The true source of the Adige is in some small lakes on the summit of the Reschen Scheideck Pass (4902 ft.), and it is swollen by several other streams, near Glurns, where the roads over the Ofen and the Stelvio Passes fall in.
Thence to the Reschen Scheideck Pass the main chain is ill-defined, though on it rises the Corno di Campo (10,844 ft.), beyond which it runs slightly north-east past the sources of the Adda and the Fra g ile Pass, sinks to form the depression of the Ofen Pass, soon bends north and rises once more in the Piz Sesvenna (10,568 ft.).
The little Reschen lake which forms the chief source of the Adige is only 13 ft.
Below the Reschen Scheideck Pass (4902 ft.), and by it is but 5 m.
As regards the main divisions, three are generally distinguished; the Western Alps (chiefly French and Italian, with a small bit of the Swiss Valais) being held to extend from the Col de Tenda to the Simplon Pass, the Central Alps (all but wholly Swiss and Italian) thence to the Reschen Scheideck Pass, and the Eastern Alps (wholly Austrian and Italian, save the small Bavarian bit at the north-west angle) thence to the Radstadter Tauern route, with a bend outwards towards the south-east, as explained under (2) in order to include the higher summits of the SouthEastern Alps.
Strictly speaking, we should follow the Reschen Scheideck route down the Adige valley, but as this would include in the Central Alps the Ortler and some other of the highest Tirolese summits, it is best (remembering the artificial character of the division) to draw a line from Nlals southwards either over the Umbrail Pass (the old historical pass) or the Stelvio (wellknown only since the carriage road was built over it in the first quarter of the 19th century) to the head of the Valtellina, and then over the Aprica Pass (as the Bergamasque Alps properly belong to the Central Alps) to the Oglio valley or the Val Camonica, and down that valley to the Lake of Iseo and Brescid.
Bernina Alps (from the Maloja to the Reschen Scheideck and the Stelvio, south and east of the Val Bregaglia and of the Engadine and north of the Valtellina).
Silvretta and Rhatikon Ranges (from the Fluela Pass to the Reschen Scheideck and the Arlberg Pass).
Ortler, Oetzthal and Stubai Ranges (from the Reschen Scheideck and the Stelvio to the Brenner Pass, south of the Inn Valley, and north of the Tonale Pass).
Io,640 Ramoljoch (Vent to Gurgl), snow ï¿½ 1'0.479 Langtaufererjoch (Vent to the Reschen Scheideck Pass), snow.
6,870 Reschen Scheideck Pass (Landeck to Meran), carriage road 4,902 Brenner Pass (Innsbruck to Verona), railway over.