j6 Quaternary Formations of Southern New Jersey. 



difficult when exposures are poor, and it seems probable that 

 much of the material of the younger formation was derived from 

 the older. 



Xortheast of Trenton the northern part of the larger areas 

 of the Pensauken formation lap up on shales of the Newark 

 series. The relations are shown by Figs. 33-35. Far north of 

 the Raritan Bay-Trenton valley there are remnants of the Pen- 

 sauken formation on the Newark beds, but they are scattered and 

 small. At King"ston the Pensauken occurs in a valley cut in the 

 shale before the Pensauken epoch. 



The larger part of the Pensauken lies on Cretaceous forma- 

 tions. It has been more completely removed from the Raritan 

 than from the younger members of the system, apparently because 

 the Raritan was more easily eroded than the others. Southwest 

 of Trenton, remnants of the Pensauken overlie the Raritan 

 between Rancocas and Coopers creeks ; but elsewhere the out- 

 crops of the Raritan formations have lost the Pensauken beds 

 which overlay them. To the northeast, South River has re- 

 moved the Pensauken from a large area, and this stream appears 

 to have adjusted its course to the Raritan formation after it had 

 cut through the Pensauken. Between Jamesburgi and Trenton, 

 more of the Pensauken remains on the Raritan formation. This 

 is because the Millstone, which drains much of this region, 

 crosses the Rock Hill ridge, the hard rock of which prevents the 

 river from lowering its basin south of the ridge, as rapidly as 

 South River lowered its basin. 



The Merchantville to Wenonah formations, which constitute 

 the Matawan group and overlie the Raritan-Magothy beds, were 

 less completely planed down before the deposition of the Pen- 

 sauken formation, and much less of that formation was deposited 

 over their outcrops. Parts, indeed, were too high to be covered 

 by the younger formation. 



The outcrops of the Cretaceous beds above the Matawan group 

 were still less generally covered by the Pensauken, because they 

 were somewhat higher than the outcrops of the underlying for- 

 mations; but in the basin of the Rancocas Creek, the surface of 

 these beds was lower than elsewhere, and was more gen- 



