Solifluction

Under solifluction (soil flow, associated with periglacial processes also Gelifluktion ) are slow, large-area, downslope flow movements of loose rock material in the Auftauzone the permafrost to understand.

Basics

Cause is the thawing of upper soil layers above the permafrost region at a certain inclination of the relief. The thawing layer ( the active layer " active layer " ) of soil is usually saturated with water, as the permafrost in the ground to prevent water seepage. The water saturation is reduced, the friction in the bottom substrate, which allows the downslope flowage.

Solifluction is the main ablation and transport processes in Periglazialgebiet. It works even with very gentle slopes of about 2 ° inclination.

In addition to a water saturation solifluction is bound to a sufficiently high proportion of fine material ( fine sands, silts, clays ). Moving amounts of about 5-10 centimeters per year can be achieved. In Solifluktionsböden be found parallel to the slope is governed Stones and often pressing structures.

In contrast to soil creep in the solifluction downslope movement is effected by actual flow processes caused by the water-saturated soil on frozen ground and form characteristic morphological forms on the surface. At the bottom of the crawling movement is carried out exclusively by means of offset, which is caused due to the periodic action of contraction and expansion.

Morphological forms

The solifluction is the relevant process leading to the formation of periglacial layers ( layers, talus ) as the spread in Central Europe main location leads.

• Solifluktionszunge: Solifluidal shifted towards bottom substrates generally have a tongue-like shape.
• Solifluktionslobe: Damage caused by the flow of the soil hangabwärtige bulge at the front of Solifluktionsbereiches. Also the front of a Solifluktionszunge can be regarded as a praise. As a fossil landform is called the shape Riedel.
• Solifluktionsnische: In practice, the area of ​​origin of the displaced solifluidal soil substrate. By shifting resulting dent in the hillside above the solifluidal displaced material.

Types and special shapes

• Times of day / seasons - solifluction: Underground Times- solifluction is defined as a daily freeze-thaw cycles ( nächtl. freeze, thaw daily ) and seasons solifluction meant a seasonal freeze-thaw cycles (summer / winter)
• Periglacial solifluction: occurrence in Arctic and subnivalen mountainous areas in the vicinity of the large ice sheets and mountain glaciers.
• Free solifluction: relieved floor tiles in the absence of a closed -binding vegetation cover.

• Bound solifluction: Tearing the sod and formation of demolition niches (lawn stairs) in the vegetation cover. At the foot of the slope is rolled grass mats can accumulate. In Switzerland, this form of solifluction is called garland.
• Kammeissolifluktion: bottom parts are lifted by growing ice perpendicular to the ground surface. Thawing of ice ridge, the soil substrate settles down the slope. This results depending on the inclination of the relief a small valley directional offset.
• Mikrosolifluktion / Kryoturbation: occurs at freeze-thaw cycles in the upper soil layers in addition to the ground motion is also a material sorting. Cause of the formation of patterned ground.
• Makrosolifluktion: similar to the Mikrosolifluktion, but on steeper slopes and therefore with greater effect.