TRANSACTIONS. 


I.—On the Volcanic Geology of the Vivarais (Ardéche). By James D. Forpgs, 
Esq., F.R.S., Sec. R. S. Ed., Professor of Natural Philosophy in the University 
of Edinburgh. 
(Read 3d and 17th January 1848.) 
THE limited district of country which I am about to describe, is one of those 
which may rank amongst the least frequented in the civilized part of Europe, yet 
which might justly claim for France the character of romantic beauty which 
travellers on her beaten highways commonly, and not without reason, deny 
to her. 
The modern department of the Ardéche, corresponding in part to the ancient 
province of the Vivarais, includes country of very dissimilar features, the southern 
and eastern part, forming the right bank of the Rhone near Viviers, being com- 
paratively flat; whilst the north-western boundary is the irregular chain of the 
Cevennes, including the localities more immediately to be described. This chain 
is not so remarkable for its absolute height, although that be considerable, rising 
at the Mont Mezenc, in the neighbouring department of the Haute Ebire, to an 
elevation of 5750 English feet above the sea, as from forming the separation of 
a remarkably elevated tract stretching to the north and west, and which suddenly 
subsides, at the point of which we now speak, into the wide champaign country of 
the Lower Rhone, possessing a very different aspect, soil, climate, and population. 
The high ground, or plateau, of which we have spoken, being thinly peopled, 
bleak, and steril (in its general character), compared to the fertile and vine-clad 
banks of the Rhone and Saone, immediately to the eastward, is but little tra- 
versed. In fact, only one great road passes through it, the post-road from Paris 
to Perpignan. It will readily be understood, also, why the Cevennes Mountains 
themselves are rarely visited, being left between this great road and the more 
VOL. XX. PART I. A 
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