With aid of diagrams, explain the formation of a U shaped valley

U shaped valleys are formed from V shaped valleys. Ice and snow accumulates in the V shaped valley and enters the cracks where it freezes and expands overnight. As the snow melts during the day this relieves the pressure in the cracks and weakens the rock. This process is called freeze thaw weathering. The ice will form a glacier and move downwards through the valley due to gravity. The weakend rock is pulled from the valley floor through a process called plucking. These rocks will abrade the valley floor and begin to steepen and widen the shape of the valley. The valley is the left with a flat floor and steep walls which is the final form of a U shaped valley.