Downhill creep

Soil creep is a slow downward movement of a hill or mountain slope without the formation of demolition forms. The decisive factor is the continuous flow of movement. Soil creep occurs in unconsolidated material by expansion and contraction of the material by freeze-thaw cycles ( Regelationsfließen ) and the swelling and shrinking of argillaceous material, or in soft, deformable rocks by the load overlying rock layers (continuous creep, Eng. Continuous creep ). In the subordinate importance because of the very low rates of locomotion can soil creep by displacement due to the felling of raindrops arise (splash - creep) or go back to the formation of Kammeis.

Overview

However, the operations of the soil not creep back to various causes, as opposed to on the flow as a result Solifluction water saturation. The Versatzdenudation caused by dislocation of material on an inclined surface, such as mountain slopes, in the expansion and contraction of loose material or increase due to ice formation. Continuous creep is caused by the deformation of soft rocks under load, and splash - creep by the impact of raindrops.

In contrast to the denudation by slipping or sliding the soil creep does not take place at a certain sliding surface. Thus, the downslope displacement of material is not at any point of the slide mass equal; The offset amounts are lowest in the control of the surface at the highest, near the output surface. It is an unbroken, plastic deformation.

Soil creep is up to date sickle growth of trees and on the hook hitting rock layers visible, partly also to subsidence at the bottom of a slope, on Plaiken and increased erosion during heavy rain. The threshold speed is of the order of one to two centimeters in, but may be significantly lower.

Versatzdenudation

The Versatzdenudation has a downslope movement of the result by the soil particles are displaced downslope (hence the term ). In the case of Versatzdenudation by expansion and contraction of the soil material extends perpendicular to the slope and contracts later back together. However, the reversal of the movement is no longer perpendicular to the slope, but the force of gravity vertically downward, as a result, so obliquely down the slope.

This directed movement depends on following factors:

• The amount of the increase in volume,
• The slope - the bigger it is, the greater the amounts of movement,
• And the frequency of expansion or contraction cycles or rainfall events.

The amount of downslope movement is at the surface and decreases to the base of freezing and thawing of soil from. This is due to that the extension of the soil from below summed up, so that the top -most soil particles lifted from its original location and thus offset the decline also furthest down the slope.

Soil creep through freeze-thaw cycles

Soil creep in freeze-thaw cycles ( Regelationsfließen derived from refreezing ) is caused by the freezing of soil water and thus caused the increase in volume (ice has a larger volume than water). It occurs in freeze-thaw - climates and at sufficiently moist soils. The expansion of the Locker material is only upward and corresponds to the change in volume of water present in the soil pore water. This process is in temperate latitudes, the type of soil creep with the largest movement amounts.

Soil creep by swelling and shrinkage

The soil creep by swelling and shrinkage goes just as in Regelationsfließen on alternating expansion and contraction back. The increase in volume creates hydrophilic in this case by water uptake and release, swellable clay minerals ( especially montmorillonites ). Swellable clay minerals are phyllosilicates, which have the ability to store water in their crystal lattice and release it again. This process is associated with volume expansion and reduction. In alternating drying and moisture a slope downward displacement is similar to the Regelationsfließen the result. Since the sinking of the soil particles is next directed at drying as a result of cohesion (cohesion ) of the clay-rich soil material not alone of gravity vertically downward, but always includes an upwardly extending portion perpendicular to the slope, the offset amount is less than in the case of Regelationsfließens.

Soil creep by precipitation

Completely different kind is the Versatzdenudation by rainfall. During heavy rainfall the soil particles are thrown by the impact of raindrops on all sides. If this is done on inclined surfaces, then the trajectory of the soil particles downslope greatest, so that a total of downslope movement of soil particles top. This process occurs (sand, silt, clay ), especially in fine soil material with small grain size. In randlichem impact of large raindrops and coarse soil particles may start moving up to the gravel. The strength of the impact is not enough in their case from though to hurl the gravel through the air, a slight shift from the point of impact off shall take place. This is done on an inclined surface, a downslope movement also occurs in this case.

Soil creep by Kammeis

With the emergence of Kammeis due to the sublimation of water in the uppermost soil layers, the uppermost soil particles are lifted by the comb-like growing ice needles. During thawing of the ice, the soil particles drop straight down or the needles fall down the slope, it creates a downslope movement. Since this process is limited to the top layers of soil, the amount of that motion are small. The soil creep by Kammeis However, this soil layer fans greatly, so that other removal processes such as rinsing and Auswehung can attack more easily.

Continuous creep

If soft, deformable rock layers are heavily loaded by overlying rock or soil layers, the slope can be set in motion by the deformation of the material. This movement is very slow and depends on whether the material has a high clay content, and the degree of moisture. Furthermore, the steepness of the slope as well as the magnitude of the applied load play a crucial role if the process gets into gear. In many cases, the persistence of the continuous creep to the loss of strength of the overlying layers and thus to the development of rock falls, landslides and Slumps leads.