[ 422 ] 



LI I. Notes on the Chemical Geology of the Gold-fields of Cali- 

 fornia. Bij J. Arthur Phillips. 

 [Concluded from p. 336.] 

 Hot Springs. 



HOT and boiling springs are exceedingly numerous through- 

 out California; and considerable accumulations of sulphur, 

 together with evidences of extensive solfatara action, are met with 

 in different sections of the State. To attempt even a mere enume- 

 ration of all the various localities where these phenomena have 

 been observed would occupy more space than it is my intention 

 to devote to the subject; and I shall therefore confine myself to 

 a description of two or three of the more remarkable examples, 

 selecting such only as appear to have the most direct bearing on 

 some of the chemical and geological changes which have been 

 produced, and are, to a certain extent, still going on in this por- 

 tion of the American continent. 



Borax Lake. — Lying about a mile beyond the ridge which 

 borders Borax Lake on the north-east is a locality in which sol- 

 fatara action is still exceedingly active, and where a large amount 

 of sulphur has accumulated. This is called the " Sulphur 

 Bank," and is of some six or seven acres in extent. It consists 

 of a much decomposed volcanic rock traversed by innumerable 

 fissures, through which steam and gas are constantly issuing, 

 and over and through which large quantities of sulphur have 

 been deposited in such a way that, at a little distance, the whole 

 mass appears to consist of this substance. Into some of the ca- 

 vities a pole may be inserted for several feet ; and they are often 

 lined with stalactites and beautiful crystallizations of sulphur. 



This sulphur is being constantly deposited, and its deposition 

 is attended by the evolution of aqueous vapour, carbonic and 

 boracic acids ; but this apparently takes place without the emis- 

 sion of sulphuretted hydrogen. The gaseous matters issuing 

 from the crevices have usually a temperature of about 95° F., 

 and appear to be the agency by which various mineral substances 

 now deposited in the cavities were brought to the surface. Sul- 

 phur is deposited on the sides of the various fissures, either in 

 groups of crystals, as stalactites, or in translucent amorphous 

 masses of a beautiful yellow colour. It is sometimes intermixed 

 with cinnabar, but more frequently with minute crystals of iron 

 pyrites, and with pulverulent silica, blackened by the presence 

 of a hydrocarbon having the appearance of coal-tar. With these, 

 according to Dr. Oxland, are found silver and traces of gold*. 



* Mining and Metallurgy of Gold and Silver, by J. Arthur Phillips, 

 p. 11. E. andF. N. Spon : London. 



