370 DARTON — GREEN POND, N. J., TO SKUNNEMUNK MT., N. Y. 



Martin in 1871 of the discovjery of Devonian plant remains in the flags 

 of Skunnemunk mountain. 



The classification by Horton and Mather of all the conglomerate beds 

 in Orange county with the Shawangunk grit was based largely on the 

 association with Helderberg limestone and red shales near Cornwall 

 Station. 



In the " Geology of New Jersey," 1868, Cook described the New Jersey 

 portion of the region in considerable detail, and in the accompanying- 

 colored map of the Azoic and Paleozoic formations, represented the ex- 

 tension of the rocks in Orange county. The principal occurrences of 

 fossiliferous limestones in the Green Pond region were announced in this 

 report, but unfortunately they were mistaken for the Trenton formation. 

 As the conglomerate of that region was clearly seen to underlie these 

 limestones, it was classed as Potsdam, together with its supposed exten- 

 sion northward and the associated flags. This o]3inion prevailed for 

 many years, and no new light was thrown on the subject until the dis- 

 covery by Martin of Devonian plant remains in the flags on the south- 

 east slope of Skunnemunk mountain. This discovery did not appear to 

 attract much attention until in 1884, when Smock reexamined portions 

 of the region and prepared a report for the Annual Report of the State 

 Geologist of New Jersey for that year. Smock found additional plant 

 remains in the flags, and pointed out that as the conglomerate which 

 caps Skunnemunk mountain lies on these flags, its age was approximately 

 Middle Devonian. Ajjparently the conglomerates in the Green Pond 

 region in New Jersey were supposed to belong to the same horizon, but 

 lying directly on the Archean to the eastward and on " Trenton " lime-, 

 stone to the westward. 



1 began my studies of the belt by a short visit in the autumn of 1884, 

 and I have revisited it many times since for short trips. In the summer 

 of 1885 I found that the fossiliferous limestones in the Green Pond 

 region were Helderberg in age, and this fact was communicated to the 

 ^ate Dp. G. H. Cook, then state geologist of New Jersey. At the same 

 4me it was ascertained that the "Green Pond conglomerate was under- 

 lain by the older limestones east of New^foundland, and from these two 

 facts it was inferred that it was approximately Oneida in age. The 

 discovery of Upper Silurian fossils in the overlying limestones was also 

 announced to Dr. T. Sterry Hunt early in 1886, and by him published 

 in his Mineral Physiology and Physiography, 1886, page 591. 



In 1886 Dr. Cook sent Messrs Britton and Merrill to examine the 

 Helderberg limestones in the Green Pond region, and further supplies of 

 fossils were obtained, together with Oriskany fossils from an associated 

 quartzite. Dr. Merrill remained in the region for some time and worked 



