Flashcards in Coastal Processes Deck (10)
What are the six forms of coastal erosion?
Abrasion - Bits of Rock and sediments are transported by the waves and grind against rocks and cliffs, breaking bits off.
Hydraulic action - Air in cracks is compressed
Cavitation - The compressed air then expands violently
Wave quarrying - The energy of a wave itself is enough to break pieces off
Solution - Soluble rocks get gradually dissolved by the sea water
Attrition - Bits of rocks in the water smash against one another breaking into little pieces.
What are 5 processes of transportation?
Solution - Substances are dissolved and transported in the water.
Suspension - Very fine material is whipped up by turbulence and carried along in the water.
Saltation - larger particles which are too heavy to be suspended are bounced along the sea bed.
Traction - Very large particles are pushed along the sea bed by the force of the water.
Long shore drift - Swash carries sediments to a coastline in an angle die to prevailing winds, the backslash the. Brings the sediments back at a right angle slowly moving sediments along the coast.
What are the 4 forms of sub-Ariel weathering?
Salt weathering - after salt dries it forms crystals which expand and expert pressure.
Freeze-thaw - Over time expansion and melting of water exerts pressure weakieng cliffs etc.
Wetting and drying -
Rocks such as clay expand when wet and detect when dry.
Chemical weathering -
Breakdown of rocks by dissolving them
Biological weathering - Plants grow and expand.
What are the 3 landforms caused by erosion?
Cliffs and wave cut platforms As the sea eroded the coastline a notch above the high tide mark develops which eventually collapses leading to a procession of cliff retreat leaving a wave cut platform behind.
Headlands and Bays -
Largely found at discordant coastlines where alternating bands of rocks erode at different speed leaving headlands of harder rock and bays.
Caves Arches and Stacks -
Some landforms are found in cliffs, notched form caves caves form arches and arches collapses leaving stacks.
What are some depositional coastal landforms?
Beaches - When constructive waves deposit sediment on the shore, they are a large store of sediments shingle beaches are steep and narrow, beaches have features such as Berms and ridges of san and pebbles found at high tide marks, tunnels and groves are caused by backslash draining Into the sea.
Spits - When longshore drift drags sediments into a coast area that has changed direction. Such as river channels, the end of the spit has a recurves end and when many of these build up as the spit rebuilds they create a compound spit where behind is ofeten created into mudflats
Offshore Bars and Tombolos -
Formed when a spit joins two headlands together, a lagoon is formed behind this and tomblos are when spits connect an island.
Barrier islands -
Are narrow islands of deposition that run parallel to the coastline and are formed in areas small tidal ranges.
Sand dunes - When vegetation stabilises sand blown in from the ocean causing more sand to build up creating embryo dunes hawker W mature dunes can reach heights of up to 10meters
Mudflats and salt marshes -
Created in sheltered low energy environments, deposition allows Vegatatuon that can survive by being submerged to grow and encourage more deposition increasing the height of the mudflat meaning the grace exposed for longer positive feedback loop
What is isostatic and Eustatic sea level change?
Eustatic is changes caused by the volume of water in the sea they are largely caused by changes in the climate that melts icecaps increasing water a decrease in temperature causes accumulation and hence sea levels will fall.
Tectonic movements can also alter the shape of the ocean basin increasing or decreasing the volume.
Isostatic - veritable movements of the land relative to the sea isostatic rebound, subsistence of land die to groundwater extraction, tectonic process may uplift plates.
How does climate change cause changes in sea level.
Sea levels are around 130 meters higher that during the last glacial peak, over the last 4000 years sea level has fluctuated at its present value but has grown exponentially since 1930
> global warming has lead to a 1.08°c rise in temperatures leading to thermal expansion. Into the oceans, they are rising at approximately 2mm per year it’s is expected to rise another 16mm per year by 2100
What are the impacts of these sea level changes on the coastal areas?
Storms are likely to become more frequent and intense causing more damage to ecosystems
Submergeebce of lying islands for example a sea level rise of around 0,5 meters would submerge almost all of the Maldives.
Contamination of water and farmlands damaging ecosystems.
Raised beaches are formed when the fall in sea level leaves the beach above the high tide mark allowing it to develop soil and vegetate. This also crates relict cliffs.