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University of California Publications in Geology [Vol. 13 



These rocks correspond in every way to igneous rocks which have 

 been rendered schistose. There are other rocks in this vicinity, how- 

 ever, which are of more doubtful origin. On the ridge two miles south- 

 west of the peak where the trail turns suddenly down into High Creek 

 there are schists dipping 30° NW sunken into the granite. The indi- 

 vidual bands are rather long, although very thin. Under the micro- 

 scope the rock appears to consist largely of quartz grains intimately 

 intergrown. Orthoclase is the only feldspar present and is in small 

 amount. Biotite is abundant and with it is a little muscovite and a 

 few grains of titanite. Small patches of schist are seen the rest of the 

 way down the slope imbedded in the granite and usually isolated from 

 each other. They appear to partake of the nature of roof pendants 

 rather than inclusions, since they have, for the most part, approxi- 

 mately the same attitude, striking N 60° E and dipping 30° NW. In 

 the lower portions of the first little gully east of the ridge forming the 

 divide between Mill Creek and Whitewater there are schists, quartzite, 

 and limestone sunken into the granite. They are in conformable 

 sequence, the quartzite being at the bottom and overlain by schist and 

 this by limestone, a relationship entirely normal for these rocks. The 

 thickness of the limestone is 30 feet, the schist 10 feet, and only 30 feet 

 of quartzite is exposed. This quartzite is of vitreous rather than sac- 

 chroidal variety. One specimen, which appeared rather pure in hand 

 specimen, was found on microscopic examination to contain a few 

 flakes of biotite and muscovite. The quartz grains are intimately inter- 

 grown and exhibit undulatory extinction. A few crystals of feldspar 

 are present, but so altered as not to be determinable with certainty. 

 They are probably orthoclase and oligoclase. Another specimen, some- 

 what darker in general and showing dark and light streaks, was found 

 to contain more biotite. The quartz grains have a tendency toward 

 elongation parallel to the streaks of biotite. A few grains of titanite 

 and magnetite are present as well as some round crystals which are 

 isotropic and highly refractive, probably garnet. There are also a 

 few prisms of apatite. The limestone is much broken and is entirely 

 recrystallized ; in it are developed contact minerals : epidote, garnet, 

 and tremolite. They are best developed along fissures, and in some 

 cases they follow planes of stratification. The schist between the 

 quartzite and limestone at first looks like a fine-grained sandstone con- 

 taining considerable biotite. Under the microscope it has somewhat 

 the appearance of a fine-grained granite, largely due to its granoblastic 

 texture. It contains orthoclase, albite, oligoclase, possibly a more 



