hemisphere) less than 2 degs. from orchideous parasites, and within a
single degree of tree-ferns!
These facts are of high geological interest with respect to the climate
of the northern hemisphere at the period when boulders were
transported. I will not here detail how simply the theory of icebergs
being charged with fragments of rock, explain the origin and position
of the gigantic boulders of eastern Tierra del Fuego, on the high plain
of Santa Cruz, and on the island of Chiloe. In Tierra del Fuego, the
greater number of boulders lie on the lines of old sea-channels, now
converted into dry valleys by the elevation of the land. They are
associated with a great unstratified formation of mud and sand,
containing rounded and angular fragments of all sizes, which has
originated [15] in the repeated ploughing up of the sea-bottom by the
stranding of icebergs, and by the matter transported on them. Few
geologists now doubt that those erratic boulders which lie near lofty
mountains have been pushed forward by the glaciers themselves, and that
those distant from mountains, and embedded in subaqueous deposits, have
been conveyed thither either on icebergs or frozen in coast-ice. The
connection between the transportal of boulders and the presence of ice
in some form, is strikingly shown by their geographical distribution
over the earth. In South America they are not found further than 48
degs. of latitude, measured from the southern pole; in North America it
appears that the limit of their transportal extends to 53.5 degs. from
the northern pole; but in Europe to not more than 40 degs. of latitude,
measured from the same point. On the other hand, in the intertropical
parts of America, Asia, and Africa, they have never been observed; nor
at the Cape of Good Hope, nor in Australia. [16]
On the Climate and Productions of the Antarctic Islands.--Considering
the rankness of the vegetation in Tierra del Fuego, and on the coast
northward of it, the condition of the islands south and south-west of
America is truly surprising. Sandwich Land, in the latitude of the
north part of Scotland, was found by Cook, during the hottest month of
the year, "covered many fathoms thick with everlasting snow;" and there
seems to be scarcely any vegetation. Georgia, an island 96 miles long
and 10 broad, in the latitude of Yorkshire, "in the very height of
summer, is in a manner wholly covered with frozen snow." It can boast
only of moss, some tufts of grass, and wild burnet; it has only one
land-bird (Anthus correndera), yet Iceland, which is 10 degs. nearer
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