E. B, Andrews on the Geological Relations of Rock Oil. 87 
At Smith’s Ferry, in Western Pensylvania, on the Ohio River, 
much of the oil is of a light straw color, while it is said other 
wells yield an oil of the more usual dark-greenish color. On 
the same lease of land and within six or eight rods of the well 
marked 8 in the previous figure, is a well two hundred and 
fifty feet deep. The oil from this well is not only different in its 
specific gravity from that in the other, but the deepest well con- 
tains fresh water, while the other contains salt water. m. 
these and similar facts, it is evident that the oil is in distinct and 
iy fissures and that these are vertical rather than hori- 
zontal, 
With gas. The gas rushes up 
but no oil. If again the well 
18 bored at b, it will strike oil, 
and the gas pent up in the 
Upper part of the fissure will ccmereamemmaees: 
force the oil up through the well }. There are several oil wells 
on Little Kanawha in which the gas has forced up very large 
quantities of oil. The action of the gas however soon becomes 
‘ful and intermittent. If again the well is bored at ¢, it will 
strike that part of the fissure which contains water. In suc 
Case oil can be obtained only by pumping out the water. Doubt- 
ss many good oil wells are thought to be worthless, and aban- 
doned because they contain at first only water. If bored at the 
point c, in the water part of the fissure, water alone is to 
expected until the pump has been used. There may be floating 
upon the water, higher up in the fissure, a large quanti of oil. 
the oil is found in fissures in the rocks, it is natural to sup- 
pose that in those places where the fissures are the most numerous 
and largest, the oil would be formed in the largest quantity. 
This antecedent probability is fully verified by the facts. The 
tocks of Western Virginia and Southeastern Ohio may be divi- 
ded into three classes, those which are almost entirely orizonial, 
those which have a dip of from fifteen to forty feet in the mile, and 
