9 



14 E. the surface is wind-scored and very unlevel, while along the 

 blutt' .southwest of Mesquite Lake, in T. 15 S., R. 14 E., the land is 

 much cut by gullies, in some places 8 or 10 feet deep. 



The sandy loam soil is formed by the coarsest sediment of the Colo- 

 rado River deposit mixed with wind-blown sand. The sandy loam 

 extends to a depth of 3 feet and is underlaid by a loam or heavy loam. 

 This soil will take water readily, and where level and free from alkali 

 is adapted to cultivated crops or alfalfa. Some of the best and some 

 of the worst lands of the valley are composed of this type. A refer- 

 ence to the alkali map will show that this soil ranges in alkali content 

 from practically nothing to more than 3 per cent. Thirty-seven per 

 cent of the soil has less than 0.2 per cent alkali, 21 per cent has from 

 0.2 to 0.4 per cent, and 42 per cent has more than 0.4 per cent alkali. 



IMPERIAL LOAM. 



The Imperial loam was found to comprise a part of each township 

 mapped. The surface is smooth and level as a floor, almost devoid of 

 vegetation. It has the peculiar, slick, shin}' appearance often seen in 

 localities where water has recently stood. It is the direct sediment 

 of the Colorado River which has been deposited in strata when the area 

 was under water. These strata are from 0.01 inch to 2 or 3 inches thick, 

 resembling shale very much, in fact, to all external appearances being 

 exactly similar. When water is applied, however, the soil softens up 

 and is a reddish sticky loam, a little heavier than a silt loam. It is 

 from 4 to 6 feet deep, underlaid by a clay or clay loam, and contains 

 considerable organic matter, including an abundance of nitrogen and 

 potash. When free from alkali it is well adapted to the growth of 

 wheat, barle}', and alfalfa. This soil is in the main alkaline and in 

 some places to such a degree as to preclude all possibility- of profitable 

 agriculture. Of the 30,000 acres mapped 16i per cent has less than 

 0.2 per cent alkali; 21 per cent has from 0.2 to O.-i per cent, while 

 62 per cent has more than 0.4 per cent alkali. 



IMPERIAL CLAY. 



The Imperial clay as soil or subsoil is found throughout the entire 

 area. It is usually comparatively level, although in some places small 

 hummocks have been blown up on its surface. It is this soil that sur- 

 rounds both the towns of Calexico and Imperial the only difference 

 in the soils of the two districts being in the alkali content. The soil 

 has been formed by the deposition of the finest sediment of the Colo- 

 rado River and is stratified in the same way as the loam. It is a 

 heavy, sticky, plastic soil, very much resembling the clay subsoil 

 found in the Mississippi River Delta. When dry and in its natural 

 state it exists in hard cakes and lumps, which ma}' be cut with a knife 



