REPORT OF THE STATE PALEONTOLOGIST I903 



175 



INTRODUCTION 



Trilobite mountain, which is situated 3 miles southeast of Port 

 Jervis, Orange co. N. Y., is a ridge with a maximum hight of about 

 750 feet, trending in a northeast-southwest direction. The ridge is 

 about 2 miles long by i mile wide and is bounded on the northwest 

 by the Neversink river and on the southeast by the marsh separating 

 this ridge from Shawangunk mountain, which like all other of the 

 Blue Ridge ranges trends from the northeast to the southwest. 



Both the valley of the Neversink and that containing the marsh 

 between the Shawangunk and Trilobite mountains are simple mon- 



Fig. I Simple monoclinal valley (Rogers) 



oclinal valleys [fig. i]^. The Onondaga and Marcellus formations 

 underlie the former, the upper Medina to Manlius the latter valley. 



Trilobite mountain, as noted by Dr Barrett^, constitutes one of a 

 series of anticlines extending in a northeast-southwest direction. In 

 other words, this monocline is crossed by a " secondary system of 

 flexures which cause the Helderberg Ridge to rise and sink in a 

 succession of anticlinal and synclinal folds . . . The roads are in 

 the synclinals and the limestone quarries are in the southeast fronts 

 of the anticlinals . . . Bennett's quarry is in one of these; Near- 

 pass's and Buckley's quarries lie south and north of it respectively." 

 To the central one of these ridges Mather and Horton gave (about 

 1840) the name Trilobite mountain, from the great abundance of 

 trilobites found here in the rocks of the Lower Oriskany.^ 



The first paper published in reference to the geology of this region 

 was by Dr William Horton on the geology of Orange county. Dr 

 Horton, who was a resident of Craigville, Orange co. and a well 



'Rogers, H. D. Geol. of Pa. 1858. v. 2, pt2, p. 921. 

 -Am. Jour. Sci. Ser. 3. 1877. 13:385. 

 ■''Mather. Geol. N. Y. ist dist. p. 333- 



