how are coastal landforms developed - geomorphic processes Flashcards
5 processes of mass movement
landslides
rockfalls
mud flows
rotational slip/ slumping
soil creep
rock fall
- cliffs 40 degrees or more rocks can become dethatched by physical weathering
- rocks fall to foot of cliff bc of gravity
- waves then remove this material
landslides
cliffs made of softer rock slip when lubricated by rainfall
mud flows
heavy rain causes fine material to move downhill
rotational slip/ slumping
where softer material overlies resistant material and excessive lubricant takes place
soil creep
very slow movement of soil particles downslope
WAVE PROCESSES
5 types of erosional wave processes
abrasion
attrition
hydraulic action
pounding
solution
abrasion
sand/shingle/boulders picked up by the sea and hurled against the cliff
attrition
the wearing down of rocks and pebbles as they rub against each other - making them smaller and rounder
solution
when fresh water mixes with salt water - carbon-based rocks are broken down
pounding
the mass of breaking wave exerts pressure on the rock causing it to weaken
hydraulic action
the force exerted onto rocks from pounding waves
saltation
SMALL stones BOUNCED along the seabed
traction
LARGE boulders ROLLED along the seabed
suspension
SMALL particles carried in moving water
solution
materials that have been dissolved into a mass of moving water
what is LDS
- when sediment it deposited onshore it is moved along shoreline by LSD
- waves approaching the shoreline at an angle due to prevailing wind direction
- when wave breaks, swash carries particles diagonally up the beach and the backwash perpendicular back down
- this creates a zig zag motion
what is deposition
- material is deposited when there is loss of energy caused by decrease in velocity or volume of water
when does deposition take place in a coastal system
- when sediment accumulation goes above the rate of removal
- when waves slow straight after breaking
- at the top of swash in the brief second when the water isn’t moving
- low energy environments -> like estuaries sheltered from winds
whats settling velocity
- the velocity at which sediment particles are deposited
- the larger and heavier the particles, the more energy it takes to transport them
what are fluvial processes - 3 types
- movement of water within a river system which helps create landforms
Erosion
Transportation
Deposition
fluvial erosion
- fluvial erosion in the upper catchment of a river is its main source of sediment load
- rivers use the same erosional processes to waves
fluvial transportation
- rovers also transport material same to waves - traction, suspension, saltation, solution
fluvial deposition
- when river enters sea, there is less velocity bc flowing water through narrow channel goes into static ocean.
- energy is reduced and so all rivers sediment load is deposited
- largest particles get deposited first and the finer materials taken further out
- FLOCCULATION (clumping) of clay particles happens bc fresh and salt water meet bc to the differences in electrical charges. they become heavier then and sink to bottom of seabed
what are aeolian processes - 3 types
- erosion, transport, and deposition of sediments by wind which forms landforms
erosion
transportation
deposition
aeolian erosion
- wind picks up sand and moves by DEFLATION
- erosion happens by surface rolling and saltation
aeolian transportation
- moving air can transport material the same as in water
aeolian deposition
- materials carried by wind can b deposited when the wind speed falls as a result of surface friction
- this happens inland in coastal areas where friction from vegetation is much greater than in the open sea
