A hanging valley is a distinct landform in a glaciated landscape that forms when a smaller glacier, typically a tributary glacier, enters a main glacial valley. The term “hanging” refers to the fact that the floor of the smaller valley is elevated or “hangs” above the floor of the larger, main valley.
Hanging valleys are a result of the differential erosion that takes place during glacial activity. Main valleys, often carved out by larger glaciers, tend to be deeper and wider due to the greater erosive power of the ice. When smaller tributary glaciers flow into these larger valleys, they lack the same erosive force and are not able to carve as deep into the landscape.
As a result, the floor of a hanging valley is situated at a higher elevation compared to the floor of the main glacial valley. When the glaciers recede, the tributary valleys are left perched above the main valley, creating a noticeable step or cliff-like feature. This elevation difference can be observed in the form of waterfalls cascading down from the hanging valley into the main valley, as the smaller stream that flows through the hanging valley encounters the larger main valley below.
Hanging valleys are commonly found in areas that have been shaped by glacial activity, such as regions with U-shaped valleys and other glacial landforms. They are often seen in mountainous landscapes and are indicative of the complex erosional processes that occur during glaciation and subsequent deglaciation. The study of hanging valleys contributes to our understanding of past glaciations, landscape evolution, and the interactions between different glaciers within a larger glacial system.