Cold Environments Flashcards
Altitude
The height above sea level
Cold environments
Icy landscapes found in high latitudes and high altitudes
Glacial periods
Times when temperature has dropped significantly
Glaciers
Masses of ice which are continually changing
Ice caps
A dome shaped mass of ice
Ice sheets
Ice covering an area the size of a continent
Interglacials
Times when temperatures are warmer extended periods of time
Interstadials
Short and temporary period of warming during a glacial.
But not long enough to be a proper interglacial
Latitude
The angular distance north or south from the equator of a point on the earths surface
Periglacial areas
Areas Not permanently covered in ice
Permafrost
Permanently frozen ground which remains below 0 for two years or more
-key characteristic of periglacial areas
Tundra
Areas of the world which have permafrost and long cold winters so little vegetation growth
Stadials
Colder periods which for a short time cause advances in the ice masses
Ablation
The loss of ice from a glacier through melting
Accumulation
The net gain in ice mass to form glaciers
Calving
When a mass of ice breaks away from a glacier or sheet creating an ice berg
Firn/equilibrium
The dividing line between the accumulation zone and zone of ablation.
The boundary where gains and looses are equal
Glacial budget/net balance
Difference between total accumulation and total ablation for the whole of the glacier over 1 yr
Glacial advance
When accumulation is greater than ablation + the snout moves down the valley
Glacial retreat
When ablation is is greater than accumulation and the glacier moves up the valley
Glacier mass
Masses of ice that are continually changing/ moving
Steady state
When the amount of accumulation and ablation are equal
Sublimation
The process of ice changing directly from a solid to a vapour
Alpine areas
High altitude areas within mountain ranges where glaciers and small ice caps can be found
Pressure melting point
The temperature at which the ice is in the verge of melting because some ice is warmer
Internal flow
The movement within the glacier as a result of gravity.
Crevasses may develop
Basal flow/slippage
As the glacier moves over the bedrock there is friction and pressure which causes melting meaning the ice flows more rapidly
Regelation slip
Occurs when a glacier meets a small obstacle
As the glacier moves over an obstacle there is is pressure on one side-leads to melting causing ice to slip over obstacle.
Once over the obstacle the meltwater refrezes
Creep
Occurs when stress builds up within the glacier causing the glacier to become more plastic and flow.
Tends to occur when glacier meets a large obstacle and results in the glacier creeping or flowing around the obstacle
Extensional(extending flow)
When gradient becomes steeper and ice accelerates.
Becomes thinner and stretched
Causing crevasses
Compressional flow
When gradient is reduced and ice becomes thicker and slower
Crevasses close
Rotational flow
Between the two zones of extensional and compressional flow.
The ice moves in a curved/rotating manner.
Occurs within a corrie
Lateral moraine
Formed from debris fallen from the SIDES of the valley and transported along the EDGE of the GLACIER
Medial moraine
Formed where two glaciers meet. May be where the lateral moraine of both glaciers meets towards the middle of the main glacier
Terminal / end moraine
High mound/ series of mounds of debris that extends across a valley. Marks furthest point reached by the ice
Recessional moraine
Often parallel to terminal moraine.Forms when glacier retreats and halts for a time. Each one marks where it halted long enough for deposition to occur.
Push moraine
When the glacier advances again and pushes against previously deposited terminal moraine. It becomes shunted up into a mound
What is supraglacial debris
Material carried on the surface of the glacier
What is englacial debris
Carried within the ice
What is subglacial debris
Carried beneath the ice, material may have started in surface and fallen down a crevasse
What is till (Boulder clay)
Material deposited directly by the ice and is generally unsorted
Two types of till
Lodgement till
Ablation till
What’s lodgement till (forms drumlins)
Subglacial material deposited by moving glacier
What is ablation till
Produced at snout when ice melts but is not carried by meltwater
What is fluvioglacial material
Sediments deposited by meltwater streams and are usually sorted. Finer material is carried furthest by meltwaters
Features of glacial deposition
All moraines
Drumlins and erratics
Fluvioglacial deposits
Kames Kame terraces Kame deltas Eskers Kettle holes Braided streams Varves Outwash plains(sandur)
What are erratics
Fragments of glacial debris that have been carried by glacial ice before being deposited. They are “rocks in the wrong place” as their geology doesn’t match surrounding rock
Fluvioglacial landforms
Outwash plains(sandur) Eskers Kames (terrace,delta,crevasse) Braided streams Kettle holes Varves
What are periglacial areas
Not actually glaciated experience a very cold climate with intense frost action and development of permafrost.
Often near ice sheets
Continuous permafrost
Found in regions such as Arctic. Little thawing even in summer so all the ground is frozen deeply ( 700m+)
Discontinuous permafrost
Found in slightly warmer regions where freezing conditions don’t penetrate as far. There are breaks in permafrost around rivers lakes and seas.deeper active layer
Sporadic permafrost
Permafrost only occurs in isolated spots when temperatures are around or just below freezing point
Fragile environment
Susceptible to damage and where the impact is long lasting due to inability of area to recover quickly
