Cold glaciers

Cold glaciers

1. PMP: Pressure melting point is the temperature at which ice is on the point of melting. As pressure increases this temperature becomes lower.

2. The way in which ice moves depends on whether it is a warm based (temperate) glacier such as the Athabasca (Canada) or cold based polar glacier - e.g. Merserve Glacier, Antarctica

3. E.g. Arctic/Antarctic

   • High latitude locations
   • Low relief
   • Temperatures well below 0C
   • Basal temperature below pressure melting point - frozen to bed
     • As pressure melting point not reached no meltwater available.
   • Summer temperatures may be below freezing and low precipitation
   • Limited ablation and accumulation
   • Movement is slow - Meserve Glacier Antarctica 3-4m per year
   • Little erosion

4. Main mechanisms for movement in cold based glacier is internal flow or internal deformation

   • The ice deforms under its own weight because of gravity
     • Intergranular flow - Crystals reorientate in direction of glacier movement and move in relation to each other
     • Laminar flow - movement of individual layers within the glacier, slide over each other resulting in laminar flow
     • Little friction so no melting and as the surface moves slightly faster crevasses form. Movement n this way is very slow, tens of metres per year. The thicker the ice , the faster internal deformation