A high valley that converges with, and breaks off abruptly into, a deeper valley, often over a cliff, is known as a hanging valley. Hanging valleys occur when glaciations or water ﬂow erode the main valley to a depth well below that of its tributary valleys. A hanging valley might include a hanging glacier, or end in a waterfall such as Bridal Veil Falls in Yosemite or Bird Woman Falls seen from the Going-to-the-Sun Highway over Logan Pass in Glacier National Park. Seacoast streams that fall over sea cliffs, which result from erosions caused by wave action and tectonic uplift, emerge from hanging valleys. Washes in the American Southwest often form hanging valleys, such as the seventy-ﬁve-foot cliff where Johns Canyon ends above the gorge of the San Juan River in the Grand Gulch country of southern Utah.