An integral component of the mountain landscape is the valley. This is a special form of relief, which is an elongated cavity. It is formed more often from the erosive effects of flowing water, and also due to some features in the geological structure of the earth's crust.
What does the word "valley" mean
All kinds of beams, ravines, and gullies caused by intermittent watercourses are the rudimentary forms of valleys. As a result of washing off the soil with river water along the coast, lowlands arise, which, when combined with each other, can form whole systems.
Their relief is unstable and is able to change depending on the direction of river flows. A mountain or river valley is part of a complex ramified system of landscapes. It consists of several elements:
- Slopes are surface areas that delimit the valley from the sides. They vary in height and, in addition, may have the same or different steepness (when one shore is gentle and the other is steeper).
- The bottom (bed) is the most even and lowland part of the valley.
- The sole is the place where the bottom and slopes connect.
- Brow - the line of contact of the slopes with the surface of the surrounding area.
- Terraces. These are small aligned horizontal platforms located at different heights from the bottom of the valley.
Varieties of valleys
Geologists divide all valleys into mountain and plain. They are formed, according to the name, in a particular area. Mountain valleys are landforms characterized by considerable depth and uneven steep slopes.
The plains are wider, with less pronounced depth and with gentle flat slopes, significantly inferior to the width. The main element is the wide bottom of the cut. The estuarine part of the valley is often a bay where the river flows.
Depending on the location of the valley, the meaning of this word is interpreted in different sources. In some, a “valley” is an elongated hollow between mountains or hills, and in others it is a space below the surrounding area, usually located along a river.
River valley
It is formed as a result of exposure to flowing water. The river valley is an elongated lowland on the surface of the land, which has a length from source to the mouth. By its appearance, experienced geographers can easily determine the age and stage of development, as well as the geological structure of the area, the movement of the earth's crust in the river basin, learn about the forces of weathering and much more.
A river valley is a branched, isolated system that contrasts sharply with the surrounding landscape. A direction-changing river flow often leads to variability and rebuilding of valleys that periodically rejuvenate. Their hydrological features have no analogues among other types of landscapes. This applies to seasonal floods and rain floods. Spills occur synchronously throughout the valley profile.
The slopes of the river valleys are usually covered with forest, and floodplains are used for grasslands, sowing crops, and the most secure places from erosion in these areas are settlements.
For large rivers, the floodplain can occupy an area with a width of 15 to 30 km. It can be low, flooded annually, and high, which goes under water only during severe floods.
The terraces that the river valley has are peculiar notches that can tell a lot about the history of the river. Root rocks lie at their base , and the surface is covered with river sediments. On such terraces one can find various deposits of former swamps and lakes, the remains of plants and animals that existed for a long time.
Gorges and valleys are components of a mountain landscape. They differ in steep slopes and rapids. The river cuts through the rock with a powerful stream, forming gorges and canyons with almost steep slopes where there are no terraces.
The profile of young valleys has areas where rivers swiftly rush along the rapids. Over time, under the influence of the flow, the place is leveled. The flowing profile that the valley acquires is a sign of its maturity.
Forms of river valleys
The formation of the valley is influenced by many factors. Among them are tectonic processes that determine the direction, rocks, creeping of soils and their erosion by atmospheric precipitation. All this contributes to the creation of various forms of river valleys.
Presses, or gorges, are formed due to deep erosion and are distributed mainly in high mountain regions. Their steep slopes consist of strong rocks. The bottom in its entire width is a river bed.
Canyons are narrow valleys that form in areas where beds of different strength occur. The deepest canyon on the Colorado River (in the USA) is considered to be up to 2 km deep.
In the floodplain valleys , the river bed occupies only a small part. They are characteristic of the plains. The whole valley along with terraces can have a width of up to 100 or more kilometers. In these areas, crops are grown and cattle grazed. Not without reason in many encyclopedic sources the word "valley" is interpreted as "fertility", "life", "cultivation".