2o8 Quaternary Formations of Southern New Jersey. 



The phenomena between Spotswood and Old Bridge are con- 

 tinued east of Old Bridge, affecting most of the surface of the 

 low area (below 45 feet or so) nearly to Brownstown. The 

 formation also borders South River on the east, in a narrow 

 belt down to the Raritan. 



Lawrence Brook. — In the valley of Lawrence Brook the for- 

 mation has little representation above Westons Mills, but it has 

 some slight development between the lower end of the brook 

 and the mouth of South River. The amount of material is 

 small, and reaches levels of 60 feet (about the same as at James- 

 burg), but does not cover all the surface up to this level. It is 

 shown as well as anywhere on the island near the mouth of the 

 brook, an island having a maximum altitude of 44 feet. Its top 

 is covered with Cape May sand and gravel, though its basal part 

 is Cretaceous. The Cape May material here contains no northern 

 material, such as is found on the north side of the Raritan, and 

 up the Raritan to Bound Brook. Traces of Cape May benches 

 are to be found at various points up Lawrence Brook, but they 

 are trifling both in extent and in amount of material. In this 

 respect, Lawrence Book is in contrast with most of the streams 

 of southern New Jersey. The absence or paucity of the late 

 deposits in this valley probably is the result partly of lesser de- 

 position at the outset, and partly of greater erosion since. The 

 formations, the topography, and the situation of the basin of 

 this brook with reference to glacial drainage, all contribute to 

 this view. On the other hand, if the region were submerged to 

 60 feet, little deposition would need to have taken place in the 

 narrow strait which would have occupied this valley. 



Raritan River. — The remnants of glacial gravel below Bound 

 Brook, up to altitudes of 60 feet or so, suggest that the lower 

 part of the Raritan Valley was filled with sediment during the 

 last glacial epoch, up to elevations corresponding with the filling 

 of the Delaware; but this conclusion is not altogether decisive. 

 If there was such filling, the deposits have been almost wholly 

 cairied away; there is even less glacial gravel down the Raritan 

 than up the Millstone. There is also the question as to whether 

 the valley was drowned to the level of 60 feet, allowing trans- 



