122 Quaternary Formations of Southern New Jersey. 



The material of the Pensauken formation north and north- 

 east of Trenton is essentially the same as in the areas north of 

 Crosswicks Creek, already described. The stony material is 

 chiefly of quartz and sandstone, with a little Newark shale and 

 a little crystalline rock: The amount of shale present varies 

 much from point to point. 



On the hypothesis that the Pensauken is a marine formation, 

 the 130-foot line marking its upper limit was the shore line of 

 the sound which extended from Trenton to Raritan Bay. In 

 this case, the shore gravels should have been largely of red shale. 

 While this is true in spots, it is not the rule, and though th& 

 constitution of the gravel is perhaps not altogether decisive, its 

 suggestion is rather that the gravel along the original border of 

 the formation was not derived by wave action from a shore of 

 shale. 



Southeast of Asylum Station, some sections of Pensauken 

 show much clay, mingled with plentiful cobbles and bowlders, 

 among which brownish quartzitic sandstone, white conglomeratic 

 quartzite, and Stockton conglomerate are most conspicuous. 



A mile and a half south of Lawrenceville, a Pensauken section 

 shows : 



3) 3 to 4 feet of gravel, the stony matter imbedded in clay and 



loam. 

 2) 1 foot of red shale gravel, little worn. 

 1) J /2 to 2 feet of red shale gravel, mixed with quartz, very compact. 



In the uppermost member, the stony matter is made up of about 

 one-third chert, one-third quartz, with sandstone, quartzite, and 

 shale in decreasing proportions in the order named. At numer- 

 ous points in the area between Trenton and Princesville, the 

 Newark conglomerate, when decayed, has a superficial resem- 

 blance to the Pensauken, and might be mistaken for it on hasty 

 inspection. 



At Clarksville there is an area of Pensauken on the divide 

 between Port Mercer and Lawrence Station. Locally at least 

 it contains much red shale. Similar gravels occur at other points 

 to the northwest, but in none of these places do the gravels con- 

 tain more red shale than at one point south of New Sharon, 9 



