CRETACEOUS AXD TERTIARY FORMATIONS 13 



foraminifera, while in the siliceous phase elements of the 

 Hornerstown fauna occur in association with forms characteristic 

 of the calcareous phase. Its thickness varies from 25 to 70 feet, 

 but well-borings have shown that it thickens greatly down the clip. 

 It rests conformably upon the Hornerstown marl and is overlain 

 conformably by the Manasquan marl or overlapped by Miocene 

 beds. It includes the "limesand" and "yellow sand" of Cook, the 

 former of which was regarded by him as a part of the Middle 

 Marl. 



Manasquan marl. — The Manasquan marl in its lower portion 

 (13-17) is composed chiefly of glauconite, but the upper part 

 (8-12 feet) is made up of very fine sand mixed with greenish- 

 white clay, piles of which look like heaps of ashes — hence the 

 name "ash marl." The invertebrate fossils are not abundant and 

 are poorly preserved, the commonest occurring also either in the 

 Hornerstown or Vincentown. Its thickness is about 25 feet. It 

 corresponds to the "green" and "ash" marls of Cook's Upper 

 Marl bed and is the youngest of the Cretaceous formations ex- 

 posed in Xew Jersey. It probably rests conformably upon the 

 Vincentown and at most exposures is succeeded unconformably 

 by Miocene or Pleistocene deposits, although locally it is overlain 

 by a bluish marl of Eocene age without apparent unconformity. 



Correlation of the Hornerstown, Vincentown and Manasquan. 

 — The invertebrate faunas of these three formations are closely 

 related and form a larger fauna sharply separated from the 

 Ripleyian fauna of the underlying Magothy and Tinton beds. 

 This fauna has not been recognized south of Maryland. It shows 

 certain affinities with the lower or Maestrichtian division of the 

 Danian series of Western Europe (Weller). 



Eocene system. 



Shark River marl. — Eocene deposits in New Jersey are 

 limited in outcrop to small areas near Allenhurst (Deal), Shark 

 River and Farmingdale, in Monmouth County, where a mixture 

 of greensand and light-colored earth 11 feet in thickness and 

 carrying Eocene fossils rests without apparent unconformity 



