1012 HISTORICAL GEOLOGY. 



chamber witliin. These high qualities of the " Calaveras " skull are part 

 of the objection which has been brought forward to its being of Pliocene 

 Tertiary age, and the Neolithic character of accompanying implements is 

 another part. 



Flint implements have been described by C. C. Abbott from stratified 

 drift, along Delaware Eiver, near Trenton, N.J. The dejDosits in which 

 they occur are probably of Champlain age. At Loveland and Madison- 

 ville, Ohio, C. L. Metz found chipped implements in deposits of loess and 

 stratified gravel. N. H. Winchell has rejDorted the discovery of imple- 

 ments of polished stone aud copper, with human bones, in terraced and 

 stratified deposits near Minneapolis. In the loess of the Missouri valley, 

 Neb., according to Aughey (1874), two chipped implements were found, 

 associated with the vertebra of an Elephant. McGee reports his discovery 

 of a chipped obsidian implement in the deposits about Lake Lahontan, 

 Nev. Hartman's Cave, near Stroudsburg in Monroe County, Penn., has 

 afforded T. D. Paret, and later H. C. Mercer, teeth of the Eeindeer, a tooth 

 of the American Bison, and remains of Dicotyles Pennsylvanicus, Gastoroides 

 Oliioensis, Horse, Lynx, Gray Fox, Wolf, Skunk, Beaver, Woodchuck, Musk- 

 rat, with a bone fish-hook, bone awls, harpoon, etc. There is apparently a 

 mixture in the cave of Pleistocene and Eecent. In Brazil, human remains 

 were found many years since, by Lund, in caverns, along with extinct Quater- 

 nary Mammals ; and Clausen has reported the occurrence of pottery in a 

 bed of stalagmite containing these Mammals. 



4. Recent Period. 



After the great alternations in level and in climate of the Early and 

 Middle Quaternary, the earth appears to have reached, as the Eecent period 

 opened, one of its stages of relative quiet. The excavation of valleys, the 

 distribution of earth and gravel over the rugged surface, and the filling of 

 valleys with drift and alluvium had prepared the way for Man, the domi- 

 nant species of the period. At the final stage in the preparation, the Brute 

 Mammals had become diminished in size, and greatly also in number of 

 species. 



But the geological agents of change are still at work — the air, rivers, 

 ocean, heat, chemical forces and interior causes of earth movements ; and 

 thereby rock-deposits are still in progress : metamorphism and vein-making 

 by quiet methods ; volcanoes with somewhat lessened activity ; and upward 

 and downward changes of level. Absolute equilibrium and rest will not be 

 attained until the earth no longer contracts from cooling and waters cease 

 to move and transport. 



In the organic kingdoms, interactions among species, and conflicts with 

 natural conditions, are producing variation in Eecent time as hitherto, but 

 with this prominent difference : that Man, on leaving the wilderness, and 

 taking full possession, became a powerful agent of modification and exter- 



