G. W. Btilman — Glacial Geology. 409 



connexion with this point some remarks of Sir Charles Lyell in 

 relation to existing conditions in Greenland should be borne in mind. 



" The perpetual snow," he writes, " usually begins at the height 

 of 2000 feet, below which level the land is for the most part free 

 from snow between June and August, and supports a vegetation of 

 several hundred species of flowering plants, which ripen their seeds 

 before winter. There are even some places where phenogamous 

 plants have been found at an elevation of 4500 feet, a fact which, 

 when we reflect on the immediate vicinity of so large and lofty 

 a region of continental ice in the same latitude, well deserves the 

 attention of the geologist, who should also bear in mind that while 

 the Danes are settled to the west in the ' outskirts,' there exists due 

 east of the most southern portion of this ice-covered continent, at 

 the distance of about 1200 miles, the home of the Laplanders with 

 their Eeindeer, Bears, Wolves, Seals, Walruses, and Cetacea. If, 

 therefore, there are geological grounds for suspecting that Scanda- 

 navia or Scotland or Wales was ever in the same glacial condition 

 as Greenland now is, we must not imagine that the contemporaneous 

 fauna and flora were everywhere poor and stunted, or that they may 

 not, especially at the distance of a few hundred miles in a southward 

 direction, have been very luxuriant." ^ 



Nor must we lose sight of the possibility that the land extended, 

 further south in glacial times than now ; or was even perhaps joined 

 to the continent. For it is still a moot point whether glacial Britain 

 was a cluster of low, ice-covered islands, or a highly elevated, 

 glaciated region surrounded and united to continental Europe by 

 a great plain inhabited by an abundant flora and fauna. 



We must further remember that the supposition that the ice-sheet 

 extended thus far south is founded on the hypothesis that the Till 

 was formed beneath the ice-sheet, and this view of its formation is 

 by no means certain or universally received. 



Prof. Boyd Dawkins, for example, points out that the evidence 

 from " causes now in operation " is against this view. For, as he 

 remarks, no similar deposit is found where glaciers or ice-sheets have 

 retreated ; whereas in Davis Strait an analogous formation is being 

 laid down by the water from the melting ice entering the sea. 



If this view of the formation of the Boulder-clay be adopted, the 

 ice-sheet may be supposed to have terminated much further to the 

 north, and the difficulty of supposing a part of the pre-glacial fauna 

 and flora to have found an asylum much lessened. 



The peculiar flora of the south-west of Ireland seems to me to 

 afford a hint that a portion, at least, of our plants and animals were 

 not entirely driven out of the country. For there are difficulties in 

 the way of the supposition that this peculiar flora — not now found 

 further north than Spain and Portugal — migrated there after the 

 glacial epoch ; and Prof. Forbes, in his essay on the fauna and flora 

 of the British Isles, inclines to the view that the migration took 

 place before. 



If this is true, these plants must have survived the Glacial epoch ; 

 and if these, why not many others of our plants and animals ? 

 1 Antiquity of Man, p. 278. 



