Non-water made landforms

Non-water made landforms

1. Arid Geomorphological processes

   • Weathering
     • rock attacked/broken down into smaller pieces
     • happens quickly in deserts
       • shortage of plants/soils for protection
         • exposed to weather
     • mechanical weather def:
       • rocks physically broken down in situ - pieces of rock made smaller but its appearance doesn't change
   • Mechanical Weathering
     • Exofoliation
       • high diurnal temperature range
       • Day - insolation makes rock expand
       • Night - rock cools down/contracts
       • Repeated process makes layers peel off
     • Granular disintegration
       • diurnal/annual temperature range
         • Shattering
           • expansion/contraction
             • basalt
             • shatters from stresses
       • different minerals
         • contract/expand
           • at different rates
             • stresses in rock structure
               • 'granite' - breaks down
     • Block seperation
       • cooling/heating
         • of sedimentary rocks
           • limestone
           • rock breaks on horizontal/vertical joints
     • processes also rely on a little water from fog/dew to trigger

2. Wind Action

   • Erosion
     • transporting broken down rock
   • Deflation
     • wind removes
       • finest/loosest material
         • happens when there's sand
           • dry/not bound together by roots
             • makes reg
               • desert pavement
               • or deflation hollow
         • VIA SUSPENSION
       • wind
   • Abrasion
     • sharp particles of sand
       • carried by wind
         • rub against exposed rock
           • wear away surface
             • new features
             • under 2m off ground
               • most erosive particles are heaviest
         • IN SUSPENSION & SALTATIO
     • rate of erosion
       • slower than deflation
         • depends on
           • wind frequency
           • speed/direction
           • rock hardness
           • regolith
   • Suspension
     • finest slit/sand
       • diameter under 0.15mm
       • carried in atmosphere
         • causes UK 'red rain' from Sahara
   • Saltation
     • particles 0.15-0.25mm diameter
       • lifted by strong gusts of wind
         • hop along surface
           • close (1m) to ground
           • bounce & loosen other grains
             • they hop too
     • main form of transportation
   • Surface Creep
     • heavier grains
       • over 0.25mm diameter
       • too heavy to be lifted
       • rolled along surface
         • by wind
         • some grains dislodged by saltation then rolled
       • pushed along surface
         • by other grains
   • Deposition
     • wind speed drops
       • particles dropped
         • happens on downward/leeward side
           • of rock/vegetation
           • of obstacle
     • makes dunes

3. Landforms made from Wind Action

   • Regs
     • wind removes finest/loosest material
       • leaves larger stones closely packed
   • Deflation hollows
     • low rounded basins over 100s of km
   • Made by Abrasion
     • Zeugens
       • long ridges of land & horizontal layers of rock
         • narrower at bottom
           • abrasion eroded away less resistant rock
             • upto 1.5m high
             • uses sand from suspension/saltation
     • heavy particles close to ground
     • Yardang
       • long ridges of vertical layers of rock
         • ridges seperated by troughs
           • created by less resistant vertical layers of rock
             • eroded by abrasion
               • sand from suspension/saltation
               • ridges of tougher rock each side
                 • parallel to prevailing wind
       • streamlined
         • narrower at bottom
           • end facing wind is widest/highest
           • massive variations in height - fewscms to 100m
             • 4x longer than tall
   • Sand Dunes
     • both transportation AND deposition landform
     • transportion of large quantities of sand particles
       • suspension
       • saltation
       • surface creep
       • wind velocity drops
         • particles deposited
           • form dunes in Erg
             • where vegetation, other dunes or hollows trap sand
             • size/shape depends on
               • wind direction
               • duration and strength
               • availability of sand
               • amount and type of vegetation
     • mobile
       • constantly move downwind with prevailing wind
     • asymmetrical
       • windward gently sloping side
         • formed by saltation/surface creep
           • makes ripples
       • steep leeward side
         • formed as sand lips/slumps
           • due to eddying