FEATURES OF TRAP EXTRUSIONS IN NEW JERSEY 325 



structure of the region. There are, however, excellent reasons for 

 supposing that a series of northerly and southerly faults runs through 

 the country. 



A little west of Garret Rock there is a very evident displacement, 

 described and figured by Davis in his paper on the " Triassic Traps and 

 Sandstones," and referred to by Darton,'' who figures a displacement 

 of about seventy feet, with downthrow on the eastern side, and with 

 this allowance calculates a thickness of seven hundred feet for the trap 

 sheet along this section. On this supposition the underlying shales 

 should lie not less than two hundred feet beneath the surface at the 

 West Paterson quarry. As they are brought up again at this point a 

 displacement of something like two hundred feet by faulting is shown 

 to have occurred, in addition to the seventy-foot throw referred to by 

 Darton. In the quarry itself there are many nearly vertical planes 

 of cleavage, running from top to bottom of the quarry and having a 

 direction nearly north and south. Over much of the country covered 

 by the map there is a prominently developed set of cleavage planes 

 having a general northerly and southerly direction (N. o E. to N. 30 E) . 

 Frequently where a little quarrying has been done they appear as 

 innumerable sharply defined breaks in the quarry walls. Near the 

 road which runs through the gap of the Great Notch a series of pinna- 

 cles on the northern side indicates a faulted structure. This same 

 series of faults continued southward follows the line of valley along 

 which the N. Y. & G. L. R. R. has been built from the station at 

 Montclair Heights northward, and apparently has resulted in the two 

 parallel crests of the ridge here. The faults are well shown in the 

 large quarry near the railroad line in this inner valley and the move- 

 ments have resulted in the formation of slickensides and gouge matter. 

 There is reason to believe from the evidence at hand that a multitude 

 of displacements of slight throw, and a few well-developed faults of 

 greater throw, all having a northerly and southerly course, have affected 

 the country. The appearance of the underlying lake bottom at West 

 Paterson subtracts two hundred feet from Darton' s estimate, and 

 possible displacements to the west of this are likely to reduce the figures 

 still more. 



I Bulletin 67, U. S. Geological Survey, "The Relations of the' Traps of the Newark 

 System in the New Jersey Region," p. 23. 



