THE NEW VERNON TRAP 203 



•with the facts ; but, on the whole, one of the hypotheses of scant eruption 

 seems most probable. 



The New Vernon trap. — The trap crescent near New Vernon is a thin 

 extrusive sheet exactly similar to that of Long hill, and the structure of 

 the shales shows that it has been brought up by a dome-like anticline, or 

 quaquaversal. Darton* thought it might be continuous with either the 

 second or third Watchung sheets (Second mountain or Long hill) or an 

 independent local extrusion. Kiimmelf regarded it as either the western 

 border of the third Watchung flow or an independent sheet. The struc- 

 ture of the intervening shales, however, makes it quite probable that the 

 New Vernon trap is continuous with the third Watchung (or Long hill) 

 extrusive, or at least contemporaneous with this, and therefore occupy- 

 ing the same horizon. The outcrop was thrown so far eastward by the 

 anticline that it escaped being cut off by the great boundary fault along 

 the adjacent border of the crystalline Highlands (cross-section, plate 1). 



Sand Brooh and New Germantown traps. — These two small remnants 

 of extrusives have been preserved by spoon-shaped synclines with west- 

 ward pitching axes, and in both cases they have been cut off to the west- 

 ward by faults. Each contains remnants of two separate masses of trap, 

 and the forms and relations seem to be exactly the same in both. The 

 larger mass in each outcrops in a westward pointing crescent and curves 

 downward beneath the shales within; the smaller caps a rounded hill be- 

 tween the points of the crescent, thus resting on the sediments overlying 

 the synclinal sheet below. At New Germantown this upper fragment is 

 separated, probably by erosion, into two small, disconnected masses. 



Kiimmel,! finding the contacts of these smaller masses so obscured by 

 soil covering at both localities that their relations to the sediments could 

 not be directly observed, was uncertain as to their extrusive character; 

 but from their structure, lithic character, and the absence of metamor- 

 phic effects on the sediments, there can be little doubt of it. 



Here, then, in each case are remnants of two lava flows separated by 

 several hundred feet of shales, and both Darton§ and Kiimmelf have 

 shown that they occupy approximately the same horizons as the Watchung 

 extrusives. The former, however, makes no reference to this point in the 

 discussion, and the latter concludes that "there is no evidence that they 

 are parts of the same flows." On the other hand, it may be shown that 

 such a correlation is not at all improbable. The present Watchung sheets 



* BuU. U. S. Geological Survey, no. 67, 1890, p. 34. 



t Annual Report of the State Geologist of New Jersey for 1897, p. 91. 



t Loc. cit., pp. 91, 92. 



§ Bull. U. S. Geological Survey, no. 67, 1890, fig. 11, p. 35. 



