210 TRANSACTIONS OP THE 



The i-ed soils of the foothills have already been mentioned. The character of the foothills of 

 the Sierra Nevada throughout its course along the Great Valley, varying from a moderately 

 clayey loam (as in the placer region of El Dorado and Placer Counties) to a heavy, though not 

 uncommonly gravelly, is an orange-red clay. This character seems to be sensibly the' same, 

 whether the soil be derived from the decomposition of the ancient shale "bed-rock" or directly 

 from the granitic rocks, thus creating a presumption that the two rocks'are closely related. 



Where the foothill soils either obtain a sufficiency of moisture naturally, or can be irrigated, 

 they prove abundantlj^ productive, and are rapidly acquiring a special reputation for the excel- 

 lence of their fruit j^roduct, both of orchards and vineyards. While at present it is in the main 

 a region of Spring pastures, it is doubtless destined to be in the future one of small farms pro- 

 ducing products of high value. The soils are highly charged with iron (ferric hydrate or rust) 

 to the e.xtent of from seven to over twelve per cent; which being finely divided, imparts to 

 them the intense orange-red tint so familiar in the region of the placer mines, and during the 

 dry season manifesting itself in the equally familiar red dust that disguises the natural tints 

 even on the trees themselves. The soils of the foothills, so far as they have been analyzed, 

 agree with the soils of the valley in having a high percentage of lime from about one third to 

 one and a half per cent; while the supply of potash and phosphates, as well as of organic 

 matter, is smaller and sometimes low, though never, apparently, inadequate for present pi-o- 

 duetiveness, in the presence of so much lime. 



The soils of the Coast Eange vary greatly in the different 20ortions of that broad belt of hilly 

 land. In the middle portion, more or less directly related to the Bay of San Francisco, the 

 " adobe" character is prevalent, not only in the valleys, but even on the summits of its rounded 

 ridges, where in favorable seasons the yields of grain may be as high as in the valleys them- 

 selves. The soil is usually many feet in depth, with only here and there a rocky knoll pro- 

 jecting through it; ci-acks wide open in Summer, and when the rains come somewhat abruptly 

 and violently, the water, descending quickly to the underlying bed-rock, gives rise to innu- 

 merable land slides, sometimes of considerable extent, and of vital import.anee to land owners. 

 In the valleys intersecting such regions, and notably along the border of San Francisco Bay, 

 there lie highly fertile tracts of " black adobe," or black prairie soil, sometimes so stiff and waxy 

 as to be difficult to till, but under good treatment and in favorable seasons profusely productive. 

 The adobe tracts are intersected, at right angles to the bay, by the belts of lighter sediment 

 brought down by the present streams. In the country lying northward of the bay, the soils 

 ■formed by the eruptive and volcanic rocks assume increased imjoortance, and constitute the lead- 

 ing feature of the grape-growing region of Sonoma, NajDa, Solano, and Yolo Counties, as well as 

 further north, in Lake and adjoining portions of Colusa and Mendocino. Here the lower 

 portions of the mountain sides are frequently constituted of the heavy tertiary and cretaceous 

 materials which form adobe, while the upper portion consists of igneous rocks yielding lighter 

 soils, often deeply colored with iron, and more especially adapted to truit culture. The valley 

 soils are of course a mixture of both, and it is on such composite soils that the enormous yields 

 of from twelve to fourteen tons of grapes per acre are sometimes obtained. 



Of the soils of the mountainous regions of Mendocino and the country northward to the 

 Oregon line, but few data have thus far been obtained. Specimens of valley soils, especially 

 that of Eel River, in Humboldt County, seem to show a great similarity to those of the coast 

 valleys south of San Francisco Bay. It is a gray silt with very little coarse sand, many feet in 

 depth, with high percentages of potash and phosphates, but deficient in lime, and, probably 

 from that cause, difficult to till, and somewhat unthrifty after continued cultivation. South- 

 ward of San Francisco Bay, where with otherwise similar composition the lime percentage is 

 large, this inconvenience is not observed, and these silty valley soils are remarkable for their 

 retention of moisture near the surface throughout the dry season — a highly valuable property 

 in the dry climate. "Adobe" soils are exceptionally in the southern Coast Range region* gray 

 loams or silts, or sometimes sandy soils, beiug on the whole predominant in the uplands also. 

 In the " semi-troj)ic" region of Los Angeles, San Bernardino, and San Diego, the uplands or 

 "mesas," which occupy the larger portion of the surface, have usually a reddish, gravelly loam 

 soil, more or less heavy in different localities, but on the whole remarkably uniform in its 

 character. It seems to be a modification of the " foothills" soils northward of the Sierra San 

 Fernando, but of greater depth, more easily tilled, and with higher percentages of plant food, 

 especially of phosphates. Hence, though of the disconsolately arid aspect of a gravel bed in 

 the dry season, these mesa lands when irrigated prove profusely fertile, and in Spring are 

 covered with a dense carpet of bright flowers. For fruits adapted to the climate they are 

 probably excelled by few so far as quality is concerned ; although on account of greater facility 

 for irrigation the lower levels and the terraces, or benches along the streams, have chiefly been 

 occupied. 



The soils of the Colorado River bottoni is a light, pale-colored loam of great depth, highly 

 calcareous, with over one per cent of potash, but a comparatively low amount of phosphates 

 for a river bottom. It proves extremely fertile when cultivated. 



The soils of Mojave and Colorado Deserts have received but little attention and examina- 

 tion thus far. Wlaile a portion of the surface is covered simply with drifting sands underlaid 

 by rock or hard-pan, there are in the Mojave Desert, at least, extensive tracts possessing a soil 

 of fine gray silt, on which the -Tucca tree attains a luxuriant development; while others are 

 covered with low but dense growtii of hardy shrubs, and grasses enough to render the Spring 

 pasture valuable and nutritious, while the sheep crop the leaves of shrubs later in the season. 

 Plainly a large portion of this desolate-looking country evidently awaits only the life-giving 

 influence of water to be at least available for stock-raising, and to no inconsiderable extent for 



