IRRIGATION FROM SAN JOAQUIN RIVER. 221 



exception to the above condition is found in the bottom lands of the river from Pol 

 lasky downstream. These are composed of loose sand washings and river sediment, 

 mixed with claj^ loam; are fertile, readily absorb water, and are easilj^ irrigated. 



As we proceed southward and westward along the river the rolling lands on 

 either side are lean, compact, dry reddish cla\- and igneous mud deposits, with "hog 

 wallow" formations prominentlj* in evidence. The hardpan approaches close to the 

 surface and is sometimes bare. The soil is so puddled by the clay ingredients that 

 it is almost nonabsorbent of water; and irrigation, particular!}' by means of lateral 

 absorption and subirrigation, is almost impossible. Some of these lands are summer 

 fallowed, and thus are made to produce fair crops of cereals. 



As we move farther in a southwesterly direction into the plain and irrigation 

 sphere of Kings River we find the soil deep, absorbent of water, and remarkably well 

 adapted to the best methods of using water and to the production of heavy crops. 



This character of soil holds except within a strip a few miles in width south of 

 the San Joaquin. On the north bank of that river the " hog wallows " and rolling 

 lands run far down into the vallej', and owing to their nonabsorbent character the 

 country is difficult to irrigate, except in small areas here and there where alluvial 

 deposits are found. This condition prevails until the middle plain is attained. There 

 the high river banks and hills are left behind; the plain is only 40 or 50 feet above 

 the river bed, and the soils on either side are looser, lighter, and better adapted to 

 irrigation. On the south side they are deep, sand}', and nearly free from alkali. 

 On the north side they are not as light, with the exception of the alluvial spots before 

 mentioned. The surface is somewhat rolling, and often contains spots of alkaline 

 soil. The depth to hardpan is not great, and altogether the soil is not as fertile nor 

 as easily cultivated and irrigated as on the south side of the river in Kings River 

 domain. 



As we proceed toward the lower plain and the trough of the San Joaquin we 

 encounter soils varied in constitution in different localities, often changing quickly 

 within limited areas, being sometimes black adobe, then loose, sandy loam and river 

 sediment, and again hard, alkali soil and compact hardened clay loam. 



The lowest valley trough is subject to occasional overflow from the river, and in 

 some parts to annual inundation. 



Dr. E. W. Hilgard, professor of agriculture in the University of California, says 

 of the soils of the San Joaquin Valley.' 



The higher plains have very uniformly, from Kern County to Stanislaus, a very sandy loam soil of 

 great depth, and almost everywhere made of granite debris instead of quartz grains; hence, continu- 

 ally increasing their stores of mineral plant food by the weathering of the minerals present, a process 

 which in so porous a material, subject, in its natural condition, to the free access of air during the 

 greater part of the season, was evidently very rapid and as a consequence has developed unusually 

 large amounts of the soluble products, which often appear in an inconvenient abundance in the guise 

 of alkali. But little trouble arises from this cause in the high-lying sandy tracts, where irrigation or 

 the natural rainfall carries the soluble salts annually into the country drainage. But in the low-lying 

 and less pervious soils of swales and valley troughs, which are at the same time intrinsically the richest 

 in available mineral plant food, the accuijiulation frequently causes considerable trouble and difficulty. 

 There is on the whole, however, but little of the heavier class of adobe soils to be found in the San 

 Joaquin Valley; what is currently so designated would in other regions sometimes be hardly classed as 



'California Station Rpt. 1888-'89, pp. 115, 130. 



