Page 92 - 1915, Springs of CA.

88 SPRINGS OF CALIFORNIA.

The waters form a remarkable series. The analyses indicate that
all are alike in being sulphureted and nearly free from chloride
radicle and in containing a relatively small proportion of primary
bases. The bathing water and Indian and Eye springs are similar
in many respects. Secondary alkalinity is the most prominent
property in the three, but in the bathing water the alkalinity is due to
borates, in the Indian Spring to carbonates, and in the Eye Spring
to silicates, if the analyses are correct and complete. In all the
other waters tertiary salinity is specially noteworthy, being an unusual
characteristic of natural waters. Excess of magnesium over calcium
is also of interest.
The rocks of this region consist of crushed and altered sandstones
and shales, with cherts, schists, and associated serpentine, which form
a part of the Franciscan formation. In the localities where the
vapors and hot waters issue the sandstone is greatly altered, being
changed to a clinker-like siliceous material. Serpentine is exposed
along the canyon side between Steamboat Geyser and the main
ravine. The presence of the serpentine at this place is of interest
from the fact that two magnesia springs issue near what appears
to be its southern border. Water from one of these springs is car-
bonated and bottled as Geyser Water.
At several places on the north side of Sulphur Creek, both above
and below The Geysers, there are areas where the rock has been
bleached and decomposed by solfataric action, and at a few of them
hot water and vapor still issue. Indian Spring, of which an analysis
has been given, is a warm pool about three-quarters of a mile west
of the hotel.
LITTLE GEYSERS (SONOMA 5).
About 4 miles above The Geysers, at a locality known as Little
Geysers, vapor and hot water issue in notable amounts. At this
place there is an area of perhaps one-quarter of a square mile on open
slopes within which the rock has been bleached and altered, but the
surface activity of heated water is now mainly confined to an area
about 200 yards in diameter. Three small hot springs, seven hot
pools, and four vapor vents were counted here. A cabin has been
built near by and a small bathhouse at one of the springs has been
used by miners and, in summer, by campers. About 250 yards below
the cabin the largest hot spring that was noted in this locality rises
at the creek edge and is used as a drinking pool. It yields about 5
gallons a minute of faintly sulphureted water, 160° in temperature.
About 1 mile southward from Little Geysers is the Socrates quick-
silver mine. The relation of the quicksilver deposits to hot springs
and to areas of lava has been mentioned by Becker,1 with special ref-
1 Becker, G. F., Geology of the quicksilver deposits of the Pacific slope: IT. S. Geol. Survey Mon. 13,
p. 404, 1888.