283 



It is however not merely the occurrence of these species and the 

 oceurrenee of Ilex, Tilia grandifolia, Yiscnm and Taxas, also not known from 

 our postglacial bogs, which prove in faet that the bog is inter glacial; 

 the situation of the bog above and below glacial deposits is a further proof 

 of its interglacial age, and lastlv the distribution of the species in the dif- 

 ferent lavers of the bog points in the same direction, or more correctly, it 

 is only by aceepting an interglacial age for the bog that \ve obtain a natural 

 and unforced explanation of the appearance of the species in the different 

 lavers of the bog. 



An ideal section in an interglacial bog (or other interglacial, plant-con- 

 taining deposit) would in faet have the following appearance: 



Uppermost: glacial beds (moraine or fluvio-glacial deposits). 



Lowermost: glacial beds (moraine or fluvio-glacial deposits). 



Of the plant-containing layers the uppermost and the lowermost with 

 the purély arctic flora are wanting, whilst the section otherwise — as can 

 be seen from the tables — satislies very well the requirements of the ideal 

 section : 



glacial bed, 6 meters. 



laver with arctic flora wanting, probably eroded away! 



Sphagnum peat, with a subarctic flora: Bctnla subalpina and nana and 



a few »warmer« species. 



Sphagnum peat with several »warm« species: I lex, Taxas, Tilia grandifolia. 

 freswater laver with subarctic birches and Populus tremula; the »warm« 



species, as also Picea, have not yet arrived. 



laver wit h arctic flora not reached, probably lying deeper. 



glacial bed, not reached. 



To illustrate these features more clearly, I have drawn up a list of the 

 species of trees and bushes found in the bog (see Table p. 159 and 284). and 

 arranged them in the ordcr in which they lirst appear in (have come to) 

 the bog. It appears clearly from this Table that the species occurring last 

 in the series of layers also disappear earliest, in other words, are only found 

 in the intermediate parts of the bog which correspond to the temperature 

 maximum of the interglacial period. 



The order in the Table agrees on the whole with the geographical distri- 

 bution of these plant species at the present time, in this way that those 

 named first in the Table go furthest to the north and have the most moderate 

 requirements as to temperature, whilst the species mentioned last in the 

 Table cease to appear at a greater distance from the Polar Circle and make 

 greater demands on the temperature than the first. Tilia grandifolia, Ilex and 

 Taxas, probably the most thermophile of these species, are only found in 

 the intermediate parts of the bog. 



