Page 160 - 1915, Springs of CA.

144 SPRINGS OF CALIFORNIA.

minute, and nearly all its water apparently came from two hot springs
in the bowlder-strewn drainage channel on the slope 10 or 15 yards
northwest of it. The slope immediately north of the springs is
altered to white siliceous material, but the water has no distinctly
mineralized taste.
It is said that during the seventies the main spring cast water to a
height of 10 feet or more and was more truly geyser-like in action.
Residents in the region say that its energy has been gradually di-
minishing and has noticeably decreased within the last few years.
Information is not at hand, however, regarding the influence of the
seasons on its action or the extent to which its vent has been choked
by rocks thrown into the pool.
Lassen Peak and the country that surrounds it for a number of
miles are composed of lavas of comparatively recent geologic age,
being assigned to the Neocene epoch of geologic history. In at least
one place, however, which is at Cinder Cone, there is evidence of an
eruption that is believed to have taken place within two cen-
turies.1 The existence of numerous hot springs in this region there-
fore seems to be connected with the presence of the recent lava, and
the water probably receives its heat from underlying masses of lava
that have not yet cooled down to the normal temperature of the sur-
rounding rocks at that depth. This condition is strongly indicated
by the renewed activity of the peak in May and June, 1914.

HOT SPEINGS ON MOUNT SHASTA (SISE3YOU 14).
Vapor and small amounts of hot water rise at two localities near
the summit of Mount Shasta. These localities are of relatively little
importance as hot springs, but their presence at such an elevation
and position is of geologic interest with respect to the mountain,
which is a volcano that has become extutct within comparatively
recent geologic time. The heat of the water, as at the springs near
Lassen Peak, is probably derived from heated lava within the moun-
tain.
HOT SPEINGS ON PAOHA ISLAND (MONO 7).
Along the eastern front of the Sierra there are other groups of hot
springs whose existence seems to be closely related to lavas of recent
geologic age. One of the northernmost of these groups is on the
east side of Hot Spring Cove, on Paoha 2 Mand in Mono Lake. The
western part of the island is covered with lake sediments, but the
eastern part is formed of black lava, and on its most southeastern point
vapor and small amounts of hot water issue from numerous crevices.
1 Diller, J. S., U. S. Geol. Survey Geol. Atlas, Lassen Peak folio (No. 15), p. 4,1895.
2 Because of the hot springs an Indian term (pa-6-ha) meaning "spirits of the mist" was applied to the
island by Prof. I. C. Russell in The Quaternary history of Mono Valley, California: U. S. Geol. Survey
Eighth Ann. Kept., pt. 1, p. 279,1889.