Pensauken Formation — Local Details. 149 



Adjacent to the plain of degradation developed by the main 

 stream, there were minor plains along minor streams. The 

 Woodstown Plain and its correlatives Knapp thinks traceable, by 

 means of the parts remaining, nearly to Matawan. From this 

 point east, the topography was developed by drainage to the 

 northeast; all the rest of the way to Delaware Bay, the larger 

 features of the topography near the broad valley between Amboy . 

 and Bordentown and Salem were developed by drainage which 

 flowed to the northwest when the Pensauken gravels were de- 

 posited. 



If major streams are made the basis of comparison, the broad 

 plain from Amboy to Salem was controlled by a southwest 

 flowing stream, while a narrow belt, northeast of a line from 

 Wickatunk to Browntown, was controlled by drainage to the 

 east. 



After the main plain of degradation was developed, the drain- 

 age was changed, and Hudson River and Raritan River reached 

 the ocean where Raritan Bay is now. Whether this change took 

 place before or after the close of the Pensauken epoch is not 

 now clear. After this change, present drainage was established, 

 and the continuation of the old main divide east of Wickatunk 

 was destroyed. 



Description of deposits. — Within this area there is a series of 

 gravel patches which Knapp regarded as Walnford (p. 147), 

 which are of uncertain correlation. Several of them are elongate 

 north and south, roughly parallel to the present streams. The 

 westernmost is just south of Matawan, at an elevation ranging 

 from 130 feet at the south to 60 feet at the north. At the south 

 end only is the gravel well exposed. It contains much ironstone, 

 some of which is in slabs a foot in diameter. Some of it is from 

 the Red Bank formation of the Cretaceous system, and some 

 from younger gravelly formations. The gravel and sand have 

 a maximum thickness of at least 20 feet, are poorly stratified 

 and poorly assorted, so far as the structure has been seen. With 

 the gravel is more or less sand and marl from local terranes 

 just to the south, exposed in the slopes north of Beacon Hill. 

 Exposures in the west part of this area show the Cretaceous 

 surface to be very irregular, and the gravel fills small gully-like 



