318 KRAMM— SERPENTINES OF THE CENTRAL [June 6. 



General Location of the Serpentines. 



For the sake of description and convenience the areas have been 

 divided into districts. These are named and situated as follows : 



I. The Sulphur Creek district is about twenty miles east of 

 Clear Lake. It is situated about the headwaters of the Sulphur 

 Creek, a tributary to Cache Creek, and embraces the Lake and 

 Colusa County dividing line. 



IL The Knoxville and Clear Lake district comprises all those 

 serpentine areas which are found about the point at which Lake, 

 Yolo and Napa counties meet. It is limited in the north by Cache 

 Creek and in the south by Putah Creek. It also includes the areas 

 found in the immediate neighborhood of Clear Lake. 



III. The Mayacmas district is bounded in the north by Putah 

 Creek. It embraces the serpentines found along the Mayacamas 

 range, which from Mount St. Helena extends to the northwestwards. 



IV. The San Francisco district takes in all areas of serpentine 

 found on the San Francisco peninsula, and areas in the vicinity of 

 San Francisco. 



V. The Coyote Creek and Black Mountain district comprises all 

 serpentines which are found in the country drained by the Coyote 

 Creek, south of San Jose, besides these the serpentines found in 

 the Black Mountain region. 



VI. The Mount Diablo and Mount Hamilton district includes 

 all serpentine areas which are found in the country between these 

 mountains. 



I. The Sulphur Creek Serpentines. 



The serpentines of this district form two belts, each one several 

 miles in length, and in width varying from lOO feet to one half mile. 

 Besides these, there are two smaller areas. 



The first and most important belt is encountered about lOO yards 

 west of the Wilbur Springs Hotel. From here it extends five miles 

 in a northwest direction, forming the backbone of a ridge which 

 stands out prominently above the surrounding country. To the 

 south it extends a distance of one mile, and closely approaches the 

 second belt of serpentine. 



