STATE GEOLOGIST. BLT 
depth from 98 to 372 feet. Oil was found at 450 feet and at 632 
feet. At Geneva gas was found at depths ranging from 130 to 1,375 
feet, the strongest flow having been obtained at the latter depth. Sim- 
ilar results have been found at many other points. It is significant that 
in those parts of Ohio where the shales in question are covered by Carbon- 
iferous strata, the former do not appear to be any richer in oil or gas than 
where they are uncovered. This certainly would not be true unless the 
shales themselves are impervious. 
The following extract from Dr. Orton’s report expresses very 
clearly the quantities of organic matter which these shales now contain :1 
“Although no great accumulations of oil are found in the shales 
proper, it would-be wrong to infer that they are poor in petroleum. On 
the contrary, they contain much more than any other strata with which 
they are associated, the great sandstone reservoirs not excepted, but it is 
in a distributed condition that the petroleum occurs. The entire body of 
the shale carries a determinable percentage. The percentage is small, but 
the aggregate is vastly larger to the square mile than any square mile of 
the most prolific oil field that has ever yielded to the drill. Prof. N. W. 
Lord, chemist of the Survey, determined the petroleum existing as such 
in normal samples of Ohio black shale. He found the amount to be slightly 
less than one-fifth of one per cent., but he learned from his investigations 
that the finer the divisions of the shale, the larger was the percentage of oil 
obtained. It was therefore certain that the true percentage exceeded that 
reported; further than this, there had undoubtedly been some loss of the 
petroleum from, the exposure of the shale, but even on the percentage ob- 
tained, if the shale series is counted at the low average thickness of 1,000 
feet for its entire area, the total amount per square mile passes far beyond 
the limits of clear comprehension. 
“Calculations show that it would exceed ten million barrels (10,000,- 
000) to the square mile, and such figures stand, of course, merely for 
numbers that turn up in arithmetical processes, but to which we are unable 
to attach any definite significance further than to recognize in them very 
large numbers. 
“The oil-stock of the shales is large, as thus appears, but the oil pro- 
duction is very small. The case, however, stands somewhat better with 
natural gas. Here again the lack of sandstone reservoirs forbids large 
accumulations, but the shales themselves yield gas in such volume as to 
become of considerable economic importance. There can be no question 
but that the gas is derived directly from the oil of the shales. Deep as 
the drill goes down the shales are found charged to the extent noted above 
with petroleum, which begins to break up at once into volatile compounds 
when exposed to the air.” 
1Geol. Sur. of Ohio, Vol. VI., p. 413-4. 
