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THE POPULAR SCIENCE MONTHLY 



question to that as to species. It is not necessarily each time a 

 different people, but sometimes the same, at first using a more simple 

 and then a more complex implement. All mankind have not pro- 

 gressed equally. Some are in the Stone age now. There have been 

 arrests in development, and a comparison of the points which the 

 different races have reached will show the differences in standing 

 between them. In Europe, Lyell has given a very complete account 

 of the different kinds of implements found in one locality, the valley 

 of the Somme. In the peat-bogs on either side of the river are found 

 Roman weapons, belonging to the age of metals. In the gravel and 

 clay-beds below, polished and rough stone implements are found. In 

 North America the iron tools are wanting. The Indian was in the 

 Stone age at the advent of Europeans. The Mound-builders had used 

 copper, but the process of smelting and the use of iron had not been 

 reached by them. 1 



QU ATERNARY. 



AGE OF MAN. 



Autocene. 



Holocene. 



Pleistocene. 



Ice-Period. 



Alluvium. Peat-beds. 



Age of Metals. Neolithic implements. 

 Mastodon. 



Gravel-beds. Unstratified drift. 



Paleolithic implements. Paleolithic implements. 

 Horse. Reindeer. 



In the accompanying diagram, while I have indicated the geologi- 

 cal succession of the implements of man, you must bear in mind 

 that, since stone implements are yet used in some parts of the world, 

 they are there found in surface or alluvial deposits. But for our race 

 the Stone age has passed, and, to find in Europe the implements our 

 forefathers used, we must go in most cases into lower than surface- 

 beds. And Dr. Abbott has drawn attention to the fact that there 

 is a great similarity between the North American and European 

 rough-stone implements. This does not indicate so much identity of 



1 The difficulty of supposing man to have been originally introduced into North 

 America during the Quaternary lies in the fact that he was most probably in the Paleo- 

 lithic age when the migration was made. This difficulty vanishes, if, as I suppose, man 

 entered upon possession of this continent during the Pliocene, before the Ice period had 

 interfered with a passage from the north by land. This will leave us free to consider 

 the American civilizations indigenous. 



