Rhine

At 1,320 km (820 miles), the Rhine (German Rhein, French Rhin, Dutch Rijn, Romansch: Rein) is one of the longest rivers in Europe. The name of the Rhine in all these languages comes from Celtic Renos, literally "that which flows", from the Proto-Indo-European root *rei- ("to flow, run"), which also gave the word "to run" in English.

Geologic History

Alpine Orogeny

Since the Rhine flows from the Alps, a precondition of its existence is the uplifting of the Alps, which began in the Alpine Orogeny. The stage was set in the Triassic Period of the Mesozoic Era, with the opening of Tethys Sea between the Eurasian and the African plates, between about 240 MBP and 220 MBP. The Mediterranean descends from this somewhat larger Tethys sea.

Related Topics:
Alps - Alpine Orogeny - Triassic - Mesozoic - Tethys Sea - Plates - MBP - Mediterranean

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At about 180 MBP, in the Jurassic Period, the two plates reversed direction and began to compress Tethys floor, causing it to be subducted under Eurasia and pushing up the edge of the latter plate in the Alpine Orogeny of the Oligocene and Miocene Periods. Several microplates were caught in the squeeze and rotated or were pushed laterally, generating the individual features of Mediterranean geography: Iberia pushed up the Pyrenees; Italy the Alps, and Anatolia, moving west, the mountains of Greece and the islands. The compression and the orogeny continue today, as the ongoing raising of the mountains a small amount each year and the active volcanoes signify.

Related Topics:
Jurassic - Oligocene - Miocene - Pyrenees - Italy - Anatolia - Greece

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Just to the north of the Alpine Orogeny were highlands resulting from an earlier orogeny (Variscan) along similar lines. These highlands helped to divert the Rhine to the west; however, the Rhine's course is set by the Rhine graben, a rift that opened in the Eocene and Oligocene periods between the western Alps and the central Alps, caused by their moving in slightly different directions. The rift does not seem to be active now.

Related Topics:
Variscan - Eocene - Oligocene - Alps

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Stream Capture

The watershed of the Rhine reaches into the Alps today, but it did not start out that way (Berendsen & Stouthamer, 2001; Fig. 2.2). In the Miocene period, the watershed of the Rhine reached south only to the Eifel and Westerwald hills, about 450 km north of the Alps. The Rhine then had the Sieg as a tributary, but not yet the Mosel. The northern Alps were drained by the Donau then.

Related Topics:
Alps - Miocene - Eifel - Westerwald - Sieg - Mosel - Donau

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Through stream capture, the Rhine extended its watershed southward. By the Pliocene period, the Rhine had captured streams down to the Vosges mountains, including the Mosel, the Main, and the Neckar. The northern Alps were drained by the Rhône then.

Related Topics:
Stream capture - Pliocene - Vosges - Main - Neckar - Rhône

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By the early Pleistocene period, the Rhine had captured most of its current Alpine watershed from the Rhône, including the Aare. Since that time, the Rhine has added the watershed above Lake Constance (Vorderrhein, Hinterrhein, Alpenrhein; captured from the Rhône), the upper reaches of the Main (beyond Schweinfurt), and the Vosges mountains (captured from the Meuse) to its watershed.

Related Topics:
Pleistocene - Aare - Lake Constance - Vorderrhein - Hinterrhein - Alpenrhein - Schweinfurt - Meuse

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Ice Age

The Pleistocene (~2.5 million years ago - 10,000 years ago) was the geological period of the Ice Ages. Since approximately 600,000 years ago six major Ice Ages occurred, in which sealevel dropped 120 m, and much of the continental margins became exposed. In the Early Pleistocene, the Rhine followed a course to the NW, through the present North Sea. During the so-called Elsterien glaciation (~420,000 yr BP, marine oxygen isotope stage 12) the northern part of the present North Sea was blocked by the ice, and a large lake developed, that overflowed through the English Channel. This caused the Rhine course to be diverted through the English Channel. Since then, during glacial times, the river mouth was located near Brest(France), and rivers like the Thames, and Seine became tributaries to the Rhine. During interglacials, when sealevel rose to approximately the present level, the Rhine built a delta in what is now called The Netherlands.

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During the last Ice Age (~70,000-10,000 yr BP= Before Present), at the end of the Pleistocene, the lower Rhine flowed roughly west through the Netherlands and then to the southwest, through the English Channel, and finally to the Atlantic Ocean. The English and Irish Channels, the Baltic Sea and the North Sea were still dry land, mainly because sea level was approximately 120 m lower than today. At about 5000 BC, flooding and erosion began to open the English Channel.

Related Topics:
Ice Age - Pleistocene - Baltic Sea - North Sea

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Most of the Rhine's current course was not under the ice during the last Ice Age, although its source must then have been a glacier. A tundra with Ice Age flora and fauna stretched across middle Europe from Asia to the Atlantic Ocean. Such was the case during the Last Glacial Maximum, ca. 22,000-14,000 yr BP, when ice covered Scandinavia and the Baltic, Britain and the Alps, but left the space between as open tundra. The loess, or wind-blown dust over that tundra settled in and around the Rhine Valley, contributing to its current agricultural usefulness.

Related Topics:
Tundra - Last Glacial Maximum - Loess

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These events were well within the residence of man. Melt water adding to the ocean and land subsidence drowned the former coasts of Europe. The water is still rising, at the rate of about 1-3 mm per year. Further drowning is to come.

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Rapid warming and change of vegetation to open forest began about 13,000 BP. By 9000 BP, Europe was fully forested. About 7000-5000 BP a general warming encouraged migration up the Danube and down the Rhine by peoples to the east, who may also have been encouraged by the sudden massive expansion of the Black Sea as the Mediterranean burst into it through the Bosphorus at about 7500 BP. At least one unsuccessful search for remains of villages on the floor of the Black Sea has been conducted.

Related Topics:
Danube - Black Sea - Bosphorus

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