landforms deposited by meltwater from glaciers.
some found within the glacier and some under the glacier.
outwash plains- composed of sand, gravel and clay (from snout).
deposited during times of inc. ablation (glacial retreat).
material is sorted by meltwater at the snout.
as it moves away carrying capacity decreases so less is carried.
varves- layer if silt on top of sand on top of coarse material.
form where there was a glacial lake.
as discharge decreases the river can only carry finer material.
meltwater deposits material when the stream divides,
if the velocity of flow decreases,
if the channel widens decreasing the pressure,
if the stream flows upwards.
kames- mounds of sand and gravel.
surface streams on glaciers deposit material in crevices.
when ice melts debris is left as a pile on the valley floor.
kame terrace- glacier melts the debris collected in troughs fall to
the side of glacier.
esker- long narrow ridge of sorted sand and gravel deposited by
roads can be built on them.
kettles- detached blocks of ice left by an ice sheet buried by
ice melts and leaves a depression which may fill with water.
drainage diversion and proglacial lakes- ice blocks the path of the
water form a lake.
lake overflows and cuts a gorge.
river flows in opposite direction.
zone in front of the ice sheet.
at the fringe of the glacier.
area where frost and snow have an impact on the environment.
charateristics = permafrost (permanently frozen ground) covers 25% of
- continuous permafrost (400to1500m, -12to-6c).
- discontinuous permafrost (45m, -6to-1c), islands of frozen ground
seperated by warmer areas e.g.rivers.
- sporadic permafrost (12m, temp. below 0c).
active layer (layer that thaws in the summer).
talik (unfrozen ground, geothermal activity prevents freezing).
periglacial processes and landforms:
ground ice - 1. ice crystals/lenses 2. ground contraction 3. freezing
of groound water.
1. sorted stone polygons 2. ice wedges/unsorted polygons 3. pingos.
frost shatter - 1. frost shattering.
1. blockfields 2. scree 3. tors.
snow - 1. nivation.
meltwater - 1. solifluction 2. streams.
1. solifluction sheets 2. rock streams 3. braiding 4. dry valleys.
wind - 1. windblow.
frost heave - thermal conductivity of stones is greater so area under
stone becomes cool and damp.
ice crystals form.