Origin of Species Variorum

Alternate Glacial Periods of the North and South .

But we must return to our more immediate subject. .. .. .. I am convinced that Forbess 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 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 4000 feet down its valleys. ↑ 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 gigantic ancient moraines. Southward of the Asiatic continent, .. on the opposite side of the equator, we now know, from the excellent researches of Dr. J. Haast and Dr. Hector, that immense glaciers formerly descended to a low level in New Zealand; 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 glacial 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 lat. 36°— 37°, and on the shores of the Pacific, where the climate is now so different, as far south as lat. 46°. Erratic boulders 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 Chile I examined