The action of subterranean forces in breaking through and elevating
strata of sedimentary rocks,--of which the coast of Chili, in
consequence of a great earthquake, furnishes an example,--leads to the
assumption that the pelagic shells found by MM. Bonpland and Humboldt
on the ridge of the Andes, at an elevation of more than 15,000 English
feet, may have been conveyed to so extraordinary a position, not by a
rising of the ocean, but by the agency of volcanic forces capable of
elevating into ridges the softened crust of the earth.