Pensauken Formation — Local Details. 123 



miles from the nearest shale outcrop. Conditions of deposition 

 were therefore such as to permit the deposition of red shale 

 gravel, in quantity, at this distance from its source. The shale 

 could hardly have been carried across a sound, unless by floating 

 ice. 



Between Assanpink Creek and Millstone River. — In the vicinity 

 of Princeton Junction, the crystalline rocks are but thinly cov- 

 ered with Pensauken, the contact being at an elevation of about 

 90 feet. To the south the Pensauken is thicker, covering unin- 

 terruptedly a broad area which extends through Dutch Neck to 

 Edinburgh, Windsor, and Aliens Station. From an elevation 

 of about 90 feet at Princeton Junction, its surface rises to an 

 elevation of about 150 feet near Aliens Station. Only at the 

 extreme southeast, however, is much of the surface above 130 

 feet. 



Within this area, the lowest level of the base of the forma- 

 tion is not at the contact of the Cretaceous with older forma- 

 tions, but along a line running northeast from Mercerville, 

 through Dutch Neck and Gravers Mill, to Plainsboro. Along 

 this line the base of the Pensauken is below 70 feet at many 

 points, and perhaps all the way. This would seem to place the 

 lowest part of the pre-Pensauken surface a mile or two south- 

 east of the surface contact between the Cretaceous system with 

 the Newark series. 



To the southeast, about Newtown, Windsor, and Hightstown, 

 the drainage was from the southeast to the northwest. It is 

 clear that between these points and the northwest edge of the 

 Cretaceous, these streams must have turned either to the north- 

 east, to the lower Raritan, or to the southwest, to the Delaware. 

 There was a deep valley between Trenton and Bakers Basin, 

 but its continuation to the northeast has not been traced 



There was a considerable pre-Pensauken valley between Prince- 

 ton Junction and Penns Neck, and it is probable that at this time 

 the Millstone went southwest from Princeton Junction through 

 Bear Swamp to Port Mercer, and thence southwest to Trenton, 

 though it may have flowed north nearly to Princeton, and then 

 southwest between Penns Neck and Princeton to Port Mercer. 



