GEOLOGY. 2r)3 



iiatiiral-inas vents were known to und were for jijjfcs venerated by tlie 

 lire- worsliipcrs, whose cult they inspired ; it is also true that springs 

 of mineral oil have been known from history's dawn, and that the oil 

 was utilized sometimes as fuel or illuminant, though more commonly 

 as a n»edicine or lubricant ; and it is (M[ually true that natural oils and 

 tars were extracted by primitive means and used for primitive pur- 

 l>oses by barbarous Oriental peoples long before their fame spread to 

 tlie Occident; but it is oidy within a few years that these natural 

 products have been utilized so extensively as to materially modify the 

 course of human progress. 



rati passK with the industrial development accompanying the utili- 

 zation of rock gas, geologic science made an unparalleled stride within 

 a few months. During the last thirty years Hunt, Newberry, Peck- 

 ham, Leslie, and several other geologists in this country, and Einney, 

 Cocpiand, Daubree, Lartet, and others abroad have indeed made im- 

 l)ortant contributions to our knowledge concerning the constitution and 

 origin of petroleum and its associates; and the exploitation of the 

 I'ennsylvania-New York fields afforded valuable additional data relat- 

 ing to these minerals. Nearly four years ago Prof. 1. C. White enun- 

 ciated and vigorously maintained the theory — now recognized as a 

 fundamental law' in gas prognostication — that gas, oil, aud brine are 

 accumulated in the order of their weight within inverted basins ami 

 troughs formed by flexure of the rocky strata. The importance of 

 these contributions to our knowledge of the lighter bitumens must not 

 be under-estimated; yet when exploitation for gas began in Ohio in 

 188G, the geologist literally sat at the feet of the prospecter gathering 

 such crumbs as fell from his haiids, and found himself utterly unable 

 either to guide efforts or i)redict results. Less than two years later the 

 laws governing the distribution and accumulation of gas and oil were 

 so fully developed that the rock-gas problem claimed a solution as sat- 

 isfa<5tory as that of the well-known artesian water problem ; and today 

 the geologist jn-edicts the success or failure of a prospect bore for gas 

 or oil about as readily and reliably as he can prognosticate artesian 

 water, or coal, (xieater advance was i)robably never before made in so 

 limited time in any economically important branch of knowledge. The 

 solution of the ]>roblem of rock gas and petroleum marks an era in 

 science no less than in industry. Vast sums of money, reaching some- 

 times into the millions, were spent by prospecters in gathering data; 

 but the credit for the solution of the problem belongs chietiy to three 

 indivi'duals — I. C White, of the University of West Virginia; Edward 

 Orton, State geologist of Ohio; and A, J. Phinney, a practicing physi- 

 cian and amateur geologist of Muncie, Indiana. 



GLACIATION. 



The general tendency of glaciation is to obliterate surface irregularity 

 both by grinding down elevations and by tilling up depressions, and 

 thus to supplement bydric gradation ; but glaciatiou may alao acceut- 



