SURFACE FORMATIONS OF SOUTHERN NEW JERSEY. 483 



The followini:: i)ai)er was then read : 



SUIiFA CE FOEMA TlOyS OF SO UTIIERN NE \V JERSE Y 

 I5Y KOLLIN I). SALISBUllY 



Contents 



Page 



Beacon Hill formation 48:J 



Distribution, altitiuie aiul ilefoniiation 483 



Composition 484 



Thickness and extension 484 



Age of the formation 485 



Orogenic and erosive changes 485 



Pensauken formation 485 



Distribution 485 



Composition 485 



Development and thickness 48G 



Oroirenic and erosive changes 486 



Jamesburg formation 486 



Origin and composition 4SG 



Topographic features and their history 487 



Relation to the Trenton gravel 487 



The coastal terrace 487 



Conclusions 487 



Beacon Hill Formation 



DISTRIBVTIOX, ALTITCDE ASD DEFOKMATIOS 



The iX)st-Ci'etaceoiis surface materials south of the Triassic belt of New Jersej' 

 are believed to be divisible into several distinct formations. The oldest of these 

 several formations caps the series of more or less elevated and isolated hills which 

 crosses the state from the northeast to the southwest alonji: the strike of the Cre- 

 taceous beds and which includes the Xavesink hi«,dilaiid,s, the INIount Pleasant hills, 

 the hills in the vicinity of Perrineville, Mechanicsville and Ellisdale and the iso- 

 lated elevations known as Arneys mount, mount Holly, mount Laurel and the 

 ridge near .Tuliustown. These hills are of very unequal altitude. In the Nave- 

 sink highlands the base of the oldest member of the " yellow gravel " series 

 has a minimum elevation of less than 200 feet. In the Mount Pleasant hills its 

 elevation is something like 3G0 feet; in the Perrineville hills (Pine hill) it is about 

 270 feet; near Ellisdale about 210 feet; in mount Holly about 150 feet. These 

 figures show that the base of the formation rises along the strike of the Cretaceous 

 beds from the Xavesink highlands to the Mount Pleasant hills, and that it declines 

 thence to the southwest. On the Delaware, near the mouth of Pensauken creek, 

 its ba.H; has less than half the elevation it possesses in mount Holly. In all the 

 hills mentioned the formation under description rests on the Middle marl. 



North of this series of isolated remnants of the oldest member of the " yellow 

 gravel" series, the formation is known with certainty in but two places, and these 

 are near each other. Roth lie to the north of Monmouth Junction. One is the 

 Sand hills two or three miles north of the station, an«l the other is a small area four 

 or five mile.'^ farther northwe.>^t and about two miles northeast of Rocky hill. In 

 the Sand hills the l)a.se of the formation has an elevation of alxjut 200 feet and rests 

 on the Karitan clav. 



