404 Bulletin American Museum of Natural History. [Vol. XV J, 



The Inyan Kara Peak section is remarkable for its thick- 

 ness. This is most marked in the No. 15 bed of sandstone 

 which is here 75 feet thick. The layer is very generally a 

 fairly heavy one and occurs in all the sections. 



Next follow several thin layers of variable character, con- 

 sisting of clays, sandstones and limestone concretions. There 

 is no constant bed till No. 22 is reached, which is a band of 

 maroon clay filled with tiny concretions. It is present in 

 three of the sections and occupies the same position as a simi- 

 lar band in the centre of Wyoming. It is a very good horizon 

 marker, being so distinctive in texture and conspicuous in 

 ■color. Just above a very constant layer of limestone nodules 

 (No. 23) occurs. 



The layers from 24 to 28 are a series of brilliantly colored 

 clays, red, purple, and green in color, and popularly called 

 the "varigated clays." These clays have occasional beds of 

 limestone nodules. In the variegated beds, especially toward 

 the top, Dinosaur remains are not infrequent, but without 

 exception the bones are in a wretched state of preservation, 

 the iron in the colored beds having eaten into them till great 

 spots are mere powder. In all the sections some traces of 

 Dinosaurs were found at this horizon, but they were especially 

 abundant along the lower reaches of the Inyan Kara Creek. 

 On Inyan Kara Creek in these same beds Mr. Thompson found 

 several specimens of IJnio baileyi L. and Valvata leei L. similar 

 to those found by Logan in the Freezeout Mountains. These 

 variegated clays occur on the east side of the Hills, as well as 

 on the west side, also in the Freezeout Mountains, and in the 

 southeastern part of Wyoming. 



The top of the freshwater series is everywhere a bed of olive- 

 green clay of considerable thickness, in which Dinosaur re- 

 mains are extremely rare, but do occur; and where present, 

 the bones are in a good state of preservation. Fragments 

 were found at the Belle Fourche station and near Inyan Kara 

 Peak. The whole is capped by the heavy bedded Dakota 

 sandstone. The sections are often compHcated by this sand- 

 stone faulting and slipping part way down the slope of the 

 escarpment. In fact the greatest care is required to find ex- 



