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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 34 (1950)

Issue: 11. (November)

First Page: 2200

Last Page: 2222

Title: Status of Dry Creek Shale of Central Montana

Author(s): Christina Lochman (2)


The name "Dry Creek shale" was originally proposed by Peale for a small non-fossiliferous unit in the Upper Cambrian sequence of the vicinity of Three Forks, Montana. In 1899 Weed used the same name for a formation of brick-red shales and dolomites, a unit entirely different in age, lithology, and stratigraphic position from that of Peale. Subsequent usage of the name has been both erroneous and variable. The name should be used as originally defined by Peale, but the strata involved do not constitute a mappable lithic unit by present mapping standards. Peale's Dry Creek shales are the lower member of the Snowy Range formation. The name "Sage pebble conglomerates" is proposed for the upper member of this formation.

Weed's 1899 formation of brick-red shales and dolomites is a mappable lithic unit of Devonian age. It is the basal Devonian unit (unit C) of Sloss and Laird and should be called the Maywood formation, the name proposed by Emmons and Calkins for the same lithic unit in the Philipsburg Quadrangle.

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