Pensauken Formation — Local Details. 115 



fast as the lower parts, and so in the more or less ponded waters, 

 the marly material from the uplands accumulated in marshy 

 tracts. This hypothesis is, however, not altogether satisfactory, 

 for distinctive lacustrine deposits are wanting. 



Along the Assiscunk Creek and Barkers Brook, in the vicinity 

 of Jobstown and Jacksonville, glauconitic sands are accumulating 

 as ridge-like beds bordering the present streams, which head 

 back in the marl beds, whence they derive their greensand. 

 During floods, these streams deposit the greensand on their 

 flood plains several feet above the ordinary stages of water. 

 When the flood-plain becomes dry, the greensand is blown about, 

 in many cases to higher levels, and piled up into low dune ridges. 

 The ridges now seen are slight, rarely more than 3 or 4 feet 

 high. It seems therefore quite possible that floods and winds 

 may have been important agents in the distribution of the green- 

 sand loams. It is also probable that they did not all originate in 

 one way or at one time. 



Along Blacks Creek there are numerous patches of gravel 

 between Jacobstown and Chesterfield which may or may not be 

 of Pensauken age. Some of them appear to be younger. They 

 are characterized by local (southeastern) gravel, in which iron- 

 stone and glauconitic sand are conspicuous elements. Materials 

 from the Navesink marl and the Kirkwood sand can be recognized 

 distinctly in some places. Glauconitic loam overlies gravelly, 

 glauconitic sand in many places. Oh the whole, the sections 

 along Blacks Creek above Chesterfield show more gravel up 

 stream, and less below. 



Along this creek there are gravels and sands of undetermined 

 age. Some of them seem younger than the Pensauken, and 

 older than the Cape May. Gravels of intermediate age are of 

 course quite possible. There are small beds of gravel classed as 

 Pensauken on benches at an altitude of ioo± feet, a mile or so 

 south of Chesterfield. 



Northeast of Woodstown, the Woodstown Plain appears to 

 have terminated somewhat abruptly against a scarp such as that 

 now seen east of Juliustown, west of Fountain Green, at Spring- 



