Chattanooga Shale in Kentucky. 



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are shown more clearly in tig. 3, in which the hammer 

 rests with one end against the shale and the other against the 

 limestone. Fig. 3 also shows more clearly than fig. 2 the walls 

 of a small water-worn cavity in the lower half of the ledge 



Fig. 3. 



Fig. 3. Close view of a portion of the black shale and limestone contact 

 line shown in fig. 2. A solution cavity in the limestone filled with black shale 

 is seen under the hat. The shale is marked A, and the limestone B. 



which extends nearly, if not quite, to the bottom of the lime- 

 stone. This cavity, tilled with a deposit of the black shale, is 



