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this land had been broken up by climatic and geological causes. 
Mr. Wallace supposes an emigration to have taken place from 
Chili by way of the South Shetland Isles, 500 miles south of 
Cape Horn, thence by way of an antarctic continent or group 
of isles, which probably extend around the South Polar area 
to Yictoria Land, again on to the outlying Young Island, across 
750 miles of sea to Macquarie Island, and, finally, across 
another similar distance to the 1000 fathom line, which, he con- 
siders, 4 probably marks the former southern extension of 
Tasmania/ This appears a route beset with obstacles both 
climatal and geographical, and broken up by extents of sea, which 
Sir Joseph Hooker has expressly stated many of the plants com- 
mon to these remote lands to be specially unfitted to traverse.* 
The bed of the ocean is as undulating as the surface of the 
land ; and this is hardly the condition it would have as- 
sumed had its state been that of eternal rest. The objection 
that oceanic islands, with the exception of Hew Zealand and 
the Seychelles, hardly ever afford traces of Palaeozoic or 
Secondary formations, and cannot therefore be remains of 
continents, is far from insuperable. The smaller oceanic 
islands, to which the statement alone seems to apply, would, j 
if belonging to continental areas, be only the summits of 
mountains that are either rising or sinking; and as they are 
mostly of comparatively recent volcanic origin, it is hardly 
likely that we should meet with Palaeozoic or Mesozoic stratified 
rocks exposed on them. It is even more curious, if they have 
been uplifted from the great depths which surround them, that 
no traces of the bottom sediment, which must have been accumu- 
lating continuously from the Palaeozoic period, should have been 
brought up with them. Speculation is, however, useless, for 
the only geological fact regarding them about which we 
can be certain is that whatever secrets they have to dis- I 
close lie buried deeply under volcanic outbursts. It is 
certainly strange that Mr. Wallace makes no difficulties 
whatever in admitting changes of level in the sea bottom j 
to the extent of 1000 fathoms, but will not entertain the j 
possibility of any greater upheaval. Yet some oceanic 
islands must have been upheaved from vastly greater depths, 
and mountain chains have been raised to three times that ex- 
tent in comparatively recent times. 
It is well known that these forces are unceasingly acting, 
yet no reason is put forward to show why an elevating force once 
set in action in the centre of an ocean, should not continue 
gradually to act until even a continent is formed. In the 
* The elevation of from 400 to 1800 feet which Chili and Patagonia have 
undergone for several hundred miles since the existence of the living species 
of Mollusca must imply at least correspondingly great subsidence elsewhere. 
