CHAPTER XII. 
PLAINS OF SAN FEENANDO, LOS ANGELES, AND SAN BERNARDINO. 
Position and extent of the alluvial plain at the base of the cordilleras.—Subdivision.—Altitude of the plain.—Second¬ 
ary valleys.—Variable fertility.—Vegetation of the upper plain.—Supply of water by rivers and sequias.—Variety 
AND BEAUTY OF THE FLORA —GrRAPE CULTURE.—ORANGES.—APPLES AND PEACHES.—-NUMBER OF VINEYARDS IN LOS ANGELES 
valley.—Manufacture of brandy.—Mode of cultivating the grape.—Stock supported by the valley.—Stock raised in 
CALIFORNIA IN 1854. —INCREASE OF 1855.— GEOLOGICAL STRUCTURE OF THE PLAIN.—DIFFERENT DIP OF THE STRATA.—QUATER¬ 
NARY deposits.—Artesian borings.—Nature of the soft beds.—Origin of the clays and gravel.—Absence of boulders 
AND POLAR DRIFT.—BORING IN SACRAMENTO VALLEY.—VARIABLE DEPTHS OF BEDS ABOVE BLUE CLAY.—LENGTH OF PERIODS OF DEPO¬ 
SITION.—Conditions of the plain during the deposit.—Partial denudation of the detritus.—Review of the deposit of 
QUATERNARY CLAYS. 
Lying at the base of the Cordilleras, in parallel 34°, is an extensive plain, which slopes 
gradually from that range to the shore of the ocean in a southwesterly direction, and embraces 
a vast area, being a hundred and eighty miles long from east to west, measured at the base of 
the Cordilleras, and narrowing to 30 miles at the shore of the Pacific, presenting a blunt pyra¬ 
midal form, the flattened apex being to the ocean. Its greatest extent in a line due north and 
south is 40 miles. This great expanse is broken into by a low range of tertiary hills, which 
run from west to east, at an average distance of 13 miles from the foot hills of the Cordilleras, 
and thus divide the area into an upper and a lower plain, which are connected by wide passes 
in the tertiary hills, the present valley beds of the various streams which roll from the base of 
the mountains to the sea—as the Rio de los Angeles, Rio San Gabriel, and the Rio Santa Anna. 
These have worn their way through the low hills and formed those passes during the present 
epoch, the whole range of tertiaries having formed one continuous chain previous to the last 
geological change. 
The result of the wearing down of these hills by the rivers is to connect the upper and lower 
plains together, and thus divide the whole Pacific slope into several smaller valleys, which 
receive distinct names, as the San Fernando valley, the San Bernardino, and the Los Angeles 
valleys or plains; strictly speaking, they are not valleys, but ancient alluvial plains. 
Between these and the ocean is another low range of tertiary hills, which separates the slope 
from the present shore, and gives rise to the accumulations of water both on the surface and in 
extensive deposits beneath. The elevation of the plain varies exceedingly in its upper and 
lower limits ; the following are the altitudes of a few points examined, given in feet: 
In the upper portion of the valley— 
Kikal Mungo ranch .. 
.... 1307 
Mission of San Fernando........... 
........ 1048 
Sycamore grove, (Cajon pass) 
.... 1900 
Jurnpa..... 
........ 1000 
San Bernardino town.................. 
.... 1118 
In the lower portion— 
Los Angeles.... 
.... 457 
i San Pedro...... 
30 
San Gabriel... ../. 
.... 354 
It may be remarked that the base of the Cordilleras along its whole extent presents consider- 
