geomorphological processes Flashcards
rotational slumping-MASS MOVEMENT
- occurs in weak. unconsolidated material (sand) or in rocks of different geology
-water adds weight which lubricates it so it reduces the friction
-EXAMAPLE:sand overlies clay, in dry weather soil cracks so water seeps into the sand to form lines of weakness
the water accumalates into lower sand as its unable to percolate into impermeable clay so the sand moves
soil creep- MASS MOVEMENT
its an extremely slow form of movement of soil particles downhill
- the particles rise due to wetting and freeze thaw
-the particles then return to the surface due to gravity as the soil dries
evidence of this is upslope sides of walls and the bending of tree trunks
rockfall-MASS MOVEMENT
this occurs on slopes less than 40 degrees where fragments of rock break off
-this is mainly due to mechanical weathering and marine erosion- this is very quick
landslides-MASS MOVEMENT
occurs on cliffs made of softer rocks which slip when lubricated due to heavy rainfall- they move very quickly along a flat slope
mudflow- MASS MOVEMENT
an increase in the water content of soil can reduce friction leading to a mudflow which is fast flowing
erosional processes
HYDRAULIC ACTION= impacts on rocks due to the sheer force of the water which exerts a lot of pressure
WAVE QUARRYING= waves trap air in the cracks causing pressure which causes an explosive effect
ABRASION= material that is picked up by the waves and is hurled at the cliff which wears it away
ATTRITION= the rocks in the sea are worn into smaller rounder pieces
SOLUTION- dissolving of rock
what factors affect the rate of erosion
- WAVE STEEPNESS= they have higher energy so have more erosive power
- FETCH= how far the wave travels determines the amount of energy it will generate
- COASTAL CONFIGURATION= headlands attract wave energy through refraction
- HUMAN ACTIVITY= people may remove material from beaches like sand which leads to more erosion
geology= THE MOST IMPORTANT FACTOR IN DETERMINING THE RATE OF EROSION
- concordant= the rock runs parallel to the sea. this means the sea can only break through a few places
-discordant= the rocks run at a right angle which means the sea can erode larger areas so produces bays and headlands - the dip in the rock is also a major factor=steep cliffs tend to form where rocks have horizontal strata (they dip inland)
rocks that dip towards the coast are gently sloping
mechanical/ physical weathering
FREEZE THAW= water enters the cracks in the rocks and then the water freeze overnight . as it freeze it expands causing the cliff to weaken
SALT CRYSTALLISATION=as sea water evaporates salt is left behind. salt crystal grow and put pressure on the rocks forcing then to crack
WETTING AND DRYING= rocks like clay expand when its wet and contract when its dry. this frequent cycle causes rocks to crack
chemical weathering
CARBONATION= rainwater absorbs co2 from the air to create a weak carbonic acid which reacts with the calcium carbonate to form calcium bicarbonate (easily erodes)
OXIDATION-when minerals become exposed to the air through cracks the minerals will become oxidised which will increase the volume to cause rock to crumble
SOLUTION= when rock minerals such as rock salt is dissolved
biological weathering
PLANT ROOTS= roots of plants growing in rocks cause pressure so they split
BIRDS= birds like puffins dig borrows in cliffs which makes them weaker
ROCK BORING= species like clams secrete chemicals that dissolve rocks and piddocks burrow into rock faces
traction =TRANSPORTATION
large stones are rolled along the sea bed by moving sea water
saltation= TRANSPORTATION
small stones bounce along the seabed. this is associated with high energy conditions
suspension= TRANSPORTATION
very small particles of sand and silt are carried along by the moving water
solution= TRANSPORTATION
dissolved materials are transported within the mass of moving water
