Occasionally not a trace of this inclosure is visible, and the
volcano, which is not always conical rises immediately from the neighboring
plateau in an elongated form, as in the case of Pichincha,* at the foot of
which lies the city of Quito.
[footnote] *[This mountain contains two funnel-shaped craters, apparently
resulting from two set of eruptions: the western nearly circular, and
having in its center a cone of eruption, from the summit and sides of which
are no less than seventy vents, some in activity and others extinct. It is
probable that the larger number of the vents were produced at periods
anterior to history. Caubney, op. cit., p. 488.] -- Tr.
As the nature of rocks, or the mixture (grouping) of simple minerals into
granite, gneiss, and mica slate, or into trachyte, basalt, and dolorite, is
independent of existing climates, and is the same under the most varied
latitudes of the earth, so also we find every where in inorganic nature that
the same laws of configuration regulate the reciprocal superposition of the
strata of the earth's crust, cause them to penetrate one another in the form
of veins, and elevate them by the agency of elastic forces. This constant
recurrence of the same phenomena is most strikingly manifested in volcanoes.
Pages:
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481