Page 83 - 1915, Springs of CA.

HOT SPBINGS. 79

The spring has been known since 1848, and was first used to supply
sheep-watering troughs. Water is scarce in this region, and the
Mercey spring is still valuable for stock watering, as well as for its
mineral character. There was formerly a small resort here, and the
bathing accommodations were in 1908 still patronized by people from
the surrounding towns. For several years prior to the earthquake of
April 18, 1906, the water was bottled for table use, but the market
was interrupted at that time, and in 1908 had not been resumed.
The main spring rises in an open draw at the base of low, cherty
gravel slopes. About 100 yards eastward, at the opposite side of a
low ridge, another small warm spring issues that is more strongly
sulphureted, and 400 yards westward, in a ravine, is a small cool
spring that is not noticeably mineralized.
A dike of serpentinous gabbro 50 yards or more in thickness cuts
across the slopes a short distance south of the springs. It may par-
tially account for their issuance, though it is on the slope above, not
below them.
GILBOY HOT SPRING (SANTA CLARA 9).
Gilroy Hot Spring is situated on the side of Coyote Creek canyon,
in the southeastern part of Santa Clara County. The spring, which
has an observed temperature of 110° and a flow of perhaps 15 gallons
a minute, issues in a ravine on the western side of the canyon, 200
feet above Coyote Creek. The rocks of the area are chiefly sand-
stones, cherts, and conglomerate. Some serpentinous and gabbrofd
rocks were noted on the slopes to the southeast, within half a mile of
the spring, and suggest that intrusive rock may have given rise to
the heated water at this place. The following is an analysis of water
from the spring:
Analysis of water from Gilroy Hot Spring, Santa Clara County, Cal.
[Analyst and authority, Winslow Anderson (1888). Constituents are in parts per million.]
43° C. (110° F.)
Properties of reaction:
60
31
0
Primary alkalinity. ............................................................. 0
Secondary alkalinity. . .......................................................... 9
62
By Reacting
Constituents.
weight. values.
228 9.93
17 .42
66 3.30
43 3.57
2.1 .075
Sulphate (SOO ................................................................... 185 3.85
Chloride (Cl). ....................................................................... 422 11.91
Iodide (I)........................................................................... Trace. Trace.
46 1.53
Trace, Trace.
Silica (SiO2)............... .......................................................... 57 1.88
1,066.1
114 5.16
61 3.58