Bui. 502, U. S. Dept. of Agriculture. 



Plate III. 





Fig. 1 .—Pressure has Caused Shearing Along Bedding Planes; when Excavated 

 THE Shale Comes Out in Large Flakelike Pieces. 



Fig. 2.— Where Pressure has Been Extreme, Fault Planes have Developed. 

 EFFECTS OF INTENSE PRESSURE ON SHALE. 



