RELICS OF MAN IN THE GLACIAL PERIOD. 245 



border down to tide-water, the terrace is not remarkably 

 high, being only about fifteen or twenty feet above the pres- 

 ent flood-plain. But it is continuous, and similar in com- 

 position with the great enlargement in the delta at Tren- 

 ton. Without doubt, therefore, the deposit represents the 

 overwash gravel of the Glacial period. 



Fortunately for science, Dr. 0. 0. Abbott, whose tastes 

 for archaeological investigations were early developed, had 

 his residence upon the border of this glacial delta terrace 

 at Trenton, and as early as 1875 began to find rough- 

 stone implements of a peculiar type in the talus of the bank 

 where the river was undermining the terrace. In turn- 

 ing his attention to the numerous fresh exposures of gravel 

 made by railroad and other excavations during the follow- 

 ing year, he found several of the implements in undisturbed 

 strata, some of which were sixteen feet below the surface. 

 Since that time he has continued to make discoveries at 

 various intervals. In 1888 he had found four hundred 

 implements of the palaeolithic type at Trenton, sixty of 

 which had been taken from recorded depths in the gravel, 

 two hundred and fifty from the tains at the bluff facing 



a 





b 











b 



a 



f'V--"- ' -'- '•'•'•' 



"' •■ v7 



^s?- ,• '■?-'-'. J.:.-'-.- 



f;> '7 V"V '"•'''• 





£&?.■ .' ■:.'- '- '• -•.". -• ;-■ 



|-:rT.:-: v. 



.-•:■ •• •'■•■■■ ••■-: ' 



'•'.--:■.-• 



■ •Zl- ■■■'■:■ - : - 



■■-■/ <. ? 



--.;:■■■ •■-.. : -. 



■ ... ■ - - : : 



Fig. 65.— Section across the Delaware Eiver at Trenton. New Jersey : a, a, 

 Philadelphia red gravel and brick clay (McGee's Columbia deposit) ; b. b, 

 Trenton gravel, in which the implements are found: c, present flood-plain of 

 the Delaware River (after Lewis). (From Abbott's Primitive Industry.) 



the river, and the remainder from the surface, or derived 

 from collectors who did not record the positions or circum- 

 stances under which they were found. 



The material from which the implements at Trenton 

 are made is argillite — that is, a clay slate which has been 

 so metamorphosed as to be susceptible of fracture, almost 

 like flint. It is, however, by no means capable of being 

 worked into such delicate forms as flint is. But as it is 



