Wright. J 
244 
[Feb. iS 
by the pump from near the bottom than would be required to fill 
the six-inch hole, and that very likely there was drawn into the 
pump the material from a good many square feet about the bottom. 
The evidence of this is as follows: — As I had before ascer- 
tained, the water in the well rose to within about 85 feet of the 
surface, and remained constant at that depth. Now when the 
tube was being driven through the clay, it entirely shut off the 
water from above, but when going through the quicksand the 
water would again come in. At first, after the tube had been 
driven some distance into the quicksand, or near the bottom into 
the gravel, rapid progress would be made with the’sand pump 
until they had reached the bottom of the tube, when the pressure 
of water from above would force before it into the tube a consid- 
erable additional amount of sand and gravel. Toward the bottom 
of the well, when this operation took place, it would force up a 
great blast of air which had occupied the tube. Through this 
cause the work was greatly delayed, an.d, as they reported, an im- 
mense amount of quicksand and gravel had to be brought out. 
From this it will be evident that quite a large cavity was made 
near the bottom, some of them saying that the pile of material 
thus brought out was as large as a small house. But most of it, 
when I was there had been hauled away to make sidewalks. It is 
pretty evident, however, that most of this must have come from 
below the last thick stratum of clay, which was 250 feet below 
the surface. At any rate, it must all have come from the strata 
below the lava, and must be older than the lava flow. 
As bearing upon the age of the lava, I have been able to make 
some important observations. I estimate that about 12,000 square 
miles in Idaho are covered with basalt. Roughly speaking, this' 
maybe looked upon as coming from four centres of eruption : 1st. 
Three or four hundred square miles from a centre twenty or 
twenty-five miles north of the abrupt turn made by the Bear River 
near Soda Springs; 2d. A much larger area from fissures north 
and north-east of Market Lake, in the vicinity of Henry’s Fork 
of Snake River; 3d. A much larger area from fissures radiating 
from a line joining Big Butte and Pillar Butte, near the 36th 
meridian ; 4th. An area of several hundred square miles from cen- 
tres in the neighborhood of the Oregon Short Line R. R., ex- 
tending from 25 to 50 miles eastward from Nampa. 
