TRANSACTIONS OF SECTION K. 575 



limit stretched to South Wales, where tongues of ice reached the Bristol 

 Channel in big glaciers like those of the Antarctic Regions or Greenland. In 

 South Wales a few hills may have escaped, though surrounded by ice. 



The glaciation in Ireland was even more extreme, for apparently no part of 

 Ireland escaped. Even the wannest parts of the south-west are striated and 

 covered by morainic material, the ice extending well out into the Atlantic. The 

 icebergs were so big, or the ice-foot so thick, that, breaking away from the 

 Irish coast, the masses were able to float across to the Scilly Isles before they 

 melted ; for they carried with them numerous striated stones of well-known 

 rocks, now found stranded on the highest parts of the Isles of Scilly. Thus it 

 is evident that in those days Scilly, our most southerly and warmest point, was 

 surrounded by a bitterly cold ocean, and it was submerged to such an extent 

 that it could be overridden by pack-ice. Could any temperate plant survive 

 such treatment? I particularly want you to realise the climate that Scilly en- 

 joyed in those days, for it is now one of the warmest spots in our islands, and 

 its temperate flora has come back, though the islands are surrounded by fairly 

 deep sea. 



It seems evident, therefore, that a temperate flora could not have survived 

 the cold in Ireland or in the Scilly Isles. But there is still the non-glaciated 

 area south of the Severn and Thames to consider, and botanists may tell us that 

 the temperate flora survived in some warm nooks in Devon or the Isle of Wight. 

 Here, however, we can point to evidence that the botanist himself must accept 

 us conclusive. 



In the south of Devon one of the warmest of the sheltered valleys is that 

 through which the Teign flows to Newton Abbot. But in the alluvial de- 

 posits of this valley, and only a few feet above the sea-level, Professor Oswald 

 Heer and Professor Nathorst discovered leaves of the dwarf Arctic birch and 

 some Arctic mosses. 



Time will not allow us to go into all the evidence; so I will only point to 

 one or two other areas which prove the extreme rigour of the climate in the 

 South of England. Close to Salisbury are found in profusion remains of various 

 Arctic mammals — reindeer, musk-ox, Arctic fox, lemming, and several others. 

 Unfortunately plants do not seem to have been searched for, and the sections 

 were obscured when I visited the pit; however, the flora associated with this 

 assemblage of mammals can only have been the flora of the Arctic regions. 



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 Spit- 

 head 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 conditions ? 



If the southern plants were completely swept away by the cold, the ques- 

 tion 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 

 geographical 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 distribution. One of the 

 most striking peculiarities is the Pyrenean element in our flora. It is practi- 

 cally confined to two areas, the one in Cornwall and the other in the West of 

 Ireland. Geologists nowadays will not agree to the reconstruction of a lost 

 Atlantis to account for this peculiar distribution. 



Undoubtedly since the Glacial Period our islands haye seen several oscilla- 

 tions of level. There has also been widening and narrowing of straits and 

 channels. England has been connected with France near Dover, and also across 



