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SKETCH OF THE GEOLOGY OF CENTRAL FRANCE
TERTIARY LACUSTRINE FORMATIONS .. .. .. .. .. .. ..
1. Limagne d'Auvergne. 2. Cantal. 3. Haute Loire. 4. Montbrison.
INTRODUCTORY ACCOUNT OF THE NOTICES WHICH HAVE BEEN
HITHERTO PUBLISHED CONCERNING THE VOLCANIC REMAINS OF
GENERAL ACCOUNT OF THE VOLCANIC FORMATION3 OCCURRING
UPON THE ELEVATED GRANITIC PLATFORM OF CENTRAL FRANCE
FIRST VOLCANIC REGION. — MONTS DOME AND THE LIMAGNE
1. Chain of Puys. 2. Products of earlier Eruptions.
REGION II.-THE MONT DORE .. .. .. .. .. .. .. ..
§ 1. The Volcanic Mountain-Its general Outline--Conglomerates.
and Basalt. $ 3. Recent Eruptions.
LIST OF ILLUSTRATIONS.
VI. Valley of Villar and Plateau of Prudelle .. .. .. VIII. Clinkstone Rocks, Tuilière and Sanadoire, from the Puy
Gros (Mont Dore) .. .. .. .. .. .. .. X. Montagne de Bonnevie (a cluster of Basaltic Columns),
above the Town of Murat (Cantal) ..... .. XII. Basaltic Plateaux of the Coiron (Ardêche), from the
South .. .. .. .. .. .. .. .. .. XIV. Valley of Montpezat (Ardêche) .. .. .. .. ..
XV. La Coupe d'Ayzac (Ardêche) .. .. .. .. .. XVII. Profiles and Sections, &c. .. .. ..
163 187 194
XIII. Volcanic Cone and Basaltic Lava-current of Jaujac
(Ardêche) .. .. .. .. .. .. .. ..
I. Panoramic View from the Puy Girou, 6 miles South
of Clermont (Puy de Dôme) .. .. .. .. .. At the end of the Volume. II. General View of the Chain of Puys, from the West,
above the Valley of the Sioule, near Pont Gibaud .. III. Transversal View of the Monts Dôme, from the summit
of the Puy Chopine .. .. .. .. .. .. .. IV. Eastern View of Monts Dôme, from the Croix de
Pirobot, between Volvic and Channat .. .. ..
Gros on the North .. .. .. .. .. .. ..
and of the Mont Mezen, taken from the Mont d'Ours XVI. Sections of Granitic Plateau from East to West and
from N.N.E. to S.S.W... .. .. .. .. ..
GEOLOGY AND EXTINCT VOLCANOS
GRANITIC PLATEAU AND MARINE STRATIFIED FORMATIONS.
The parallel of 46-30, passing near the towns of Châteauroux and Châlons-sur-Saône, will be found to divide France into two nearly equal portions, of which the northern may be considered as a vast plain, whose waters flow gently towards the north and west through the Seine and the lower Loire. South of this line the surface continues to rise with a gradual slope, so as to form an inclined plane, which progressively acquires an elevation of more than 3000 feet above the sea in the Auvergne and Forèz, and a still greater in the Gevaudan and Vivarais, where it reaches the height of 5500 feet. Here it is abruptly cut down by the deep valley of the Rhone, which, running nearly due north and south, separates it from the ranges east of that river, in the departments Drôme, Isère, and Hautes Alpes. On the south - west also this high ground rapidly descends through broken and irregular embranchments to the basin of the Gironde. It may, in fact, be considered as a triangular