at
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. 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 Zealand 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 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
latitude 36 and 37 degrees, and on the shores of the Pacific, where
the climate is now so different, as far south as latitude 46 degrees.
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
a vast mound of detritus with great boulders, 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 13 to 30 degrees south, at about the height of
12,000 feet, deeply-furrowed rocks, resembling those with which he was
familiar in Norway, and likewise great masses of detritus, including
grooved pebbles. Along this whole space of the Cordillera true glaciers
do not now exist even at much more considerable heights. Further
south, on both sides of the continent, from latitude 41 degrees to the
southernmost extremity, we have the clearest evidence of former glacial
action, in numerous immense boulders transported far from their parent
source.

From these several facts, namely, from the glacial action having
extended all round the northern and southern hemispheres--from
the period having been in a geological sense recent in both
hemisp