FORMATIONS OF THE SKUNNEMUNK MOUNTAIN REGION 53 



rock is considered as belonging to the Catskill shaly limestone, 

 which here has been upturned on its edges like the adjoining 

 slate, grits and other rocks." 



An examination of this mine was made by Prof. W. B. 

 Dwight^ who states, " that the limestones are of the lower 

 Helderberg group, and that the adjoining red sandstone and 

 conglomerate are not of the Triassic, like the New Jersey red 

 sandstone, but are the Oneida conglomerate and the fine grained 

 sandstone of the Medina epoch." 



The geology in the vicinity of the Townsend iron mine has 

 been studied in some detail by Darton.^'^ His reports include 

 the stratigraphic and paleontologic determinations and maps and 

 sections of the region studied are given. 



At the Townsend iron mine we find the strata nearly vertical 

 and the New Scotland beds rest against the Longwood shales. 

 This condition was noted by Darton, who states that it was due 

 to faulting or thinning out of the formation below the New 

 Scotland. 



In the railroad cut the formations between the New Scotland 

 and the Longwood shales are 95 feet thick. As the Townsend 

 mine is but -| mile away from this cut and in the same limb 

 of the syncline, it did not seem possible that the formation could 

 thin out in such a short distance. On tracing the intervening 

 formations south from the cut at a short distance south of the 

 small quarry, just beyond the highway, the limestone formation 

 below the New Scotland suddenly ceases and we come upon an 

 area of red shale. The increased thickness of the Longwood 

 shale at this point clearly indicated that they had been faulted. 

 There is a small depression which marks the fault line passing 

 at an angle and meeting another parallel to the strike of the rocks. 

 It is evident that in faulting a wedge-shaped block was forced 

 out carrying the limestone with it, the red shales thus coming 

 into contact with the New Scotland. The steep ridge now left 

 standing is composed of red shales, and it appears that only in 

 very recent times has the limestone cap been removed and thus 

 made possible this steep ridge of red shales. There are other 

 indications of faulting in the vicinity of the mine. In some 

 exposures the rocks are partly overturned and the red shales 

 show induced cleavage. From the red shales at this mine a 

 number of specimens of a lamellibranch were obtained. With 



•Vassar Brothers Inst. Trans. 1883 

 *Am. Jour. Sci. 1886. 31: 209-10. 

 ^Geol. Soc. Am Bui. 1893. 5: 379. 



