Coastal Landscapes And Systems Flashcards
Definition= Geology
Rock type
High energy coastlines:
Where rocky coasts are generally found ( high energy environments). Erosional landforms such as headlands, cliffs, and shoreline platforms ( wave-cut platforms) tend to be found in these environments
- waves are powerful for much of the year
- the rate of erosion exceeds the rate of deposition
Low-energy coastlines:
Sandy and estuarine coasts are generally found in low-energy environments. Landforms such as beaches, spits and coastal plains tend to be found in these environments.
- stretches of the coast where waves are less powerful, or where the coast is sheltered from large waves
- where the rate of deposition exceeds the rate of erosion
Coastal system:
Inputs:
Marine- waves, tides, storm surges
Atmospheric- weather/climate, climate change, solar energy
Land- rock type and structure, tectonic activity
People- human activity, coastal management
Processes:
Weathering
Mass movement
Erosion
Transport
Deposition
Outputs:
Erosional landforms
Depositional landforms
Different types of coasts
Littoral zone:
The wider coastal zone including adjacent land areas and shallow parts of the sea just offshore (tides and storms affect a band around the coast)
Why does the littoral zone vary?
Short term factors:
Individual waves, daily tides and seasonal storms
Long term factors:
Changes to sea levels or climate change
Four zones that the literal zone is divided into:
Backshore:
This is the inland limit of the beach and the waves only reach this area during exceptionally high tides, usually above the influence of the waves
Foreshore:
This is the area between the high tide and the low tide mark
Nearshore:
The area of shallow water beyond the low tide mark, within which friction between the seabed and waves distor the wave sufficiently to cause it to break
Offshore:
The area of deeper water beyond the point at which waves begin to break. Friction between the waves and the sea bed may cause some distortion of the wave shape. ( beyond the influence of the waves)
Sub-Ariel processes:
Process of weathering and mass-movement
Factors that affect the coastline:
- sub-ariel processes
- marine processes
- vegetation
- geology
- human management
- climate
- time
Sedimentary rocks:
- formed in the sea, youngest
- layered
- made up of very small, old, decayed sea creatures and vegetation
- tectonic plates lift the rock up/ brought to the surface as a result of falling sea levels
Metamorphic rocks:
- made up as a result of great pressure, gets squashed by tectonic processes
- rocks come out with very different properties
- very hard, impermeable, resistant
Igneous rocks:
- made from molten magma, cooled under earths surface
- comes out in volcanic eruption
- hardest rock and oldest
Lithology:
Refers to a rocks features, such as wether it is permeable ( allows water through) or soluble (dissolves), hard or soft and it’s texture. It is the general physical and chemical characteristics or structure of a rock or the rocks in a particular area
Strata:
Layers of rock
Bedding planes:
(Horizontal cracks) natural breaks in the strata caused by gaps in time during periods of rock formation
Joints:
(Vertical cracks) these are fractures, caused either by contraction as sediments dry out, or by earth movements during uplift
Folds:
Formed by pressure during tectonic activity, which makes rocks buckle and crumple
Faults:
Formed when the stress or pressure to which a rock is subjected, exceeds its internal strength (causing it to fracture) the faults then slip or move along fault panes
Dip:
Refers to the angle at which rock strata lie (horizontally, vertically, dipping towards the sea, or dipping inland)
Morphology:
Shape and form of coastal landscapes and their features, affected by geology and its geological structure (lithology)
Weathering:
Breaking up of decomposition of rocks in situ
Physical weathering:
Water expands when changed into ice, expansion puts pressure on the rock around it, fragments of rock break off
- salt weathering
- wetting and drying
Chemical weathering:
Weak acids in rainwater react with calcium carbonate in rocks, rocks break up or dissolve
- carbonation
- hydrolysis
- oxidation
Biological weathering:
Plants grow in cracks, roots break up rock, may cause cliff to collapse
- plant roots
- rock boring
- animals
Concordant coastlines:
Bands of more-resistant and less-resistant rock run parallel to the coast
Discordant coastlines:
Geology alternates between bands of more resistant and less-resistant rock, which run at right angles to the coast
Dalmatian coasts (concordant coastline):
Formed as a result of a rise in sea level, when sea level rises the ridges of valleys remain above the surface of the sea
Refraction:
-waves bend and change direction
- bays become more sheltered, headlands have full force of energy from the sea
Rate of cliff retreat depends on:
- rock type
- geological structure
- wave power
- fetch
- weather/ seasons
Sediment supply:
Processes of weathering and erosion produce output in the form of sediment, which is transported and deposited to produce coastal landforms
Submergent coastline:
-flooded coastlines due to a rise in sea levels at that location
-the impact of a rise in sea-level
-marine transgression
Emergent coastlines:
-coastlines that are formed where water level has fallen or land has risen due to isostatic change eg. ice on top of land has melted
-impact of a fall in sea level
-marine regression
Mass movement:
The downward movement of material under the influence of gravity. It includes a wide range of processes