POST-CRETACEOUS HISTORY OF WESTERN WYOMING 331 



Cirques of the Buffalo stage are no longer to be identified with 

 confidence, and it is now uncertain whether the glaciers were of the 

 valley type or parts of an ice-cap. In most cases even the general 

 outline of the ice-mass is uncertain. But few traces of morainic 

 topography now remain in the drift of this age, because most parts 

 of the region have been dissected to maturity by the growth of 

 valley-systems. This condition is clearly shown on the broad sheet 

 of till along the new branch of the Oregon Short Line between 

 Marysville and the north fork of Teton River in eastern Idaho 

 (Fig. 47). Nevertheless, on some of the broadest plateaus, where 



Fig. 47. — The present topography of the ancient till sheet (Buffalo) south of 

 Conant Creek on the northwest slope of the Teton Range. 



relief is still sHght, there are shallow depressions filled with peat, 

 or still containing marshy lakes. Such features are to be found 

 twenty miles east of Ashton, Idaho, and near the branching of 

 Buffalo Fork of Snake River. 



The surface of the old drift in the western half of the region is 

 generally smooth and almost devoid of bowlders. This probably 

 is due not so much to the decay of bowlders as to their burial by the 

 eolian deposition of loess in that district to a depth of from two to 

 five feet. Bowlders of granite on the isolated hills of sedimentary 

 rock south and east of Kendall in the Green River valley are outside 



