Chapter 2 Glaciated landscapes

Flashcards about glaciated landscapes, pingos, patterned ground, and periglacial environments.

Pingos

Rounded ice-cored hills in periglacial environments, ranging up to 90 m in height and 800 m in diameter.

Open-system pingos

Valley bottoms where water collects from surrounding slopes, freezes and expands under artesian pressure, forcing the surface to dome upwards.

Closed-system pingos

Beneath lake beds where the water supply is from the immediate local area; groundwater is trapped and compressed by permafrost, forcing overlying sediments upwards.

Talik

Area of unfrozen ground.

Ognip

The term for a depression that forms when a pingo collapses.

Patterned ground

Relatively minor, small-scale features that are often colonised by vegetation, making them hard to identify in post-periglacial periods.

Outwash plain (sandur)

A flat expanse of sediment in the pro-glacial area, formed as meltwater streams lose energy and deposit their load.

Braided streams

River channels subdivided by numerous islets and channels, common in outwash plains due to seasonal discharge fluctuations.

Modification of glacio-fluvial deposits

Repeated advance and retreat modify and alter the appearance of landforms which are also subject to weathering, erosion and colonisation by vegetation in post-glacial times.

Periglacial environments

Perennially frozen ground overlain by an active layer, with seasonal temperature variations and freeze-thaw cycles dominating geomorphic processes.

Freeze-thaw weathering

A dominant process in periglacial environments due to seasonal fluctuations in temperature around freezing.

Frost heave

A sub-surface process that leads to a vertical sorting of material in the active layer and the formation of stone polygons.

Patterned ground

The collective term for small-scale features of periglacial environments, consisting of stone polygons and stone stripes.

Stone stripes

Formed on slopes of 60° and over when polygons in patterned ground lose their shape.

Stone garlands

Formed on slope angles of 3-50° when larger stones move greater distances downslope and polygons become elongated.