124- T J le American Geologist. K.'i.niary, 1893 
able l\)r milking- (iiseoveries, iuid hence lii.s own prMininencc in the 
whole matter. 
It is important, liowever, to note that before taking up witli Dr. 
Abbott's work, professor Putnam took ample pains to satisfy himself 
of its character and correctness. In 1M7S Prof J. 1). Whitney visited 
Trenton in company witli ]Mr. (Jarr, assistant curator of the museum. 
In the twelfth annual report Mr. Carr writes: " We were fortunate 
enough to find several of these im|)lements in i)lace. Prof. Whitney 
has no doubt as to the antitjuity of the drift, and we are both in full 
accord witli Dr. Abbott as to the artificial character of many of these 
implements." In reporting further upon this instance at the meeting 
of the Boston Society of Natural History, on January 19, 1881, Mr. 
Carr states that tiie circumstances were sucli that " it [/. v., one of the 
particular implements] must have been deposited at the time the 
containing bed was laid down." In 1879, and again in 1880 ]n-ofessor 
Putnam spent some time at Trenton, and succeeded in finding with 
his own hands "five unquestionable paheolithic implements from the 
gravel, at various depths and at diflferent points." One of these was 
four feet below the surface soil and one foot in from the perpendicu- 
lar face which had just been exposed, and where it was clear tiiat the 
gravel had not been disturbed. A second one was eight feet lielow 
the surface. ( Proc. Boston, 80c. of Nat. Hist, for Jan. 19, 1881.) 
Up to 1881 Dr. Abbott had reported sixty implements of pahcolithic 
type from recorded depths in the gravel. In several instances the 
implements were found in railroad excavations far back from the 
river front, at a de])th of from ten to sixteen feet from the surface, 
wliere there could have been no " creep " of the strata, and where it 
is impossible to believe thattliere could have been previously any ex- 
cavations. 
As confirming the entire trustworthiness of Dr. Abbott's observa- 
tions, it is to be noted tliat, with a single exception, all the imple- 
ments reported below the loam which constitutes the surface soil, are 
of argillite, while those upon the surface, which are innumerable, are 
cliieMy of a different type, made from flint and jasper, or of other 
material of relative character. Another fact, which has always had 
great weiglit in my own mind, is one mentioned by the late professor 
Carvill Lewis, in his chapter upon the subject at the end of Dr. Ab- 
bott's volume on "Primitive Industry." I have tlie more reason to 
feel the force of his conclusions, because the proof-sheets passed 
through Lewis' hands at the time we were together conducting the 
survey in Pennsylvania, soon after we had visited the deposits in ques- 
tion. The fact was this: professor Linvis liad been at work for a con- 
siderable time in classifying and mapping the gravels in the Delaware 
valley, being all the time in ignorance of Dr. Abbott's work until his 
own results were definitely fornuilated. Put after he liad accurately 
determined the boundary between the glacial gravels and the far 
older gravels which surround them and spread over a considerable 
portion of the territory beyond, he found that the localities where 
