Aare-Doubs

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In geology, the Aare-Doubs or Aare-Sundgau-Strom denotes a common phase in the development history of the rivers Aare and High Rhine , as well as Doubs , Saône and Rhone .

Geological classification

Today's Aare was the Aare-Doubs, the upper reaches of a river directed towards the Mediterranean , and today's High Rhine was one of the tributaries (still without the Alpine Rhine). The Aare-Doubs lasted about four million years; it originated in the Tertiary , towards the end of the Pliocene , and ended in the older Pleistocene , about a million years ago , when the water from the Aare and Upper Rhine found its way through the lowering Upper Rhine Plain to the North Sea . Before that, the Aare was the upper reaches of the original Danube . After the phase of the Aare-Doubs it became the main branch in the river system of the Rhine until today .

Name-giving section in Burgundy

In the oldest Pliocene, the later Jura Mountains also rose under the influence of the elevation and folding of the Alps ; the resulting depression between the Vosges and the still little uplifted Jura was drained by a river to the southwest, which began in today's Elztal in the Black Forest ("Ur-Elz"). In the middle of the Pliocene, the Aare-Danube erupted to the west near today's Waldshut into this lower valley, which became the new drainage line of the former upper course of the Urdonau. In the gradually rising Jura plateau, between Montbéliard and Dole , for example , the river cleared the forerunner of the deep Doubs valley. Further down, in the northern Rhone rift system , the meandering river flowed through a large, shallow lake ( Lac bressan ) in what is now the Bresse plain . It filled its northern part with an extensive river delta facing west . The remnants of this loamy gravel (in what is now the Chaux forest ) lie under a younger silt layer. The Aare-Doubs also left comparable deposits further up, in the Sundgau .

Lower section in the Rhone Trench

Its abundance of water from the Aare and Hochrhein made the Aare-Sundgau-Strom the main river up to its confluence with the Mediterranean. The Saône flowed into it from the right and the upper Rhone from the left near today's Lyon . The current ended a little south of Lyon at the beginning, as the gorge , which originated from the time of the dried up Mediterranean Sea , was initially filled with the rising Mediterranean Sea along the entire course of the lower Rhone and only then gradually filled with the river sediments of the Aare-Sundgau-Strom and the Rhone has been.

Individual evidence

  1. ↑ State Office for Geology, Raw Materials and Mining (LGRB), Baden-Württemberg: Outline of Geological Development ( Memento from November 26, 2013 in the Internet Archive ) , information 12
  2. ↑ Daniel Contini, Michel Campy: La néotectonique de Franche-Comté (France), Vosges méridionales, Jura septentrional . Bulletin de l'Association française pour l'étude du quaternaire Année, vol. 18, no. 18-3-4, pp. 193-205 1981 (French)
  3. ^ Pierre Chauve: Guides géologiques régionaux, Jura . Masson & Cie., Paris 1975 (French)
    Michel Campy: Signification dynamique et climatique des formations et terrasses fluviatiles dans un environnement de moyenne montagne . In: Significations dynamique et climatique des formations et terrasses fluviatiles quaternaires (Colloque de l'Association Française pour l'Etude du Quaternaire, Paris, January 29, 1983) = Bulletin de l'Association française pour l'étude du quaternaire, vol. 21, No. 21-1-3, pp. 87-92 1984 (French)