THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



NOVEMBER 1868. 



XLII. Notes on the Chemical Geology of the Gold-fields of 

 California. By J. Arthur Phillips*. 



DURING three separate visits to the Pacific coast of North 

 America I have had numerous opportunities of studying 

 the geology of the Californian gold-fields, and of investigating 

 the circumstances attending the chemical and physical changes 

 which have formerly occurred and which, to a certain extent, are 

 still taking place in those regions. Whilst carrying out these 

 researches, various facts have come under my notice which appear 

 to throw some light on the formation of auriferous veins, as well 

 as on the distribution of the precious metal in the rocks in which 

 it is found. 



I have endeavoured to embody in the following paper some of 

 the results of my inquiries, in the hope that, should the con- 

 clusions to which I have arrived be shown to be fallacious, the 

 facts which have been collected may nevertheless assist other in- 

 vestigators in arriving at a correct interpretation of the pheno- 

 mena attending the formation of auriferous veins. In doing 

 this, I propose to first give a short description of the gold regions, 

 and subsequently to treat of their quartz veins, alluvial deposits, 

 hot springs, and salt lakes, all of which are intimately connected 

 with the chemical geology of the districts in which they occur. 



Rocks of the Gold-Region of California. 



The great sedimentary metalliferous belt of California lies on 

 the western slope of the Sierra Nevada, beginning in the neigh- 



* Communicated by the Author, being the substance of a paper read 

 before the Royal Society, March 12th, 1868. 



ML Mag. S. 4. Vol. 36. No. 244. Nov. 1868. Y 



