Abbott.] 
130 
[January 19 , 
remains for me only to briefly call attention to one or two points 
that may not be touched upon by those who will further discuss 
the significance of these chipped implements. 
In the spring of 1877, Mr. Henry C. Lewis was detailed by the 
State Geologist of Pennsylvania to critically examine and map 
out the various gravels in the neighborhood of Philadelphia, Pa. 
The result of his studies showed that these several gravel beds 
were to be referred to different geological eras, as the Bryn Mawr 
gravel (Upper Tertiary), Glassboro gravel (Pliocene), Phila- 
delphia brick clay (containing boulders), the Trenton gravel, and 
the recent Alluvium ; the oldest being that first named, and 
coming down to the present in the order named ; and further 
showed that the “yellow gravel” (a marine gravel), which forms 
the boundaries of the newer Trenton gravels, was high and dry 
during the deposition of the circumscribed Trenton gravel, which 
is purely river drift , derived from the terminal moraine lying in 
the upper valley of the Delaware, and extending across the State. 
This most important discovery has an important bearing on the 
age of the palaeolithic implements, in that, he shows, that there 
was an extensive area of habitable land from Trenton southward 
during the close of the glacial period ; and which Professor Cook, 
the State geologist of New Jersey, has asserted in his latest reports, 
to have been submerged during this same period; — thus demon- 
strating that a habitable country enclosed or bordered the latest 
in time , or Trenton gravels , during the time that they were accu- 
mulating — and further showing, beyond question, that if any- 
where^ relics of man are to be found, other than on the surface, it 
would be in this Trenton gravel. Furthermore, Mr. Lewis care- 
fully mapped this gravel, and practically completed his labors 
before he was aware of my discoveries. 
Then, on comparing his results with my own, he found that 
the implements I had collected, in situ , were gathered only from 
those localities where this Trenton, or newest gravel, occurs. 
Thus, he, from a geological standpoint, working upward, to the 
present ; and I, pushing my researches backward, from the his- 
torical point, met upon common ground, and each in total igno- 
rance of the other’s labors, until our respective studies brought us 
face to face. 
