A tributary to a U-shaped glacial valley which, instead of entering the valley at the same level as the main stream, enters at a higher elevation, frequently as a waterfall. These different stream levels are a result of the rapid downcutting of the glacier being much faster than the slower downcutting of the tributary stream.
a valley eroded by a small tributary glacier, such that the elevation of the valley floor is higher than the elevation of the valley floor that the hanging valley joins. The erosive power of glaciers is dictated by their size: the larger a glacier, the farther down into the landscape it can erode. Thus the valley floors of small tributary glaciers will be higher in elevation that the valley floor of the larger glacier that the small tributary glacier joins.
Usually a river valley or small canyon that has been cut across by a glacier, leaving it at a high elevation above a larger valley floor. Several waterfalls in Yosemite Valley flow through hanging valleys.