Abstract

The name “Kawkawlin Bentonite” is proposed for a thin subsurface bentonitic dsh-fall bed in the Michigan basin Lucas Formation (upper Detroit River Group, Middle Devonian). Post-Detroit River emergence and erosion of the flanks of the basin resulted in truncation of the ash bed to its present limits. The Kawkawlin Bentonite may be equivalent to the Tioga Bentonite Bed of the Appalachian and Illinois basins.

The Tioga Bentonite Bed has been reported on the Appalachian basin flank of the Algonquin arch in Norfolk and Oxford counties, southwestern Ontario. That this bentonite is in strata equivalent with the Dundee Formation of the Michigan basin is questioned. Because of dissimilarities there is some doubt whether the Ontario bentonite is properly related to the Tioga Bentonite.

A bentonite reported as Tioga Bentonite in northern Indiana on the southern flank of the Michigan basin is probably stratigraphically older than the Tioga and the Kawkawlin benlonites.

The Kawkawlin Bentonite has proved invaluable in analyzing upper Detroit River, Dundee, and Rogers City stratigraphy and correlations in the Michigan basin.

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