In the high mountains, at the far western end of the Catalan Pyrenees, on the French border, in the upper valley of the Garonne, Vall d'Aran has the peculiarity of being an Atlantic valley on the northern slopes of the range, which descend to the plains of Aquitaine. That is why the climate is colder, with heavy snowfalls, and the inhabitants speak an offshoot of the Gascon language, which belongs to the Provencal family. Surrounded by towering peaks (Tuc de Molières, Besiberri, Gran Tuc de Colomers), with huge glacial corries (Saboredo, Colomers, Restanca, Mar, etc.) are the sources of the Garonne, which flows through the middle of the valley where most of the population is concentrated, the Noguera Pallaresa (NE) and the Noguera Ribagorçana (S), tributaries of the Segre. The Port de la Bonaigua is the traditional road over the pass to Catalonia, though the Vielha tunnel has provided easier access in modern times.