POST-CRETACEOUS HISTORY OF WESTERN WYOMING 201 



at least two small remnants of an apparent peneplain still exist 

 north of the Grand Teton; one is the flattish summit of Mount 

 Moran (12,100 feet) and the other a triangular flat summit at 

 10,000 feet on the north side of Birch Creek several miles to the 

 west. Only the latter of these has ever been examined by a 



Fig. i8a. — Waterworn cobbles of quartzite among limestone fragments on the 

 flat summit of a peak (10,100 feet) in the Teton Range. 



Fig. 18b. — Diagram of the occurrence of the gravel shown above. The gravel 

 lies on the surfaces (AA). 



geologist (Figs. iSa and 186). Its surface is strewn with the usual 

 frost-cracked debris of the underlying Madison limestone, but 

 also with well-rounded cobbles of quartzite which still retain their 

 original poHsh. That this is a bit of an old stream-worn surface 

 is thus clearly shown. It may be a part either of the Wind River 

 or later peneplains, or of the unconformity at the base of the Pinyon 

 conglomerate. It may be argued that the peneplain would not 



