Chickaloon Formation

The Chickaloon Formation is a geologic formation in Alaska. It preserves coal measures deposited in a high-latitude basins during the Paleocene–Eocene thermal maximum. It is an important record of high-latitude terrestrial ecosystems during a period of global warmth, providing evidence for how arctic vegetation and ecological interactions responded to elevated temperatures and atmospheric carbon dioxide levels.

Chickaloon Formation
Stratigraphic range: Thanetian–Ypresian ~
Exposed shales, sandstones, and coal beds of the Chickaloon Formation at Coal Creek, Alaska
Type	Formation
Unit of	Matanuska–Susitna basin sedimentary sequence
Sub-units	Informal coal-bearing and fluvial facies divisions
Underlies	(varies locally; younger Eocene units in Cook Inlet–Matanuska region)
Overlies	Mesozoic basement and/or Upper Cretaceous strata (locally unconformable)
Thickness	Several thousand meters (locally variable)
Lithology
Primary	Sandstone, siltstone, shale, mudstone, conglomerate
Other	Coal
Location
Region	Matanuska Valley, Alaska
Country	United States
Extent	Matanuska Valley and adjacent basins, south-central Alaska
Type section
Named for	Chickaloon River area
Named by	Martin & Katz (1912)

Stratigraphic sections of the Chickaloon Formation

The formation preserves a diverse fossil leaf assemblage derived from floodplain and crevasse splay environments within fluvial sediment processes. These plant fossils represent a forested ecosystem dominated by a variety of broadleaf trees and conifers, including Metasequoia, along with aquatic and wetland plants. Analysis of leaf characteristics suggests that the region experienced a much warmer and wetter climate than present-day Alaska, with warm-temperate conditions and high precipitation under early Eocene climates.

See also

• List of fossiliferous stratigraphic units in Alaska
• Paleontology in Alaska