coastal landscapes

define weathering

the breaking down of rock in situ caused by day-to-day changes in the atmosphere

what is chemical weathering caused by? give an examples of

caused by rainwater hitting rocks and decomposing it. hydrolysis- when acidic water rots away the rock

what is mechanical weathering? give an example

results in rocks being disintegrated rather than decomposed. freeze-thaw weathering: when water enters cracks in rocks and freezes and grows in volume at night, placing pressure on the crack, before thawing in daytime temperatures. this diurnal cycle results in rock fragments to break away.

what is mass movement?

downslope movement of rocks/soil/mud under the influence of gravity

define rock falls and slumping

• rock falls: when rocks prone to freeze-thaw weathering lose contact with the cliff face + fall

• slumping: when material rotates backwards into the cliff face along a concave slip plane as it slides downwards

define landslides, rock slides and mud slides

• landslides: downhill movement of a large amnt of rock/soil/mud

• rock slides: large amnt. rock slides down a cliff

• mud slides: saturated soil and debris fall down a slope

define erosion

the wearing away and removal of material by a moving force

name and define the main types of coastal erosion

• hydraulic action: when the force of flowing water pushes air into cracks in rocks, rapidly increasing and releasing pressure which breaks the rock down.

• abrasion: when destructive waves hurl sand + shingle onto the cliff face, scratching and scraping the cliff

• attrition: the grinding down of load particles (rocks collide during transport which wears away the jagged edges resulting in smooth round pebbles).

name and define the different transportation processes

• traction: large boulders rolled onto sea bed. requires more energy

• saltation: small pebbles bounced along sea bed. low energy

• suspension: fine, light material held up and carried within the sea’s flow

• solution: minerals dissolved in water

define deposition. what criteria is needed for the rate to increase?

• when waves drop and leave behind the load they were carrying.

  increased erosion in area, lots of material transported into area

define and explain the process of longshore drift

• the zigzag movement of material along a beach caused by prevailing winds

  prevailing winds cause waves to hit beach at an angle → swash brings material up the beach at the same angle → backwash carries material down at a 90 degree angle due to gravity → process continues, carrying material along the beach in a zigzag pattern

name characteristics of a constructive wave

• stronger swash than backwash

• low frequency + wave height

• long wave length

• creates gently sloping beaches

name characteristics of a destructive wave

• stronger backwash than swash

• high frequency + wave height

• short wave length

• creates steep slopes