THE FOSSIL MAN. 351 



by the phrase " the fossil man " is intended in this article man as 

 the contemporary of certain species of animals now either totally or 

 locally extinct, which we know only from their bones, dug out of the 

 earth, but as to whose existence history and tradition are silent. Such 

 animal remains are found, mingled with those of species still living ; 

 but they occur under geological conditions which show that the for- 

 merly existing surface of the earth differed in certain respects from 

 its present state. This geological epoch, the nearest in point of time 

 to the present, is called the Quaternary period. It is characterized 

 by extensive deposits of rolled and water- worn pebbles, gravels, and 

 clays, underlying the cultivable surface-soil, and due to the action of 

 former extensive glaciers and of great and rapid currents of water. 

 These latter were produced by the melting of that sheet of snow and 

 ice which once covered large regions of the northern portions of Europe 

 and America, combined with a climate much more humid than the pres- 

 ent, and a consequent greater rainfall. This moister climate arose 

 from a different relative arrangement of the then existing continents 

 and seas. The general contour of the earth's surface, then, so far as 

 existing elevations are concerned, seems to have resembled very nearly 

 its present appearance ; thus these great currents in many instances 

 took the courses of the present river-systems in northern and central 

 Europe and North America. The Quaternary deposits, consequently, 

 have often been left in the neighborhood of existing streams, which 

 now seem like shrunken rivulets in comparison with these mighty riv- 

 ers of old. Through these deposits and the underlying strata the pres- 

 ent rivers have cut their channels, leaving the Quaternary gravel-beds 

 sometimes as high up as two hundred feet on the slopes of their valleys. 

 In some cases oscillations of level of the surface, or other causes, have 

 left such deposits where there are no longer existing rivers. They are, 

 however, all characterized by similar features, and are called by geolo- 

 gists indifferently Quaternary gravels or drift / while the beds com- 

 posed of the finer particles, often of great thickness and spread like a 

 carpet over extensive plateaus, are named loess or brick-earth. That 

 such beds of gravel or loess were not deposited by the sea is proved 

 by the fact that such animal remains as occur in them are all those of 

 land or fresh-water, and never those of marine, species. 



But it is not only in the Quaternary gravels and loess that the bones 

 of extinct animals are found ; they occur more frequently in numerous 

 caverns and fissures in the rocks. As these are met with most com- 

 monly in limestone formations, the bones are in consequence generally 

 imbedded in or covered by a stalagmitic formation, produced by the 

 percolation through the roof of water charged with carbonate of lime. 

 Such a floor of stalagmite, sometimes of great thickness, covering and 

 completely sealing up the contents of the underlying beds, is at once a 

 proof of their antiquity and a guarantee against the possibility of sueh 

 contents having become confused with objects of a later date. 



