4 
BULLETIN 1456, U. S. DEPARTMENT OF AGRICULTURE 
Area B (fig. 5) is underlaid by more fine material than is the case 
with area A. The logs of 10 deep wells drilled in this area show 
coarse water-bearing materials within 250 feet of the surface in 
strata little more than half as thick as and at greater depths than 
those in area A, but, as will be shown later, these differences have 
little or no effect on the yield of wells. 
Area C represents most favorable conditions for drainage by 
pumping from wells. A strip at least 7 miles long and in places ~3 
miles or more wide, on the north bank of Salt Eiver, is underlaid 
by a great bed of coarse water-bearing gravel and bowlders known 
to be more than 150 feet thick in places. This extensive under- 
ground reservoir affords a place for seepage water to accumulate 
from the surrounding tighter formations, and thus makes the re- 
