proccesses

• geomorphic processes = the natural mechanisms of weathering, erosion and deposition that changes the surface materials and landform on the earths surface
• weathering = the break down of rocks soils and minerals into smaller fragments in situ - caused by climate and living organisms
• chemical weathering - affects limestone: rainwater is slightly acidic and when it contacts rocks, the acid attacks and dissolves it = rocks crumble away over time - different rocks are affected differently
• chemical weathering can be affected by oxidation, carbonation or hydrolysis
• oxidation = reaction of substance with O2 = rust

  eg. iron in rocks reacts with O2 to make iron oxide and weakens rocks
• carbonation = mixing of water and CO2 to make carbonic acid = forms caves

  reacts with minerals in rocks - CO2 in rain or moist air
• hydrolysis = the chemical breakdown of a substance when with water

  eg. feldspar in granite rocks turns to clay
• biological weathering - affects sedimentary rocks as they have layers and is easier for roots: caused by living things (animals and plants)
• biological weathering = when seeds are blown into cracks in rocks and grow into small plants, growing roots force the cracks to widen as they grow = over time pressure of being forced open makes them collapse
• mechanical weathering - affects metamorphic rocks: water becomes trapped in cracks and joints of rocks - temperatures drop below freezing = water becomes frozen and expands 9-10% = increases pressure, temperature rises = water melts, process repeats = weakens rocks and creates rockfalls
• mass movement = movement of masses of bodies of rocks, debris, soil, bedrock or mud which occurs along steep sided hills because of the pull from gravity = causes landslides, mudslides and avalanches
• mass movement occurs on hills with high relief (steep sides) = eg. the penines
• rockfalls = after mechanical weathering and freeze thaw = loosens rock = falls from gravity and scree slope is formed
• landslides = caused by weathering (wet, dry, wet), large area of land slips down in singular movement because of gravity and leaves behind a curved surface - slippery zone is where the material moves down and is made up of wet sediment and years of movement and layers
• mud flows = it is a rapid sudden movement, happens after lots of rainfall, slope must be over 10 degrees and there is no vegetation or roots to hold soil in place
• rotational slip = a slump of soil and weak rock along a curved surface: gravity pulls soils down that are saturated with water - happens slowly, creates a stair like feature, heavy rainfall can speed up the process
• cliffs collapse = marine processes - eroded by hydraulic action = steeper, weathering = weaker rocks, heavy rain = saturates permeable rocks and erodes cliff face, water flow = flows through permeable rocks and adds weight, human actions = building increase weight = push down on weak cliff and break rocks
• erosion happens through 4 processes: hydraulic action, abrasion, attrition and solution
• hydraulic action = the sheer force from the water hitting river banks and cliff faces. the water enters the cracks and causes pockets of air to compress and 'explode' = rock crumbles away - joints or fault planes encourage this
• abrasion = different sized rocks and materials rub and grind against the banks and cliff faces. the rocks are thrown at the base of cliffs - worn down in a sandpapering action
• attrition = where rocks bump and collide = breaks rocks into rounder and smaller pieces but doesn't affect the bed or cliff
• solution = rocks and materials forming banks a cliff bed are dissolved by acids in the water
• there are 4 types of transportation in rivers - traction, saltation, suspension and solution
• traction (needs a high rate of flow) = large heavy boulders and rocks are rolled along the river bed - usually happen in flood because the current is strongest and has most energy
• saltation = smaller stones and pebbles bounce along the river bed in a 'leapfrog' motion - less energy than traction but still a lot
• suspension = very small particles of sand and silt are held/suspended in the water and carried down the river - needs less energy than saltation - changes the river colour
• solution = where fine minerals are dissolved by acids in the river and carried downstream - least energy and isnt visible