THE GLACIAL PERIOD. 371 



with parts of South Africa or Australia, we see countries 

 closely 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' view may be largely extended. 

 In Europe we meet with the plainest evidence of the Glacial 

 period, from the western shores of Britain to the Ural 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, accord- 

 ing 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. Southward 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 Zeal- 

 and immense glaciers formerly descended to a low level ; and 

 the same plants found by Dr. Hooker on widely separated 

 mountains 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 former gla- 

 cial action on the mountains of the south-eastern 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 thirty-six and 

 thirty-seven degrees, and on the shores of the Pacific, where 

 the climate is now so different, as far south as latitude forty- 

 six degrees. Erratic bowlders have, also, been noticed on 

 the Rocky Mountains. In the Cordillera of South America, 

 nearly under the equator, glaciers once extended far below 

 their present level. In Central Chili I examined a vast 

 mound of detritus with great bowlders, crossing the Portillo 

 Valley, which, there can hardly be a doubt, once formed a 

 huge moraine ; and Mr. D. Forbes informs me that he found 

 in various parts of the Cordillera, from latitude thirteen 

 to thirty degrees south, at about the height of 12,000 feet, 



