The two main branches of the Rhine, the Hinter Rhine and the Vorder Rhine, unite at Reichenau, 6 m.
(1) The principal stream is considered to be that of the Hinter Rhine, which issues (7271 ft.) from the glaciers of the Rheinwaldhorn group, and then flows first N.E.
Above sea-level), the Fuschl-see (2095 ft.), the Hinter-see (2580 ft.), the Ober-Trumer-see and Nieder-Trumer-see are all situated in the Alpine foothill region.
In the former class are the Isere, the Rhone, the Aar, the Ticino, the Tosa, the Hinter (or main) Rhine and the Linth; while in the latter class we have the Durance, the Po, the Reuss, the Vorder and middle branches of the Rhine, the Inn, the Adda, the Oglio and the Adige.
The route quits that of the Albula Pass at Thusis, passes first through the celebrated gorge of the Via Mala, then through the Schams basin and past Andeer, beyond which the Rofna gorge gives access to the village of Sphigen (from which the pass takes its name) in the upper reach of the main or Hinter branch of the Rhine.