CHAPTER XII. 



PLAINS OF SAN PEENANDO, LOS ANGELES, AND SAN BERNARDINO. 



Position and e.xtent of tbe allcviai, plain at the base of tue Cordilleras. — Sdbdivision. — Altitude of the plain. — Second- 

 ary VALLEYS. — A'ARIABLE FERTILITY. — VEGETATION OF THE UPPER PLAIN. — SdPPLY OF WATER BY RIVERS AND SEQUIAS. — VARIETY 

 AND BEAUTY OF THE ffLORA. — GrAPE CULTURE. — OrANGES. — AppLES AND PEACHES. — NuMBER OF VINEYARDS IK LOS ANGELES 



VALLEY. — Manufacture of brandy. — Mode of cultivating the grape. — Stock supported by the valley. — Stock raised ik 



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. — BoRINQ IN SACRAMENTO VALLEY. — VARIABLE DEPTHS OF BEDS AEOVH 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 elopes 

 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 



Sycamore grove, (Cajon pass) 1900 



San Bernardino town 1118 



Mission of San Fernando .' 1048 



Jurupa 1000 



In the lower portion — 



Los Angeles 457 j San Pedro 30 



San Gabriel 354 | 



It may be remarked that the base of the Cordilleras along its whole extent presents consider- 



