The river rises near the border with Ticino and is surrounded by up to 3100m high mountains. The river flows through the Lumnezia. In Suraua, the Vals Rhine flows into the Glogn. After a few more kilometers, the Glogn flows into the Vorderrhein at Ilanz. In the upper reaches of the river has cut a deep gorge, which has uncovered black shale in a few places. During the snow melt and after rains the river water is usually dark gray.
