342 W. B. CLARK — UPPER CRETACEOUS FORMATIONS OF NEW JERSEY. 



layer is commonly found at the top of the formation in the limited area 

 where it has been observed. 



Strike, dip, thickness. — The strike and dip of the Shark River formation 

 are similar to those of the preceding formations, so far as is revealed from 

 the few surface exposures and the records obtained from well-borings. 



The thickness of the beds is between 10 and 15 feet, and at points exposed 

 in the Shark River and Manasquan valleys is estimated as pretty constant 

 at about 12 feet. As the Shark River formation has only been observed 

 upon its beveled edges near its contact with the Manasquan formation, 

 it is highly probable that it increases considerably in thickness to the 

 southeastward beneath the Miocene cover. 



Stratigraphic relations. — The Shark River formation rests conformably 

 upon the underlying Manasquan formation, and its deposits are not sepa- 

 rated b}^ any sharply defined lithologic distinction, although the general 

 character of its materials is somewhat different from that of the under- 

 lying strata. The Shark River formation is unconformably overlain by 

 the Miocene deposits, and the line of contact is always clearly marked. 

 The Miocene deposits have a considerably smaller angle of dip than the 

 Shark River beds, as shown by the general overlapping of the former 

 upon the subjacent members of the Cretaceous series. 



Fossils. — The fossils of the Shark River formation have much interest, 

 since they are supposed to represent a fauna of a later geological period 

 than that to which the previous formations are referred. Among the 

 characteristic and prominent species are the following : 



Ostrea glauconoides, Whitfield. Astarta castanella, Whit. 



Gryphxa vesicularis, Lamarck. Cardita perantiqua, Conrad. 



Pecten kneiskerni, Conrad. Protocardium curtum, Conrad. 



Nucula circe, Whit. Veleda equilatera, Whit. 



Nuculana albaria, Conrad. Corbula {Nesera) nasutoides, Whit. 

 Axinea conradi, Whit. 



Fusus angularis, Whitfield. Volufilithes sayana, Conrad. 



Fasciolaria hercules, Whit. Pleurotoma surciditiformis, Whit. 



Caricella ponderosa, Whit. Conus subsauridens, Whit. 



Voluta lelia, Whit. Calyptraphorus velatus, Conrad. 



Voluta perelevala, Whit. Xenophora lapiferens, Whit. 



Voluta (Scaphella) newcornniana, Whit. Mesalia elongata, Whit. 



Nautilus cookana, Whit. Aturia vanuxemi, Conrad. 



Interpretation of the sedimentary Record. 



general character of the deposits. 



The deposits of the upper Cretaceous, as described in the preceding 

 pages, consist of a great variety of materials, among which sands and 



