PALEOZOIC TIME — DEVONIAN. 607 



descend to a coarse oil-yielding porous sandstone called an oil-sand; and 

 on reacliing it, the oil, if the well is successful, usually rises to, or above, the 

 surface ; or if a gas well, the gas comes out with great force. The number 

 of different oil-sands in a region is one to three; they are confined to 

 about 300 feet in thickness of the beds, and each is 20 to 60 feet, or more, 

 thick. The productive counties lie in a belt, nearly northeastward in course, 

 from Greene County, in the southwest part of the state, to McKean County, 

 on the northern border ; and they pass this border into Alleghany County, N. Y., 

 and also on the south, into Monongalia County, W.Va. See map, page 731. 

 In the counties from Warren to Washington the oil-sands are within 400 feet 

 of the summit of the Devonian ; in the part of the belt more to the northeast, in 

 McKean County, and in New York, they are in its lower part, or between 1200 

 and 1800 feet of the summit. The latter is a high region, the surface 1800 

 to 2600 feet above the sea level. The wells often let up much salt water from 

 different levels. Frequently water rises with the oil or gas, making the well 

 valueless unless tabing to the bottom will exclude the water. 



The oil-sands are coarse, open-textured sandstones — so open in texture 

 that they are able to hold a vast amount of oil in the spaces between the 

 grains. All the oil-bearing regions are also gas-producing ; but the well is 

 available for gas only when the latter comes to the surface free from oil as 

 well as water. Moreover, the gas is abundant, according to I. C. White, 

 only where the rocks passed through in the drilling lie in a low anticline. The 

 open-textured sandstones are possibly sandstones that have lost the finer 

 material between the grains by percolating waters. As some of the Chemung 

 beds are more or less calcareous, they may originally have been calcareous 

 sand-beds, and have become porous by the removal of the calcareous part ; 

 but this is only conjecture. 



The oil is usually projected in jets, and the power has been shown to be 

 Artesian, or hydrostatic, by I. C. White, in agreement with Orton's view for 

 the Trenton limestone gas of Ohio and Indiana. A well near Kane, in 

 McKean County, Pa., drilled to a depth of 2000 feet, in 1878, but abandoned 

 because of the small yield of oil, became afterward a water-and-gas geyser, 

 gas and not steam being the moving agent. Fig. 925 is from a photograph 

 received in 1879 by the author from C. A. Ashburner, accompanying a 

 description by him of the geyser. The well at that time threw up a column 

 of water and gas, at intervals of 10 to 15 minutes, to heights varying from 

 100 to 150 feet. On August 2d four successive jets had heights of 108, 

 132, 120, and 138 feet. When the gas of the columns was lighted at night, 

 "the antagonistic elements of fire and water were promiscuously blended, 

 at one moment the flame being almost extinguished, but only to burst forth 

 the next instant with increased energy and greater brilliancy." Mr. Ash- 

 burner explains the action thus : " The water flows into the well on top of 

 the gas until the pressure of the confined gas becomes greater than the 

 weight of the superincumbent water, when an explosion takes place, and a 

 column of water and gas is thrown to a great height." The gas comes 



