regarded as retaining walls, [124], [125];
relation to mountain ranges, [144];
sequence of events within chimney of, during eruption, [134], [135];
solfataric activity of, [97];
three types of, [105].
V-shaped valley, [172].
Vulcanello, [119].
Vulcanian eruptions, [117], [125].
Waltershausen, S. von, cited, [148].
Walther, Johannes, cited, [201], [202], [203], [204], [205], [206], [211], [215], [221].