488 NEW YORK STATE MUSEUM 



the fashion of the great fields of Pennsylvania and Ohio. 

 The gas apparently occurs throughout the entire formation, ex- 

 cept where the physical condition of the limestone is such that 

 storage is wanting. While there can not be said to be any defi- 

 nite horizons of the gas, there are two divisions of the Trenton 

 formation that furnish the main supply. The first is found 50 

 to 100 feet below the surface of the limestone; the second 50 to 

 100 feet above its base. There is no dolomite in either of the 

 horizons, but the drillings show the presence in abundance of 

 characteristic Ordovician fossils. The limestone holds com- 

 paratively little water and what water is found is generally 

 saline, but not sulfurous. 



3 The rock pressure of the gas ranges from a score or two of 

 pounds to 1540 pounds to the square inch. The last named 

 figure is the highest gas pressure known to be reported from any 

 field in the world. From some unexplained cause, the depth at 

 which the gas is struck has a general relation to the rock pres- 

 sure, but adjacent wells differ widely in the figures reached. 

 The rule seems to be, the deeper the gas vein, the greater the 

 pressure. 



4 As to the volume of the gas wells, a large range is also 

 found. The largest volume reported thus far is 3,000,000 feet 

 a day, but the ordinary wells show only thousands or tens of 

 thousands of cubic feet, or, in rare instances, hundreds of thou- 

 sands. The Trenton limestone is not thus far a source of large 

 wells nor has it proved itself a large producer of gas to the 

 acre or square mile. 



5 When wells are wisely used they show a good degree of 

 vitality. This is also characteristic of shale gas. 



6 An exact determination of the dip of the strata is not pos- 

 sible from the data available. In fixing the different horizons 

 of the rocks we are obliged to depend largely on the discrimina- 

 tions of the well drillers, and there is no certainty that they will 

 agree as to the boundaries of the several formations that they 

 undertake to identify. Neither are their records of the same 

 well in all cases entirely harmonious. There is special liability 

 to confusion in the case of the Trenton limestone. The lower- 

 most beds of the Utica shale are generally highly calcareous, 

 and the highest beds of the Trenton limestone are sometimes 



