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Monday, VI th January 1848. 



Dr CHRISTISON, Vice-President, in the Chair. 



The following Communications were read : — 



1. Account of a Geological Examination of the Volcanoes 

 of the Vivarais. By Professor Forbes. 



The author having, on former occasions, stated some results of his 

 travels in Auvergne and the Cantal, gives a more detailed descrip- 

 tion of the volcanoes of the Vivarais, which have been less fre- 

 quently and less accurately described. 



He first gives an account of the journey from Le Puy across the 

 chain of the Cevennes which culminate at the volcanic summit of the 

 Mezeuc, by the course of the Loire, to Montpezat in the department 

 of the Ardeche. 



The best descriptions of the Vivarais are those of Foujas de St 

 Fond and Mr Scrope. The plates illustrating the work of the lat- 

 ter leave almost nothing to desire. These authoi's have described 

 more or less fully the following volcanic orifices — Coupe de Jaujac, 

 Souillolsor Neyvac, Mouleynes or Thuez ; Montpezat and Aysac. 

 Other writers have described the cone of Bauzou, and the (so-called) 

 crater of Elevation of Pal, which are generally supposed not to have 

 wiven birth to any lava stream. The present author has given a 

 more minute and detailed account of each of these volcanoes, and of 

 the great beds of basaltic lava to which they have respectively given 

 birth. He discusses the relative age, the remarkably columnar struc- 

 ture, and the surprising erosion by water of these (comparatively 

 modern) lava flows, which he illustrates by an exact map of the 

 formations, based upon Cassini's, and by very numerous levels baro- 

 metrically determined. He has also been able to add to the list of 

 known volcanoes in this district, two craters which he beheves never 

 to have been described, occurring in remarkable positions, and giving 

 rise to extensive lava streams, one in the valley of Budzet, the other in 

 that of la Bastide. The former he believes to be unparalleled amongst 

 ancient or modern lavas for the length and slenderness of its stream, 

 shewing a surprising liquidity, which he illustrated by some experi- 

 ments on the powers of melted iron solidifying in narrow channels. 



A series of specimens illustrating the paper had formerly been 

 presented to the Society. 



