Note 10 — PHYSIOGNOMY OF PLANTS.

p. 14.—“The mass of the earth in solidifying and parting with its heat.”

If, according to the hypothesis of the Neptunists, now long since obsolete, the so-called primitive rocks were precipitated from a fluid, the transition of the crust of the earth from a fluid to a solid state must have been accompanied by an enormous disengagement of heat, which would in turn have caused fresh evaporation and fresh precipitations. The later these precipitations, the more rapid, tumultuous, and uncrystalline they would have been. Such a sudden disengagement of heat might cause local augmentations of temperature independent of the height of the pole or the latitude of the place, and independent of the position of the earth’s axis; and the temperatures thus caused would influence the distribution of plants. The same sudden disengagement of heat might also occasion a species of porosity, of which there seem to be indications in many enigmatical geological phenomena in sedimentary rocks. I have developed these conjectures in detail in a small memoir “über ursprungliche Porosität.” (See my work entitled Versuche über die chemische Zersetzung des Luftkreises, 1799, S. 177; and Moll’s Jahrbücher der Berg- und Hüttenkunde, 1797, S. 234.) According to the newer views which I now entertain, the shattered and fissured earth, with her molten interior, may long have maintained a high temperature on her oxydised surface, independently of position in respect to the sun and of latitude. Would not the climate of Germany be wonderfully altered, and that perhaps for centuries, if there were opened a fissure a thousand fathoms in depth, reaching from the shores of the Adriatic to the Baltic? If in the present condition of our planet, the stable equilibrium of temperature, first calculated by Fourier in his Théorie analytique de la chaleur, has been almost completely restored by radiation from the earth into space; and if the external atmosphere now only communicates with the molten interior through the inconsiderable openings of a few volcanoes,—in the earlier state of things numerous clefts and fissures, produced by the frequently recurring corrugations of the rocky strata of the globe, emitted streams of heated air which mingled with the atmosphere and were entirely independent of latitude. Every planet must thus in its earliest condition have for a time determined its own temperature, which afterwards becomes dependent on the position relatively to the central body, the Sun. The surface of the Moon also shows traces of this reaction of the interior upon the crust.