Bridgeton Formation — Summary. 19 



ing to the Amboy-Trenton valley from the Coastal Plain brought 

 in sand and gravel from the Cretaceous and Tertiary formations 

 over which they flowed. 



West and southwest of Berlin, the Trenton-Salem valley 

 (assuming the drainage to have followed this course) is thought 

 to have been filled up to the level of the divide on its southeastern 

 side, while northeast of Berlin, where the divide was higher, 

 the valley is thought not to have been filled completely. Where 

 the divide was buried, as south of Berlin, material of the sort 

 which filled the valley was spread out to the southeast over the 

 the seaward slope. 



The deposits made by the southward-flowing drainage came 

 from areas of crystalline rock, and were somewhat arkose, and 

 the arkose (Glassboro) phase of the formation probably finds its 

 explanation in the drainage of the time. It is limited to the 

 area reached by streams from the crystalline rock to the north. 

 The material of the Woodmansie phase, deposited by streams 

 heading in the Coastal Plain, is not arkose, and is without the 

 distinctive northern constituents which characterize the Glass- 

 boro phase. 



The composition of the Glassboro phase of the formation 

 seems to be best accounted for on the supposition that the 

 drainage which was responsible for it was glacial drainage, and 

 therefore that the formation was contemporaneous with a glacial 

 epoch. If this is the case, the glacial epoch was the earliest of 

 which there is record in this region. On this hypothesis, the 

 materials of the formation came partly from the basin of the 

 Hudson River by way of Amboy and Old Bridge, and partly 

 from the basins of the upper Raritan and Delaware rivers, both 

 of which joined the main stream through the Amboy-S'alem 

 valley. All of these streams are thought to have flowed from 

 the ice, and to have carried such debris as glacial streams 

 carry. 



The points which have led to the tentative adoption of this 

 view, may be stated briefly. (1) Much of the material of the 

 formation has the composition which glacial outwash would 

 have had. The association of Triassic, granitic, and Paleozoic 



