The valley begins at the Maloja Pass (1815 m) which connects it to the Engadin (the valley of the Inn, which is part of the Danube basin). There the Orlegna river extends westwards and joins the Mera river to Chiavenna shortly after which the Mera joins with the Liro and turns south towards Lake Como. From Chiavenna to Maloja, a distance of 32 km, the valley rises 1482 m.