*
Moreau de Jonnes, 'Hist. Phys. des Antilles', t. i., p. 136, 138, and 543;
Humboldt, 'Relation Historique', t. iii., p. 367.
A small colitic bed, formed in Lancerote, one of the Canary Islands, and
which, notwithstanding
p 251
its recent formation, bears a resemblance to Jura Limestone, has been
recognized as a product of the sea and of tempests.*
[footnote] *Near Teguiza. Leop. von Buch, 'Canarische Inseln', s. 301.
Composite rocks are definite associations of certain crytonostic, simple
minerals, as feldspar, mica, solid silex, augite, and nepheline. Rocks very
similar to these consisting of the same elements, but grouped differently,
are still formed by volcanic processes, as in the earlier periods of the
world. The character of rocks, as we have already remarked is so
independent of geographical relations of space,* that the geologist
recognizes with surprise, alike to the north or the south of the equator, in
the remotest and most dissimilar zones, the familiar aspect, and the
repetition of even the most minute characteristics in the periodic
stratification of the silurian strata, and in the effects of contact with
augitic masses of eruption.
[footnote] *Leop. von Buch, op. cit., p. 9.
We will now enter more fully into the consideration of the four modes in
which rocks are formed -- the four phases of their formative processes
manifested in the stratified and unstratified portions of the earth's
surface; thus, in the 'endogenous' or 'erupted rocks', designated by modern
geognosists as compact and abnormal rocks, we may enumerate the following
principal groups as immediate products of terrestrial activity:
1.
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