Bridgeton Formation — Summary. . 15 



up to 60 feet. The maximum thicknesses may represent approxi- 

 mately the original thickness of the formation in the localities 

 where they occur. Sixty feet is probably more than its original 

 average thickness, and less than its maximum. 



Since its deposition, much of the Bridgeton formation has 

 been removed by erosion. From large tracts all of it has been 

 taken away, and it occurs in considerable areas only on broad 

 divides. 



Original extent. — The Glassboro phase of the Bridgeton for- 

 mation is believed to have been continuous, at the time of its 

 origin, from Long Island, over much of Staten Island, and 

 across New Jersey along the inland margin of the Coastal Plain; 

 that is, from Long Island to Bordentown and thence down the 

 Delaware Valley to the sea. If this view is correct, it has been 

 removed completely from an area of 5-10 miiles wide and 100 

 miles in length, from Amboy to Salem. The only escape from 

 this conclusion lies in the possibility that the Bridgeton formation 

 has been confused with the Pensauken in the northeastern part 

 of this tract. About Amboy, for instance, the Pensauken reaches 

 high elevations, but its base nowhere seems to reach the alti- 

 tude which would have been expected o>{ the Bridgeton base. 



THE WOODMANSIE PHASE. 



Characteristics. — The second phase of the Bridgeton forma- 

 tion is found east and north of the Glassboro phase, southeast 

 of a line extending from Glassboro to Keyport; but within 

 this area the formation is represented at the surface by small 

 areas only, if present identifications are correct. In much of 

 this area, however, the differentiation of the several Quaternary 

 formations is very unsatisfactory. The Woodmansie phase is 

 not arkose, and is without the crystalline rock, shale, red sand- 

 stone, etc., of the Glassboro phase. It is more largely of sand 

 than the other phase of the formation, and it is thinner. Its 

 materials were derived chiefly from the Miocene and Cohansey 

 formations. In this region, too, the Bridgeton formation is less 

 distinct topographically than in the Berlin-Bridgeton region, 



