276 
THE ANTIQUITY OF MAN 
of the brain are most sharply preserved. The main 
fissure of the brain — the fissure of Sylvius — is clearly 
represented, and the size and shape of the important 
convolutions which surround the hinder end of the fissure 
can be studied as clearly as on the brain itself. In size 
and shape the convolutions do not differ from those of 
the brain of modern man. The cranial fragment is clearly 
part of a parietal bone, which in size and shape agrees 
with the corresponding bone in a well-developed cranium 
of an American Indian. The thigh bone is flattened 
from back to front in its upper third — a feature seen in 
American Indians, and also many modern and ancient 
primitive races (fig. 92). No one can study the Trenton 
fraffments and remain unconvinced that the man who 
Fig. 92. — Section across the upper third of Trenton femur (B) compared with 
corresponding sections of a modern European femur (A) and that of a 
Neolithic European (C). 
lived in the valley of the Delaware when the Trenton 
gravels were being deposited was a man of the modern 
type, and almost certainly of the Indian race. In size of 
brain and in posture of body he did not diff^er from the 
men who succeeded him in post-glacial times. 
The antiquity of modern man in the Delaware valley 
thus turns on the age of the Trenton gravels. They are 
admitted by all geologists to belong to the glacial period ; 
but to what point of the glacial period ?^ Dr G. Frederick 
Wright regards the gravels as deposits of the milder 
interval which preceded the last extension southwards of 
the ice sheet — the extension to which American geologists 
give the name of " Wisconsin," because the efi^ects or 
deposits of that, the final glaciation, are particularly 
evident in the State of Wisconsin. Dr Wright is of 
opinion that a period of twelve thousand or even 
