8.6 SUB-AERIAL PROCESSES Flashcards
what is weathering?
-the in situ breakdown of rocks by chemical, mechanical or biological agents
what is erosion?
-breakdown of rock due to action of some external force which then transports the eroded material to a new location
what are the three different types of weathering?
-mechanical
-chemical
-biological
what does mechanical weathering do?
-breaks down rocks due to exertion of physical force
what does chemical weathering involve?
-a chemical reaction and generation of new chemical compounds
what is biological weathering?
-often speeds up mechanical/ chemical weathering through the action of plants, bacteria or animals
what is mass movement?
-downslope movement of rocks and soil
give 2 examples of a mechanical process.
-freeze-thaw (water expands by 9% in volume when freezing repeated cycles force cracks open
-salt crystallization (growth of salt crystals in cracks exert a breaking force)
give 3 examples of chemical weathering.
-carbonation (slow dissolution of limestone due to rainfall producing calcium bicarbonate)
-hydrolysis (breakdown of minerals to form new clay minerals)
-oxidation (addition of o2 to minerals which produces iron oxides and increases volume
give 2 examples of biological weathering.
-plant roots (tree+plant roots growing in cracks forcing rocks apart
-rock boring (clams bore into rocks)
what is fall (mass movement) (2)
-when rock is dislodged by mechanical weathering
-undercuts the cliffs by creation of wave cut notches which leads to larger falls
what is topple (mass movement) (3)
-rock strata have steep seaward dip,
-undercutting by erosion leads to instability
-blocks of material topple seaward
what is translational slide? (mass movement)
-material slides down dip slope towards sea because of low angle dip
what is rotational slide? (mass movement)
-masses of material slowly rotate downslope
what is a flow? (mass movement)
-materials become saturated and flow downslope
