What is the valley of the river and what are its features?
The valley is a view of the earth's surface, formed as a result of the long-term influence of water flows, even if at present this area is dry and waterless. The relief form of the valley is always elongated and negative (reduced) in relation to the adjacent neighborhood. And in the longitudinal profile of the valley one-sided bias is necessarily observed.
Such a surface has several varieties of configurations, a certain structure, different origins and features, which will be described in detail. There will also be considered material about what a mountain valley and a flat valley are, how they came about, how they differ, how they relate to gorges and canyons, which valleys in the world are the most famous and interesting.
Rivers for centuries flow through the channels formed by water flows. In various places on their way, they rush at different speeds, destroying the coast, carrying away the eroded rock, silt and sand.Where the flow rate increases, destruction, dissolution and leaching of the rocks (erosion) occur. And in places where the movement of the river is quiet, the material carried by the water is deposited (accumulated). The width of the channel and the rate of flow of the rivers vary in different years, and also depending on the season during heavy rains and spring floods. Gradually, the channel deepens. In some areas it can periodically change its position, transforming the surrounding relief. Thus, by the destruction, erosion, transfer of rocks from one place and their accumulation in another, each river forms its own valley.
What is a mountain valley?
Compared with the rivers of the plains, mountain streams have a smaller width and much faster. Water moves along natural rifts and hollows, flowing down to the lowest places. The rock holds back the water flow, preventing the river bed from expanding; therefore, the river bottom rather quickly deepens, forming stepped, steep or convex slopes. Mountain streams can wash out narrow channels, called cracks (gorges), with high steep slopes. Or form canyons - the same gap, but much wider.Also, mountain rivers form gorges - depressions with steep convex or stepped slopes. Gaps, canyons, gorges are some of the many types of mountain river valley forms.
But there are vast mountain spaces in shape in the form of depressions resembling giant troughs, or, as geographers say: trough-shaped in transverse profile. It is known that such a valley was originally created by glaciers, and the meltwater flows continued to form the landscape.
What is a valley? On spacious land areas, where the elevation drops do not exceed 200 m, and the slope angle is no more than five degrees, the river slows down its course, spreading out a wide channel. As a rule, material accumulates in such places, which is carried by water in the form of different types of soil, rock, organic residues, which forms a fertile green valley with a diverse plant and animal world.
The structure of the plain valley
The river channel is linear, winding, wandering (with changing location), branched into several sleeves. Every year, for a short time, floods and floods raise the water level in the river and increase the flow velocity.During these periods, water flows erode the coast, transforming the coastline and making the slope steeper. This undermined part of the coast and the riverbed form a floodplain.
The valley of the river on the sides is limited by the slopes, on which the steps can have terraces. These are areas that once belonged to the river floodplain, which were exposed after a change in the position of the channel and its deepening. Both lowland slopes of the river are low, high, gentle, steep, different or the same in height and steepness and can repeatedly change their relief along the channel.
The structure of the mountain valleys is similar, although the relief and the landscape accompanying the rivers are significantly different.
Origin of the valleys
In geology and geography, fluvial, tectonic, erosion, and glacial origin is distinguished for river valleys.
- Fluvial Valley is formed exclusively by the action of water flows. These include the majority of lowland valleys.
- Tectonic - mostly mountainous river valleys, which pass through the deep faults and depressions of the earth's crust, repeating their direction. An example is the Valley of Geysers.
- Erosion valleys are formed by leaching the rock with a water stream to form furrows, which gradually deepen. A great example is the Grand Canyon in the United States.
- Glacial valleys are deep hollows that have been plowed out, advancing, giant glaciers during the period of the last global glaciation. When warming in these areas formed river valleys. Such troughs are called trogs, which means “trough” in German. This definition characterizes the transverse profile of hollows with concave steep slopes and a wide bottom. This origin has the Lhasa Valley.
Most famous valleys
The green valley of the Amazon with its winding, divided into many branches of the channel is considered the largest in the world. This plain valley of South America is of fluvial origin with rich flora and fauna.
The most famous and unique valley is the Grand Canyon, formed by the Colorado River in Arizona. He is not only one of the most beautiful and deepest in the world. For 65 million years, the river flow washed out a rather soft rock of shale, limestone, sandstone, revealing traces of several geological eras of the planet.The maximum depth of the canyon reaches 1800 m. The object is included in the UNESCO list of protection.
Kamchatka Valley geysers - the only geyser field of Eurasia and one of the largest on the planet. This is a volcanic canyon of tectonic origin, formed by the confluence of two rivers: Noisy and Geysernaya. Approximately on a two-kilometer square gush forth with boiling water 20 large geysers and there are many smaller hot springs. This object is one of the wonders of the Russian land.