Elements of geology / by Charles Lyell.

  • Charles Lyell
Date:
1838
Catalogue details

Licence: Public Domain Mark

Credit: Elements of geology / by Charles Lyell. Source: Wellcome Collection.

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    these last have been poured forth into the sea, and there mingled with aqueous sediment. On pursuing downwards either the small dikes or large masses of volcanic rock, we find them pass gradually into plutonic formations, D, which are coloured red, and which underlie all the rest. These last again are seen to be in contact with a zone of contemporaneous metamorphic strata, C, coloured blue, which they penetrate in nu- merous veins. In that part of the section which is uncoloured, a more ancient series of mineral masses are seen* belonging also to the four great divisions of rocks. The strata from a to i represent as many dis- tinct aqueous formations, which have originated at different periods, and are each distinguished by their peculiar fossils. The mass v v is of volcanic origin, and was formed at one of those periods, namely, when the strata g were deposited. The strata m m are ancient metamorphic formations, and the rocks 1, 2, are plutonic, also ancient, but of different dates. Now it will be shewn in the course of this volume, that portions of each of these four distinct classes of rocks have originated at many succes- sive periods. It is not true, as was formerly sup- posed, that all granite, together with the crystal- line or metamorphic strata, were first formed, and therefore entitled to be called “ primitive,1” and
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