130 



EARLY MAN IN BRITAIN. 



[CHAP. vi. 



of the temperature after the forest-bed ceased to flourish. 

 In No. 3 of the accompanying section, Mr. Nathorst, 1 

 an eminent Swedish botanist, remarked in 1872 not only 

 that the plants of the forest-bed became very much 

 dwarfed in size, but that two new forms appear, now 

 only found in severe climates ; the polar willow (Salix 

 polaris), now living within the Arctic circle, and a moss 

 (Hypnum turgescens) common to the Arctic regions and 



FIG. 26. Physical Relations of Forest-bed. 



1. Upper chalk, with flints. 



2. Forest-bed, with stumps of trees and fossil mammalia. 



3. Fluvio-marine sands and clays, with beds of lignite. 



4. Boulder clay. 



5. Contorted drift. 



6. Sands and gravels. 



the summits of lofty mountains. The flu vio- marine sands 

 and clays imply also a change of level, by which the trees 

 of the forest were brought within the reach of the waves 

 of the sea. Above them is the boulder clay, No. 4, 

 containing large blocks of granite and other igneous 

 rocks, which have been transported by ice possibly from 

 Scandinavia. This stratum corresponds with the older 

 boulder clay of Messrs. Harmer and Searles Wood. 



1 Lyell, Antiquity of Man, 4th edit. p. 261. 



