Geologic map of alaska compiled by helen m. Beikman

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Tpc PLIOCENE CONTINENTAL DEPOSITS—Pebble to boulder conglomerate, coarse sandstone, siltstone, claystone, and thin lignite beds. Includes Nenana Gravel (Pliocene?)

uTc UPPER TERTIARY CONTINENTAL DEPOSITS—Sandstone, siltstone, claystone, minor conglomerate, and coal beds. Includes upper part of Kenai Group in Cook Inlet area and Nenana Gravel and related unnamed rocks in west-central Alaska Range. Rocks range in age from Oligocene(?) through Pliocene
Tmc MIOCENE CONTINENTAL DEPOSITS—Sandstone, siltstone, shale, claystone, conglomerate, and coal beds. Includes the Sanctuary, Suntrana, Grubstake, and Lignite Creek Formations in central Alaska Range and the Frederika Formation in Wrangell Mountains
mTc MIDDLE TERITARY CONTINENTAL DEPOSITS—Sandstone, siltstone, claystone and coal beds. Includes the Healy Creek Formation in central Alaska Range, the Gakona Formation in east-central Alaska Range, and the Tsadaka Formation in Matanuska Valley. Rocks range in age from Oligocene through Miocene
lTc LOWER TERTIARY CONTINENTAL DEPOSITS—Claystone, siltstone, sandstone, conglomerate, and coal beds. Includes lower part of Sagavanirktok Formation in the Arctic Coastal Plain and the Chickaloon and Wishbone Formations in the Matanuska Valley. Rocks range in age from Paleocene through Oligocene
Txc PALEOCENE CONTINENTAL DEPOSITS—Conglomerate, sandstone, coaly shale, and shale. Includes Cantwell Formation in central Alaska Range
Tc TERTIARY CONTINENTAL DEPOSITS—Sandstone, coal, conglomerate and shale of the Kootznahoo Formation on Admiralty, Kuiu, Kupreanof, and Zarembo Islands
TKc TERTIARY AND CRETACEOUS CONTINENTAL DEPOSITS—Conglomerate, breccia, sandstone, arkose, mudstone, shale, tuffaceous rocks, and lignite. Includes Arkose Ridge Formation (Cretaceous?) in Matanuska Valley.
uKc UPPER CRETACEOUS CONTINENTAL DEPOSITS—Sandstone and conglomerate and interbedded shale, clay, silt, and bentonite of the Niakogon Tongue of the Chandler Formation of the Nanushuk Group and the Prince Creek Formation of the Colville Group on the Arctic Coastal Plain; shale and siltstone in the Yukon-Koyukuk basin; and pebble conglomerate around the margins of the basin
lKc LOWER CRETACEOUS CONTINENTAL DEPOSITS—Shale, claystone, siltstone, sandstone, conglomerate, coaly shale and coal, ironstone, and bentonite. Includes Corwin Formation (Lower and Upper Cretaceous) of the Nanushuk Group and Killik Tongue of Chandler Formation of Nanushuk Group on Arctic Coastal Plain

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