Le problème de la stabilité des îles du Rhône pendant la période historique au sud du confluent actuel du Rhône et de l'Aigues

Résumé En Fr

This study has been performed to test a new position of the so-called antique Orange C cadastre. It allows us to show that the Rhône river's channels and islands were very stable during the historical period. This stability is due to lithologic and tectonic features. First, the downcutting is very slow towards the Rhône-Cèze-Aigues confluence, owing to outcrops of hardrocks (limestone and sandstone). Second, the Würmian alluvial terrace has been lifted up from Montfaucon to Sorgues, so that the accumulation was favoured northwards. Using the numerous CNR drillings, it is possible to show that the position of the Rhône's channels is very stable, that the islands have belonged to the flood plain for several centuries and that dead channels have been filled by silts.

L'étude entreprise dans le cadre de l'hypothèse d'un nouveau positionnement spatial pour le cadastre C d'Orange montre que les conditions lithologiques et tectoniques sont réunies pour assurer, au cours de la période historique, une grande stabilité de la position des bras du lit mineur et des îles du Rhône.