526 PREHISTORIC E UROPE. 



The submergence, which in Central Scotland attained some 

 50 feet, appears to have been somewhat less in Ireland and 

 England, and on the opposite shores of the Continent. I am not 

 aware that the shells and other marine exuviae which occur in 

 the raised-beaches of Ireland and England afford any indubitable 

 evidence of colder seas than now lave our shores. In the Scot- 

 tish raised-beaches we have remains of the large Greenland 

 whale, but the shells belong to species all of which are still 

 living in the adjacent seas. The larger size attained by some 

 of these shells, and the greater abundance of certain species, 

 such as Scrobicularia piperata, would even seem to afford testi- 

 mony to a formerly higher temperature, but such shells may be 

 looked upon as survivors from the previous mild and genial 

 period — they come into the same category as the Mediterranean 

 species, which are still dredged in our seas. The cold was not 

 such, in fact, as to affect the marine fauna to any considerable 

 decree. But that the sea was somewhat colder seems to be 

 indicated by the fact that the Greenland whale and the walrus 

 ranged as far south as the coast of Lincolnshire. The change of 

 climate, however, is more strikingly evinced by the re-appear- 

 ance in Scotland of local glaciers, torrential streams, and rivers 

 laden with glacial mud. That Scotland was alone in this respect 

 can hardly be believed : if considerable glaciers occupied the 

 mountain-valleys of the Highlands and Galloway, the Cumber- 

 land district and "Wales could hardly have escaped having their 

 perennial snow-fields and glaciers, and I should expect evidence 

 of the same in the Irish mountains. I think it is highly prob- 

 able, therefore, that the small moraines which occur at the heads 

 of many of the upper valleys in those regions ought to be 

 assigned to the same stage of the postglacial period as the 

 simdar relics in Scotland. The perfect state of preservation of 

 these moraines, and the extreme freshness of the associated 

 glacial markings, have always been difficult to reconcde with 

 the belief that these date back to so remote a period as the 

 close of the Glacial Period. But if they really belong, as I 

 have endeavoured to show, to postglacial times, this difficulty 



