Page 269 - 1915, Springs of CA.

CAEBONATED SPEINGS. 249
Nearly all the carbonated springs are found in the sedimentary
and metamorphic rocks of the Coast Ranges north of San Francisco
Bay, in the lava area in the northern part of the State, and in the
granitic and metamorphic rocks of the Sierra, but the character of the
rocks appears to have little influence on the carbonated character of
the springs. In the tabulated summary, therefore, they are grouped,
as were the thermal springs, as impartially as possible, into general
localities, with respect, first, to the formation of notable carbonate
deposits; second, to the presence of lava near by; and third, to the
rock from which they issue, in order to show what evidence they fur-
nish as to the effect of lava on the formation of spring deposits.
The water of several of the springs at which there are deposits is
cool, but the maximum temperature of most of them is noticeably
above the normal. In the tabulated list of carbonated springs the
10 localities at which hot springs have formed deposits are included
(in italics) in order to bring together those springs at which there
are notable deposits. As noted in the summary of the hot springs
(pp. 151-153), most of these carbonate-depositing thermal springs issue
from or near lava.
In the descriptions of the hot springs it has been suggested that the
gas at a few of the carbonated hot springs may possibly be derived
from the deeper layers of the lava, for carbon dioxide is a large con-
stituent of the vapors that are given off during volcanic eruptions,
and it may plausibly be considered to be occluded in the lower portions
of the lava flows. The same suggestion is offered to account for the
carbon dioxide in several of the larger cool carbonated springs, but it
is based only on the evidence that is furnished by the most vigorously
effervescing springs, especially Oxone Spring and Table Rock Spring,
both of which issue from lava. This evidence is, however, partly
counterbalanced by that furnished by the Gas Spring, on the Bartlett
Springs property (Lake 9, p. 200), which issues from altered sediments.
The list shows 29 general localities having no deposit and 31 having
a deposit but offers little suggestive evidence as to the cause of depo-
sition. The seemingly approximate equality in the number of locali-
ties in each group disappears if the individual springs are counted, as
the totals are 119 springs without deposits and 45 springs with de-
posits. Of these 45 springs 21 issue from sedimentary or metamor-
phic rocks, 10 from, granitic material, and 14 from or near lava.
With the carbonated springs are tabulated the localities learned of
at which there are notable carbonate deposits that are probably of
spring origin, for some of them are of interest in connection with
existing springs.