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



any of the others, and although they are really but little more than sub- 

 divisions of a general fauna, yet they are sufficiently distinct from one 

 another to be readily followed from the Raritan bay to the eastern shore 

 of the Chesapeake, while beyond the distinctive characters of the Matawan 

 fauna are continued to the Potomac at Fort Washington. The Rancocas 

 fauna is very distinct both from that above and below it, and is highly 

 characteristic of the formation in which it occurs. Its Terebratula 

 harlani zone is the most persistent fossiliferous band in the whole Creta- 

 ceous series. The Manasquan and Shark River faunas are equally dis- 

 tinctive, although having, so far as can be determined from surface indi- 

 cations, a far less wide geographical distribution. Almost no species 

 common to earlier faunas have been found, and practically no forms con- 

 tinue on from the Manasquan into the Shark River epoch. 



CORRELATION OF THE DEPOSITS WITH THOSE OF OTHER AREAS. 



The first four formations above described have been, with a single ex- 

 ception, generally recognized as belonging to the upper Cretaceous, while 

 the fifth or Shark River formation has been assigned to a later date, since 

 Conrad* first in 1848, and again more fully in 1865, maintained the Eocene 

 age of the deposits. More recently Whitfield f has claimed the identity 

 of several of the species with -forms found in the Eocene of the Gulf, 

 although they occur there at somewhat widely separated horizons; but 

 since all of the specimens thus referred are casts, he expresses some 

 doubt as to their identity. So far as the generic relations of the molluscan 

 types are concerned, most of them certainly have a more Eocene than 

 Cretaceous aspect, yet many could as well be referred to the one as the 

 other. With one or two exceptions, all have been found as early as the 

 Cretaceous in some portions of the world. There are, it is true, no dis- 

 tinctively Cretaceous types, while the genus Aturia and one or two verte- 

 brate types are not known earlier than the Eocene, yet it has been hitherto 

 impossible to satisfactorily correlate the Shark River formation with any 

 known Eocene deposits. It is, of course, readily conceivable that deposi- 

 tion went on in the moderately deep waters which prevailed in this region 

 continuously during late Cretaceous and early Eocene time, but else- 

 where upon the Atlantic and Gulf coasts a marked stratigraphic break 

 occurs at or near the close of the Cretaceous, and sediments of a different 

 type characterize the oldest of the known Eocene strata. 



Some light may perhaps be thrown upon the subject by indicating the 

 equivalents of some of the other Coastal Plain formations where the 



* Jour. Acad. Nat. Sci. Philadelphia, U. S., vol. i, 1848, p. 129. Proc. Acad. Nat. Sci. Philadelphia, 

 1865, pp. 71, 72. 

 f Monograph U. S. Geol. Survey, vol. ix, 1884. Ibid., vol. xxi, 1890. 



