222 W. LINDGREN — CALIFORNIA GOLD-QUARTZ VEINS. 



or differ in other respects from the normal gold-qiiartz veins, though the 

 latter are not without representatives. For many notes and valuable 

 suggestions I am under obligation to Messrs G. F. Becker, H. W. Turner 

 and J. S. Diller. The reports of the state mineralogist of California have 

 also been frequently consulted in the preparation of the maps. 



Geographic Distribution. 



The general map of California accompanying this paper indicates the 

 extent and distribution of the gold-quartz veins. Beginning in the penin- 

 sular range south of the Mexican boundary, the deposits continue in 

 scattered form and with many intermissions up to Fresno county, a few 

 of them also occurring at isolated points along the coast ranges south of 

 San Francisco. In Fresno county they become more abundant, and in 

 Mariposa county the auriferous belt rapidly widens. From here north- 

 ward to the point where they are covered by the great lava fields of 

 northeastern California the maximum development is obtained. In 

 latitude 40° the gold deposits extend from the great valley on the west 

 to the summits of the Sierra Nevada on the east. In a northwesterly 

 direction the continuation of the gold-bearing area is found in Shasta, 

 Trinity, Siskiyou and Del Norte counties in California, and its northerly 

 end occupies the counties of Jackson, Josephine and Curry in south- 

 western Oregon. Volcanic flows and more recent superjacent formations 

 cover the gold-bearing area toward the east and north. 



A smaller auriferous belt of less importance runs along the eastern 

 slope of the Sierra Nevada, beginning in Alpine county and continuing 

 southward through Mono, Inyo and San Bernardino counties. Most of 

 the deposits along this line differ more or less from the normal type of the 

 western slope. 



Geologic Relations. 



In the northern part of the Mexican peninsula and in San Diego 

 county granitic rocks prevail, but in them are imbedded numerous more 

 or less contact-metamorphosed areas of slates and schists of uncertain 

 age. The gold-quartz veins usually occur in, or at least close to, these 

 areas. The principal mining districts in San Diego county are Julian and 

 Banner, in the central part, and Pinacate, near the northern boundary.* 



Granitic rocks, with smaller schist areas, continue through San Ber- 

 nardino and Los Angeles counties. Placer deposits and smaller veins 



* Ml' W. H. Storms has described interesting lenticular veins from the former locality, which, 

 according^to his explanation, doubtless correct, are only modifications of normal fissure veins. 

 Eleventh Ann. Rep. State Mineralogist of California. 



