254 QUICKSILVER DEPOSITS OF THE PACIFIO SLOPE. 



rather than an agreeable one. AVork in these cuts is so trying that few 

 white miners have ever accepted employment in them a second day and 

 almost all the labor is performed by Chinamen. 



Origin of the basalt. — To my mind there is little question that the basalt of 

 the Sulphur Bank was erupted on the spot. In the comparatively little 

 decomposed portions of the area contorted forms and cindery masses of the 

 lava still exist. This shows that it has expes^ienced but little erosion. The 

 two craters shown on the map are also extremely recent, as has been 

 pointed out in the preceding chapter. Between the craters is a lava stream 

 of very evident character; but the lava is not continuous from the craters 

 to the bank, the highest portion of which is over 50 feet above the level 

 of the ground at the points of discontinuity. Had the basalt of the Sul- 

 phur Bank come from the volcanoes, its original surface must have been 

 lower than that of any point in the lava stream connecting the localities, 

 and, if they were once thus connected, at least 50 feet of the rock has since 

 been eroded. There is no ravine crossing the track of the flow to produce 

 a local effect of this kind, and the surface indications entirely preclude the 

 supposition that there has been any general degradation approaching such 

 an amount since the basalt was extruded, or, indeed, any sensible amount 

 of degradation. 



I look upon the hot springs as of volcanic origin and as a later phe- 

 nomenon than the ejection of the basalt. There appears to be nothing to 

 warrant the hypothesis that these springs were in action before the basalt 

 eruption. On the contrary, the basalt lies upon recent lake deposits, some- 

 times filled with tule roots, and a part of these are within the influence of 

 the solfataric action, as is shown by their petrifaction. Had these springs 

 existed for an indefinite time before the basalt was ejected the tule roots 

 could not have grown.' 



Deposition of sulphur. — Tlic composltiou of tlic waters from different portions 

 of the Sulphur Bank varies considerably, but that a large portion of them 

 carrv hydrosulphuric acid is evident from the smell. The formation of 

 sulphur and sulphuric acid from hydrosulphuric acid by oxidation is one of 



'These silicilieil roots of tbe tule {Scirptts lacustris) bear a stroag resemblauce to Cauliniles, and 

 ray specimens, in tbe absence of sufficiently full information, have been described and figured by Mr. 

 Leo Lesquereux as a new species of tbat genus (Pioc. U. S. Nat JIiis., 18Sr, p. 3(;). 



