What types of stream valley forms in mountainous areas?

In mountainous areas, stream valleys typically form as either V-shaped valleys or U-shaped valleys. V-shaped valleys are created by the erosive action of fast-flowing rivers cutting downwards through the landscape, while U-shaped valleys are formed by glacial activity that carves out a broader, deeper valley. Additionally, hanging valleys can occur where tributary streams flow into a main valley at a higher elevation, often resulting in waterfalls. Each type reflects the geological processes and climate of the region.