PERIGLACIAL LANDSCAPEVictoria Neufeld

Active Layer

Active layers are made of moisture-saturated material overlying permafrost that melts during the short summer season of high latitude regions

Permafrost

Permafrost is permanently frozen water found in high latitude soils and sediments.

Five Types of Permafrost

Continuous: exists across a landscape as an unbroken layer

Discontinuous: contains numerous scattered pockets of unfrozen ground

Sporadic: exists as small islands of frozen ground in otherwise unfrozen soil and sediments

Alpine: exists within mountains of high altitudes

Subsea: exists beneath the sea in ocean sediments

Cryosol Soil

Cryosol soil is common to high latitude tundra environments. There is usually layer of permafrost within one meter of the soil surface.

Exfoliation Exfoliation is the expansion,

cracking, and peeling of rock layers off a newly exposed rock surface. This process is a result of erosion of overlying bedrock causing a release of pressure.

Frost Action Frost action is a process of physical

weathering carried out by the constant freezing and thawing of water.

Frost Creep and Frost Shattering Slow mass movement of a soil downslope that

caused by freeze-thaw action is called frost creep.

Where the temperatures frequently rises and falls in high altitude and high latitude regions, frost shattering occurs. Frost shattering is the splitting apart of rocks by the freezing and expansion of water in fractures and joints.

Gelifluction and Solifluction Gelifluction is when soil material moves

over a permafrost layer in lobe-shaped masses.

Solifluction is the slow, downhill movement of water-saturated rock and soil materials in high latitude climates across a permafrost layer.

Ice Wedging

Ground ice that extends into the top of a permafrost layer forms an ice wedge. They form during winter because of thermal contraction. In the spring, these cracks fill with liquid water from melting snow which subsequently re-freezes. The water expands in volume when it freezes increasing the width and depth of the crack, which enlarges each time water fills and freezes in the crack.

Patterned Polygon Ground

A patterned polygon ground is formed when the ground surface is broken into regular polygon shapes by intense frost action of high latitude landscapes.

Pingo

A pingo is a hill with a core of ice, water, and mud that rises above the land surface.

Peat and Palsa

Peat is partially decomposed remains of plants that once flourished in a waterlogged environment.

A palsa is a mound of peat that develops as the result of the formation of a number ice lenses beneath the ground surface. This land feature is similar to a pingo.

Thermokarst

Thermokarst is a landscape consisting of depressions, pits, and caves that are created by the thawing of ground ice in high latitude locations. These features resembles that of a karst landscape but they are not created by chemical weathering.

Felsenmeer

A German word, felsenmer (meaning “sea of rock”), describes the mountain-top spreads of angular boulders.

Rock Falls

A rock fall is a type of mass movement that involves the detachment and movement of a small block of rock from a cliff face to its base. Normally occurs when the rock has well defined bedding planes that are exaggerated by freeze-thaw action or thermal expansion and contraction.

Stone Circles

A stone circle is a dome-shaped area of fine soil surrounded by a circular ring of stones. This feature is caused by intense frost action.

Rock Glacier

A rock glacier is a large volume of rock fragments moving downhill slowly. This usually happens in mid- and high latitude mountains where frost shattering, or ice wedging, is common.