Page 43 - 1915, Springs of CA.

HOT SPRINGS. 41
MUD VOLCANOES (IMPERIAL 5).

About 7 miles south of west from Imperial Junction, in the alluvium
on the eastern side of Colorado Desert, is an area in which vapor and
hot water vents are numerous. They were submerged by the rise of
Salton Sea 1 during 1905-1907, but they will become accessible again
as the water subsides. They were early visited by Le Conte 2 and by
Veatch,3 who describe them as covering a space of about 350 by 500
yards in an area of blue elay slightly elevated above the desert surface.
Vapor and hot water issued from numerous low conical mounds in this
area, and from some of the vents water was formerly thrown to a
height of 15 to 40 feet. Veatch reports that the water was strongly
saline and had a specific gravity of 1.075. He also reported unmis-
takable evidence of free boracic acid in it. Small amounts of sulphur
and of a salt that was considered by Le Conte to be sal ammoniac
(ammonium chloride), were deposited around the vents, and small,
coral-like stalagmites of lime carbonate were built up by the spray
from several of the more active springs. In 1905, before their sub-
mergence by the rising water of Salton Sea, they had become much
less active, and the locality contained only pools of hot water and
boiling mud, with the usual vapors and sulphur and saline deposits
that are characteristic of solfataric regions. There was a smaller
group of extinct or at least quiescent craters about a mile southeast
of the main group.4
These solf ataras are near a row of knobs or small buttes of obsidian,
pumice, and other varieties of volcanic rock which extend southwest-
ward from a point about 6 miles west of Imperial Junction, and the
presence of the hot waters probably represents a final phase of the
volcanic activity that produced the lava knobs. Since the rise of
Salton Sea these have become islets and have been made breeding
places by pelicans.
A similar but more extensive group of mud volcanoes is found on
the western side of Volcano Lake, in Mexico, near the base of the
Cerro Prieto, about 20 miles south of the international boundary, and

1 Salton Sea occupies the central part of Colorado Desert. Normally it receives only the occasional over-
flow from distributaries of this river, and it has been dry during a considerable portion of the last half cen-
tury. In the spring of 1905 Colorado River during its flood stage greatly enlarged the intake of a canal which
supplied irrigation water to a portion of Imperial Valley, and a large part of its discharge, and finally the
entire stream flowed northward to Salton Sea or Salton Sink. Several attempts were made to close the
break and stop the destruction that was being wrought in the valley, the river finally being forced back
to its natural channel in February, 1907. Since the summer of that year the sea has been gradually sub-
siding as its water has been removed by evaporation.
2 Le Conte, J. L., Account of some volcanic springs in the desert of the Colorado in Southern California:
Am. Jour. Sci., 2d ser., vol. 19, pp. 1-6,1855.
a Veatch, J. A., Notes of a visit to the mud volcanoes in the Colorado Desert in the month of July, 1857:
Am. Jour. Sci., 2d ser., vol. 26, pp. 288-295,1858.
* Mendenhall, W. C., Ground waters of the Indio region, California, with a sketch of the Colorado Desert:
U. S. Geol. Survey Water-Supply Paper 225, p. 14,1909.