CRETACEOUS AND TERTIARY FORMATIONS. 15 



At Atlantic City clays, sands and marls from 390 to 1,225 feet 

 below tide carry Miocene fossils, and at Wildwood those from 

 300 feet to 1,090 feet and perhaps to 1,244 are Miocene. From 

 the fossils it is evident that strata referable to the St. Marys, 

 Choptank and Calvert horizons of the Chesapeake group are 

 present. 



Cohansey sand. — Overlying the Kirkwood at its outcrop is a 

 formation composed chiefly of quartz sand, locally with laminae 

 and lenses of light-colored clay and occasional lenses of gravel. 

 This formation outcrops over a wider area of the coastal plain 

 than any of those heretofore discussed. Obscure casts of 

 molluscan shells have been found in it, but these are of no value 

 in determining its age. Plant remains from near Bridgeton 

 indicate a flora comparable with that of certain European upper 

 Miocene localities. It dips southeastward 9 or 10 feet per mile, 

 and overlies the Kirkwood with seeming unconformity. 



Inasmuch as sands and clays similar to the Cohansey are re- 

 vealed in borings along the coast and there overlie clays carrying 

 Miocene fossils characteristic of the St. Marys, the highest divi- 

 sion of the Chesapeake group, the Cohansey apparently belongs 

 to a still later stage of the Miocene or perhaps even to the Plio- 

 cene. It is possible, however, that as now defined it may repre- 

 sent in part at least the' shoreward phases of the fossiliferous 

 Miocene clays found in the borings along the coast, and that it 

 should be correlated with the Choptank and St. Marys of 

 Maryland. In the light of all data at present available, how- 

 ever, the former view seems most probably the true one. 



PLIOCENE SYSTEM. 



Beacon Hill formation. — Under the term Beacon Hill there 

 were described certain beds of gravel and sand occurring as 

 outliers on the higher hills of Monmouth County. Later the 

 sand beds were correlated with the great body of sand now in- 

 cluded in the Cohansey formation, leaving only the gravel in 

 the Beacon Hill formation. It is chiefly quartz, but contains 

 much chert and some hard sandstone and quartzite. The chert 

 pebbles are uniformly much decayed and are frequently very 



