James Geihie — On Changes of Climate. 167 



*' Pleistocene " times came, as they do now, from the south-west, we 

 cannot but admit that they must have been colder. The occurrence 

 of glaciers in Britain pre-supposes a greater extension of the Arctic 

 ice-fields, more plentiful crops of icebergs, and consequently a 

 colder sea. Indeed, it seems more than likely, that with permanent 

 snow-fields in Great Britain, icebergs would sail southwards in large 

 numbers from Scandinavia, and from not a few of the fiords of 

 the west of Scotland. The winds that set towards the western 

 coasts of Europe would thus have to traverse a sea more or less 

 filled with floating ice, and would be compelled to part with their 

 warmth before they reached our shores. But, more than this, Mr. 

 CroU has shown that, under a glacial condition of things in the 

 Northern Hemisphere, it is highly probable that a large propor- 

 tion of the heat which our island now derives from the Gulf-stream 

 would be transferred to the Southern hemisphere ; and the result 

 of this would be to give to England a very much cooler summer 

 than she at present enjoys. It matters little, however, from what 

 point of the compass we suppose the prevalent winds to have come ; 

 so far as that goe's, they may have issued from the north, south, 

 east, or west : but under the physical conditions assumed to have 

 characterized " Pleistocene " Britain, they never could have con- 

 ferred a Siberian summer upon these latitudes. 



It would not be difficult to show that, with the presence of 

 perennial snow and ice in the high grounds of Great Britain, our 

 rivers would remain frozen over for a great part of the year. During 

 the summer they would burst their icy bonds, and, swollen with 

 heavy rains and the torrents derived from the melting of the snow- 

 fields and glaciers, would overflow the low grounds, and carry de- 

 vastation far and wide. Over broad areas in our valleys, therefore, 

 there could be little vegetation. Such areas as were not covered 

 with snow might perhaps support scraggy birch and pine ; and here 

 and there tall grasses and dwarf willows might nestle in sheltered 

 hollows; but mosses and lichens would most probably form the 

 prevailing growths. If the " Pleistocene " hippopotamus could live 

 oa such fare, he must have been a more easily satisfied animal than 

 his modern representative. It is true that in Arctic regions the 

 short summer brings into bloom a number of pretty flowerets, and 

 causes the grasses to shoot up with surprising rapidity. But this is 

 due to the influence of a sun that keeps above the horizon during 

 the greater part of summer. A glacial period in England, however, 

 would not be tempered by the presence of a midnight sun in summer- 

 time. For these and other reasons it may be safely concluded that 

 the hippopotamus could not have lived in this country when glaciers 

 filled our mountain valleys. 



But putting aside climatal conditions altogether, and admitting for 

 the moment that the warmth of Post-glacial Britain in summer-time 

 was fitted to woo the hippopotamus northwards, there would still be 

 a fatal objection to the hypothesis under review. The hippopotamus 

 is not, properly speaking, a migratory animal. This objection, 

 which has been frequently urged, appears unanswerable. Unless 



