What type of valley is characterized by a narrow and steep shape in the upper course of a river?

A V-shaped valley is characterized by its narrow and steep shape, particularly found in the upper course of a river. This type of valley is formed primarily through the process of vertical erosion, where the river cuts downwards into the landscape, creating steep sides that converge at the bottom. This process is common in mountainous or hilly terrains, where the flowing water has a high energy level, enabling it to carve through the rock and soil more effectively. As the river continues to erode the landscape, the result is a sharp, V-like profile, which distinguishes V-shaped valleys from other types of valleys.

In contrast, U-shaped valleys are typically formed by glacial activity, resulting in a wider and flatter valley floor with steep sides, rather than the narrow, pointed shape seen with V-shaped valleys. Broad valleys are expansive and gentle, often seen in the lower course of a river where the landscape becomes flatter and the river slows down. Flat valleys, similarly, lack the steep, narrow characteristics of V-shaped valleys and are usually associated with areas of minimal erosion.