Coastal Envronments Flashcards
Hydraulic action
Waves hit cliffs and force air into cracks causing the rock to break apart
Abrasion
Waves pick up pebbles and hurl them against the cliff
Solution
The dissolving CaCO3 rocks like limestone or chalk by the sea
Attrition
Pebbles carried by the waves collide with each other and become smaller and more rounded over time
Deposition
Occurs when waves lose energy/material carried is too large to transport with the amount of energy the wave has
Mechanical weathering
Breaks down rocks by processes such as freeze-thaw, salt crystal growth and wetting and during of clay rich rocks
Biological weathering
It is when rocks are broken down by plant roots, burrowing animals and nesting birds
Chemical weathering
It is when rocks are broken down by carbonation, oxidation, and acid rain. Usually impacts CaCO3 rock
Slumping
Waves erode the cliff base and cause instability. Rain water permeates through the rock saturating it, until it becomes in stable and slumps along bedding planes. Leads to a stepped appearance to the cliff
Sliding
Weathering loosens the rock, which slides down off bedding planes. Leads to landslides and mudslides
Geology
Rock type like granite, chalk and etc
Lithology
Characteristics of the rock eg relative hardness, permeability etc
Discordant coastline
Rock outcrops are at 90 degrees to the sea. Leads to headlands and bays where there are bands of soft and hard rock interspersed with each other
Concordat geology
Rock outcrops are parallel to sea. Creates straighter coastlines. Though can create coves, like Lulworth Cove, Dorset
Bedding planes
In cliffs determine how susceptible the cliff is to collapse
How does vegetation influence the coastline
-biological weathering
-can create sand dunes via encourage deposition, and then stabilise them
-can protect and preserve coastal landforms by buffering and reducing wave energy(mangroves
Influence of wave refraction by bays and headlands
-waves approach parallel to the coastline as a whole
-as the sea shallows, on approach to the coast the waves refract to mirror the individual shape of the coastline
-this leads to energy being concentrated on headlands(due to converging waves). Despite this, headlands remain sticking out to sea more than bays due to their relatively harder lithology
Formation of cliff/cliff retreat
-erosion is concentrated at the base of the cliff between the low tide and high tide mark in the wave attack zone through hydraulic action and abrasion
-the creates a wave cut notch
-the cliff above is undercut, is therefore unsupported and collapses due to gravity
-this creates a wave cut platform
-over time, this repeats and the cliff retreats inland
Longshore drift
-waves approach the coast at an angle because of the direction of the prevailing wind
-the slash will carry the material towards a and on to the beach at an angle
-the backswash then flows back to the sea, directly down the slope of the beach due to gravity
-the process repeats itself along the coast in zigzag moments
How does sea level influence the coast by
-coastal flooding is caused by rising sea level
-fjords form when glacial landscape are flooded - rias from flooded areas
-retreating sea level due to land uplift creating landforms such as relict cliffs and raised beaches
-saltwater incursion - loss of groundwater causes sea water in coastal region to be drawn into permeable rock
How do people influence the coast
-settlements
-fishing
-trade
-tourism
What are beaches
They are areas where there is an accumulation of sand and shingle, caused by deposition. They often form in bays, where the coast is sheltered from high energy, erosion all waves, or where long horse drift provides a large supply of material
How does a spit form
-sudden change in coastline shape or direction
-longshore drift has momentum and so continue to transport and deposited material at sea, following the original direction of longshore drift
-over time, sediment builds up creating a sandy ridge outcrop (a spit) on the coast
-salt marshes form behind spits as these water are low energy and stagnant. Rivers often deposited their sediment too, growing the spit
-spits often become curbed due to secondary prevailing wind or the impact of cross-currents/storm
What are cuspate forelands
-triangular shapes accumulations of sand and shingle
-develop due to LSD from two directions
-collision of two LSD directions encourages deposition and creation of the foreland )Dungeness, Kent)