172 Miscellaneu us. 



Australia has already brought us, we may expect to find that the 

 animal world of the southern hemisphere has a more antique cha- 

 racter — in the same way as North America may be contrasted with 

 Europe, on the ground of the occurrence in the United States of 

 animals and plants now living here, the types of which are only 

 found fossil in Europe. 



A few more words upon another subject. During the first three 

 decades of this century, the scientific world believed that the erratic 

 boulders which form so prominent a feature of the surface geology 

 of Europe had been transported by currents arising from the rupture 

 of the barriers of great lakes among the Alps, or started from the 

 north by earthquake- waves. 



Shepherds first started the idea that within the valleys of Switer- 

 land these huge boulders had been carried forward by glaciers ; and 

 Swiss geologists (Veuetz and Charpentier foremost among them) very 

 soon proved that this had been the case. This view, however, re- 

 mained confined to the vicinity of the Alps in its application, until 

 1 suggested that the phenomenon might have a cosmic importance, 

 which was proved when I discovered, in 1840, unmistakable traces 

 of glaciers in Scotland, England, and Ireland, in regions which could 

 have had no connexion whatever with the elevation of the Alps. 

 Since that time the glacial period has been considered by geologists 

 a fixed fact, whatever may have been the discrepancies among 

 them as to the extent of these continental masses of ice, their origin, 

 and their mode of action. 



There is, however, one kind of evidence wanting to remove every 

 possible doubt that the greater extension of glaciers in former ages 

 was connected with cosmic changes in the physical condition of our 

 globe. All the phenomena related to the glacial period must be found 

 in the southern hemisphere with the same characteristic features 

 as in the north, with this essential difierence, that every thing must 

 be reversed : that is, the trend of the glacial abrasion must be from 

 the south northward ; the lee side of abraded rocks must be on the 

 north side of hills and mountain-ranges, and the boulders must have 

 been derived from rocky exposures lying to the south of their present 

 position. Whether this is so or not has not yet been ascertained by 

 direct observation. I expect to find it so throughout the temperate 

 and cold zones of the southern hemisphere, with the sole exception 

 of the present glaciers of Tierra del Euego and Patagonia, which 

 may have transported boulders in every direction. Even in Europe, 

 geologists have not yet sufficiently discriminated between local 

 glaciers and the phenomena connected with their different degrees 

 of successive retreat on the one hand, and the facts indicating the 

 action of an expansive and continuous sheet of ice moving over the 

 whole continent from north to south. Unquestionably the abrasion 

 of the summits of the mountains of Great Britain, especially notice- 

 able upon Schiehallion, is owing to the action of the great Euro- 

 pean ice-sheet during the maximum extension of the glacial pheno- 

 mena in Europe, and has nothing to do with the local glaciers of the 

 British Isles. 



Among the facts already known from the southern hemisphere are 



