Principal Dry-Farming Regions 521 



to 350 feet at higher elevations. Excellent dam sites are available 

 with sufficient drainage areas to allow the irrigation of possibly 

 15,000 or 20,000 acres. Precipitation varies from twelve to fifteen 

 inches annually. 



BIG CHI NO VALLKV 



The Big Chino Valley, about seventy miles long and an aver- 

 age of seven miles wide, joins the Little Chino on the north and 

 slopes towards the northwest. The soil is a fine sandy loam, largely 

 of granitic origin, and is somewhat similar to that of the first mesas 

 of Lonesome and Little Chino Valleys. 



No precipitation records are available, but the average annual 

 rainfall is probably between twelve and fifteen inches. Apparently, 

 there is ample underground water near the surface for domestic use 

 and a supplemental irrigation supply. A dam site at the upper end 

 of the Valley, subjacent to a large drainage area, makes irrigation 

 of a considerable acreage feasible. 



AUBREY BASIN 



Aubrey Basin, forty miles long and an average of ten miles 

 wide, lies between Aubrey Rim on the east, Yampai Clififs on the 

 west, the Santa Fe Railroad on the south, and the Grand Can- 

 von on the north. Drainage is toward the south with no outlet, 

 and there are no water courses of importance in the Basin, ^fhe 

 elevation in the center of the valley is about 5200 feet. The sod is 

 a fine loam resulting from decomposition of red sandstones and gray 

 limestones. In the center of the valley the soil is probably twenty 

 feet deep, while near the edges it is only two or three feet deep. 



The basin is mostly covered with a growth of native grasses, 

 including grama and galleta, but barren spots are found where the 

 grasses probably have been killed out by overgrazing. In these 

 places the soil is shifted badly by winds. The average annual pre- 

 cipitation is probably about fifteen inches. Groundwater is far be- 

 low the surface. Along the Santa Fe Railroad a small quantity 

 of water is obtained at a depth of 1200 feet; while a strong flow, 

 which rises to within 1000 feet of the surface, is found at a depth of 

 1600 feet. In the center of the valley a well 680 feet deep furnishes 

 a fairly large quantity of water of excellent quality. 



