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No truth is more certain or important in geological reasoning than the formation of all our continents and islands by causes acting below the sea. As far as relates to the stratified rocks this is obvious; but it is not the less certain for the unstratified rocks, these having undoubtedly been uplifted to our view from beneath the strata. It is possible there may yet be found some granitic rocks which were raised above the general spherical surface before the production of any deposits from water, and which may therefore be presumed to form an exception to this general rule; but such truly "primitive" rocks have nowhere been seen, nor is there any ground of expectation that they will be discovered. The elevation of the dry land out of the sea is therefore one of the great truths to which we must compare general speculations; and it affords a test, and prescribes conditions, which no false "theory" can fulfil.

The actual distribution of land and sea is very remarkable. London being taken as the centre of a hemisphere, nearly all the land is included therein. The antipodal hemisphere includes a vast abundance of small islands; but there are no considerable antipodal surfaces of land, except where Chili and Patagonia oppose the eastern part of China, and the volcanic islands of Sumatra, &c., oppose the volcanic mountains of Quito. The continent of Australia is opposite to the deep centre of the Atlantic Ocean. Only $$\scriptstyle \frac 1{27}$$th part of the present continents and islands has land opposed to it.

The meridian of least land (about 16° W. long.) passes by Kamschatka, the east side of Hecla, the west coast of Africa (near Madeira. Teneriffe, the Cape de Verde islands), the west side of New Caledonia, and