Page 331 - 1915, Springs of CA.

MAGNESIC SPRINGS. 311
The principal springs rise from the northern border of an area of
pyroxene rock and serpentine which cover the slopes to the south,
the slopes north of the springs being of siliceous sandstone. The sand-
stone probably belongs to the Franciscan group of altered sediments,
which occupies considerable areas in the Coast Ranges, and the
serpentine bears its usual intrusive relation to the sediments.

ISHAM SPRING (SAN DIEGO 15).
In the granitic ranges northeast of San Diego there are a number
of small springs whose waters have been developed commercially for
table and medicinal use. Isham Spring is probably the best known
of these, as its water has been on the market for many years. It was
formerly known locally as Baldhead Spring, as the use of its water
was thought to aid in preventing baldness. The spring is situated in
a swale near the head of a small tributary of Sweetwater River, 12
miles by road north of east from S.an Diego. The water issues in a
small cemented and inclosed basin at the side of the drainage channel,
from two crevices in the bedrock. It is piped thence to a small reser-
voir and to a bottling house.
The water is noticeably mineralized, magnesia apparently being
the constituent most evident to the taste, and the analysis, which
is tabulated on page 312 with that of another commercially developed
spring in the same locality, shows that the water is primary and sec-
ondary saline and secondary alkaline in character.
The rock of the locality is considerably decomposed and evidently
furnishes the main soluble constituents of the water. A small amount
of lime carbonate has been deposited along the side of the ravine near
the spring and also on the hillside a few hundred yards eastward.
NUVEDA SPRING (SAN DIEGO 16).
Nuvida Spring is a few miles southeast of Isham Spring, being 8
miles by road from La Presa railroad station. Its water has been
placed on the market for table and medicinal use. The following
analysis shows that it is essentially secondary saline in character,
with magnesia fairly well represented though not very noticeable to
the taste.