GEOGRAPHICAL DISTRIBUTION 167 



similar in all their physical conditions, with their 

 inhabitants utterly dissimilar. 



Alternate Glacial Periods in the North and South 



But we must return to our more immediate subject. 

 I am convinced that Forbes's view may be largely ex- 

 tended. In Europe we meet with the plainest evidence 

 of the Glacial period, from the western shores of Britain 

 to the Oural range, and southward to the Pyrenees. We 

 may infer, from the frozen mammals and nature of the 

 mountain vegetation, that Siberia was similarly affected. 

 In the Lebanon, according to Dr. Hooker, perpetual snow 

 formerly covered the central axis, and fed glaciers which 

 rolled 4,000 feet down the valleys. The same observer 

 has recently found great moraines at a low level on the 

 Atlas range in North Africa. Along the Himalaya, at 

 points 900 miles apart, glaciers have left the marks of 

 their former low descent; and in Sikkim, Dr. Hooker saw 

 maize growing on ancient and gigantic moraines. South- 

 ward of the Asiatic continent, on the opposite side of the 

 equator, we know, from the excellent researches of Dr. 

 J. Haast and Dr. Hector, that in New Zealand immense 

 glaciers formerly descended to a low level; and the same 

 plants found by Dr. Hooker on widely separated moun- 

 tains in this island tell the same story of a former cold 

 period. From facts communicated to me by the Rev. W. 

 B. Clarke, it appears also that there are traces of for- 

 mer glacial action on the mountains of the southeastern 

 corner of Australia. 



Looking to America; in the northern half, ice-borne 

 fragments of rock have been observed on the eastern side 

 of the continent, as far south as latitude 86°-37°, and on 



