Geomorphological Processes Flashcards
What are the 4 processes?
Coastal weathering
Mass movement
Transportation
Erosion and deposition
Which are the marine processes?
Transportation
Erosion and deposition
What are the sub aerial processes (on land)?
Weathering
Mass movement
What are the 3 types of coastal weathering?
Biological
Chemical
Mechanical (physical)
What is biological weathering?
-the breakdown of rocks by organic activity
What are some examples of biological weathering?
- thin plants roots grow into small cracks in a cliff face, these cracks widen as the roots grow, breaks up the rock
- water running through decaying vegetation becomes acidic, which leads to increased chemical weathering
- birds e.g. puffins, and animals e.g. rabbits dig burrows into cliffs
What is chemical weathering?
A chemical reaction where salts may be dissolved or clay like deposit may result which is then easily eroded
What are some examples of chemical weathering?
Carbonation = rainwater or sorbs c02 from a weak carbonic acid. This reacts with calcium carbonate in rocks e.g. chalk, to form calcium carbonate, which is easily dissolved
Oxidation = the reaction of rock minerals with oxygen e.g. iron, to form a red rusty powder
Solution = the dissolving of rock minerals e.g. halite
What is mechanical weathering?
Involves the breakup of rocks without any chemical change taking place
What are some examples of mechanical weathering?
Frost shattering (freeze thaw) -occurs when water enters a crack when it rains and then freezes making it expand and crack
Salt crystallisation - when slat water evaporates it leaves salt crystals behind , grows overtime and exerts stresses in the rock causing it to break up
Wetting/drying - rocks rich in clay expand when they get wet and contract when dry, causing them to crack and break up
How does geological climate affect rate of biological weathering?
Need plants and animals living there
A climate that is good for plant growth
How does geological climate affect rate of chemical weathering?
Dependant on human activity (pollution and factories releasing acid/chemicals)
Rock type is important e.g. ones that go through oxidation
How does geological climate affect rate of physical weathering?
Climate/temperature changes - temperature fluctuations e.g. uk, freezing over night then melting during day
What is positive feedback?
If the rate of debris removal exceeds the rate of weathering and mass movement then a positive feedback can operate, as the rate of weathering and mass movement could increase
What is negative feedback?
If debris removal is slow and ineffective, this will lead to a build up of an apron debris that reduced the exposure of the cliff face. Weathering and mass movement rates will decrease
What is mass movement?
The downhill movement of weathering material under the force of gravity
What are some types of mass movement?
Soil creep/solifluction
Mudflows
Run off
Landslide/slip
Rock fall
What are the 5 processes of erosion?
Hydraulic action
Wave quarrying
Abrasion
Attrition
Solution
What are some factors effecting a rate of erosion?
- rock type/structure
- coastal defences
- wave type
- wind speed
- weather conditions
- beach size
- cliff profile
- air pressure
- acidity of water
- fetch lenght
What are the 4 processes of transportation?
- traction
- saltation
- solution
- suspension
What 2 factors will be key in determining how an individual particle is moved at a coastline?
- size of sediment
- energy of the waves
What process moves material along a beach?
Long shore drift
How do grones (coastal management) create a positive feedback leading to higher rates of erosion?
As they prevent sediment from moving along, so an area will have little beach to absorb wave energy, therefore its easier to erode as nothing will be in the way
How do sea walls affect erosion rates?
Received sea walls will push waves back out to sea, meaning that all the energy will be focused along the front sides of walls
How does coastal deposition work at high energy coasts?
Small particles (clay/sand) easily transported whilst larger and heavier material is deposited, forming shingle beaches
How does deposition work at low energy coast lines?
Even the smallest material is deposited forming mudflats and salt marches
