Geological Aspects of Evolution 101 
was warmer than at present. Evidence of the existence of man 
during the glacial period comes mainly from Europe, where frag- 
ments and skeletons of fossil man are associated with the bones 
of extinct animals and stone implements, which were covered 
by geological deposits. The first well-fashioned stone implements 
were shaped by chipping and belong to the Paleolithic culture. 
This culture was followed by the Neolithic in which stone imple- 
ments were polished. The Paleolithic culture of Europe is divided 
into the Lower Paleolithic consisting of the Pre-Chellean, 
Chellean, Acheulean and Mousterian, and the Upper Paleolithic 
consisting of the Aurignacian, Solutrean and Magdalenian epochs. 
The order or sequence of these cultural epochs has been estab- 
lished by finding the implements buried in strata one on top of 
another. Along the Somme River in France implements belong- 
ing to the Chellean, Acheulean and Mousterian stages of Lower 
Paleolithic culture occur below the recent loess which contains 
implements of Upper Paleolithic culture. At some localities the 
geologic horizon containing stone implements may also contain 
bones of extinct animals. As the vertical range of cultures and 
animals is fixed with reference to the glacial and interglacial 
Stages there has gradually developed a three-fold method of dat- 
ing the rarer finds of human remains, for human bones may be 
embedded in a geologic deposit of a known glacial stage, or these 
may be associated with the bones of animals which did not live 
beyond a certain glacial stage, or there may be present implements 
belonging to a culture limited to a known glacial stage. In Ger- 
many the Heidelberg jaw was found eighty feet below the surface 
and below the loess of two glacial periods. Stone implements 
are absent, but the sands of the Mauer containing the jaw have 
yielded a large fauna which has helped to fix the age of the jaw 
as not younger than the second interglacial period. Some writers 
have been criticized for attaching too much significance to a single 
jaw, but a half dozen jaws of Sinanthropus Pekinesis all show 
the same chinless feature. Besides the jaws and teeth, two good 
skulls and fragments of other bones of Sinanthropus were found 
embedded in travertine in a cave near Peking, China. In an ad- 
joining cave stone and bone implements and evidence of the use 
of fire were discovered along with jaw and skull fragments, but 
