—, causes and effects of, I. Lea, ix, 209.
—, remarks on, xiv, 72.
—, G. Bischof on the natural history of, xxxvii, 41.f
—, —, instances of, xxxvii, 41, 47.
—, —, causes of, xxxvii, 42.
—, —, connection with volcanoes, xxxvii, 43.
—, —, propagation of, xxxvii, 46.
—, —, direction of, xxxvii, 47.
—, —, elevation from, xxxvi, 273.
—, —, elevation of the Andes, xxxvii, 49.