mass movement Flashcards
describe negative feedback in beaches and waves starting w constructive waves >
deposition > steep beach profile > favours destructive waves > erodes beach > reduces beach profile > favours constructive waves > beach in dynamic equilibrium
what causes tides
the gravitational forces exerted on the earth by the moon, and to a lesser extent, the sun.
define tidal range
difference between high tide and low tide
when do the highest high tide and lowest low tide occur
when the sun and moon are in allignment
define wave refraction
when waves lose their energy around a headland on uneven coastlines
what time of year do destructive waves cause most erosion
in winter when storms are more frequent
which rock type is most susceptible to erosion
sedimentary rocks like sandstone
positive feedback w weathering starting w rate of removal of weathered rock quicker than weathering
> increases area of exposed rock > increases amount of weathering + erosion
negative feedback starting w removal of weathered rock from cliff base is slower than weathering >
build up of debris > protects cliff base > reduces weathering + erosion
define freeze thaw
water enters cracks in rocks, water freezes at night due to temp differences, water expands and widens crack, weakening the rock
define carbonation
rainwater absorbs co2 creating weak carbonic acid which reacts w calcium carbonate
eg. acid rain + limestone- easily eroded
example of biological weathering
animals can burrow into a crack in a rock, making it bigger and splitting the rock
what does mass movement add inputs to
the littoral zone
define soil creep
damp soil moves very slowly down the slope as the weight of water pushes it forwards, rain splash may release soil grains that fall further down slope.
define landslide
It occurs when a block of intact rock moves down the cliff face very quickly
heavy rainfall leads to water between joints and bedding planes which can reduce friction and lead to a landslide
