20 DROUGHT RESISTANCE OF OLIVE IN SOUTHWESTERN STATES. 



Table III. — Maximum and minimum temperatures and precipitation at Palm Springs 



station — Continued. 

 PRECIPITATION (INCHES). 



T.=trace. 

 SOIL AT PALM SPRINGS. 



The soil of the oUve orchard is typical of this district. The rock 

 formation is coarse sandstone and granite. The southern face of the 

 mountains is broken by canyons of various widths and depths, origi- 

 nating as rents and fissures in the uplifted rock, but enlarged by the 

 erosion of the mountain torrents, which were apparently during 

 glacial times of vastly greater volume than at present. The result 

 has been an enormous talus of water-worn liowlders from each of the 

 main canyons extending out into the basin to an unknown distance 

 and depth and spreading laterally along the mountain base. Over 

 this is a varying depth of coarse sandy and gravelly soil, in places 

 mixed with a considerable quantity of finer material from the sorting 

 action of wind and water. Several square miles in the Palm Springs 

 and Palmdale region have thus a fair quality of sandy soil, which is 

 lacking in sufficient clay or fine binding material and because of the 

 scanty rainfall and sparse vegetation is low in organic matter. Judg- 

 ing from the quantity of feldspar in the original granitic rock, there 

 is doubtless a good deal of available potash in this soil. 



On the particular 40 acres in the olive orchard there is rather less 

 of the finer material in the soil than in that of the Indian reservation 

 lands adjoining on the south. Layers of coarse gravel and cobble- 

 stones are often encountered at depths of 3 to 4 feet. The longest 

 winter rains sink so quickly into the soil that there is no trace of 

 stickiness or mud on the following day. 



Table IV. — Mechanical analyses of soils frovi olive orchards at Casa Grande, Ariz., 

 and Pcdm Springs, Cal., made by the Bureau of Soils, U. S. Department of Agricul- 

 ture, from samples collected by Mr. S. C. Mason. 



192 



