igii. Rkid. — British Plants and the Glacial Period. 205 



To come nearer home, around Portsmouth itself we have 

 abundant evidence of this icy sea, for in the peninsula of 

 Selsey especially we find numerous large erratic blocks 

 floated by ice. Some of them have been identified as coming 

 from the Isle of Wight, others from Bognor and Cornwall, 

 and a number came from the Channel Islands. Thus even 

 the north coast of France had its shores fringed with ice. 



I have attempted to show on a map what the Channel 

 was like when Spithead was thus blocked with ice-floes. Is 

 it possible to believe that the plants of the south of England, 

 many of which can barely hold their own during a severe 

 winter nowadays, could have survived these arctic con- 

 ditions ? 



If the southern plants were completely swept away by the 

 cold, the question arises : How did they come back again 

 especially to islands like Ireland and the Isles of Scilly, and 

 how did they obtain their very singular present geogra- 

 phical distribution ? We are told that the matter is simple 

 enough, for Britain has often been connected with the 

 Continent, and the plants spread slowly overland. However, 

 before we adopt the view that for animals and plants to 

 spread to islands it is needful to have land-connection, you 

 should remember Krakatoa, and the rapidity with which the 

 exterminated flora has come back. Also I must point out 

 that there are peculiarities in the distribution of the different 

 elements that go to make up the existing British flora that 

 no land-connection will explain. Look at the recent dis- 

 tribution. One of the most striking peculiarities is the 

 Pyrenean element in our flora. It is practically confined to 

 two areas, the one in Cornwalhand the other in the West of 

 Ireland. Geologists nowadays will not agree to the recon- 

 struction of a lost Atlantis to account for this peculiar 

 distribution. 



Undoubtedly since the Glacial period our islands have 

 seen several oscillations of level. There has also been 

 widening and narrowing of straits and channels. England 

 has been connected with France near Dover, and also across 

 the North Sea with Holland and Denmark. But 20 or 25 

 metres seem to have been the approximate extent of the 

 rise in the south of England. I have searched in vain for 



