244 MAN AND THE GLACIAL PERIOD. 



least trace of cementation to the masses. The various ele- 

 ments are rather confusedly arranged ; the large boulders 

 not being grouped on any particular level, and their major 

 axes not always distinctly coinciding with the horizon. 

 All the pebbles and boulders, so far as observed, are smooth 

 and water-worn, a careful search having failed to show 

 evidence of distinct glacial scratching or polishing on 

 their surfaces. The type of pebble is the subovate or dis- 

 coidal, and though many depart from this form, yet nearly 

 all observed by me had been worn so as to show that their 

 shape had been determined by running water. The mate- 

 rials comprising the deposit are very varied, but all I ob- 

 served could apparently with reason be supposed to have 

 come from the extensive valley of the river near which 

 they lie, except perhaps the fragments of some rather rare 

 hypogene rocks." 



A conclusive proof of the relation of this Trenton 

 delta terrace to the Glacial period is found in the fact that 

 the gravel deposit is continuous with terraces extending 

 up the trough of the valley of the Delaware to the glaciated 



Pig. 64.— Palaeolith found by Abbott in New Jersey, slightly reduced. 



area and beyond. As, however, the descent of the river- 

 bed is rapid (about four feet to the mile) from the glacial 



