The determination of a greenish, sticky, clay forming bed about feet thick, observed in Bedford County, Tennessee, in 1920, as bentonite an altered volcanic ash,2 started a search for additional outcrops of this deposit and the collection of data that would bear on its origin, extent, and method of deposition. This paper is primarily a progress report on this subject, on which it is hoped much additional work will be done. The first observation of this clay deposit was made at the settlement of Singleton, in Bedford County, Tennessee, at which place it measured 21 inches thick.
The southernmost occurrence of the ash deposit thus far known is at Bessemer, Alabama, a suburb of Birmingham, 145 miles south of Singleton, Tennessee. At this place it is reported to measure from 14 to 18 inches thick. The northernmost exposure seen to date is at High Bridge, . . .