28 Quaternary Formations of Southern New Jersey. 



the younger formation was derived from the older, and there 

 the distinction is most difficult, for the Bridgeton is not arkose. 

 At Harris's Quarry, 1^4 miles southwest of Cohansey, and 1^2 

 miles southeast of Pecks Corners, at the 100 to 110-foot level 

 Fig. 13, p. 30), the sand is cemented into ferruginous sandstone, 

 which, for the most part, resembles the Cohansey formation 

 rather than the Bridgeton ; but the occasional cobbles and large 

 pebbles seem to indicate its correlation with the Bridgeton, for 

 coarse gravel is absent, so far as known, from the Cohansey sand. 

 Material which is similar, except for the gravel, is to be found 

 in the south bank of Hepnor Run, 2 miles south of Bridgeton. 

 In this latter place, there is nothing to favor the reference of the 

 sandstone to the Bridgeton formation, as against the Cohansey. 



Where the Cohansey sand is coarse, and especially where it 

 is associated with fine gravel, as is the case in many places, and 

 where the Bridgeton is of coarse sand with only fine gravel inter- 

 mixed, the two may be inseparable on the basis of available data. 



The Bridgeton formation of the Bridgeton region may be said 

 to center about Elmer, beyond the headwaters of Alloways Creek 

 and Salem Creek. Considerable areas extend off to the south 

 on the divides east and west of Cohansey Creek. Within this 

 general area the altitude of its surface ranges from about 160 

 feet to 100 feet, and its base has a smaller range from 120 feet 

 at the north to 80 feet at the south. 



between aeeoways creek and oedmans creek. 



Distribution. — The Bridgeton formation caps the divide be- 

 tween these creeks, extending out to the northwest from the 

 highlands to the southeast. Northwest of the main divide be- 

 tween these creeks, there are outliers of the formation on hills 

 which have been isolated by erosion. The general relations of 

 the formation are shown in Figs. 14 and 15 (p. 40). 



On the uplands to the east the surface of the Bridgeton has 

 an altitude of 140 to 160 feet. The tops of the outliers to the 

 west have an altitude ranging as low as 129 feet on Big Man- 

 nington Hill. The original surface of the formation at the east 



