weathering Flashcards
what is weathering?
the breakdown of rocks over time leading to the transfer of material into the littoral zone
when it goes to the littoral zone it become what?
an input to sediment cells
positive feedback - what happens if the rate of removal of the weathered rock from the base of the cliff is higher than the rate of weathering?
it will promote further weathering as this will increase the area of exposed rock
what will the increase in the area of exposed increase…
the amount of erosion that occurs bc it will increase the supply of rock
types of mechanical (physical) weathering?
freeze-thaw (frost-shattering), salt crystaliisation, wetting and drying
what is meant by freeze-thaw?
water enters cracks in rocks and then the water freezes and expands in volume causing cracks to develop
what is meant by salt crystallisation?
as seawater evaporates, salt is left behind. Salt crystals will grow over time, forces the cracks to widen. Salt can also corrode ferrous rock
what is meant by wetting and drying?
rocks such as clay expand when wet and then contract again when they are drying and these cycles cause the rocks to break up
examples of chemical weathering?
carbonation, oxidation, soloution
what happens in carbonation?
rainwater absorbs co2 from the air to create a weak carbonic acid acid rain with limestone to form calcium bicarbonate - which is then easily dissolved allowing erosion
what happens in oxidation?
when minerals become exposed to the air it will become oxidised which will increase its value - causes the rock to rack. Most common with iron minerals
what happens in solution?
when rocks minerals such as rock salt are dissolved
examples of biological weathering?
plant roots, birds, rock boring, seaweed acids, decaying vegetation
how Is plants roots biological weathering
grow into the cracks of rocks , exerts pressure, eventually splitting the rocks
how are birds form of biological weathering?
some birds such as puffins dig burrows into cliffs wearing them
