1888 .] 
157 
[Abbott. 
of that period, if they are not to be classed according to Mr. McGee 
as belonging to an entirely distinct epoch. 
Dr. C. C. Abbott exhibited a water- worn pebble, showing unmis- 
takable evidence of artificial chipping, which he had taken from the 
bed of the Delaware river, near Trenton, N. J., where the stream 
flows over the most extensive deposit of the “Trenton gravel and 
called attention to the identical character of its surface with that of 
the associated pebbles. The specimen was found so far from the 
banks of the stream, that it was apparent it could not have been 
recently washed from them during a flooded condition of the river, 
nor even dropped by Indians into the water, as unquestionable relics 
of that class found in the river show but a slight water- worn condition . 
The archaeological interest of the specimen centred in the fact that 
like objects (palaeolithic implements) when found in the undisturbed 
gravel always exhibit an unworn and dull surface, due to atmos- 
pheric and chemical conditions operating upon them. Thus all ob- 
jects from the gravel, where oxide of manganese or of iron occurred, 
have been found to be coated alike ; thus showing that they had been 
exposed to the action of these salts for the same length of time. 
This uniformity of the condition of the surface of both the natural 
pebbles and chipped objects was held to be important evidence that 
the latter were of the same age. 
Dr. Abbott also exhibited a quartz implement found in place in 
the Trenton gravel, at a depth of eleven feet, which was of identi- 
cal pattern with some of those found by Miss Babbitt, at Little Falls, 
Minn. But four quartz implements have been collected from the 
Trenton gravel, and three of them are of this same pattern, which 
is one that does not occur, apparently, among the objects, of like 
age, made of argillite. 
The President said that the importance of Mr. Cresson’s dis- 
coveries, in the gravel and in the rock-shelter, could not be over- 
estimated. The two implements (figs. 1 and 2) which he had found 
in the gravel, as shown by Professor Wright in the views which he 
has exhibited to us this evening, were from gravel beds much 
older than the Trenton, and corresponding to the Columbia gravel 
of McGee. Should the great antiquity now given to these lower 
gravels remain unchallenged, it would place man in the Delaware 
valley at a time long before the deposition of the Trenton gravels. 
