538 THE THEORY OF EVOLUTION 



On the European continent, man came upon the scene during the 

 Pleistocene, one of the most dramatic periods in the geologic his- 

 tory of the northern hemisphere. Great glaciers slowly spread 

 southward in Europe, as they did in America, covering a large part 

 of the continent, not once but four separate times, during a period 

 variously estimated as lasting from 500,000 to 1,500,000 years. 

 At times during the inter-glacial periods the European cHmate was 

 even more equable than now. There were extensive forests, and 

 gigantic mammahan types, like the mastodon and mammoth, the 

 woolly rhinoceros, and the saber-toothed tiger, still walked the 

 earth. Man entered Europe as a puny competitor of this mighty 

 fauna, but spread and flourished, if one may judge from the flint 

 implemcits and the occasional skeletal remains that enable us to 

 picture the lives of these early human beings. Before the dawn 

 of the historic period, other races, from which descended the 

 modern Europeans, had entered and displaced the earlier ones. 



Note. — More recent discoveries of human artifacts confirm the previous 

 evidence for the existence of man upon the North American continent during 

 the Pleistocene or Glacial Epoch. Near Folsom, New Mexico, two arrow 

 heads were found (1925) by a field party collecting for the Colorado Museum 

 of Natural History. Both of these artifacts were associated with skeletons 

 of an extinct species of bison and in one instance the arrow or spear point was 

 beside a rib in such a position that the animal must have died with the point 

 embedded in its flesh. In this deposit the bison seem to have died at the edge 

 of a lake or stream. The bones and matrix in which they are embedded 

 show the marks of trampUng by other bison, as though their possessors had 

 died at some drinking place and later been stamped deep into the soft mud, 

 which now appears as a tough clay silt cemented by lime. The age of these 

 deposits has been tentatively placed by H. J. Cook of the Colorado Museum 

 in the late Pleistocene or Glacial Epoch. Even more important finds have 

 been recently brought to the attention of scientists (1926) in a gravel pit near 

 Frederick, Okla., through the interest of Dr. F. G. Priestly, a local physician, 

 and the owner of the pit, Mr. A. H. Holloman. In this instance the artifacts, 

 which include flat grinding stones or metates and pestles, as well as arrow- 

 heads, were embedded in old river gravels at two distinct levels. The asso- 

 ciated fossils include scattered bones of extinct animals, like the mammoth, 

 Elephas columbi, and at the lower levels the more primitive mammoth, Trilo- 

 phodon; the giant ground sloths. Megatherium, Mylodon, and Glyptodon; 

 and three species of horses of the genus Equtis. These deposits, which have 

 also been studied by the Colorado Museum, are regarded as early Pleistocene, 

 because of their contained fossils and because they were laid down so long ago 

 that erosion by the present drainage svstem of the Red River has since cut to a 

 level more than 250 feet below the Holloman gravel deposits. Whatever may 

 be the final verdict of geologists upon the age of these deposits, they place the 

 existence of implement-making beings far earlier than any of the known skele- 

 tal remains or artifacts of the American Indians. The discovery of skeletal 

 remains of these early North Americans would be of great interest for com- 

 parison with those of the early human races found in Europe and Asia. 



