced geologic maps and reports for the preserve, and a Soil Resources Inventory has been completed; both are on the NPS DataStore. Fossils and other park resources are protected by federal law.

Sources

• National Park Service: "NPS Geodiversity Atlas—Noatak National Preserve, Alaska."
• Work it cites: Hamilton (2010).