Page 290 - 1915, Springs of CA.

270 SPRINGS OF CALIFORNIA.
Sandstone associated with serpentine exposed near the springs
probably belongs to the Franciscan formation of old sediments and
metamorphic rocks, which occupies considerable areas in the central
portion of the coastal region.
SULPHUR SPRINGS NEAR WALNUT CREEK (CONTRA COSTA 3).
A group of sulphur springs lies near the northeastern base of r,
low ridge about 2 miles northeast of the town of Walnut Creek. The
largest spring is on the ridge, about 100 yards from its eastern baso
and 25 yards north of the county road. When the place was visited,
the water rose in a board-curbed pool protected by a latticed house*
and was piped to a cattle trough a few yards away. It yielded about
3 gallons a minute of mildly sulphureted water, 81° in temperature
On account of this noticeably high temperature the springs are indi-
cated on Plate III (in pocket) as thermal sulphureted. Five other
smaller sulphur springs issue in a belt extending 350 yards along'
the base of the ridge, in and near the barnyard of Sulphur Springs
farm. Two of them have been piped to watering troughs near by.
The other three are of seeping flow and form only small marshy
places.
The ridge is composed of sandstone that appears to dip nearly
vertically and strike S. 30° E. (magnetic) along the trend of the
ridge. The steep inclination of the beds shows that intense move-
ment has taken place here, and a fault that is indicated on Plate III
extends along the border of the valley land. This structural break
probably accounts for the rise of the springs and also for their thermal
character.

SULPHUR SPRING IN PINE CANYON (CONTRA COSTA 4).
A moderately sulphureted spring emerges about 4 miles in a
direct line northward from Danville, in Pine Canyon, which is at
the western base of Mount Diablo. The water forms a clear pool,
about 15 inches wide and 4 feet long, in thick-bedded sandstone at
the southern side of the creek. The yield is larger than is usual for
springs of this class, being estimated at 5 gallons a minute, and the
temperature of the water (67°) is also somewhat above the normal.
The spring has not been improved, but it has been visited by occa-
sional picnic parties. There are three seepages within 5 yards of
the spring, and 1^ miles farther eastward, upstream, sulphureted
water seeps from a bluff on the northern side of the creek. Only the
one spring of appreciable flow was observed along the canyon,
however.
MAYHEW SPRING (ALAMEDA 2).
Mayhew Spring is about 200 yards north of Niles depot. It is
situated in an orange orchard and is surrounded by a cemented stone
curbing which forms a reservoir about 4 feet in diameter and 10 feet