Febkuaey 2, 1900.] 



SCIENCE, 



193 



Certain wells had been bored in New York 

 that exhibited a pressure of 1500 pounds to 

 the square inch. Professor Orton confessed 

 that he was unable to suggest where the hydro- 

 static head sufficiently high to produce this 

 pressure might be located ; though in explain- 

 ing the pressure in the Ohio and Indiana Tren- 

 ton gas wells, he had gone as far as Wisconsin 

 to get a head sufficient to explain pressures of 

 approximately 450 pounds to the square inch. 

 It has always seemed to the writer that Profes- 

 sor Orton's adduced argument here fell short of 

 a demonstration. Even admitting that the 

 Trenton rock is continuously porous under 

 cover from Ohio and Indiana Gas Fields to out- 

 crop 600 feet above sea-level in Wisconsin (a 

 condition implicitly denied elsewhere, when he 

 explains barrenness of Trenton rock in gas un- 

 der area surrounding the ' gas belt ' by the 

 ' compactness of the rock '), it would still be 

 necessary to suppose that the columns of ' Tren- 

 ton brine ' rising to 600 feet above sea level in 

 the wells, were balanced by a corresponding 

 body of water of like specific gravity saturating 

 rock up to the very limit of outcrop. Such an 

 explanation calls for the saturation of Wisconsin 

 surface Trenton with Ohio and Indiana Trenton 

 brine. Further, it would appear that the argu- 

 ment is specious that would infer hydrostatic 

 character of cause from similarity of ' observed ' 

 pressure in wells to that calculated for them 

 from the height to which salt water rises in 

 neighboring abandoned wells. Of course this 

 would be so, no matter what the nature of the 

 cause which produced the pressure. As well 

 argue that the pressure of the atmosphere is 

 ' hydrostatic ' in origin, because it holds up a 

 column of water a certain height between sucks 

 in a pump. 



In view of the objections above mentioned, 

 may it not be necessary to revive the much 

 derided theory of ' Eock pressure ' — for which 

 the term ' lithopiestic ' is proposed ? In the 

 light of facts brought out in connection with 

 the development of the petroleum industry in 

 recent years, many of the objections urged 

 against this theory no longer obtain. An ex- 

 amination of ' bituminous sandrock ' from de- 

 posits which are nothing more than old petrolif- 

 erous beds formerly deeply covered by over- 



lying strata, but now exposed by denudation and 

 with contents oxidized, shows that the bitumen 

 takes the place of cement in other sandstones. 

 In other words, it was accumulated before the 

 rocks were consolidated, or (in accordance with 

 the 'anticlinal theory') its accumulation ac- 

 companied their consolidation. In this condi- 

 tion the rocks were compressible, and with 

 them their gaseous and fluid contents. Such 

 compression could be the result both of weight 

 of overlying rooks and lateral pressure — the 

 latter the same which produced the anticlinal 

 and synclinal folds permitting of a separation 

 of the contents in accordance with their specific 

 gravities. When a body of strata is thrown 

 into gentle folds without fracture, some of the 

 beds must almost certainly undergo compres- 

 sion. It would appear that a bed of bituminous 

 shale, for instance, in contact with a bed of 

 porous, but perhaps non-compressible, sand- 

 stone or limestone, would have some of its 

 gaseous and fluid contents driven into the in- 

 terstices of such rock and held there under 

 pressure. Such pressure would become mani- 

 fest whenever the rock was penetrated by the 

 drill. 



There are a number of phenomena connected 

 with artesian and gas wells which are probably 

 better in accord with the ' lithopiestic ' than the 

 ' hydrostatic ' theory. One of these is the 

 sensitiveness of pressure to tremors and move- 

 ments of the earth. 



One experiment suggests itself that would 

 probably determine whether this pressure is in 

 the main ' hydrostatic ' or not. If all aban- 

 doned cased wells in a district can be filled up to 

 the top of the casing or higher with surface 

 water, which water will remain at that level, 

 the pressure which held the original salt water 

 to a certain level in the well could not be hy- 

 drostatic exclusiveljr. 



The contention here is not that none of the 

 pressure is hydrostatic (doubtless water is 

 mainly the medium through which it is commu- 

 nicated), but that for certain deep artesians and 

 all high pressure gas wells the ultimate source 

 of the pressure is mainly lithopiestic. 



Arthur M. Miller. 

 Statb Collkgb of Kentucky. 



