Crystal morphology

After severe freeze-thaw disintegration of bedrock, large boulder breccia is produced, which is piled up on the flat ground in situ, called Shihai; If the whole movement occurs along the surface of wet debris cushion or the top of frozen soil under the action of gravity, a stone river will be formed. The movement speed of Shihe River is very small. Usually the annual moving speed is 2 ~ 0.2 meters. As a result, rocks were carried to the foothills and piled up.

Tectonic soil refers to the surface composed of loose sediments, which is formed by freezing and thawing, and each single grid is approximately symmetrical in geometry, such as ring and polygon.

Frost heave is because groundwater is constrained by permafrost and the lower permafrost layer, and it freezes and expands in weak areas, causing surface deformation and uplift, which is called frost heave. An ice cone is a mound formed by the freezing of groundwater or river water flowing from the ice surface and the ice surface in cold season.

Freeze-thaw process is a unique geomorphic process under cold climate conditions. A series of special landforms in permafrost regions, such as ice cracking, frost heaving, thawing settlement and mud flow, are all different manifestations of freezing and thawing process.

Frozen soil landform is also called periglacial landform. Periglacial zone originally refers to the marginal area of glaciers, and now it refers to all cold climate areas not covered by glaciers, which is roughly equivalent to frozen soil areas.

The total area of frozen soil is 35 million km2, accounting for 1/4 of the land area, mainly distributed in the former Soviet Union and Canada. The area of permafrost in China is about 210.5 million km2, accounting for 22.3% of the national area, mainly distributed in the northeast, northern mountainous areas, northwest mountainous areas and Qinghai-Tibet Plateau.