... transition porphyry, nor real basalt with olivine, nor trachyte, nor burning volcano, have been observed, either in the plains or the groups of insulated mountains. The phenomena of the trachyte formation appear to be confined to the ridge and the...
A Geognostical Essay on the Superposition of Rocks in Both Hemispheres - Page 153
by Alexander von Humboldt - 1823 - 482 pages
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