Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/46

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42
RELATION OF UNSTRATIFIED.

a power whose effect in melting the most solid materials of the earth we witness in the fusion of the hardest metals, and of the flinty materials of glass.[1]

Beneath the whole series of stratified rocks that appear on the surface of the globe (see section Pl. 1), there probably exists a foundation of unstratified rocks; bearing an irregular surface, from the detritus of which the materials of stratified rocks have in great measure been derived,[2] amounting, as we have stated, to a thickness of many miles. This is indeed but-a small depth, in comparison with the diameter of the globe; but small as it is, it affords certain evidence of a long series of changes and revolutions; affecting not only the mineral condition of the nascent surface of the earth, but attended also by important alterations in animal and vegetable life.

The detritus of the first dry lands, being drifted into the sea, and there spread out into extensive beds of mud an

  1.  The experiments of Mr. Gregory Watt on bodies cooled slowly after fusion; and of Sir James Hall, on reproducing artificial crystalline rocks, from the pounded ingredients of the same rocks highly heated under strong pressure: and the more recent experiments of Professor Mitscherlich, on the production of artificial crystals, by fusion of definite proportions of their component elements, have removed many of the objections, which were onk urged against the igneous origin of crystalline rocks.

    Professor Kersten has found distinctly formed crystals of prismatic Felspar on the walls of a furnace in which Copper slate and Copper Ores had been melted. Among these pyrochemically formed crystals, some were simple, others twin. They are composed of Silica, Alumina, and Potash. This discovery is very important, in a geological point of view, from its bearing' on the theory of the igneous origin of crystalline rocks, in which Felspar is usually so large an ingredient. Hitherto every attempt to make felspar crystals by artificial means has failed. See Poggendorf's Annalen, No. 22, 1834, and Jameson's Edin. New. Phil. Journal.

  2. Either directly, by the accumulation of the ingredients of disintegrated granitic rocks; or indirectly, by the repeated destruction of different classes of stratified rocks, the materials of which had, by prior operations, been derived from unstratified formations.