138 CLAYS AND CLAY INDUSTRY. 



coarse gravel, chiefly quartz and chert, and the lower, a bed of 

 coarse quartz sand, with occasional small pebbles. Locally, the 

 sand is cemented into beds of sandstone. The lower member 

 also contains lenses of clay, which are frequently of considerable 

 economic importance. Whether these two members are a unit, 

 or are really two separate formations, has been an unsettled 

 question. Until recently they have, on the whole, been regarded 

 as but one formation, but the other alternative has not been lost 

 sight of. However, data now in the possession of the Survey, 

 the result of recent field work by Mr. Knapp, apparently indicate 

 that there is good ground for separating the two, and he proposes 

 the term Cohansey for the sand member, thus restricting the 

 term Beacon Hill to the upper gravel. 



It has been impossible to fix definitely the age of these beds, 

 No ! adequate stratigraphic ground for separating them from the 

 underlying Miocene beds has been found, but it is quite possible 

 that such a separation should be made, particularly since the 

 scanty paleontological data at hand favor slightly their reference 

 to the Pliocene, rather than the Miocene. The evidence, how- 

 ever, is not decisive, and the exact age of these formations must 

 remain doubtful. 



Fossils. — In the vicinity of Bridgeton numerous well-preserved 

 plant remains have been found in the Cohansey sandstone. Mr. 

 Hollick, who has studied these remains, makes the following 

 statement ■} "Probably about fifty species are represented in the 

 collections which have been made — all of them angiosperms, 

 many of them referable to living species, and some of them 

 identical with species now growing in the vicinity of Bridgeton, 

 such as Ilex opaea, Nyssa sylvaiica, etc. 



"A comparison between this fossil flora and the living flora 

 of eastern North America indicates a close identity between the 

 former and that now in existence at about the latitude of Vir- 

 ginia. In many of its elements it is unique and distinct from 

 that of any other American Tertiary horizon. The collections 

 of Eocene and Miocene plants which have been made in the 

 West contain different species, and those from Bridgeton are 



N. J. Geol. Surv., Report on Forests, 1899, pp. 197-198. 



