Other interesting glacially carved valleys include: A tunnel valley is a large, long, U-shaped valley originally cut under the glacial ice near the margin of continental ice sheets such as that now covering Antarctica and formerly covering portions of all continents during past glacial ages.. Valley definition is - an elongate depression of the earth's surface usually between ranges of hills or mountains. A valley carved by glaciers is normally U-shaped and resembles a trough. Financial Stability Rating affirmed by Demotech, Inc. Most present U-shaped valleys started as V-shaped before glaciation. A mountain fold is the opposite of a valley fold – the paper folds to the opposite side. The broader a mountain valley, the lower its shoulders are located in most cases. Their cross-sections exhibit steep-sided flanks similar to fjord walls, and their flat bottoms are typical of subglacial glacial erosion. Hanging valleys are also simply the product of varying rates of erosion of the main valley and the tributary valleys. Trough-shaped valleys occur mainly in periglacial regions and in tropical regions of variable wetness. As the ice melts and retreats, the valley is left with very steep sides and a wide, flat floor. The severe slope denudation results in gently sloping valley sides and their transition to the actual valley bottom is unclear. A long, narrow region of low land between ranges of mountains, hills, or other high areas, often having a river or stream running along the bottom. In some stress-tectonic regions of the Rockies or the Alps (e.g. Examples of U-shaped valleys are found in every mountainous region that has experienced glaciation, usually during the Pleistocene ice ages. Shallower slopes may produce broader and gentler valleys. The glaciers carved it out wider and deeper, simultaneously changing the shape. Depending on the topography, the rock types and the climate, a variety of transitional forms between V-, U- and plain valleys can form. Often, waterfalls form at or near the outlet of the upper valley. What does mountain expression mean? This term is commonly used in Ireland, New England, Appalachia, and the Ozarks of Arkansas and Missouri to describe such geographic features. Since the surfaces of the glaciers were originally at the same elevation, the shallower valley appears to be 'hanging' above the main valley. This article is about the physical-geographic term. Valley Anesthesia Educational Programs, Inc. Valley Association for the Education of Young Children, Valley Association of Retarded Children and Adults. Box valleys have wide, relatively level floors and steep sides. There are various forms of valley associated with glaciation that may be referred to as glacial valleys. the Tyrolean Inn valley – the shoulders are quite low (100–200 meters above the bottom). The exact shape will depend on the characteristics of the stream flowing through it. Die Region Silicon Valley ist ungefähr 100 Kilometer lang und 30 Kilometer breit und umfasst eine Fläche von rund 4000 km². However, in the lowest stretch of a river, where it approaches its base level, it begins to deposit sediment and the valley bottom becomes a floodplain. Historic siting of villages within the mainstem valleys, however, have chiefly considered the potential of flooding. 2. The tributary valleys are eroded and deepened by glaciers or erosion at a slower rate than that of the main valley floor, thus the difference in the two valleys' depth increases over time. Learn how and when to remove this template message, Black Canyon of the Gunnison National Park, List of largest rifts, canyons and valleys in the Solar System, "Illustrated Glossary of Alpine Glacial Landforms - Hanging Valley", List of rivers that have reversed direction, https://en.wikipedia.org/w/index.php?title=Valley&oldid=989535601, Articles needing additional references from May 2013, All articles needing additional references, Wikipedia articles needing clarification from November 2017, Creative Commons Attribution-ShareAlike License.