146 Quaternary Formations of Southern New Jersey. 



Pensauken. They are at altitudes ranging from 120 to 150' feet, 

 and the depth of the gravel is known to range up to 8 feet. 

 Higher hills east of Browntown, at 200 ± feet, do not have 

 gravel caps, though surface pebbles suggest the. former presence 

 oi a higher stratum carrying gravel. The gravel caps southeast 

 of Browntown are all of southeastern material. 



The gravel is similar, in all essential respects, to that between 

 Englishtown and Freehold. It is not certain that it ever covered 

 all the area within which the present remnants exist. As in 

 most of the gravel caps of this region, the base is uneven. The 

 floors of the pits, after the gravel has been removed, resemble 

 the channels of small streams in some cases, the pockets of gravel 

 being in more or less sinuous lines, comparable to scour holes in 

 the beds of streams. In one of the gravel pits southwest of 

 Morganville, the gravel after removal, was seen to have occu- 

 pied a trough (channel) in what is now the crest of the elevation 

 on which the gravel rests. 



Locally, the ironstone makes up 95 per cent, of the gravel, 

 though in most places it is subordinate to the quartz. Large 

 pieces of both materials are of local occurrence. Two miles 

 southwest of Morganville, the matrix of the gravel contains 

 much marl, clearly from the Navesink marl. 



Some of the beds of gravel here suggest displacement down 

 slope. The original level of deposition seems to have been 130 to 

 150 feet. One fact leading to this inference is the greater depth 

 of the gravel on the hilltops at these levels. 



The surface on which the Pensauken was deposited northwest 

 of Matawan, sloped toward the northwest, as if developed by 

 drainage in that direction. Raritan Bay probably did not exist 

 when this plain was developed. The valleys of Matawan and 

 Cheesequake creeks have developed since Raritan Bay came into 

 existence. They are clearly young creeks. They will, if not 

 interfered with, send their heads farther and farther back into 

 the country to the southwest. 



The 1 50- foot plain, remnants of which appear west of Mata- 

 wan, and thence to Freehold and Englishtown, would seem to 

 be too high (now) for development at this level, with the drain- 



