ALLUVIAL FORMATIONS—VOLCANIC, 85 
rocks being principally granite, containing much feldspar, the surface around is generally 
strewed with little angular fragments of this mineral; and thus, although it may have the 
appearance of a mere surface of gravel, it has all the elements of a fertile soil, except the vege- 
table mould, which would soon accumulate if the climate or supply of moisture favored the growth 
of vegetation. We have already seen that in the formation of the slopes the coarser and heavier 
materials are not transported far down, but remain on the upper portions near the sides of the 
mountains, while the finest materials are carried far down. In some cases, where the supply 
of water is great, and forms ponds or lakes in the valleys, the finest parts of the soil, held in 
suspension by the water, are deposited there, so that a horizontal layer of clay is left when the 
water evaporates. In this way the Playas are formed. These deposites contain too much clay, 
and become too firmly impacted, to be of any service for cultivation ; moreover, the climatic con- 
ditions are not favorable. The slopes, however, in favorable situations, have all the qualities 
of soil necessary for abundant erops of the cereals, and would become exceedingly verdant and 
luxuriant with vegetation if water could be artificially supplied. 
Valley of the Mojave.—There is much fertile land on the banks of this stream, which sustains 
a vigorous growth of grass and willows. The river-bed is very sandy, and large areas of the 
bottom-land, which are subject to overflow, are covered with the sand. The fertile and desirable 
land forms but a thread-like strip along the river, when we compare it with the broad and 
semi-desert surface of the Great Basin which surrounds it, 
Valleys of San Bernardino and Los Angeles.—The valley of San Bernardino lies at the south- 
ern or western base of the Bernardino sierra, and is entered by the road from the Cajon Pass. 
It is not possible, within the limits of this brief notice, to do justice to its extreme fertility and 
the salubrity of the climate. "The bottom-land, along the streams, is well adapted to all kinds 
of crops, and the higher portions, or the surface of the main slope from the mountains, could 
undoubtedly be successfully cultivated, if it was supplied with water by irrigation. The 
Mormons, now occupying this valley, are covering it with neat dwellings and well-tilled fields, 
and the evidences of substantial prosperity abound. The generally fertile character of all the 
valleys, and of the whole slope from the mountains to the Pacifie, is well known, and the pro- 
duetions are a sufficient evidence of the depth and richness of the soil and the favorable climate. 
The soil of the slope may be regarded as formed of the wash from the mountains, together with 
the débris of Tertiary strata and the remnants of ancient beach accumulations, formed previous 
to the comparatively recent elevation of that coast. The river-bottoms are of much finer mate- 
rials, and often contain more sand than is desirable for cultivation. 
VOLCANIC. 
Volcanoes, or the evidences of their former activity, appear to have been almost constantly in 
view from the valley of the Rio Grande to the Mojave river, in California, Indeed, if we 
glance at the map, the line of the survey appears characterized by volcanoes and their outpour- 
ings. This, however, is probably more apparent than real, as an exploration further south 
would probably reveal a similar number of volcanic vents. The principal cones or volcanoes, 
as they succeed from east to west, may be enumerated as follows: 
Name. Position. 
south of Santa Fé. 
west of Santa Fé. 
s . south and west of Cumino del Obispo. 
Cerritos 
San Mateo 112.2. E 
San Francisco--.------ 
pil Williams'.--- 
ERA A y 
High peak, N.W. of Bill Williams' mountain. 
west of Aztec Pass. 
Cygnus mountain 
Artillery peak Cerbat mountains. 
east of Soda lake. 
near the Mojave. 
Salt chatte l7 E 
