RAMSAY— ON GLACIERS IN WALES. 



531 



question was, however, raised in this imprinted matter which I do 

 not yet remember to have seen in any published paper, and I now 

 mention it because of late the attention of many persons have been 

 more and more drawn to the discussion of the subject. 



The opinion I then held was that cold great enough to have pro- 

 duced the first and larger set of glaciers in our own neighbouring 

 counties might have arisen from an elevation of land equal to, or 

 greater than, the amount of depression that it underwent during the 

 middle portion of the glacial period. I then stated " that I hold it 

 as a sound doctrine in Geology that any amount of depression that 

 any part of the earth's crust may have undergone, may have been 

 equalled there or elsewhere by an opposite movement, giving an 

 equivalent amount of deviation. Bearing this in mind, it seems 

 within the limit of fair speculation to suppose a possible upheaval, 

 equal to, or exceeding the above-mentioned known amount of de- 

 pression (2,300 feet*) — an elevation probably sufficient to have pro- 

 duced a degree of cold, taken in connection with other conditions, 

 equal to the production of glaciers on the first and greater scale. 

 This land (Wales) would then consist of a lofty central cluster of 

 mountains, with numerous valleys, down which the larger glaciers 

 flowed, debouching upon an elevated plateau of land, part of which 

 now forms Anglesea and the sea-boards of Carnaervonshire. A 

 further extension of this flat, dotted by other clusters of mountains, 

 now forming the high grounds of Britain and Ireland, would spread 

 as far as the 100 fathom line indicated by Sir Henry De La Beche 

 in his ' Theoretical Researches,' including the German Ocean, the 

 the Irish Sea, and a wide tract of the Atlantic stretching northward 

 along the coast of Norway." 



In 1846 the late Professor E. Forbes published his celebrated 

 memoir " On the Distribution of the Fauna and Flora of the British 

 Islands," in which, in consequence of a partial ideality in the littoral 

 fauna of the North of Europe and of North America, he inferred a 

 former direct union of these continents across the area now occupied 

 by the North Atlantic. Generalizing on this idea, I conceived it 

 probable that this northern continent might have stretched so far 

 south " that the mean annual Isothermal line, and the January 

 Isothermal line, that in Central Asia and in North America run nearly 

 east and west in latitudes about 55 degs. and 38 clegs., would be 

 continued in the same direction across the continent instead of curv- 

 ing northwards, as they now do, under the influence of the Gulf 

 Stream. The mean annual Isothermal line of 32 degs. Fahr. would 

 then pass across the south of Scotland, and the January line near 

 the south of Spain. Across the Altai Mountains, in Central Asia, at 

 points between these lines in latitudes 49 degs. to 51 degs. north, 

 the snow-line is 7,034 feet above the sea, and in those mountains 

 (from 9,000 to 10,000 feet high) at the Colonne de Katoune, there 



* Mentioned in a previous part of the Memoir, and printed in the Society's 

 Journal. 



