Ur-Rhine

The primordial Rhine refers to earlier conditions in the course of the Rhine , especially before the river system of the Rhine received the growth from the Alpine region that is decisive for the current situation at the beginning of the current Ice Age .

Course and catchment area

Before the sinking rift valley of the Rhine caused the former Aare-Danube, which had already erupted to form the Rhône Valley, to flow northwards and become the Rhine at the beginning of the Pleistocene (around 2.6 million years ago), the sources of the Rhine were, as far as we know today, a little southwest of the Kaiserstuhls near Freiburg . The original Rhine, probably 400 kilometers long, was initially a river of the low mountain ranges such as the Weser or the Maas and in today's Rheinhessen it was about 45 to 60 meters wide. He went up to 20 kilometers to the west (today Mainzer Rhein knee did not yet exist), and then crossed a hill country that later became the Rhenish Slate Mountains should lift and the Rhine still in the valley trail of the former, yet easily recognizable Mulde the rugged Mittelrheintal cut leaves. Its mouth lay in the area of the Lower Rhine Bay . The paleogeographic situation is south of the Rhenish Massif still little known. The hypothesis that there was a section in Rheinhessen as a cave river is no longer relevant.

Early forerunners

Around 30 million years ago, in the Rupel stage of the Oligocene , a strait of sea stretched in the rift structures of today's Upper Rhine Rift and the Hessian Basin . This also meant that this area was not yet part of the catchment area. The upper reaches of this even smaller Ur-Rhine ran in the area of today's lower Lahn and the lower Moselle . The oldest forerunners can be traced through selectively preserved river sediments ( Vallendar gravel ), especially along the Moselle.

After the area of the Hessian Depression had become land-based in the course of the gradually rising low mountain range , the largest part of the Upper Rhine Graben also became the catchment area of the original Rhine. The initially much shorter forerunners of the Main and Neckar temporarily formed a common tributary system that reached the Rhine above the mouth of the Nahe .

Later stages of development

Selection of rubble from Rhine gravel from the lower terrace of the Upper Rhine , location: Schertle Lake near Karlsruhe

About 3 million years ago (towards the end of the Pliocene ) the former upper reaches of the Urdonau erupted to the Doubs and the Rhone . Not much later, in the Gelasium , this Sundgau stream broke through to the north to the Upper Rhine Rift. After this enormous increase in water volume, today's Alpine Rhine was still missing, which only gave up its northern course to the remaining so-called Feldberg-Danube in the middle Pleistocene around 450,000 years ago in favor of a more sloping drainage path west to the Upper Rhine via today's High Rhine Valley . There it followed different flow paths, alternating cold-age gravel and erosion phases , up to the Riss cold period of the Klettgau channel between today's Schaffhausen and Lauffen near Ettikon . Then he cut his present valley, which runs southwards. Since the valley was temporarily filled in during the Würm cold period , it has only found its way back to this river bed above it, which is still filled by fluvioglacial gravel, with the Rhine Falls .

The lowering of the Upper Rhine Rift, which continues to this day, causes a steeper gradient in its tributaries, which also causes them to erode backwards into the neighboring river catchment areas. In this way, several earlier Danube tributaries, coming from the north , were diverted ( tapped ) one after the other to the Main and Neckar , which explains their characteristic change of direction today. The Moselle was also able to make the old upper reaches of the Meuse its own. Most recently, the Wutach cut the upper reaches of the rest of the Danube in the southern Black Forest and has since fed its water to the Rhine.

Fauna on the Ur-Rhine

Ten million years ago, elephants and rhinos (sometimes also without horn), claw-footed ungulates , tapirs , three- toed original horses , small stags , forest antelopes , pigs , bear dogs (with the characteristics of bears and dogs ), cat bears , lived on the Ur-Rhine . insectivores , hyenas , saber-toothed cats and apes .

literature

René Hantke , River History of Central Europe. Sketches for a history of the earth, vegetation and climate of the last 40 million years , Stuttgart, Enke, 1993 ISBN 3432997817
Hans Schneider , On young crust movements in the pre-Alpine landscape between the southern Rhine rift and Lake Constance , In: Mitteilungen der Naturforschenden Gesellschaft Schaffhausen , 1973 and 1975

Individual evidence

↑ Note: For a while (from 1998) the Mainz geologist Winfried Kuhn put forward the hypothesis that the Ur-Rhine in Rheinhessen could have been a cave river. The assumption was based on the previously unique find of a limestone chunk about 35 cubic meters in size discovered in the former river bed of the Ur-Rhine.
↑ Oskar Keller: When the Alpine Rhine turned from the Danube to the Upper Rhine (PDF; 2.0 MB) on the diversion of a river in the Ice Age in: Writings of the Association for the History of Lake Constance and its Surroundings. Ostfildern 2009, pp. 193-208

[1] Note: For a while (from 1998) the Mainz geologist Winfried Kuhn put forward the hypothesis that the Ur-Rhine in Rheinhessen could have been a cave river. The assumption was based on the previously unique find of a limestone chunk about 35 cubic meters in size discovered in the former river bed of the Ur-Rhine.

[2] Oskar Keller: When the Alpine Rhine turned from the Danube to the Upper Rhine (PDF; 2.0 MB) on the diversion of a river in the Ice Age in: Writings of the Association for the History of Lake Constance and its Surroundings. Ostfildern 2009, pp. 193-208