CRETACEOUS AND TERTIARY FORMATIONS. 17 



locally a dark astringent clay of Miocene age overlies the Shark 

 River marl. Under these circumstances there is some uncer- 

 tainty as to the formations from which the fossils came. Inas- 

 much, however, as the Shark River marl was better exposed 

 here than elsewhere in the State most of the species are prob- 

 ably referable to this horizon, unless there is specific evidence 

 to the contrary. , 



Farmingdale and Squankum. — Immediately north of Farm-, 

 ingdale in a large pit along the railroad there is an extensive 

 exposure of the Manasquan marl overlain by a dark clay of 

 Miocene age. Southwest of the village along Manasquan River 

 is a line of openings mostly in the Manasquan marl, overlain 

 by Miocene or Pleistocene deposits, but, as stated by Cook, two 

 of them in the "blue and ash marls," i. e., the Shark River and 

 upper part of the Manasquan marl. Whitfield 1 cites numerous 

 Eocene invertebrate forms "in the upper layers of the Upper 

 Green marls at Shark River, Farmingdale and Squankum, New 

 Jersey," so that it seems to be well established that Eocene fos- 

 sils have been collected from Farmingdale and Squankum, al- 

 though the Manasquan marl is the one most commonly exposed. 

 In this report specimens labelled simply "from Farmingdale," 

 "from Squankum" are tentatively referred to the Manasquan 

 marl, although it is recognized that they may be from the Shark 

 River formation. In the case of others there is no doubt since 

 their labels expressly state "from the Eocene marl at Farming- 

 dale," etc. The Miocene clay also may have yielded some forms. 



Hornerstonn. — Of the specimens herein described from 

 Hornerstown it is probably safe to refer them all to the Horners- 

 town marl bed (Cook's Middle Marl), since that layer was ex- 

 tensively opened for marl at various points near Hornerstown 

 during the years when these collections were made. However, 

 the Red Bank sand occurs along the creek west of the village 

 beneath which at a slightly lower level the Navesink marl is 

 found. It is possible, therefore, that some material was ob- 



1 Gasteropoda and Cephalopoda of the Raritan Clays and Greensand Marls 

 of New Jersey. Geol. Survey of N. J., Paleontology, Vol. II ; also U. S. G. 

 S. Monographs XVIII, 1891. 



2 GEOL 



