128 



roughest and rudest tools of flint, chert, or other hard 

 rock, and only distinguishable from naturally-formed 

 fragments by their determinate shapes, and the chip- 

 pings for that purpose to which they have been sub- 

 jected. Such primitive implements have been found 

 in the river-drifts, lake-silts, and cave-earths of Eng- 

 land, France, Belgium, and other European countries, 

 under conditions that imply great changes in the 

 physical arrangements of these countries, and, as ex- 

 tensive geological changes require long periods for 

 their accomplishment, a consequent high antiquity for 

 the contemporaneous tribes who fashioned and left 

 them. We have some idea of the time when iron 

 and bronze were respectively introduced into "Western 

 Europe ; we occasionally find a comminglement of 

 bronze and iron, or in other words, the age of bronze 

 overlapping the age of iron ; and we also here and 

 there discover the age of finely-formed stone tools 

 overlapping that of bronze ; but with regard to these 

 ruder implements we have no standard of comparison — 

 no idea of their epoch save what can be gathered from 

 the change of physical conditions since their entomb- 

 ment, or the character of the organic remains im- 

 bedded along with them. 



When we investigate the physical conditions, we 

 find lake-silts — clays, marls, peat-earths, etc. — often 

 of great thickness, and which, judging from the known 



