What is lateral erosion

Erosion; Side erosion; Deep erosion; Valley formation; Retreating erosion

weathering is a chemical and physical destruction of the rocks and minerals on the earth's surface. When the rock materials become small, they come about transport to a lower level through flowing water, wind (deflation) and ice cream (Exaration). If material is carried away by the surf on the coast of the sea, one speaks of Abrasion. These processes, i.e. the destruction, transport and deposition of rocks and minerals are called erosion designated. The erosion consequently compensates for differences in relief on the earth's surface. The level of the sea level forms the lowest possible erosion base. A lake or basin, for example, can be a local erosion base be.

Illustration 1 : Physical destruction and transportation by rain, wind, ice and running water

As Figure 1 shows, water plays a key role in destruction and transport. The flowing water transports rock particles and "sandes" them further on the subsurface. The strength of the erosion in running water therefore depends on several factors:

  • Amount of water and speed
  • Condition of the subsoil
  • Amount of "emery material" carried along

The speed of the water varies within the river. In the areas of greater speed it comes to Removal while slow speeds too Deposits to lead.

Figure 2: In straight rivers, the greatest speed is in the middle and on the surface. The river bed is primarily eroded into the depths
Figure 3:In curved rivers, the greatest speed of the water, but also the lowest speed is on the sides. This leads to erosion (side erosion) on one side and deposits on the other.

Through the deposition described in Figure 3 and simultaneous erosion (Side erosion) rivers follow the usual meandering course. The single loop of such a gradient is called a meander designated. Over time, these meanders break through.

The sideways wandering of the rivers brings next to the linear removal (erosion) also involves extensive removal. In the Duisburg area, for example, there are still flat areas on the Rhine that are still flooded (Floodplains). Also the Terracing of the Lower Rhine is partly due to the erosion work of the rivers (see terracing)

In addition to the previously described Side erosion there are still those Deep erosion of the river. The river cuts deeper and deeper into its bed. The Side erosion in cooperation with the Deep erosion then leads to valley formation. In addition to the two forms of erosion, the valley cross-section is still from the Hang denudation (Denudation = surface removal) dependent. The following table gives a rough overview.

TABLE A: Factors for shaping the valley cross-section
Deep erosionSide erosionHang denudationValley type
large----KLAMM
largelowmoderateKERBTAL
moderatemoderatemoderateKERBSOLENTAL
lowlargemoderateSOLEN-KASTENTAL
lowlowlargeMULDENTAL

 

Figure 10: Morphologically resistant limestone e.g., mostly in high mountains (morphologically resistant means Not physically hard) Since the limestone quickly enables the formation of a deep drainage channel, the surrounding area remains "spared", so to speak.

Figure 11: Slight side erosion and moderate slope denudation slope the side walls.The slopes are therefore not caused by the river itself, but by weathering, landslides, frost blasting, etc.
Figure 12: If the deep erosion does not progress so quickly and allows the side erosion and the denudation a little time, it comes to bottom valley formation. The material is no longer as morphologically resistant as with the gorge. The river with its loop movements (see above) deposits accumulation material.
Figure 13: In the case of very large side erosion and low depth erosion, the bottom or box valley forms. Here, too, there can be accumulations due to the flow (Fig.12). The name is then Kastental with accumulation
Figure 14: If the slope denudation predominates, only hollows are formed. Side erosion and deep erosion are relatively low. Basin valleys are mostly a result of solifluction (see below).

The one mentioned in Figure 14 Solifluction is the strongest form of ablation at all. It only occurs during the Ice Ages or in polar regions as the condition is a Permafrost layer, i.e. a permanently frozen layer of soil and a soil that thaws in summer.

Figure 15: The basis of the solifluction are the three layers: the soil that only thaws in summer, the permanently frozen permafrost layer and the soil that never freezes due to geothermal energy.
Figure 16: Triggered by gravity, the summer thawing ground slips on the mash of rubble, water and ice into the valleys.
Figure 17: If solifluction often occurs, the relief levels out. Large areas of flat land arise.

 

Figure 18: The canon does not fit into the scheme of the valley shapes mentioned. It stands roughly between the gorge and the Kerbtal. Canon's have a clear staircase of walls and heaps. The reason for this is the alternation of flat, hard and soft sediments.

A very important factor in the erosion performance of water described so far is the proportion of rubble, sand and similar emery material. The water alone has almost no erosion capacity. If the emery material is removed from the water from the start, there will be no erosion.

Figure 19 : If the "emery material" is withdrawn from the river by an upstream lake (a local erosion base), it loses its erosion power in the further course. It is only thanks to this fact that waterfalls such as the Niagara Falls or the Rhine Falls near Schaffhausen do not lose their steep flanks.
Figure 20: If the emery material is not withdrawn from the river by an upstream lake as a catch basin (Fig. 19), it will remove the steep flanks. Over time, waterfalls become rivers with a slight gradient. If such a flank is removed, the gradient and inevitably the erosion force greatly reduced, then geographers speak of Retreating erosion.