352 SKETCHES OF CUE ATI ON. 



archaeology and stepped upon the ground consecrated to 

 the researches of geology. 



The chief sources of our information respecting the earli- 

 est periods of human history are, 1st. The remains of man 

 himself, which have been found in caves or buried in de- 

 posits of gravel or peat. 2d. Human works, of which we 

 have the so-called Druidical remains of Great Britain and 

 other countries, known as dolmens or cromlechs — rude 

 megalithic monuments of unhewn stone, which we now 

 know to be ancient tombs. Other human works more 

 abundant and more universally distributed are implements 

 of war, of the chase, of industry, or of ornament. These 

 are found in gravel-beds along the valleys of rivers or at 

 their mouths ; in peat beds ; in caves, and among the re- 

 fuse piles contiguous to the camping or dwelling-places of 

 tribes which subsisted partly upon molluscs. These refuse 

 heaps are composed mostly of shells of recent species, bones 

 of domestic or wild animals suitable for food or service, 

 fragments of pottery, arrow-heads, fish-hooks, stone imple- 

 ments, ornaments, and the like. A vast supply of the rel- 

 ics of primeval man has been obtained from the pile-hab- 

 itations, or ancient dwellings constructed upon platforms 

 supported by piles driven in the water. The dredging of 

 the bottoms of these lakes has brought to light immense 

 quantities of the remains of pre-historic art and industry. 

 3d. The manner in which the relics of man are associated 

 with those of other animals enables us to extend to our 

 race many of the generalizations deduced in reference to 

 the earlier history of the existing fauna. Lastly, the na- 

 ture and magnitude of the geological changes which have 

 transpired during the existence of man throw some light 

 upon the antiquity of the race. 



As in the history of organic life in general, so in the ge- 

 ological history of man, we find him mounting; from lower 



