30 NEW YORK STATE MUSEUM 



At the stone-crusher near the quarry the basal contact ascends 

 abruptly for at least 20 feet, but it is not clear whether the ascent 

 is caused by a fault or by breaking across the beds. The gap at 

 Trough Hollow, particularly when viewed from the river, has some 

 appearance of a fault gap, and the alignment of the escarpment 

 is slightly broken, as if offset by an oblique fault of small throw. 

 The relations near the stone-crusher lend strength to the fault 

 hypothesis, though they do not establish it beyond a doubt. 



In the quarry the trap rests on brown, feldspaithic sandstone. 

 North of the quarry these beds can be traced continuously till 

 they disappear beneath the river, while the base of the trap 

 ascends to an elevation of between 100 and 200 feet. The small 

 fault which may cut the trap at Trough Hollow can not account 

 for this. On the contrary, the topography suggests that the base 

 of the trap ascends obliquely at an angle of about 15°. 



Between Trough Hollow and Waldberg landing at Long Clove, 

 2£ miles, the base is not exposed, but is high up the face of the 

 bluff, at elevations varying from 150 to 250 feet above the river. 

 It is certainly not conformable for all this distance, since the dip 

 and trend of the shales are such as to carry outcrops downward 

 and out of sight at a rate varying locally from 300 to 900 feet a 

 mile. The fact that within the distance mentioned above (2J 

 miles) the contact remains high above the river proves that the 

 base of the trap must ascend geologically many hundred (1000 to 

 1500) feet (d to e, fig. 4). 1 



A few hundred yards below the quarry at Long Clove (Wald- 

 berg landing) a dike of trap varying from 3 inches to a foot in 

 thickness cuts the arkose sandstones which lie at least 50 feet 

 below the main trap sheet. The dike in general follows a mean- 

 dering, wavy course nearly parallel to the bedding of the sand- 

 stone, and can be traced for 50 yards or so. At one point it 

 shows the relations represented in figure 5. 



At Long Clove the base of the trap changes its elevation some- 

 what. Whether it is due to faulting or to a change of horizon is 

 not clear. Seen from the river, the gap of Long Clove did not im- 



iThe vertical scale is exaggerated nearly three times the horizontal, 

 consequently the dip of the sedimentary beds is too great. 



