western spur of the Cottian Alps (q.v.) in southeastern France, lying between the Arc and Isère river valleys (north) and the upper Durance River valley (south). Many peaks rise to more than 10,000 feet (3,050 m), with Barre des Écrins (13,459 feet 【4,102 m】) the highest. The mountains include the Massif du Pelvoux (Massif des Écrins) and the Belledonne and Grandes Rousses ranges. Skiing and mountain climbing are popular in the region.