Solifluction

Sunflower terrace, formed by the descent of material by a slope and that has been cut by the sea

The solifluction is the characteristic geomorphological process of periglacial climate zones (although it can even occur in the tropics), consisting of the massive and slow displacement by gravity of clayey formations or other types of soil over permafrost because of the plasticity and fluidity acquired by those when they absorb large amounts of water.

Solifluction is typical of soils that have been weakened by the recurrent action of frost and, consequently, the original characteristics of the terrain are often greatly altered. In periglacial climates, the alternation of ice and thaw causes the clay to precipitate in the form of very fine layers, in which sliding is easier. This can be generalized to an entire slope of moderate slope (laminar solifluction) or is limited to a part that, when detached, forms a detachment niche. In less cold climates, solifluction requires greater proportions of clay or marl in the soil, and the flows are usually small.

The water that soaks the ground can come from snowmelt; in this case the phenomenon is described as gelifluction. It can also come from infiltration of the groundwater table, but most of the time it is rainwater or snow.