U- shaped Valley
A U-shaped valley or also known as glacial trough is formed by the process of glaciation. Glaciation is the process, condition, or result of being covered by glaciers or ice sheets. The U-shaped valley has the characteristics of U-shape, with steep, straight sides and a flat bottom. Glaciated valleys are formed when a glacier travels across and down a slope, caving 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.
As a glacier moves downhill through a valley, the shape of the valley is transformed. A V-shaped valley is transformed into a U-shaped valley through the glacial erosion processes of plucking and abrasion. This results in large rocky material (glacial till)
being carried in the glacier. A material called boulder clay is deposited on the floor of the valley. As the ice melts and retreats, the valley is left with very steep sides and a wide, flat floor. A river or stream may flow through the valley due to melt-water from the glacier.
As a glacier moves downhill through a valley, the shape of the valley is transformed. A V-shaped valley is transformed into a U-shaped valley through the glacial erosion processes of plucking and abrasion. This results in large rocky material (glacial till)
being carried in the glacier. A material called boulder clay is deposited on the floor of the valley. As the ice melts and retreats, the valley is left with very steep sides and a wide, flat floor. A river or stream may flow through the valley due to melt-water from the glacier.
U-shaped valley in Leh valley, Ladakh, NW Indian HImalaya. The glacier visible at the head of the valley is the last remnants of the formerly much more extensive valley glacier which carved this valley.
Hanging Valley
Valley glaciers can also leave hanging valleys in the glaciated landscape. Hanging valleys are formed when tributary glaciers converge with the primary glaciers and later retreat. The primary glacier is so thick that it meets the height of the smaller tributary glacier. When the glaciers melt, the valley is left hanging high above what is now a river in the primary valley floor. Hanging valleys today are often characterized by waterfalls where the tributary glacier used to be.
Bridal Veil Falls in Yosemite National Park flowing from a hanging valley.