4<!S Kindle — Niagara Domes of Northern Indiana. 



The highly tilted beds near Kentland occur on high ground 

 in the open prairie remote from any stream. Rocks of later 

 age have been encountered at much lower levels in all direc- 

 tions from this point within two or three miles, and it appears 

 probable that the Kentland dome remained above sea-level 

 until the end of the Devonian or later. 



The occurrence of outliers of Mansfield sandstone (Pottsville 

 conglomerate) in the center of the Niagara area of northwestern 

 Indiana near Remington and Jasper indicate that a subsidence 

 occurred after the formation of the Niagara domes in north- 

 western Indiana which submerged all or nearly all of the 

 Niagara area of that region beneath the Carboniferous sea. 

 The development of the present Niagara arch in northwestern 

 Indiana was therefore of much later date and independent of 

 the formation of the Niagara domes. While the domes date 

 back to the end of the Niagara, the Niagara arch is of Carbon- 

 iferous or post-Carboniferous age. 



The Niagara-Devonian unconformity which has been 

 described, though much more pronounced, may be correlated 

 with that which has been recognized in Shelby County,* 

 Indiana, and with the slight unconformity between the Devo- 

 nian and Upper Silurian which has been recorded by New- 

 berry,! on the east side of the Cincinnati geanticline. The 

 evidence at hand points to a general elevation of the sea-bottom 

 at the close of the Niagara in the area around the northern end 

 of the Cincinnati geanticline. The resulting shallow sea was 

 doubtless an important factor in the sudden disappearance of 

 the Niagara fauna and the substitution of the coralline fauna 

 of the Corniferous. 



U. S. Geological Survey, New Haven, Ct. 



*25th Ann. Eep. Ind. Geol. Surv. 

 f Geol. Surv. of Ohio, vol. i, p. 106. 



