Abstract

Recent stratigraphic and paleontologic studies have resulted in substantial revision of the age assignments and inter-basin correlations of the Tertiary formations of Alaska. The correlation chart given here, the first published chart to deal exclusively with the Tertiary of Alaska, had the benefit of a considerable amount of stratigraphic data and fossil collections from some oil companies. On the most recently published geologic map of Alaska, bedded rocks of Tertiary age, excluding volcanic rocks, are shown over 1.6% of the total area. The possible total land area underlain by substantial thickness of sedimentary rocks of Tertiary age, including a conservative estimate for areas as yet unmapped, may be more than 3% of the total area of Alaska. Nonmarine coal-bearing rocks of remarkably similar lithologic character are the most widespread areally, occurring in both coastal and interior basins throughout Alaska. Wholly or dominantly marine deposits are known from 3 main areas, 1 on the northeastern coast of the Gulf of Alaska where beds representing each of the epochs from Eocene to Pliocene occur in a belt 300 mi. long and as much as 40 mi. wide, 1 near the Arctic Coast in northeastern Alaska, and 1 in the Alaska Peninsula. Tertiary marine rocks have not, so far as known, been definitely identified more than 50 mi. inland from the present coast anywhere in Alaska. Volcanic rocks of Tertiary age occupy extensive areas in both coastal and interior Alaska, but they are not known N. of the Arctic Circle.

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