ice formation and movement

ice formation and movement

1. basics

   • colder areas
     • more snow
     • shortened summers
     • permanent snow cover
       • snow line
   • north facing slopes
     • less insolation
   • snow accumulates
     • compressed
       • forms a firn (still has air)
         • meltwater freezes
           • all ice
     • colour
       • white - air
       • blue no air

2. temperate and polar

   • temperate
     • alpine - warm based
       • move more
         • basal sliding
         • extending/ compressional flow
         • creep
         • surge
       • more melt water to lubricate the base
       • more erosion
       • more deposition
   • polar
     • cold based glaciers
       • moves slower
       • doesn't reach the pressure melting point

3. glacier types

   • niche
     • small accumulations of ice
   • corrie
     • small masses of ice in hollows
   • valley
     • moves down lope in a valley
   • piedmont
     • reach the valley bottom - spread out

4. movement

   • compressing flow
     • decrease in velocity - ice thickens
   • extending flow
     • velocity increases - ice extends & thins
   • basal flow
     • pressure melting point (-2*C)
       • lubricates base
         • glacier moves
   • internal flow
     • ice crystals orientate in direction of movement
       • slide past
         • surface moves faster
   • rotational flow
     • ice moving pivots around a point
   • regelation
     • slides around or over obsatcle
       • due to pressure