CORROBORATION OF THE ANTICLINAL THEORY. 209 



territory, I wrote Mr. Ashburner, suggesting that there might be some disturbance 

 of the rocks in the region of Kane, where he claimed large gas wells were found in 

 an undisturbed syncline. 



"The recent discovery of oil in the Kane region has led to the drilling of many 

 wells, and in the Oil City Derrick of a recent date the statement is made on the 

 authority of Mr. McKinney, of the Union oil company, that a rapid northward dip 

 had been found, i. e., a subordinate cross-cut anticline parallel to the main one 

 north of Kane passes through the Roy and Archer gas region. Whether this shall 

 turn out true or otherwise, there is certainly no inherent improbability against 

 rinding such subordinate waves. 



" Very unexpected and surprising was the testimony on this head which came 

 to me recently from Mr. L. R. Curtiss, of Mendota, Illinois, who, unknown to my- 

 self, made a careful study of the geological conditions under which natural gas 

 occurs in that state, and reached the same conclusions quite independently of my 

 own views, as will he seen from the following paragraphs, quoted by permission 

 from his letter to me on the subject : 



"'The principal anticlinal axis of Illinois puts out in Ogle county, in the 

 northern part of the state, and extends in a direction S. 20° E. through La Salle 

 and Champaign, and thence to Coles and Clark counties, in the southeastern part 

 of the state. Along this axis natural gas can be traced in springs and well borings 

 for a distance of 160 miles. // is, however, more prevalent mi the crovms of the cross- 

 axes. This is notably the case at Mendota, where the cross-axis intersects the 

 main anticline at an angle of 85° (running S. 65° W.), and on the summit of this 

 fold the gas belt extends southwestward into Bureau county for over twenty-five 

 miles. The other cross-axes located further to the south intersect two or three 

 low anticlinals toward the Mississippi, and trend in the direction of the gas 

 fields in McLean, De Witt, Macon, and Montgomery counties.' 



" This same story is repeated in Ohio, according to the testimony of the eminent 

 state geologist, Professor Orton (set' his letter in Ohio State Journal of recent date). 



"Now what is the effect of these cross-cut axes on geological structure? Evi- 

 dently one effect would be to cause the arches and corresponding troughs them- 

 selves to rise or sink, as we approach or recede from the cross-cut as the case may 

 be; for example, the general rule is that the rocks of western Pennsylvania dip 

 down to the southwest along the line of the anticlinals, as well as away from 

 them (N. W. and S. K.i.hut in the region of Cannonsburg this rule is reversed and 

 the rocks rise rapidly (seventy-five feet per mile) to the southwest along Loth 

 anticlinals and synclinals until the crest of the Hickory-Houstonville cross-cut 

 arch is passed, when a rapid dtp begins in the same direction (southwestward), 

 thus forming at the points of intersection a kind of " hog-back " structure fas Mr. 

 Earseman terms it) from which the rocks dip away in every direction. 



" Hence these cross-cut arches result in carrying the anticlinal structure and a 

 line of disturbance in the rocks directly across the trend of a syncline, and a fail- 

 ure to grasp this fad is the principal reason why Mr. Ashhurner insists upon his 

 readers believing that a greal gas well may be obtained in a syncline; for it 

 is quite certain thai no large gas well has ever yet been found in the trend of a 



syncline, except where the trough itself has Keen elevated by a Ion- rise from the 



Bouthwest, which is. of course, broughl aboul by the cross-cut folds. 



"These are the geological surroundings of all those wells which Mr. Ashburner 

 cites from northern Pennsylvania and southern New York as, occurring in syn- 

 clines. It is not necessary to show a reversed or northeast dip in order to 



