Kindle — Niagara Domes of Northern Indiana. 461 



Goroy. — In 1886 S. S. Gorby* described a considerable 

 number of outcrops showing tilted strata, and announced that 

 they indicated a great anticlinal, " extending entirely across 

 the State," which he called the " "Wabash arch." Many of the 

 dips recorded by the author of this hypothetical arch afford 

 evidence against it. About half of them are east or west dips, 

 while the supposed arch has a southeast and northwest axis, 

 which calls for northeasterly and southwesterly dips, and fails 

 to explain the others. Phinney in discussing the "Wabash 

 arch" points out that the gas well records furnish evidence 

 against it. 



Phinney. — The tilted strata are, according to Phinney, due 

 to irregularity of deposition rather than to deformation, and he 

 states that they are "to be attributed to the building up of 

 coral reefs and rocky prominences over portions corresponding 

 to the domes and offshoots of the Cincinnati arch or to irregu- 

 larities in the sea-bottom. "f A serious objection to the coral 

 reef theory is the absence of the reefs. Corals are not at all 

 abundant in the Niagara of northern Indiana. They have not 

 been observed anywhere in sufficient abundance to form reefs. 

 While inequalities in the sea-bottom may be responsible for 

 some of the smaller undulations in the strata, neither they nor 

 " offshoots of the Cincinnati arch " appear to offer a satisfac- 

 tory explanation of dips of 45° to 75° in the Niagara rocks, 

 which the accompanying photographs show. 



Thompson. — Maurice Thompson considered the clips to be 

 the result of the disturbance of beds originally horizontal. 

 He states : " The structure of the Niagara limestone does not 

 in the least indicate false bedding.";}; Thompson accepted 

 Gorby's hypothetical " Wabash arch," but evidently had a 

 pretty clear understanding of the local dome-like structures in 

 the Niagara. A summary of his views is best stated in his 

 own words : " The arch formed by this upheaval consists of a 

 vast series of low bubbles or cones that make the surface of 

 the Niagara limestone somewhat like that of a sea in a brisk 

 breeze. "§ 



JElrod and Benedict. — In the same volume with Thompson's 

 paper appeared a paper by M. N. Elrocl and A. C. Benedict on 

 a portion of the northern Indiana Niagara area. These authors 

 conclude that the Niagara "cones" which they describe are the 

 result of a variety of cleavage which simulates stratification, 

 and cuts across the original bedding planes. 



*15tli Ann. Eep. State Geol. of Ind., 1886, p. 241. 

 filth Ann. Eep. U. S. Geol. Surv., p. 653. 

 jlTth Ann. Eep. Ind. Geol. Surv., 1891, p. 183. 

 §Ibid., p. 185. 



