Lower Helderberg Hocks of Port Jervis, etc. 293 



numerous, and particularly the Asaphus, that Dr. Horton and 

 myself gave the hill the name of Trilobite Mountain. The 

 strata are traversed by two great systems of fracture, one 

 longitudinal and approaching more or less to the direction of 

 the strike ; the other transverse. Their usual directions are 

 S. 20° W. and N. 20° E. for the first, and S. 60° E. and N. 

 60° W. for the second.", I cannot improve this description. 

 The ridges are very narrow, often not much wider than the 

 actual thickness of the strata of which they are composed ; 

 but whether buried beneath the drift or rising above it, they 

 reach from the Hudson River many miles to the south-west. 

 At Bennet's Quarry the strata have a dip of from 40 to 60° 

 N. N. W., a dip so steep as to prevent an exposure of more 

 than their upturned edges. The hill in which these strata 

 rise in succession above each other, has a downward slope of 

 from 30° to 40° S. S. E., a direction so nearly at right angles 

 to both dip and strike, as to give, when measured, very nearly 

 the exact thickness of the sub-divisions. At Mr. Sandford 

 Nearpass' Quarry, two miles south-west of Bennet's Quarry, 

 in the State of New Jersey, and very near Mr. William 

 Nearpass' Quarry, — of which a transverse section is given by 

 Prof. Cook in the "Geology of New Jersey," pages 153 and 

 155, and a columnar section on page 158, — the dip is 15° N. 

 N. W. At Guymard, six miles north-east of Bennet's Quarry, 

 the dip is 25° N. W. The width of the entire group varies 

 with the dip ; being greater where it is least, and vice versa. 

 At Bennet's Quarry there has been more disturbance than at 

 the other places mentioned. 



At this quarry we have the following section, going from 

 below upward. 



1. Tentaculite Limestone, thirty feet exposed. It may 

 be divided into, — la; Thin-bedded, black or dark-blue con- 

 cretionary limestone, with horizontal layers of Strophodonta 

 varistriata, twenty-five feet; and lb; Quarry Limestone, a 

 fiue-grained, blue stone, excellent for lime, with horizontal 

 layers of gasteropods, five feet thick. 



