Book Description

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ...causes of the eruption. Volcanic phenomena can be studied in many parts of the world, but perhaps nowhere with more advantage than in New Zealand. In the volcanic region of the North Island, there are thousands of square miles in which volcanic activity can be seen in every stage and phase. There are active, intermittent, and extinct volcanoes, besides innumerable geysers, fumaroles, and hot springs--active, decadent, and dead. The active and intermittent volcanoes discharge their lavas and fragmentary matter from single pipes, or from lateral vents apparently connected with the main pipe; and from fissurerents. The volcanic eruption, at Rotomahana, in 1886, was from a fissure-rent, over 6 miles in length, extending from the summit of Mount Wahanga southward into the basin of Lake Rotomahana, and thence across the rhyolite plateau to Lake Okaro.2 The whole length of the rent was the scene of great activity for some weeks after the first great outburst. In New Zealand, the geysers, hot springs, and fumaroles occur in isolated groups, or along a line of fissure, which often runs along the floor of a valley, or lower flanks of a range of hills. The geysers and hot springs deposit siliceous and calcareous sinters, mostly the former; and the fumaroles, native sulphur. Everywhere the air is pervaded with the smell of sulphur dioxide (Frontispiece). The solfataric action is active, waning, or dead. With the latter, the vents are closed up by siliceous encrustations. 1 Tscher, Min. u. Petrog. Mitth., xvii. p. 33, 1897. 2 Sir James Hector, "On the Recent Volcanic Eruptions at Tarawera," N.Z. Reports of Geol. Explorations, 1886-87, p. 243. Professor F. W. Hutton, Report on the Tarawera Volcanic District; Wellington, 1887. S. Percy Smith, ...