1865. 



47 



[Lesley. 



XIL And this accounts for the great variations in the 

 aspect of the valley at different places, the appearance and 

 disappearance of cliffs, the commencement and termination of 



Fiir. 10. 



oa'sPRiNC ATW.VJEBBS 



canons, and the alternate ascent and descent of the margin 

 of arable land upon the hillsides above. 



Oil wells, then, if bored in the Paintsville country, or in 

 the upper parts of the valleys of the Paint Creek waters, on 

 the Lewis Survey, cannot calculate on any fixed thickness 

 of No. XII to go through. They may find this mass of sand- 

 rock 50 feet thick, or 250 feet thick ; and the difference 

 must materially affect their production of oil, supposing the 

 oil to reside in this sandrock, or to be collected at its base. 



The division of No. XII into two numbers is also im- 

 portant, because this ought to give two horizons of petroleum 

 instead of one. It is remarkable, that all through Pennsyl- 

 vania the Conglomerate (No. XII) shows a tendency to sub- 

 division into two or more massive sandrock members, sepa- 

 rated by somewhat softer or even soft shaly formations. It 

 is evidently a general feature of its character, produced by 

 some universally acting, still undiscovered cause. But one 

 of its effects is to establish a second line of oil springs at a 

 much hig-her elevation in the cliffs than the one I have been 

 describing. At Davis's, where the upper member of XII is 

 retired a hundred yards or so, at the top of an intermediate 

 slope, the oil is said to exude at all times as abundantly from 



