1875.] dbO [Frazer. 



the position of the ore is precisely at the junction of the limestone and 

 slate. "It is indeed only a very ferruginous variety of the metamor- 

 phosed slate regularly stratified and intercalated v^ith it." 



Again , ' ' west of the Gantner Ore Diggings, " * * " the ore 



lies in decomposed sandy talco-micaceous slate between the sandstone 

 and an outcrop of limestone south of it." And just beyond, "The 

 Conewango Ore Bank lies at the junction of the Auroral limestone and 

 the talco-micaceous slates of the primal series." In another place, the 

 section of this limestone at Strickler's Run is given, commencing at the 

 lowest number of the series : 



1. Limestone, 150 feet. 



2. Blue talcoid slate, 200 feet. 



3. Limestone, 15 feet. 



4. Dark-blue slate, 20 feet. 

 5- Limestone (?). 



6. Bluish talcoid slate, 200 feet. 



7. Limestone (?). 

 (Total 405 + feet). 



Of the iron ores of York county, it is stated simply that a belt is trace- 

 able along the southern edge of the limestone towards Littlestown, but 

 has been long neglected, owing probably to its containing a considerable 

 portion of the oxide of manganese. All these statements agree in placing 

 the limonites just beneath the Auroral limestone. The older ores seem 

 not to be mentioned at all. 



The ores of York county are of three kinds : 1st, pyritiferous and 

 partly magnetic limonites ; 2d, the limonites proper, which were the 

 special objects of my investigation last summer ; and 3d, the micaceous 

 and magnetic ores of the Mesozoic sandstone. The first fact of import- 

 ance with regard to the second of these kinds, is that (corroborated by 

 Prof. Prime), they never occur far from the Auroral limestone, but 

 always on its edges, thus skirting the entire basin (when not overlain by 

 the Red Sandstone), and forming a line of ore wherever, within the 

 limits of the basin, from folding and subsequent denudation, an edge of 

 this Auroral limestone is exposed. 2d. They are almost always in the 

 form of segregations in yellowish and bluish clay. 3d, Not only is each 

 belt of ore made up of small pockets and nests lying without regularity 

 in the decomposed slates constituting the clay, but in some cases the belt 

 itself is capricious and appears to run out whenever the rock becomes less 

 easily decomposable. 



I should hesitate to ascribe the source of this iron supply to the 

 minute crystals of pyrite which undoubtedly permeate some horizons 

 of the great Calcareous deposit, both because their number and the 

 porousness of the limestone as observed in connection with the ore. 



