TEE HEART MOUNTAIN OVERTHRUST, WYOMING 547 



the evidence of this region, one must conclude either (i) that the 

 period of erosion intervening between the deposition of the two 

 groups of breccias was brief and therefore that the floras are mis- 

 leading, or (2) that the intervening period of erosion was rather 

 long, probably persisting from upper Eocene time through Oligocene 

 and lower Miocene time, as the floras indicate. Dr. Iddings agrees 

 with the writer that the latter conclusion is more acceptable at 

 present. He further considers that the lithology and flora of the 

 tuffs and breccias between Owl Creek and Wind River warrant 

 the tentative correlation of them with the "early acid breccias" 

 of the Yellowstone Park region. It is apparent, however, that 

 considerable additional work must be done before the relations of 

 the volcanic rocks of the southern Absaroka Range are proved. 



MCCULLOCK PEAK EXPOSURES 



The foregoing statement of the lithologic features and structure 

 of the Fort Union and Wasatch beds of the Basin permit a more 

 careful consideration of the exposures near McCullock Peak and 

 the relations of the overthrust recognized by Dake west of Cody. 



In previous descriptions of this region, the name "McCullock 

 Peak" has been applied to the central part of a high rugged area, 

 about 4 miles long by 2 miles wide, 1 2 miles east of Cody. (Figure 3 

 shows a view of the McCullock Peak area from the west.) In the 

 following description of the region, three culminating summits 

 will be referred to as West Peak, Middle Peak, and East Peak, 

 respectively. Although extensive gravel-covered terraces extend 

 south from the peaks for several miles, the entire elevated region is 

 completely surrounded by typical bad lands, and the rock exposures 

 are uncommonly good. 



West Peak lies about two miles northwest of Middle Peak and 

 is connected with it by a sinuous rugged ridge. It is the culminating 

 point of a rugged bad lands area carved from nearly horizontal 

 Wasatch beds. It is almost devoid of vegetation and the terraced 

 ridges of alternating gray, olive, and red shale and sandstone 

 present an impressive picture from the east, north, and west. 

 It was not visited by the writer, but several attempts to ascend it 

 by horseback from the west are known to have failed. 



