POST-CRETACEOUS HISTORY OF WESTERN WYOMING 313 



center of the basin the tributaries have largely destroyed the plain, 

 leaving only small mesas or isolated buttes such as Crowheart 

 Butte. 



Around Lander and the southeast end of the Wind River Range, 

 there are mesas and shelves along the foothills cut across inclined 

 strata, at elevations of 600-700 feet above the present streams 

 (Figs. 30, 31, 32). These are considered by Westgate as remnants 

 of his plain No. 2, and they also have the characteristics and rela- 

 tions appropriate to the Black Rock cycle as defined in preceding 



Fig. 30. — Table Mountain, near Lander. A mesa cut on tilted strata and 

 capped with gravel. (Photograph by D. D. Condit, U.S. Geological Survey.) 



pages. The layer of coarse gravel 50-250 feet thick in places, 

 forming the top of each of these remnants, has interested geologists 

 since the time of the Hayden Survey. On account of the fact that 

 a few of the bowlders are as much as 25 feet in diameter, and many 

 of them 5-10 feet thick, it has been suggested that the deposit 

 must be glacial. Westgate, however, cites the distinct although 

 crude stratification of the material as evidence that it is stream- 

 laid. Even larger bowlders have been carried out from the canyons 

 of the Sierra Nevada by torrents.'' The hypothesis that these 



^ A. C. Trowbridge, Jour. Geol., XIX (191 1), 706-47. 



