Chacun voulant avoir le dernier mot, cela n'en finissait plus de finir.

Georges Conchon

The story edification of the "Chaîne"- Chronologic events

Le Sancy

The "Massif du Sancy" : evidence of a stratovolcano with animated volcanic past

Volcanoes story

The hunters of reindeers which traversed the places during the last glaciation probably saw the ultimate eruptions of Chaîne des Puys. Also no doubt that the few Romans who are stopped here, have compared these particular reliefs with the sicilian and Italian volcanos in activity. But of these old times we do not have any trace of scientific observation, and it will be necessary to await the century XVIII to admit the volcanic caracter of the country. At this time, Jean-Etienne Guettard, by comparing the lava with those of the Italian volcanos, put it in evidence. From that time, Auvergne became the high place of french volcanology. It is on this study area, that work of recognized geologists (Dolomieu, Lacroix, etc), succeeded, not only with développement of the local volcanology, but also in the world. Lastly, the evolution of technologies of the last half part of the century XX, such as datation tools, made progress knowledge on this country of a considerable maner..

Some reference marks in the past

The softness of the reliefs constitutes the principal characteristic of the old mountainous formations: nodes rounded, not very deep throats, low altitudes. The monotony of the reliefs is rarer in the "Massif Central". It has sudden during geological times many transformations. With the cycles of depressions, sedimentary deposits, risings, due to the movements of the earth's crust, volcanicity supplemented in a very significant way this transformation. This process started very early, witnesses the volcanic buildings eroded which paper the Solid mass, such as the Cantal, Aubrac, the Mounts Gilds, the dykes and plates of Velay, and in Limagnes, the dykes and run which constitute for examples the hillocks of Nonette, Usson towards Issoire, the "Mountain of the Serre" in reversed relief, the Coasts of Clermont, Montrognon, etc. The construction of all these formations, spread out over the end of tertiary era.

The "Massif Central" was obviously the object of significant fractures. The collision of the Eurasienne and African plates, by generating the Alpine Massif is the first cause.

La partie Nord de la Chaîne

With the geological scale the formation of "La Chaîne des Puys" is recent. Moreover what strikes it is the astonishing freshness of the buildings which gives the impression that the activity stopped yesterday perhaps. In fact the youngest craters hardly go back to 8500 years (puys of the Cow and Lassolas) and 6500 years for the Pavin system.


© Copyright Jan 2001 Photos et Tableaux: Bernard Dichamp