The Puy de Dôme

 

"A tout Seigneur, tout honneur"

It is the star and we will begin this review by it. Emblematic mountain of Auvergne, it gave are name at the department administration. The Giant of the Domes, of the Romans, while passing through Pascal, to the the famous bicycle champion couple Anquetil-Poulidor, is really a star. Moreover, it is seen by far: its altitude raised compared to the surrounding plates in fact a mythical mountain. By walk, to horse, to vapor, to bicycle, to car, franšais anglais arabe And soon, thanks to the cogwheel train, named Panoramique des Dômes, it gives desire for climbing it. And, it is true that it is attracting, because to its node, it offers an exceptional point of view.

The top view of Puy de Dôme show a west dome which was surely perfect

 

A 10 000 years " young fellow "

Puy de Dôme

Up : le Puy de Dôme aujourd'hui

Under : le Puy de Dôme il y a 10 000 ans

Le Puy de Dôme-10000

For explanation click on the picture

It is its age. It is little, compared to the first buildings of the Chain (100 000ans). Before its formation, the few habitants of the Clermont plain (which did not exist), observed in the place a modest Strombolian slag cone. Not what to put an aerial. The Western profile of the Clermont horizon was of course extremely different.

Its construction is complex, and the facts history difficult to know. It is in an initial Strombolian cone that is born, then builds a first dome of a very viscous lava which no flow, but remains at the vertical of the emission mouth. The development did not known major incident and altitude approaches an exceptional values for this type of dynamism. During this phase of the volcanic ash clouds to the limited extent, cover the neighbourhoods calcining the surrounding forests. The dome is almost perfect, comparable with the dome of the "Soufrière' in Guadelup.

The building could remained in the state, but a few time after an explosion breaks the East part.Then another dome takes the place while rising in the ploughed up part. A progression identical to the first, but more pointed which will give this characteristic form than one sees today. The most destroying phase is during this explosion. The model of comparison is the peeled Mountain in Martinique which knew apparently the same scenario (with for consequence destruction of the town of Saint Pierre).

The neighbours " is powdered " on the one, of the deposits of the volcanic clouds emitted during the formation, and on the other, fragments of the East part. The vegetation will cover the area gradually, until side events occur later on like the explosion of the Kilian crater, 8500 years ago, and which marks the end (provisional?) of volcanic episodes of the Puy de Dôme.

 

3D map

Relief

Puy de Dôme remains the highest volcano of the Chain of Puys with its 1465 Mr. His rise was done since the Romaine time by the path of the Muleteers on his South-western face. In 1907, a tram with vapor made it possible Clermontois to climb without effort the giant of the Domes. The current road uses its layout which makes 1 turn 1/4 around the building with a regular slope of 12%. We can reach in the car, or the bus for the estival period. This solution, initiated by the General council, limits circulation during the moments of strong frequentation, and goes in the direction of the safeguarding of the environment.

The pedestrian rise by the path of the muleteers is nevertheless a pleasant moment. On the basis of the "Col de Ceyssat", the path rises on uneven of 400 m, making discover a vast panorama on the Southern volcanos and the Massif du Sancy. The climbing time is about 2h to 4h according to the rate/rhythm which one asserts.

By looking at the 3D card with a pair of glasses with relief (filter right eye: blue; filter left eye: red), you will have an original sight of Puy de Dôme. If you do not have any, manufacture in one with transparent paper with the colors indicated, or buy it .Thus equipped, aim the screen directly at 0,50 m of distance (or print the map).

Antenne

Nature of the lava

Puy de Dôme did not produce lava flows (except the clouds artdentes and the blocks projected during the explosion of the East side). The emitted products are trachytes, very viscous lava, which while cooling, induces a white and friable rock. The lava of this type is called "Dômite". The paste of the rock comprises phenocrysts (large crystals) of black biotite (mica) and quartz. The silica content (SiO2) is one of highest (65%), by making an acid lava.

Science and Puy de Dôme

September 19 the 1648 node was the theatre experiment of Blaise Pascal, who, using the barométre of Torriceli, highlighted the variation of atmospheric pressure according to altitude. It is his brother-in-law, Mr. Perrier, who carried out the operation. The history tells that Pascal have never climbed the Puy de Dôme by fear to be asphyxiated. It is for that that it had entrusted work to his brother-in-law.

Pression Atmosphérique

Atmospheric pressure according to altitude

 

© Copyright Jan 2001 Photos, Cartes et Tableaux: BD avec la complicité de RA)