the Middle Atlantic Slope. 453 



designated " Glassboro Gravel "), which he referred to the 

 Pliocene.* The next year he concluded more specifically (1) 

 that the Yellow Gravel of 'New Jersey " is an ancient deposit 

 of aqueous origin, made at a time of submergence in pre-glacial 

 times ";f (2) that the Red Gravel was deposited by "an ancient 

 flood of the [Delaware] river of great volume, at a time when 

 it rose 100 or more feet higher than at present," while the bowl- 

 ders, the absence of life traces, and the altitude of the deposit 

 " point to the melting of a great glacier as the origin of the 

 flood ;" and (3) that the brick clay with its contained bowlders 

 represents the closing episode of the same submergence when 

 quiet conditions prevailed ; — low temperature being again in- 

 ferred from the absence of fossils and the presence of ice-borne 

 bowlders.:}: Still more recently the same author pointed out 

 that the Brick Clay and Red Gravel rise to the northward in 

 the Delaware and Lehigh valleys, maintaining a height of 180 

 to 200 feet above the rivers ;§ and, assigning the Yellow Gravel 

 to the newer Pliocene, supposed it to have furnished most of 

 the pebbles of the Red Gravel. | 



In northern Delaware the Philadelphia Brick Clay and Red 

 Gravel of Lewis were found by Chester to merge southward, 

 and he combined them under the name " Delaware Gravels,"!" 

 and inferred that they represent an epoch of land-submergence 

 and melting glaciers Subsequently he described the gravels, 

 sands, clays, etc., of the same formation in southern Delaware, 

 identified them with those mentioned by Booth, noted the 

 occurrence of recent marine shells within them, designated the 

 deposit " Estuary Sands,"** and demonstrated from stratigraphic 

 continuity, from petrography, and from paleontology, that it is 

 simply the peripheral extension of that which toward its center 

 is divisible into Brick Clay and Red Gravel. 



Merrill has recently described and correlated the formation 

 as found in peninsular New Jersey and on Long Island. He 

 regards the New Jersey deposit as post Pliocene (since it over- 

 lies unconformably "all the Mesozoic and known Tertiary 

 beds, and is immediately overlain in turn by the glacial drift 

 where it occurs south of the moraine"), f f and identifies it with 

 the stratified deposits of Gardiner's and Long Islands ; and on 

 Long Island he discriminates (1) the Till or Drift proper and 

 (2) the Gravel Drift — identifying the latter with the Yellow 

 Drift or Pre-glacial drift of southern New Jersey^ and noting 



* Proc. Acad. Nat. Sci. Philad., vol. xxxii, 1880, 296-7. 



\ ADtiquity and Origin of the Trenton Gravels, appended to " Primitive Indus- 

 try" by Abbott, 1881, 524. % Ibid., 525, 527. 

 § Journal Franklin Institute, xcv, 1883. 369. || Ibid., 371. 

 1[ This Journal, III, vol. xxvii, 1884, 190-2, 199. 

 ** This Journal, III, vol. xxix, 1885, 40. 

 ft Official Report Geol. Survey of N. J., 1886, 133. 

 X% Annals N. Y. Acad, of Sci., hi, 1886. 343. 



