340 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



similar to those studied by Dr. Hector near Lake Omapere, in New Zea- 

 land, where, too, the sinter contains cinnabar. (See page 50.) 



Diversities — The eflfects produced by the action of the heated waters and 

 of the gases accompanying them in the various portions of the atfected area 

 differ very materially and in an interesting manner. The heavy masses of 

 sinter near the railroad are to a considerable extent composed of carbonates 

 and all effervesce with acids. Much of the mass is silica, however, in part 

 crystalline and in part amorphous. The material is deposited in laj'ers or 

 bands, partly lining crevices and partly covering the adjacent country in 

 more or less nearly horizontal sheets. The linings of the crevices have a 

 ribbon structure precisely such as is found in veins and composed of sub- 

 stantially the materials most common in veins, excepting indeed the hy- 

 drated silica. In the northwestern part of the area carbonates occur only 

 in small quantities. The deposits here are for the most part chalcedony, 

 which also exhibits riljbon structure. In the neighborhood of the mine 

 workings only small quantities of silica and carbonates have been deposited. 

 Here, indeed, the quantity of material removed by the spring waters is 

 greatly in excess of the deposits which they have formed. In the southern 

 jiart of the ground, where mining has been carried on, an actual basin has 

 l)een formed, with a low rim to the north, which, however, is not sufficiently 

 high to be exhibited b}- the 20-foot contour lines. This basin, from which 

 there is no drainage, is not artificial, and appears be}'ond question to have 

 formed in consequence of the collapse of the decomposed granite, yet it 

 contains not only cinnabar, but a thin layer of sinter composed of carbonates 

 and silica 



There is no reason to suppose that the general character of the fluids 

 and gases which have been active in the various portions of this area dif- 

 fered qualitatively ; on the contrary, the entire character of the deposits and 

 the distribution of decomposed granite indicate that the qualitative com- 

 position was the same. Variations in the quantitative composition of the 

 waters thus seems to have been snfficient to bring about either the deposi- 

 tion of large masses of material or an actual subsidence of the surface. 

 This important inference mayssem doubtful when drawn from this locality 

 alone; for, though there is no indication of a qualitative difference in the 



