Snow and Slopes

Page 1

Patterned ground:

Mostly forms in the active layer, some in seasonally frozen ground. Most common patterned groundforms are circles, hummocks and mud boils.

Distinctive patterns due to ralative lack of vegetation.

Most common is a nonsorted circle, if it also exhibits a raised topography then it can be called a hummock; 0.5-3m diameter and 0.5m high, the underlying frost table is 'gently bowl shaped.

Cryoturbation (horizon mixing due to FT cycles) is a dominant process in the formation of earth hummocks. finer material is displaced upwards due FT cycles and gravity causing the sinking of coarser material. the distribution of sediment (by size) indicates a cell like movement of soil, further supported by periods of activity in the summer followed by long dormant winter periods.

Another theory for hummock formation is differential heave, supported by Haywards paper.

Snow cover:

influences permafrost as it is an insulator.

heavy snowfall in autumn/winter inhibits frost penetration.

ALSO if snow cover remains then later thaw can be expected.

Snow cover seems to influence PF distribution in discontinuous regions more that continuous.

French 2007