A valley is a low area that will typically contain a river or stream running from one end to the other. Rift valleys arise principally from earth movements rather than erosion.
A valley is a landform that is characterized by its formation. There are several types of valleys, such as U-shaped, V-shaped, glacial, hanging, giant, and hollow valleys.
Valley Facts for Kids
- Rivers and streams carve valleys
- Some river and stream valleys are transformed by glacier
- Gradients of rivers determine how steep the sides are and how wide the floor is.
- As waters wind toward the sea, they strip sediment creating deep, slender canyons.
- For millions of years, water carves away at the mountain to form valleys.
Formation of valleys
Valleys may arise from several processes, but typically they are formed by erosion by moving water. In polar areas, valleys may be formed by glaciers, and in high altitudes, valleys may be formed by tectonic processes such as rifting.
Types of valleys
Valleys in mountains
When the layers of rock and soil get folded, rift valleys are made. People usually travel through the valleys to get to the other side of the mountain.
High in the mountains are many valleys, the biggest of which are made by a mountain stream that washes away soft soil and the smallest stones as it flows.
Valleys in hilly country
In countries where the hills are not very steep, rivers or streams run more slowly and often make a wider valley. This makes flat land good for growing food crops and raising animals.
Valleys in flat country
Some valleys are almost flat, like a large saucer, with lots of tributaries that carry water from mountains far from the main river. During heavy rain, floodwaters spread over the flat floor and make a flat flood plain.
Valleys made by glaciers
A glacier is a river of ice that starts in a high mountain, picks up more ice, gets bigger, and then melts. It leaves a valley of a deep U-shape and the fjords of Norway, and the sounds of New Zealand.
Valleys in plateau country
High land in a plateau is flat on top, with steep sides and a bottom that is flat. The water that makes streams on top of a plateau cuts down in wide valleys.
Sometimes the hills near the coast of a country sink into the sea. These sunken valleys make good harbors.
Depending on the bedrock over which the river flows, the elevational difference between its top and bottom, and indeed the climate, a river may develop the following types of valleys: a V-shaped valley, a meandering valley, or a meandering valley with a broad floodplain.
Rapid down-cutting of streams or rivers may occur as a result of localized uplift of land or an increase in the base level to which the rivers erode.
A glaciated valley has a characteristic U-shaped cross-section and is associated with mountain areas where glaciation has occurred or continues to take place.
The uppermost part of a glacial valley often consists of armchair-shaped hollows, or cirques, excavated by the rotational movement downslope of a cirque glacier. The valley’s shape is typically a U or trough shape with steep, even vertical sides and a relatively flat bottom.
Tunnel valleys formed by subglacial water erosion are large, long, U-shaped valleys and may have steep-sided flanks similar to fjord walls and flat bottoms.
The Scandinavian ice sheet had meltwaters flowing parallel to the ice margin, forming huge, flat valleys in northern Central Europe.
Transition forms and shoulders
In the Alps, shoulders are low and are located near the top of the valley. Some stress-tectonic regions of the Rockies and Alps (e.g., Salzburg) have side valleys that are parallel to each other.
Hanging valleys are associated with U-shaped glaciers, where a tributary glacier flows into a larger glacier. The shallower U-shaped valley is higher than the main valley and is often accompanied by waterfalls.
Glaciated terrain is not the only site of hanging streams and valleys. Hanging valleys are also the result of erosion and can be associated with the composition of the adjacent rock.
Trough-shaped valleys occur in regions of heavy topographic denudation and are found mainly in periglacial regions and tropical regions with variable wetness.
A box valley has a wide, relatively level floor and steep sides. Periglacial areas and mid-latitudes, as well as tropical and arid regions, are common habitats for them.
The Great Rift Valley is a trench with mountains and volcanoes that runs from Syria to central Africa.
The Western Rift Valley is rifting away from the Eastern Rift Valley. It will create a sea between the two parts of Africa.