Page 123 - 1915, Springs of CA.

HOT SPRINGS. 115
yield is used for irrigation, but the springs have not been efficiently
developed and improved.
The hilly country several miles southeast of Santa Rosa is com-
posed largely of lavas, and it is probable that tuffaceous layers asso-
ciated with the more compact phases of the stone afford storage for
the warm water that issues on the McEwan ranch and in other similar
warm springs in this region.

MARK WEST WAJBM SPRINGS (SONOMA 11).
In the canyon of Mark West Creek, about 9 miles north of Santa
Rosa, are three warm springs that issue a few yards apart along the
east bank of the creek and supply a small plunge bath and a bath-
house containing a few tubs. The waters are not notably thermal,
being about 65° to 85° in temperature, but the springs are most appro-
priately mentioned in connection with the other thermal springs of
eastern Sonoma County. The waters of the three springs are notice-
ably sulphureted. On the west edge of the creek a small, cool,
sulphur spring forms a drinking pool, and five other cool mineral-
ized springs issue on the property. Of these, Magnesia Spring
forms a drinking pool at the creek side near the baths, and two
others, known as Arsenic and Iron springs, seep from a tuffaceous
bank in a small gulch north of the main grounds. On the west bank
of the creek, below the baths, are two other small iron-stained pools.
The Mark West springs have been improved as a resort since 1880
or earlier. In 1909 accommodations were provided chiefly by tents
and it was visited mainly as a boating and fishing resort.
The rocks of this region consist of lavas and associated tuffs that
are similar to those near Sonoma. A high temperature gradient,
due to the presence of the lava, possibly exists along this part of
the coastal ranges and may be the main cause for the rise of warm
water at Mark West Warm Springs and other warm springs in eastern
Sonoma County.
BIG BEND HOT SPRINGS (SHASTA 8).
In the northeastern part of California hot springs, seemingly re-
lated to lava flows and possibly also to local faulting that has not
yet been recognized, issue at a number of places. Such springs rise
along the course of Pit River, the lowermost noteworthy locality
being at Big Bend near Henderson post office, where .hot water
issues at numerous places for a distance of about 350 yards along the
southern bank of the river. Near the eastern end of this zone, on
a gravel bluff about 15 yards from the river's edge, a bathhouse con-
taining several tubs and vapor chambers has been built over one
of the largest springs. The temperature of the water of this spring