638 
The farm on which such generous privi- 
leges have been granted by the Misses Lalor 
is situated on the terrace upon which the 
city of Trenton is built, about a mile below 
the city, overlooking the Delaware river 
from the edge of the terrace, which here de- 
scends abruptly to the flood-plain of the 
Delaware, about forty feet below. That 
this farm is within the limits of the so- 
ealled ‘Trenton gravel’ is conceded by 
every one, and is clearly evident from a 
gravel pit which has been recently opened 
not more than three hundred yards to the 
north. In this pit, which has been worked 
to a depth of about twenty feet, the general 
sand and gravel are very distinctly strati- 
fied, with the lines of bedding and cross- 
bedding perfectly distinct up to within 
three or four feet of the surface. Many 
boulders, some of them two or three feet in - 
diameter, occur in the lower part of the de- 
posits. A large pile of boulders which had 
been thrown aside by the workmen well 
illustrates the observation early made by 
Professor Cook and Professor Shaler, that 
the material of the Trenton gravel is almost 
entirely derived from the upper part of the 
valley of the Delaware river, and is to that 
extent local material. 
There is but one theory entertained by 
geologists at the present time concerning 
this gravel, which is, that it is a delta de- 
posit made by the glacial floods which came 
down the river from the melting of the ice 
which formed the Belvidere terminal mo- 
raine, about seventy miles above Trenton. 
Through that distance the gradient of the 
river is about three and a-half feet to the 
mile, and the valley is narrow, so that the 
abundant floods of that time could easily 
bring down the excessive amount of débris 
released by the melting ice. On reaching 
tide-water and a broader valley at Trenton 
the swollen streams of that epoch rapidly 
built up the fifty-foot delta terrace upon 
which the city stands. This terrace is from 
SCIENCE. 
LN. S. Vox. VI. No. 148. 
two to three miles in diameter, upon the 
New Jersey side, and wherever excavated 
shows substantially the same phenomena 
described in the pit adjoining the Lalor 
farm, which is about the middle of the 
special enlargement of the deposit from 
north to south from which the gravel re- 
ceived its name. 
The excavations made by our party were 
upon the summit of this delta deposit, be- 
ginning from the bluff where it faces the 
river valley to the west, and which breaks 
down to the level of the flood-plain, forty 
feet below, with as steep a descent as the 
gravel would naturally maintain, the slope 
being now covered with a luxuriant growth 
of forest trees. 
AS our investigations were made with 
reference to verifying the conclusions of Mr. 
Ernest Volk, it is proper to state the main 
results of hiswork. Mr. Volk has carefully 
dug over the area stretching back from this 
bluff for a width of about three hundred 
feet and a length of something like twenty- 
five hundred feet. Over all this area he has 
sunk trenches a little over three feet in 
depth, and carefully noted the evidences of 
human occupation, together with the char- 
acter of the deposit and the depth at which 
the artificial objects have occurred. All 
this material gathered by him is to be found 
carefully labelled, but for the most part un- 
reported upon, in the museums above re- 
ferred to in our first paragraph. Mr. Volk’s 
work has shown that the upper twelve 
inches of this surface contains more or less 
signs of vegetable mould, and a very large 
number of chips and chipped implements 
made from flint and jasper, with occasional 
chipped pieces of argillite. Many other 
indications of the ordinary occupation by 
Indians also occur in this upper foot of soil; 
such as pieces of pottery, the bones of 
animals which had been used for food, and 
pieces of charcoal. Occasionally, also, 
there are pits running to a depth of two or 
