496 FLeonte Mineral Vota Formation: 
veins in ‘the country rock, but only in the crust deposit. The 
country rock is completely buried under this crust probably 
20 to 30 feet deep, and therefore completely concealed from view. 
The hot alkaline waters loaded with silica seem to have de- 
posited so abundantly that they cover and choke up their own 
vents, while other vents are constantly formed by the expan- 
sive force of steam fissuring the crust previously formed. The 
great fissures described above were probably formed in this 
way, and perhaps opened by a slight bodily sliding of the crust 
toward the bottom of the valley. The analogy of the filled 
fissures to veins is not so complete as I had expected, or as it is 
at Sulphur Bank. If we could get beneath the erust and find 
fissures in the country rock filled by deposit, then indeed the 
analogy would be complete. This is exactly what we actually 
find at Sulphur Bank. In the immediate fumarole area, the 
country rock is concealed, but wherever not covered by de- 
posit its character is evident. On the hill slope and in the 
valley to the very margin of the deposit it is everywhere a 
quartz-trachyte or rhyolite. Along the crest of the western 
ridge, however, there is an outburst of black, very basic rock, 
probably basalt. This ridge is probably a basaltic dyke break- 
ing through a rhyolitic country rock. It is not improbable 
that the fumaroles are the feeble remnants of a voleanic activity 
Inuugurated by the basaltic outburst. 
innabar mines in the vicinity.—About a mile to the west- 
ward of the springs, cinnabar mines have been opened and 
reduction works established. A considerable amount of cinna- 
bar has been taken out, but the work is now abandoned. Here 
the surface appearances are entirely different from those at 
Steamboat Springs, and more like those at Sulphur Bank. 
There is no crust deposit, but on the contrary the whole bill- 
side rock is decomposed by acid vapors into a white chalky 
earth like that at Sulphur Bank, except that in this case the 
rock being rhyolite, the chalky earth is full of disseminated 
grains of free quartz. Tunnels have been driven into the hill- 
side at various levels and the ore extracted from the decom 
posed earthy matter, but the sound rock has not been reached. 
In this loose earth are found in considerable quantities both 
cinnabar and sulphur—the former in streaks as if deposited 12 
water-ways, the latter more irregularly and widely distributed 
as if formed by oxidation of sulphuretted hydrogen gas. Ip 
some places. sulphates of iron aad alumina are very abundant, . 
even more so than at Sulphur Bank. There can be no dou t, 
therefore, that here there came up, and probably are still comin 
up, hot waters containing alkaline carbonates and alkaline sa 
phides, carrying in solution and depositing sulphides of mer 
cury and iron by cooling, and by oxidation depositing also sul 
