DYNAMICAL GEOLOGY. 267 



Von Waltershausen brings forward evidence to show that the 

 first volcanic outbreak on Etna took place during the Diluvial 

 period, while that area formed part of the Continent ; whereas 

 Pilla, writing in 1845, referred the first Etna eruption to the 

 Pliocene age, or possibly to a still more remote period. 

 According to Von Waltershausen, the volcanic eruptions are 

 concentrated along a fissure extending in N.N.W.-S.S.E. 

 direction ; and the famous Val del Bove is thought by him to 

 have originated as a crust-inthrow, and is compared with the 

 crust-basins of Somma and Santorin. 



The Lipari Islands have called forth a rich literature. 

 Special interest has been accorded to a ringed series of 

 islands and reef-rocks surrounding Stromboli on the south. 

 Hoffmann in 1832 suggested that these probably represented 

 the fragments of a former enormous crater. Professor Judd 

 in 1875 confirmed this view, and also agreed with Hoffmann's 

 conclusion that the vents of the volcanic discharges in the 

 Lipari Isles virtually occur along the course of three radial 

 fissures. Professor Suess expressed a similar opinion that the 

 ^Eolian Isles mark a saucer-shaped depression in which radial 

 faults intersect. 



The Santorin Isles form the subject of a splendidly 

 illustrated monograph by Fouque. Since its publication in 

 1878, a number of geologists have contributed special papers 

 on the surface conformation, the geological structure, the 

 origin and history of these volcanic islands. All newer 

 publications agree that the theory of the Elevation-Craters is 

 quite inapplicable to Santorin. 



The volcanoes of Iceland have been carefully investigated 

 during the past century. Mackenzie's Travels gave the 

 earliest detailed reports (1811); in 1846, the great chemist 

 Robert von Bunsen travelled through Iceland, and published 

 five years later his famous treatise on the chemical composition 

 and origin of the volcanic rocks of Iceland. Within recent 

 years the island has been accurately mapped by members of 

 the Norwegian Survey Department, and important contribu- 

 tions have been made to the knowledge of its volcanoes by 

 Thoroddsen and Keilhack. 



The extinct volcanoes of Europe have received a large share 

 of attention from geologists. The Euganian Isles near Padua, 

 and Monte Berici near Vicenza, have been studied by Dr. vom 

 Rath, Dr. Reyer, and Professor Suess. 



