Hannibal/Saverton shales

The schematic black shale sequence also can be applied to the upper New Albany Shale of the Illinois Basin, where a facies relationship of the green-gray Hannibal/Saverton Shales with the Grassy Creek has been described by Lineback (26) ... 

If Foerstia extends into northwestern Illinois, it should be found just below the base of the Saverton in the top of the western Grassy Creek. The sediment source for this great wedge of Hannibal/ Saverton and upper Grassy Creek above Foerstia would have been northwest, but the sediments below the presumed position of Foerstia in the Illinois Basin are not necessarily from that same source. Kepferle s (13) documentation of Foerstia on the eastern edge of the Illinois Basin has established that the great bulk of black shale in the Illinois Basin predates much of the black shale in eastern Kentucky and Ohio (27) and invalidates several recently published correlations. 

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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