!■ 568' 



Ashburner.] «^^^ [Feb. 10, 



A deposit of i:oii oi'c exists in the white Medina forming the crest of 

 Bhieklog mountain 4 miles south-west of Orbisonia. The ore and clay in 

 wliich it lies seem to till a transverse fissure or cleft in the white sandstone, 

 at a point where there is a slight indentation in the crest of the mountain. 



Oneida {Levant) Sandstone. 



Upper member, red and greenish-gray silicious breccia and con- ~| 



glomerate, No. (i, thickness 158 feet I 



Lower member, hard massive, greenish gray sandstone and con- 

 glomerate. No. 5, thickness 410 feet 



A striking feature of the epoch is its poverty in organic remains. 

 The Medina and Oneida rocks taken together make "all the mountain 

 ridges and higher spurs of the entire chain west of the Susquehanna, be- 

 tween the Kittaning valley and the valley at the base of the Alleghany 

 mountain," except those surrounding the Broad Top synclinal basin. 



No. III. Hudson River {Matinal) shale. 

 Thickness : (No. 4) 800 feet. 



Utica (Matinal) slate. 



Thickness : (No. 3) 1070 feet. 



The upper limit of No. Ill is well defined by the rapid and sudden 

 transition of the Oneida gray sandstone and conglomerate into the argilla- 

 ceous sandstone at the top of the Hudson River slates. The lower limit 

 has been assumed at a very lean, poor shaly brown hematite ore, which 

 seems to occur at the horizon between the shale and slate of the Utica and 

 the blue calcareous shale at the top of the Trenton or Matinal limestone 

 mass. The division between the Hudson and Utica was not positively 

 determined, and ma}^ i)ossibly be above or below the position which has 

 been given it. Unconfcrniability has been asserted to exist between the 

 Hudson and Oneida. 



Prof. Rogers speaks of it as follows: "The relations of the Matinal 

 series to the overlying Levant strata * * * plainly show that * * * the 

 earth's crust experienced a prodigious movement at the close of the Hud- 

 son period. This agitation of the floor of the sea, which Iiad just received 

 the materials of the Hudson shales, appears to have been everywhere 

 attended by an extensive displacement of its level, accompanied in some 

 districts by undulations amounting even to a close plication or corrugation 

 of its sediment, and in some districts to a lifting up of wide areas above 

 the general sea level into dry land." 



The slates of No. Ill make one flank of the mountain of No. IV, and 

 contain no strata of economical value in this district. 



No. II. Trenton {Matimil) limestone. 



Thickness: (No. 2) 500 ± feet. 



The thickness of the epoch is only approximate! j' determined from a 



