462 Kindle — Niagara Domes of Northern Indiana. 



A second paper by the same authors appeared in 1894 in 

 which they deny that there lias been any tilting of the Niagara 

 beds of the Wabash Valley.* Cleavage or a " modified form 

 of joint structure " is the explanation offered of the dips. 

 This hypothesis would deserve careful consideration but for 

 the testimony of the fossils. The occurrence of richly fossil- 

 iferous bands running parallel with the so-called cleavage 

 planes affords conclusive evidence that they are true bedding 

 planes. 



Kindle. — During the summer of '99 the writer visited a 

 number of outcrops in northern Indiana and became con- 

 vinced that the dips of the Niagara outcrops in northern 

 Indiana were not apparent but real dips. Two of the outcrops 

 showing tilted strata were described in a recent paper, f 



Distribution and Composition of Beds. — The area in which 

 tilted rocks occur extends from the Illinois line in JSTewton 

 County eastward nearly to the Ohio line, embracing the upper 

 Wabash Valley. Highly tilted beds occur in Hamilton 

 County, sevent}^ miles south of the Wabash. It is probable 

 that the Niagara rocks in the intervening territory have 

 heavy dips at many localities, but the thickness of the drift 

 over this area makes it impossible to ascertain whether or not 

 this is true. 



The Niagara rocks of this region consist principally of mag- 

 nesian limestones varying in texture from the very hard close- 

 grained gray limestone breaking with conchoidal fracture to 

 a soft, easily crumbling buff limestone. Beds of huffish or drab 

 calcareous shale are sometimes associated with the limestone. 

 Local lenses of sandstone have been observed in the Niagara 

 limestone at some localities. One of these near Kenneth has a 

 thickness of five and one-half feet, and is composed of pure 

 white quartz sand containing only a trace of calcium carbonate 

 and iron. ■ The Niagara outcrops show only a small portion of 

 the total thickness of the formation, none of the sections 

 extending down to the Lower Silurian. The information 

 which we have concerning its thickness is derived from well 

 records. From these it appears that the Niagara has a thick- 

 ness of from ■ 250' to 500'. It does not appear practicable at 

 present to divide these beds into two or more divisions, 

 although detailed study of the paleontological material which 

 has been collected may indicate the desirability of such a divi- 

 sion. 



There are local facies with characters peculiar to themselves, 

 but not persistent for any considerable distance. A good 

 example of this is seen at the quarries at Decatur. The lime- 



* 19th Ann. Eep. State Geol. of Ind., p. 22. 

 fThis Journal (4), xiv, pp. 221-224. 



