Paris Basin (geology)

The Paris Basin is one of the major geological regions of France having developed since the Triassic on a basement formed by the Variscan orogeny.

Extent

The region usually regarded as the Paris Basin is rather smaller than the area formed by the geological structure. The former occupies the centre of the northern half of the country, excluding Eastern France. The latter extends from the hills just south of Calais to Poitiers and from Caen to the brink of the middle Rhine Valley, east of Saarbrücken.

Geography

The countryside is one of plains and plateaux of limited altitude. In the south-east and east the plain of "Champagne" and the "Seuil de Bourgogne" (Threshold of Burgundy) differential erosion of the strata has left low scarps with the dip slopes towards the centre. The varying nature of the clays, limestones and chalk gives rise to the characteristics of the regions such as "Champagne Humide" (Damp Champagne), "Champagne Pouilleuse" (poor Champagne) ["Pouilleuse" means 'lousy' that is, 'infested with lice' but its meaning has broadened in use to include 'down and out'. This is a region of thin, chalk soils and little surface water. The epithet indicates the extreme poverty of the region when the name was acquired.] , the "Pays de Caux" and the "Pays de Bray".

tructure

It is a geological basin of sedimentary rocks. It overlies geological strata disturbed by the Variscan orogeny and forms a broad shallow bowl in which successive marine deposits from throughout periods from the Triassic to the Pliocene were laid down: their extent generally diminishing with time.

To the west, the strata folded by the Variscan, rise from below it in the hills of Brittany and in and east the Ardennes, Hunsrück and Vosges. To the south, it borders on the Massif Central and the Morvan. To the north, its strata link into those of the bed of the English Channel and south-eastern England. Other boundaries lie on ridges in less old rocks and scarps such as the Côte d'Or (on an Alpine fault line) and the Hills of Artois which overlie the margin of London-Brabant Island.

ee also

* Geologic time scale
* List of fossil sites "(with link directory)"

Notes

References

*Anon. "Carte Géologique de la France à l'Échelle du Millionième" ISBN 2-7159-2158-6
*Dercourt, J. "Géologie et Géodynamique de la France" 3rd. edn. (2002) ISBN 2-10-006459-2