Bridgeton Formation; — Local, Details. 65 



some question as to this correlation. It is 8 to 9 feet thick, about 

 80 per cent, quartz and 20 per cent, chert. It is very like that 

 of the Beacon Hill formation except for occasional bits of iron- 

 stone. Taylors Hill, near Hominy Hills, has a gravel cap at 180 

 feet, and this too, is regarded tentatively as Bridgeton. Other 

 hills in the vicinity, at 130 to 140 feet, in the same relations as 

 Taylors Hill, have caps of gravel interpreted as Pensauken. 



These various levels are more or less discordant. Though 

 levels at about 250 feet near Hillsdale and at 200 feet at Barren- 

 town appear to be connected with the outcrops of certain beds 

 of the Cretaceous, there are, in the same vicinity, other hills at 

 about 200 feet of which the top is Miocene. It seems probable 

 that the hills at about 200 feet near Barrentown go with the 

 140-foot levels at Allenwood. 



Constitution of the Bridgeton. — The Bridgeton gravels of this 

 region contain no material which can be identified as having come 

 from the Cretaceous. The surface during the Bridgeton epoch 

 was mostly in the Miocene and Cohansey formations, and they 

 yielded the sand and gravel deposited here in the Bridgeton 

 epoch. Cretaceous beds must have been exposed about Craw- 

 fords Corners, but there was little sedimentation there, or if there 

 was, but little of it now remains. 



In Pensauken time, on the other hand, the Cretaceous beds 

 were extensively exposed, and the deposits of that epoch north 

 of the Hominy. Hills contain much material from that system. 

 Some of the streams which flowed from the Cretaceous to the 

 Miocene, carried sediments from the former out onto the latter. 



The result was that the sediments which accumulated in the 

 Bridgeton and Pensauken epochs in this region were quite differ- 

 ent in composition. For instance, the gravels (Pensauken) which 

 are found in Swimming River valley in the vicinity of Holmdel, 

 at 140 to 170 feet, contain much material derived from the Cre- 

 taceous, and are regarded as Pensauken. 



5 QUAT 



