Ellsworth shale

Applied to the Michigan Basin in east-west cross section, the "lower black" shale (A) represents the Antrim Shale of western Michigan and that part of the eastern Antrim Shale identified by Subunits 1A, IB, 1C and 2. The "green-gray" facies (C) is the Ellsworth Shale, and the "upper black" (B) is represented by all Antrim Shale above Unit 2 and below the base of the Bedford Shale. The uniformity of the lower beds of the Antrim Shale has been noted by several others (20, 23), and a westward source for the Ellsworth has been postulated by several (20, 23-25) Nevertheless, the westward source seems more applicable to those beds above the western Antrim Shale, i.e., above the beds termed "lower black" in this paper. 

Figure 6. Regional map of the Ellsworth shale zero line, green-gray Ellsworth-type shales to the west and black Antrim-type shales to the east, (Reproduced with permission from Ref 14. Copyright 1982, Institute of Gas Technology.)...

Devonian Late Ellsworth Shale Berea Sandstone... 

A westward or northwestward source for the Ellsworth/upper Antrim, Hannibal-Saverton/upper Grassy Creek, and lower Coldwater/ upper Sunbury is appropriate for the overall geometry of those "upper shale" bodies. It is clear that in the Appalachian Basin great volumes of clastic material came from the east and that some of the black shales in that basin are true distal facies of great influxes of clastic material from the east. Nevertheless, because the authors believe that the hypothetical black shale sequence also applies east of the Cincinnati/Algonquin Arches (in mirror image), some of the black shales in the basin may prove to be more regional in nature and of the "lower shale" (A) type. 

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