32(5 KRAMM— SERPENTINES OF THE CENTRAL [June 6, 



proximately one half mile. It widens out towards Howard Springs, 

 where it has a width of about one mile. From here a series of 

 outcrops point to the southeast and can be followed for about three 

 miles. 



The serpentine, being more resistant towards erosion than the 

 associated sandstone, occupies an elevated position in places rising 

 several hundred feet. It is fairly well preserved, of a dark green 

 color, with coarse phenocrysts of bastite, and is exceedingly brittle. 

 Thin sections show that the rock is almost wholly made up of 

 serpentine. Of original constituents enstatite and chromite only 

 are found, while the mesh structure due to olivine is very promi- 

 nent. Its similarity to the Knoxville serpentine leaves no doubt 

 as to its origin from a Iherzolite. 



The road from Kelseyville to Cloverdale past Elliott Springs 

 cuts several areas of serpentine. The first one to the east of the road 

 is one and a half miles east of Highland Springs, and its extent is 

 one quarter square mile. The second and most important one is 

 met 200 yards south of Fowler. The road cuts it and exposes a 

 vertical wall of 50 feet of serpentine of a bluish green color. 

 Slickensided fragments and an advanced state of decomposition are 

 pronounced features. Fresher specimens show the porphyritic 

 appearance caused by protruding foliated crystals of bastite. The 

 area covers one half square mile. 



Single outcrops are found a mile north of Elliott Springs, near 

 Elliott Springs, and also three quarters of a mile south of it on the 

 slope of the mountain ridge which divides Sonoma from Lake 

 County. All of the serpentines are intrusive in sandstones. A 

 feature of the contact is the occurrence of glaucophane and musco- 

 vite schists thus pointing towards rocks of Franciscan age. ]\Iicro- 

 scopically the serpentines resemble those of Howard Spring. 



Serpentine is also found west of Clear Lake and in close proxim- 

 ity to it. There are three small areas. The most northern one 

 borders Clear Lake and is best reached by following the road from 

 Lakeport to Upper Lake. It is five miles from the first named 

 place. Another area is a few hundred yards south of Lakeport 

 to the west of the road leading to Kelseyville. The third area is 



