Rhine

RHINE, one of the most important rivers in Europe. It is about 85o m. in length. It rises in Switzerland, later forms the boundary between Switzerland and Austria, then between Switzer land and Germany, France and Germany, then flows through Ger many and finally through Holland to enter the North sea.

Switzerland.

In the Swiss portion two mountain rivers, the Hinter Rhein and the Vorder Rhein, unite at Reichenau, 6 m. south-west of Coire, to form the main stream. The principal stream the Hinter Rhein, issues (7,271 ft.) from the glaciers of the Rheinwaldhorn (Adula group) west of Spliigen and flows eastward through the Rheinwald as a subsequent stream, parallel to the strike of the tectonic structures at this point (for geology see ALPS). On reaching the Schams valley it is diverted north ward and flows towards Reichenau parallel to a number of conse quent streams (their direction having been determined by the original structural surface of the land) some of which the Vorder Rhein has already beheaded. It receives many tributaries, the most important being the Albula (right) below Thusis.

The Vorder Rhein, a subsequent stream flowing along the strike of the structures, rises in Toma lake (7,691 ft.) near the Oberalp pass and is joined by a number of consequent (right) and obse quent streams (left) as it flows eastward past Disentis and Ilanz to Reichenau.

The valley of the combined river now becomes wider and is alluvium-filled. The consequent northward direction is again fol lowed below Coire (Chur) as far as Lake Constance. The largest affluents still join it on the right.

Below Buchs the valley becomes wider, the river meanders about, "is corrected" in many places, shortened by a canal at Diepoldsau and finally enters Lake Constance (q.v.) across a marshy delta. Between Sargans and the lake it forms the boun dary between Switzerland and Liechtenstein and Austria. On leaving the lake at Constance the Rhine flows westward as far as Basle. It drops 400 ft. along this stretch, the first part of which is across the Tertiary and Jurassic rocks of eastern Swit zerland.

Between Constance and Basle it receives important affluents along its left bank. Draining the northern slopes of the Glarus

and Bernese Alps are a number of consequent streams the most important being the Linth (Limmat), Reuss and the Aar.

Germany.

At Basle the Rhine turns sharply northward and assumes an entirely new complexion. Its course lies through the famous rift valley of the Rhine between the Vosges and the Black forest massifs and was initiated in Lower Oligocene times. It meanders as a wide stream with low banks and containing many islands. The river, which in the interests of navigation has been frequently "corrected," lies in a flat valley 20 m. wide which ends abruptly against the massifs on both sides. Also flowing in the valley is the tributary (left), the In, which rises near Basle and flows parallel to the Rhine for over 5o m. to join it below Strasbourg.

The Rhine forms the boundary between France and Germany from Basle to near Lauterbourg, opposite Karlsruhe, beyond which the river, flowing through Germany, passes Mannheim, where it is joined by the Neckar (right), Worms and Mainz, where it is joined by the Main (right). Here its course is blocked by the Armorican range of the Taunus and so the river turns sharply westward through a steep sided gorge to Bingen where it is joined by the Nahe (left). After Bingen it again resumes a northerly course but its valley is still a narrow cut through contorted Devonian slates and greywackes. It is joined by the Lahn (left) and then at Coblenz by the Moselle (left) which rises in the Vosges and drains, with its tributary the Saar, the region between the Vosges and the Ardennes. At Coblenz the valley becomes wider only to narrow again as the river passes on to Bonn, between the Eifel and the Westerwald uplands.

At Bonn the river leaves the Armorican ranges and passes on to Tertiary, glacial and alluvial deposits, but the hills continue to rise on the right of the river as far as Dusseldorf. The Rhine now passes through the great industrial region of western Ger many, is very sluggish and meanders over an almost level plain.