On the Structure of Lavas Which Have Consolidated on Steep Slopes; With Remarks on the Mode of Origin of Mount Etna, and on the Theory of Craters of E (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1859 Excerpt: ...opinion, there appearing to me no sections sufficient to establish the fact of a long-continued series of eruptions from any fixed point, other than the present culminating focus. There is, however, such a tendency in volcanos to shift their principal points of discharge, that a geologist cannot object to such an hypothesis, if it can be shown that we can thereby best explain any observed phenomena; and it was probably owing to the limited period of my visit, that I failed to obtain proofs of two adjoining craters formed by paroxysmal explosions and then afterwards filled up to the lips by lava and scoriae. Fig. 18.--Swmmit of Etna as seen from the south or the eastern suburbs of La Motta. a. Highest cone as seen from La Motta. b, c. Margin of Piano del Lago. M. Montagnuola. The annexed sketch (fig. 18), which I made of the outline of the higher region, as seen from the south or from the eastern suburbs of La Motta, will show in how analogous a manner the modern cone rises there above the Piano del Lago. The geologist must not infer, from the term Piano, that there is really any extent of level ground or table-land near the summit of Etna. The whole area surrounding the cone might rather be compared to a flattened dome, from which rise several volcanic hills of considerable size, such as that of the Torre del Filosofo, and another much more lofty, called Monte Frumento, rising due south of the Casa Inglese. These have the ordinary external characters of lateral cones produced by single eruptions. a Elliptical crater.--I regret that I was unable to visit what is still extant of the walls of the "Cratere Elliptico" of S. Von Waltershausen, which is situated north and north west of the great cone (see Map, Plate L.); but my friend, Signor Gaetano G. ...