Theory of the Earth

THERE can be no doubt that these two different species of bodies have had the same origin, and that they are composed of the same materials nearly; but from the different circumstances of their production, there is formed a character to these bodies, by which they may be perfectly distinguished. The difference of those circumstances, consists in this; the one has been emitted to the atmosphere in its fluid state, the other only came to be exposed to the light in a long course of time, after it had congealed under the compression of an immense load of earth, and after certain operations, proper to the mineral regions, had been exercised upon the indurated mass. This is the cause of the difference between those erupted lavas, and our whinstone, toadstone, and the Swedish trap, which may be termed subterraneous lava. The visible effects of those different operations may now be mentioned.

IN the erupted lavas, those substances which are subject to calcine and vitrify in our fires, suffer similar changes, when delivered from a compression which has rendered them fixed,

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