THE VEGETATION OF DENMARK. 387 



Now the terminal moraine of the glacier covers the whole of 

 this space with great blocks of stones, thousands and hundreds 

 of thousands in number, and yet, although all these have 

 probably been brought down in the human period, I could 

 only see a few blocks on the lower end of the glacier itself. 



As far as Denmark is concerned we must, for the present, 

 rely principally on the double change which has taken place 

 in the prevalent vegetation. Beech forests are now the pride 

 of the country, and, as far as tradition goes, they have always 

 been so. But, as is shown by the peat-bogs, this is a mistake. 

 The large peat-mosses do not help us very much in this 

 matter, but there are in many of the forests small and deep 

 impressions, filled with peat, and called skov-mose. These, 

 as might naturally be expected, contain many trees which 

 grew on their edges, and at length fell into them. At the 

 bottom is usually an amorphous peat, above is a layer of 

 pines a tree which does not grow naturally in Denmark. 

 Higher up the pines disappear, and are replaced by oaks and 

 white birches, neither of which are now common in Denmark ; 

 while the upper layer consists principally of the Betula verru- 

 cosa, and corresponds to the present, which we may call the 

 Beech period. Professor Steenstrup has found stone imple- 

 ments among the stems of the pines ; and as the capercailzie, 

 which feeds on the young shoots of the pine, has been found 

 in the Kjokkenmoddings, it seems likely, to say the least, that 

 these shell-mounds belong to the pine period, and that the 

 three great stages of civilization correspond in some measure 

 to these three periods of arborescent vegetation. For one 

 species of tree thus to displace another, and in its turn to be 

 supplanted by a third, would evidently require a great, though 

 at present we have no means of measuring how great, lapse of 

 time. 



Turning now from Denmark to Switzerland, there are two 

 cases in which a more definite estimate has been attempted. 



2 c 2 



