on a aii ren Soe Ny Ten Sen a Sie aie Sel aies hy? Wea Se a, te 
ali Sa en , 
J. I. Le Conte on Volcanic Springs in Southern California. 3 
greater portion of the eastern range of the Sierra: boulders fre- 
quently of immense size, but scarcely rounded, torn in former ages 
from the adjacent ranges of mountains, are cemented together by 
a small quantity * calcareous matter enveloping gravel of differ- 
ent degrees of fineness: this cement presents somewhat the ap- 
pearance of bad nici Outside of this conglomerate was seen 
unstratified drift. Beyond the mountains, can be traced on the 
esert a tertiary formation similar to that of San Diego, and above 
this stratified drift. These formations are nearly horizontal and 
form low ridges. The vegetation was still similar to that of Val- 
lecitas, with ‘the addition of a very large Echinocactus, of which 
several grew ‘since tk from one base : —- vaginata was 
also seen, and an Ephedra appeared with a specie of Koeberlinia. 
These gradually faded out, till at last nothing a but Pro- 
sopis, Larrea, and a plant at that season leafless. The desert 
contains three principle levels; of these the upper (consisting of 
the part near mountain ridges) i is covered with gravel, small stones © 
from the mountains, silicified wood and oyster shells; the middle 
level is sandy, and the lower one clayey, with great ‘numbers of 
fresh water shells scattered over its surface : among these the only 
bivalve is a species of Anodon, now found in the Colorado River, 
(A. californiensis Zea); the other species are small univalves, be- 
longing to Physa, and Amnicola. These clayey parts extend for 
many miles, and are evidently the beds of lagoons, which on rare 
occasions may be filled with water; they belong to the New River 
system of overflow, hereafter to be described. Having travelled 
rom the mountains a nearly east course, we encamped about 4 p.m. 
on the bank of a small stream running northwardly to the Salt 
Lake: the banks were precipitous, about twenty feet in height, 
and the waters disagreeably saline. This stream is evidently Ca- 
riso creek, which being lost in the sands a few miles from its source 
here reappears on the lower level of the desert: some rushes 
growing on the edge of the water ieee food for our horses. 
Starting the next morning at 3 a. m. we arrived about 10, at an, 
Indian villace situated on New River, which i is here near its term- 
ination, and probably when the supply 
of its water to the Salt Lake: at owe: there are only ‘two or 
three small pools near the village. 
New River is an important object to thoes? compelled to cross ° 
the desert, since from it is derived the chief supply of water, to 
be found between | Cariso creek and the Colorado. It is in reality 
a slough of the latter, which is only different from the ordinary 
ghs near the river by its greater length, extending by a very 
tortuous course 70 or 80 miles from the point where it leaves the 
river. The bed of the Colorado, like that of other rivers carrying 
a large amount 0 ‘ sediment, is above the lower portions of the 
ountr y which are Sf in time of overflow w supplied 
