1 10' Quaternary Formations of Southern New Jersey. 



which is now 100 feet above sea level, as seems certain, it would 

 seem that Assiscunk Creek should have gone south to Rancocas 

 Creek, if the divide between them had not been higher than 

 now. The fact that it went westward indicates that the divide 

 was higher than now. 



The remnants of the formation within a few miles of River- 

 side suggest a measure of post-Pensauken erosion. At New 

 Albany, remnants occur at ioo feet, and others in the vicinity 

 of Cinnaminson and Deacons, have about the same elevation; 

 the surface here must have been built up to about this height 

 in Pensauken time. At Beverly the base of the formation has 

 an altitude of not more than 10 feet. These figures suggest an 

 original thickness of 90 feet or so over what were the deeper 

 valleys, and at least 30 feet over the pre-Pensauken plain which 

 is now at 70 feet. From these facts and the present fragmen- 

 tary condition of the formation, some idea may be had of the 

 erosion which has taken place. 



In the vicinity of Bustleton, pits reveal the structure and con- 

 stitution of the formation well (Fig. 31, p. 78). The material 

 ranges from coarse, with occasional bowlders 2 and 3 feet in 

 diameter to fine, with nothing coarser than pebbles. In some of 

 the pits the sand is arkose, while in others it is not, or not 

 uniformly so. The structure, too, is variable, suggesting waters 

 of varying strength of current. Within the area there is the 

 same evidence of transition from the northwest phase to the 

 southeast phase that was noted about Deacons. 



A mile and a half west of Columbus is a partially isolated 

 area which is topographically the eastward continuation of the 

 Bustleton area. It is covered with a thin bed of gravel, which 

 includes blocks of conglomerate. This is a non-arkose remnant, 

 possibly antedating the deposition of the arkose phase nearer 

 the Delaware. ' 



At Florence there is a small area of Pensauken, which has an 

 altitude of 75 feet to 80 feet. This remnant, like all others 

 near the Delaware, is arkose. Its position indicates that the 

 main valley of the Delaware was not just where it now is in 

 pre-Pensauken time. 



