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KANSAS UNIVERSITY SCIENCE BULLETIN. 



abundant as to number from five to ten on a surface of six 

 inches square. Owing to their hardness the beds give rise to 

 round-topped ridges of considerable prominence." 



Fig. 1. A typical exposure of the Hailey shales on Connant creek, Wyo- 

 ming. The Mowry beds may be seen on the left in the background. 



In those parts of Wyoming where I worked, the Mowry beds 

 stand out as prominent ridges of hard whitish shales which 

 can be readily recognized from a long distance, and on that 

 account serve as excellent landmarks for the identification of a 

 region where the Hailey shales may occur. In thickness the 

 Hailey shales vary from a few feet north of Lander, Wyo., to 

 something over 200 feet in the Big Horn region. "Near Soap 

 Creek the dark shales overlying the Mowry beds are about 200 

 feet thick," etc. (6). In most of their extent the Hailey beds 

 have numerous brown sandy clay concretions which very often 

 contain vertebrate remains. These concretions vary in size 

 from a few inches to many feet in diameter. In the Big Horn 

 region the concretions are stratified into distinct layers, but 

 such is not the case in other places where the horizon was 

 examined. 



So far as is at present known the Hailey shales outcrop along 

 the eastern flank of the Wind River mountains, in the Shoshone 

 anticline; in the anticline along Beaver creek near Hailey, 

 Wyo., the type locality; in an anticline north and west of the 



