260 



University of California Publications. 



[Geology 



embayment in the contact line and has isolated a heavy body of 

 garnet rock which caps the summit of the 11,530-foot ridge. A 

 small patch of schists at the lake at the head of Cliff Creek 

 seems to owe its position to the same cause, and is now satellitic 

 to the main mass. With these exceptions the Mineral King belt 

 constitutes an isolated, integral unit, surrounded by granites of 

 synchronous origin. 



The periphery of the belt is lined with granite peaks which 

 commonly exceed 12,000 feet in altitude — Sawtooth, 12,340 feet, 

 Florence, ] 2,405 feet, and other peaks unnamed as yet. West 

 of Vandever the granite plateau maintains a height of 11,200 

 feet with individual peaks rising to 11,800 feet. North of Cliff 

 Creek the vast assemblage of granite peaks "like the billows of 

 a choppy sea," fall into a general level at 12,000 feet. The 

 lowest exposure of the sedimentary rocks on Cliff Creek was 

 found at 7.000 feet, or a difference of 5,000 feet. Even in the 

 heart of the belt, that is, at the site of Mineral King, the differ- 

 ence in altitude between the highest and lowest exposure of the 

 sedimentary series is more than 4,000 feet. If we assume that 

 Sawtooth, which is on the immediate periphery, approximates 

 toward the former surface of the batholith, the difference will 

 amount to more than 5,000 feet. The contact passes through 

 the region of maximum glacial degradation where the mountain 

 crests have often been reduced not less than one thousand feet.* 

 It is, therefore, evident that 5,000 feet represents a minimum 

 estimate of the amount of depression of the sedimentary series 

 beneath the general level of the granite surface. 



A belt of stratified rocks thus surrounded and enveloped by 

 plutonic magmas was situated in extremely favorable environ- 

 ment for the operation of thermal metamorphic agencies. Yet 

 the alteration effected has been small, and always local. The 

 large body of clay slates, which examination shows to be the 

 most susceptible to metamorphism, are practically unaltered. 

 This is all the more surprising when considered in the light of 

 the facts from other portions of the Sierra Nevada. Turner re- 

 ports upper Jurassic (Mariposa) clays slates metamorphosed to 

 * A. C. Lawson, Bull. Dept. Geol. Univ. Cal., Vol. 3, p. 361. 



