248 EARLY MAN IN BRITAIN. [CHAP. vm. 



be remarked, are merely the outer signs or symbols of 

 three phases of culture, each of which was higher and 

 better than that which went before. The history of 

 Britain begins late in the Iron age. 



The Prehistoric period is separated from the Pleisto- 

 cene by a long interval, during which, not merely 

 great changes in the zoology of Britain took place, but 

 also corresponding changes in the geography. 



Geography of Britain in the Prehistoric Age. 



At the close of the Pleistocene age (Fig. 32), the 

 valleys which united Britain to North France, Germany, 

 and Scandinavia, as well as to Ireland, were gradually 

 depressed beneath the sea-level ; and the North Sea, 

 the British Channel, the Irish Sea, and the Western 

 Atlantic coast-line generally became very much as we 

 find them now (see Fig. 95). An examination, how- 

 ever, of the submerged forests and peat-bogs proves 

 that the downward movement had not ceased until a 

 late period in the Neolithic age. 



Submerged Forests. 



We can approach this interesting question most con- 

 veniently by examining the evidence as to the submarine 

 forest exposed between tide-marks on the coast of west 

 Somerset, admirably described by Sir Henry de la Beche 

 and by Mr. Godwin- Austen. 1 



It was shown by the latter to be rooted on "an 



1 Geological Report on Cornwall, Devon, and West Somerset. Quart. 

 Journ. Geol. Soc. Lond. 1865. 



