230 



University of California Publications. 



[Geology 



On the granites west of Vandever Mt. is a plateau surface 

 whose profile against the sky line shows smoothly flowing linea- 

 ments, and which represents the nearly obliterated remnants of 

 an earlier geomorphic cycle. 



GLACIATION. 



Evolution of the Topography. — The region bears abundant 

 evidence of a former severe alpine glaciation, which, neverthe- 

 less, must be regarded as having been of comparatively limited 

 duration. There is a general absence of well-defined terminal 

 moraines. A heavy deposit of lateral morainic material flanks 

 the west wall of Mineral King valley some 800 feet above its 

 floor. Half a mile below Mineral King striations show that the 

 glacier was not less than 1,000 feet thick. At the confluence of 

 Deer and Cliff Creeks is a great medial moraine consisting 

 almost wholly of angular blocks of quartz diorite, which has 

 shifted the junction of the tributary considerably down stream 

 along Cliff Creek. The evidence from the character of the 

 morainic material indicates that the tributary glacier, having but 

 a feeble catchment area, receded before the main glacier of Cliff 

 Creek commenced to wane, which then dammed up the mouth 

 of its affluent. Toward the head of Cliff Creek not more than 

 a quarter of a mile from the cirque a low embankment of loose 

 angular blocks spans the canon from wall to wall. This is the 

 only typical terminal moraine occurring within the confines of 

 the region under discussion. 



The extreme recency of the disappearance of glacial condi- 

 tions is shown by the preservation of highly polished surfaces 

 upon exposed granites, and of groovings and striations upon 

 soft schists, and perhaps still more emphatically, by the insig- 

 nificant amount of post-glacial stream erosion. This latter has 

 limited itself to a slight notching of tUe canon bottoms, but has 

 not yet advanced far enough to remove the veneer of glacial 

 material from the floor of Mineral King valley. 



The glaciation has left its profound impress upon the 

 geomorphic configuration of the region: in the production of 

 numerous amphitheatres and encircling arretes ; in the formation 



