H. W. FairhanTcs — Tin Deposits in California. 39 



Akt. VI. — The Tin Deposits at Temescal, Southern Cali- 

 fornia ; by Harold "W. Fairbanks. 



Introduction. — Several years ago, shortly prior to the final 

 suspension of work upon the Temescal tin deposits, the writer 

 was given exceptional facilities for a careful examination of 

 the mine and the country immediately surrounding it. Subse- 

 quently a brief description was published,* but owing to the 

 political importance of the question at the time no thorough 

 report was attempted. Descriptions of the tin veins occur- 

 ring here have been given by Blakef and Hanks,;}: although 

 little has been published concerning the conditions under 

 which the veins occur and the nature of the ore bodies. In 

 the present paper the writer will add to what is already known, 

 a more detailed description of the veins and the country 

 in which they are found. The report of Hanks referred to 

 above contains an outline of the history of the discovery and 

 the excitement following it, the purchase of the old Mexican 

 grant and the final development by the English company, so 

 that this part of the subject will not be touched upon. 



General Geology of the District. — The Temiscal tin mine is 

 located in the northwestern portion of the San Jacinto grant 

 about five miles southeast of South Riverside. This portion 

 of the grant consists of rolling hills having an elevation of 

 nearly 1,000 feet, and formed of a great variety of rocks. To 

 the west, separated by the Temescal valley filled with late 

 Miocene sediments, is the Santa Ana range, the most striking 

 topographic feature of the region. It is high and steep, con- 

 trasting strongly with the rolling though sometimes quite 

 mountainous country to the northeast. Its elevation is doubt- 

 less due to a great fault line, the northern portion of which 

 passes through the Temescal valley. Immediately adjoining 

 the valley on the east is a more or less connected strip of 

 highly metamorphosed rocks associated with porphyries, but 

 the most of the country in that direction is granite. 



The tin deposits lie nearly in the center of a rudely semi- 

 circular area of granite about two miles in diameter and con- 

 nected on the east with the great body of similar rock 

 extending indefinitely in that direction. The sedimentary 

 rocks along the edge of the granite area consist of quartzite, 

 mica schist and conglomerate of unknown age. A part at 

 least of the slates and limestones of the Santa Ana range are 



*XIth Report of the State Mining Bureau, p. III. 



f Mineral Resources of the United States, 1883-84, p. 614. 



X IVtli Report of the State Mining Bureau, p. 1 20. 



