78 Quaternary Formations of Southern New Jersey. 



Relations to the early glacial drift. — In the vicinity of Me- 

 tuchen, and between that place and New Brunswick on the one 

 hand and Raritan on the other, there are occasional patches of 

 Pensauken which are somewhat till-like in appearance, and in 

 at least one place near Metuchen, glaciated bowlders have been 

 found in it. The relations, however, do not preclude the hypothe- 

 sis that the Pensauken proper antedated the surface parts which 

 locally contain glaciated stones. In other words, it is not demon- 

 strated that the glaciated materials associated with the Pensau- 

 ken, are really parts of it. If the glaciated bowlders here are 

 really in the Pensauken, they indicate that ice pushed down to 

 the lower Raritan before the close of the Pensauken epoch. In 

 some places, as at Raritan, material which has somewhat the 

 appearance of old glacial drift overlies typical Pensauken gravel 

 and sand. From Raritan it is but a few miles north to the 

 border of well-defined glacial drift of an early glacial age. 1 In 

 this region, it is not clear that the Pensauken and the old drift 

 are closely associated in time. From all that can now be seen, 

 the former might be older than the older glacial drift of the 

 region. Other considerations, however, to be adduced later, 

 suggest their close connection in time. 



CONSTITUTION. 



Physical characteristics. — The Pensauken formation is com- 

 posed chiefly of coarse sand, with a subordinate amount of 

 gravel, and a slight admixture of material of a clayey nature. 

 Exceptionally, as at Fish House, the formation contains clay 

 in considerable beds, and bowlders, even up to 4 to 6 feet in 

 diameter, occur at its base in some places. The formation no- 

 where consists entirely of bowlders, of cobbles, of gravel, or 

 of sand. Almost everywhere it is made up of a mixture of 

 these materials, especially sand and gravel, in varying propor- 

 tions. In some places it consists of sand with occasional pebbles, 

 in others of compact gravel with interstitial sand only. The 

 gravelly parts vary from fine gravel with an occasional cobble, 



1 Glacial Geology, Vol. V, p. 753. 



