^2, Quaternary Formations of Southern New Jersey. 



and locally controlled, the drainage. This has gone so far that 

 the divides, and with them some of the elongate areas of the 

 Pensauken, correspond, in many cases, with the outcrops of the 

 certain Cretaceous formations, and the outcrops are at right 

 angles to the courses of the principal tributary streams. 



In other places, as about Mount Holly, the Pensauken has 

 been wholly removed from large areas. The underlying Cre- 

 taceous beds here were easily eroded, and the Pensauken forma- 

 tion has been more completely carried away from the upper 

 parts of the basins of the streams than from the lower parts, 

 where the underlying Cretaceous was less easily eroded, and 

 where the valleys was therefore less readily widened. 



Since the beginning of the interval of erosion which followed 

 the deposition of the Pensauken formation, erosion has been 

 the chief process affecting the topography of the region where 

 this formation occurs. The only other change of importance 

 has been the partial filling of some of the valleys, leaving them 

 somewhat less deep than formerly. 



STRATIGRAPHIC RELATIONS. 



The base of the Pensauken. — As a rule, the elevation of the 

 base of any given area of the Pensauken formation is nearly 

 the same on all sides, especially if the area is small. Further- 

 more, the elevation of the bases of various areas which are near 

 one another is, in most cases, nearly the same. This is the 

 basis for the conclusion that the surface on which the Pensau- 

 ken was deposited was essentially flat, though like all plains of 

 sub'aerial erosion, it was not without some relief. To this general 

 rule of planeness there were some distinct exceptions, as will 

 be seen. 



While the plain on which the Pensauken was deposited was 

 being developed, Delaware River had a course similar to that 

 which it now follows, and a large part of the valley plain below 

 Trenton was developed by its tributaries. As a result, the plain 

 declined slightly towards the Delaware, that is from the east- 

 southeast to the west-northwest. Between Trenton and Raritan 

 Bay, a large part of the corresponding plain was probably de- 



