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Glaciation-Topic 1 (Glacial Periods (Glacials (Col, ice-house periods…

- - - - complete submergence of regional topography , unconstrained (10-100000 KM^2)
    - - Smaller version of an Ice sheet occupying upland areas, unconstrained(3-10000 KM^2)
    - - Ice Coverage in an upland area but not thick another to cover the topography , unconstrained (10-10000 KM^2)
    - - A glacier confined between valley walls and terminates in a narrow tongue , Constrained (3-1500 KM^2)
    - - Valley Glacier that extends beyond the end of the valley into a flatter area spreading out like a fan, Constrained/unconstrained (3-1000 KM^2)
    - - Smaller Glacier occupying a hollow on the mountain side , Constrained (0.5 -8 KM^2)
    - - Large are a of floating glacial ice extending fro the coast where several glaciers have reach the sea and coalesce , Unconstrained (10-100000 KM^2)
  - - - Warm-Occur in high altitude areas outside the polar region .The temperature of the base layer fluctuates above and below the melting point causing a layer of a water at the base of the glacier . Warm based glaciers are therefore not frozen to its bed and move far faster than cold based
      - Cold- Occur in high Latitudes where the very cold temperatures mean the base never meets melting point and the glacier is frozen to the bed below, making it move far slower
      - Hybrid Polythermal glaciers- Many glaciers exist as both the above in different altitudes with the glacier being a cold based near the top and a warm based near the foot .
- - - - highest average annual temperatures from 1 degrees to -4 degrees
      - daily temperature below 0 for at least 9 months of the year and below -10 for 6 months
      - Intense frosts durning winter and on any snow free ground in summer
      - Low precipitation- typically under 600mm a year
  - - - Ice Wedge Polygons
        
        The process of frost cracking creates areas of irregular polygons 5-30m across, When the ground cracks snow and ice falls in and melts this then frees and thaws widening the shape
      - Patterned Ground
        
        The general term used for a range of stone features where stones form different polygons, circles, nets, steps and stripes. Frost Push propels the stones upwards while frost heave causes the stones to migrate outwards to form the shapes.
      - Pingos
        
        Open system- found in areas of discontinuous permafrost where groundwater is freely available and in plentiful supply , allowing the bingo to continually grow possibly rupturing.
        
        Closed System-associated with low lying flat areas and only form in zones of continuous permafrost .Occur when there is a finite enclosed water supply eg a former lake
        
        Ice core mounds, the broth of an ice core forces the overlying active layer (sediment) up causing a miniature hill almost
        
        Smaller features similar to pingos known as Palsas occur within a peat bed
    - - Freeze Thaw weathering- puts pressure on any cracks in rocks and shatters them . With water forcing its way into gaps and then the process of freezing and expanding occurs . While the process is not unique to periglacial it occurs violently in such areas and creates the following features
        
        Block Feilds
        
        the accumulation of angular , frost shattered rocks which pile up on flat surfaces
        
        Tors
        
        Areas of resistant rock that have remained where the unresistant rock has been disintegrated around leaving towering rock features
        
        Scree or Talus Slopes
        
        Block fields on a slope that accumulate lower down
        
        Pro-Talus Ramparts
        
        When snow in a small area sat the foot of a cliff causes falling boulders ad rocks to slide fall down to the foot of the snow which when melts leaves a semicircle wall almost of boulders
    - - Frost creep
        
        The movement of sediment downhill at very slow speeds a few centimetres a year seen when sediment forms up against. wall or fence post , causes sediment accumulation at the foot of a slope
      - Asymmetric Valleys
        
        One side of the valley comes far steeper than the other due to frost creep and solufution
      - Solifluction
        
        Occurs in regions underlain by permafrost , during the summer the ice melts and saturates the active layer that can move due to high saturation levels
- - - - The Process that occurs over 100 000 years where the earths orbit changes from a n almost circular town elliptical orbit , thus changing the amount of radiation the earth receives.
        
        Circular= Less radiation in Summer =More ice =More albedo=Lower Temps= Ice-house-earth
        
        Elliptical=More radiation in the summer=less ice= less albedo=warmer temps =Greenhouse Earth
    - - Varies the tilt of the earth from 21.8 to 24.4.This changes the intensity of sunlight received received at the poles and therefore the earths seaonality
        
        Minimum Tilt= Poles get less sun=more ice at poles=more albedo= Icehouse
        
        Maximum Tilt= Poles get More Sun= less ice at the poles= Less Albedo= Greenhouse
    - - The earth wobbles on its axis changing the point of the year that the earth is closest to the sun changing when different sessions occur.