U-shaped valleys, trough valleys or Glacial troughs, are formed by the process of glaciation. they are characteristic of mountain glaciation in particular. they have a characteristic U shape in cross- section, with sleep, straight sides and a flat or rounded bottom Glaciated valleys are formed when a glacier travels across and down a slope, carving the valley by the action of scouring. when the ice recedes or thaws, the valley remains, often littered with small boulders that were transported within the ice, called glacial till or glacial erratic.
Examples of U-shaped valleys are found in mountainous regions throughout the world including the andes, alps, Caucasus Moutains, Himalaya, Rocky mountains, New Zealand AND The Scandinavian Mountains. they are found also in other major European mountains including the Carpathian mountains,