Report of the State Geologist. 



belts, one passing through Port Jervis, and the other along the western side 

 of Skunnemunk mountain. The Cauda-galli grit, " Esopus slate," as it has 

 been termed by Darton, rests on the Oriskanj 7 in eastern Deer Park town- 

 ship. Outcrops of the Corniferous limestone are restricted to localities near 

 Port Jervis and Port Orange, its thickness being estimated at 250 feet. The 

 Hamilton group is well developed in the county. The Marcellus shales are 

 seen along the Neversink valley, and are estimated to attain the enormous 

 thickness of 800 feet. Overlying them in the same region are arenaceous 

 shales of the Hamilton group with a thickness of 1,800 feet. A second area 

 of Hamilton rocks in the Skunnemunk mountain region has been separated 

 into local subdivisions, viz. : the Monroe shales, Bellvale flags, and Skunne- 

 munk conglomerate. The Chemung formation caps the rock section, and is 

 represented by non-fossiliferous beds in the western portion of Deer Park. 



Following this summary statement of the distribution of the geologic 

 formations, the author enters more explicitly into a discussion of the geologic 

 relations of each, and more detailed accounts of their areal extent. The 

 following captions show the general mode of treatment: Geology of the 

 Warwick Cambrian limestones, and the granites ; Relations of the limestones 

 and Hudson river slates ; Geology of the region along Bellvale mountain ; 

 Pre-Cambrian gneiss ; Geologic relations of the area along Skunnemunk 

 mountain ; The relations along the northwest side of Skunnemunk mountain ; 

 Geology of the region east and southeast of Skunnemunk mountain ; The 

 area west of Cornwall ; Geology of Deer Park township ; Hudson river slates 

 and sandstones ; The Neelytown limestone ; Geology of Newburgh and New 

 Windsor townships ; The Highland area of gneissic rocks ; Tuxedo toAvnship, 

 Monroe township, Woodbury township, Highland township, Cornwall town- 

 ship ; Dike rocks ; Quartz porphyry ; Pleistocene geology. 



These chapters, each of which is elaborated in detail and precision, 

 precede a special consideration of the economic geology of the county. 



The various materials available for road making are described ; brick 

 clays, their quality, workers and product ; limestone, lead ore, building stone, 

 flagstone, iron ores and their workings, handling and product, are fully con- 

 sidered • and, finally, the soils, mineral springs, water power and water supply. 



