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University of California Publications. 



[Geology 



The limestones have in all eases become marmorized near 

 the contacts. In the White Chief cirque north of Vandever Mt. 

 are large beds of coarsely crystalline white limestone paralleling 

 the contact, which is marked by a four-foot zone of garnet rock. 

 The limestone contains bodies of magnetite ore, and large meta- 

 somatic deposits of zinc blende. Pieces of the sulphide ore are 

 frequently studded with small honey-yellow garnets (grossular- 

 ite ) . Under the microscope the garnet rock is seen to be com- 

 posed for the most part of common garnet, entirely isotropic. 

 Some monoclinic pyroxene of reddish brown color and of refrac- 

 tive index very near that of the associated garnet is present in 

 small amount, Its extinction angle exceeds 40°, and it there- 

 fore falls toward the hedenbergite end of the diopside series. 

 A little wollastonite is also found. Calcite forms an irregular 

 mesostasis serving to bind together the other constituents. 



A local phase of the metamorphism of the limestone is a fine 

 grained variety specked with small particles of a dark greenish 

 mineral. The microscope shows that the dominant constituent 

 is a dusty looking carbonate, Associated with it in smaller pro- 

 portions is a clear limpid mineral displaying the characteristic 

 calcite twinning. A qualitative test of the rock gave a large 

 precipitate of magnesium, indicating that the brownish car- 

 bonate is probably dolomite. Subsidiary amounts of diopside, 

 which have frequently been converted to colorless serpentine 

 aggregates, are also found. Areas of fibrous chalcedony are 

 quite common. Some little reddish broAvn garnet and a few 

 granules of magnetite, which were not associated with the ser- 

 pentine, constitute the accessories. 



Along the creek descending from the 9,883-foot Peak the 

 following section is exposed across the strike, N. 45° W. : — 

 Porphyritic hornblende — biotite granite. 



Sheared quartz porphyry 300 feet 



Siliceous schist 3 ' ' 



Clay slates .' 50 " 



Banded quartzite 150 ' ' 



(containing a granite dyke 8 feet wide.) 



Knotted schist 25 " 



Crystalline limestone, banded blue and white 75 ' ' 



Blue crystalline limestone 50 ' ' 



Laminated quartzite 40 ' ' 



Hornfels 10 " 



Schistose quartzite 50 ' ' 



