12 University of California Publications in Botany [Vol. 9 



of glacial action are not found till the region of Gold Lake is reached 

 in Sierra County. From this point southward to the Middle Kern, 

 glacial phenomena give the tone to the high mountains. 



The Sierran glaciers were, as a rule, controlled by the topography. 

 In the Grizzly Mountains of Plumas County, Turner found evidences 

 of the former existence of glaciers on eastern slopes but none on west- 

 ern or southern slopes. In the high Sierra of Tulare County, Lawson" 

 noted that all evidence pointed to an ice control "entirely of an 

 Alpine type." In the district between Yosemite Valley and Lake 

 Tahoe there was some approach to the continental type of glaciation 

 with a summit neve-field sending glaciers down both flanks, but even 

 here the highest summits remained above the ice. In the central Sierra 

 both altitude and rainfall were sufficient to send tongues of ice down 

 the valleys on the western slope to about 4,000 feet, and on the eastern 

 to 6,000 feet. In the southern section the lower level reached by the 

 ice at Mineral King was about 7,000 feet.* In Kern Canon the trunk 

 glacier ended just below the mouth of Coyote Creek at 6,450 feet." It 

 should be noted that these tongues of ice within the valleys reached far 

 lower levels than the general glaciation and were able to reach such low 

 altitudes only because of the great extent of the high mountain catch- 

 ment areas ; where such areas did not exist, the lower limit reached 

 by the ice is less distant from the summits ; in Plumas County Turner-* 

 found on the northeast slope of Grizzly Hill glacial debris somewhat 

 below 6,000 feet, though the summit of Grizzly Hill, the highest point 

 nearby, is but 6,424 feet. With the exception of some debris in Bucks 

 Valley not recognized as certainly glacial, this Grizzly Hill glacier 

 had the least elevation of any glacier known to Turner to have existed 

 in the Sierra during glacial time. In other words, at the northern 

 limit of the Sierra the ice failed to reach as low as in the central part 

 of the range and but little lower than in the extreme south. On the 

 main Sierran crest. Cirque Peak, ten miles south of Mt. Wliitney, is 

 the most southern point showing signs of glaciation.'''* On the eastern 

 flank glacial phenomena are of much less magnitude. 



The topographic forms produced in the Sierra in this period of 

 alpine glaciation are similar to those seen in other regions which have 

 been subject to the same type of ice control. The upland surfaces 

 were denuded of their soil and reduced in extent by cirque cutting 



* This for a long time was thought to be the most southern point showing 

 glacial traces on the Pacific Coast. Recently certain obscure topographic forms 

 on the north slope of the San Bernardino Mountains above 8500 feet have been 

 referred to glacial ice,2c> a conclusion not concurred in by others who have examined 

 the same region. 27 



