Kindle — Niagara Domes of Northern Indiana. 467 



unconformably on horizontal Niagara beds. Neither Devonian 

 beds nor unconformity exist in the vicinity of Huntington." 



It has been shown that the dips observed in at least three 

 localities are quaquaversal and the expression of dome struc- 

 ture. Nowhere in the area does the strike and dip of the beds 

 conform to an anticlinal or synclinal structure. The dips seem 

 everywhere to be quaquaversal and it is believed that all of the 

 tilted Niagara beds of northern Indiana represent small domes 

 similar to those at Huntington. 



Origin and Age. — There is at present no positive evidence 

 as to the nature of the forces which produced the domes. It 

 seems probable, however, that they may be analogous in origin 

 to the " mud lumps" at the mouth of the Mississippi. From 

 a recently published description of the " mud lumps " they 

 appear to have a similar structure to the Niagara domes. 

 Harris has studied these interesting masses of recently elevated 

 sea-bottom and states, " That they rise up in domes or anti- 

 clinals and preserve their regular bedding is proven by their 

 present structure." * 



Whatever the causes may have been which produced the 

 domes, there is clear evidence that they were developed about 

 the close of the Niagara period. Many of them were elevated 

 above the Palaezoic sea, while others probably did not reach its 

 surface. Some of the domes remained above sea-level during 

 a considerable portion of the Devonian age, and there is some 

 evidence that others continued as islands to the end of Devo- 

 nian time. The evidence of the exposures indicate that the 

 gradual deepening of the Devonian sea which initiated the 

 "Black shale" sedimentation submerged some of the Niagara 

 domes which had remained above sea-level throughout the 

 Corniferous and Hamilton epochs. These conclusions are 

 based upon the relations which have been observed to exist 

 between the Devonian and Niagara beds at Delphi, George- 

 town, Kentland, and other localities. At Georgetown, the 

 horizontal Corniferous limestone beds rest on Niagara beds 

 showing a small dip, but there is no evidence of land surface 

 conditions having existed previous to the Corniferous sedimen- 

 tation at that locality. 



Near Delphi, at one locality, horizontal beds of Hamilton 

 age lie unconformably above the Niagara limestone, which 

 shows a dip of 45° ; a bed of ferruginous clay and iron ore 

 separate the two. The New Albany shale is seen resting on 

 the Niagara at another locality near the one last mentioned, 

 the ferruginous clay separating these two as in the first 

 instance. 



* Geol. Surv. of La., 1902, p. 39. 

 Am. Jour. Scl — Fourth Series, Vol. XV, No. 90.— June, 1903. 



