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Lithophytes.
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In the torrid zone, where lithophytes of many species abound, and are propagated with great rapidity, their strong trunks are interwoven and accumulated so as to form rocks and reefs; and rising even to the surface of the water, shut up the entrance of harbours, and lay frightful snares for navigators. The sea, throwing up sand and mud upon the tops of these shoals, sometimes raises their surface above its own level, and forms islands, which are soon covered with a rich vegetation.
Incrustation.
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It is also possible, that, in particular places, large quantities of the animals inhabiting shells, leave their stony coverings when they die, and that these, cemented together by slime of greater or less consistence, or by other cementing substances, form extensive deposits or shell banks. But we have no evidence that the sea can now incrust those shells with a paste as compact as that of the marbles, the sandstones, or even the coarse limestone (calcaire grossier) in which we see the shells of our strata enveloped. Still less do we any where find the sea depositing those more solid and more siliceous strata which have preceded the formation of the shelly strata.