Coasts EQ1 Flashcards
What is the Littoral Zone?
The wider coastal zone, including coastal land areas and shallow parts of the sea offshore
Name the subdivisions of the Littoral Zone
Offshore, Nearshore, Foreshore, Backshore
What is offshore?
The area beyond the influence of breaking waves
What is nearshore?
Intertidal and within the break zone. It is used for fishing, trade and leisure
What is foreshore?
The part of the shore between high and low water marks, or between the water and cultivated or developed land
What is backshore?
Above high tide and the influence of normal wave patterns. It may have a storm beach further up
What are the characteristics of rocky coasts?
Subject to erosion, steep or vertical profile, resistant rocks, weathering and mass movement, high energy environment
What are the characteristics of a plain coast?
Deposited landscapes, low and flat often poorly drained, accretion process dominated, coastline advances seaward, often low energy environment
What is a primary coastline?
Dominated by land based processes (deposited from rivers or lava flows)
What is a secondary coastline?
Dominated by marine erosion and depositional processed
What is an emergent coastline?
Where the coast is rising relative to the sea level due to tectonic uplift
What is a submergent coastline?
Areas flooded by rising sea levels or subsiding land
What is tidal range?
Microtidal - 0-2m
Mesotidal - 2-4m
Macrotidal - 4+m
What is a low energy coastline?
Sheltered coasts with limited fetch and low wind speeds with small waves
What is a high energy coastline?
Exposed coasts facing prevailing winds with a long fetch and powerful waves
What are the elements of rock strata?
Different layers of exposed rock
What are the elements of rock deformation?
Degrees of tilting and folding by tectonic activity
What are the elements of rock faults?
Factoring that may have moved rocks from their original positions
What is a concordant coastline?
When rock strata runs parallel to the coastline
What is a discordant coastline?
When different rock strata intersect the coast at an angle so rock type varies along the coastline
Give an example of a concordant coastline
Dalmatian Coast in the Adriatic Sea
Describe the Dalmatian Coast as a Concordant Coastline
Limestone has been folded by tectonic activity into a series of anticlines and synclines that run parallel to the coastline
What has happened to the syncline basins?
They have drowned due to sea level rise
What has happened to the anticlines?
They have produced long, off-shore islands
Describe discordant coasts
They are dominated by headlands and bays, less-resistant rocks are eroded to form bays, more resistant rocks remain as headlands
What is wave refraction?
In deep water, wave crests are parallel. As water shallows towards the coast, waves slow down and wave height increases. In bays, wave crests curve to reflect their shape and wave height decreases
What is wave action concentrated on?
Headlands
What influences cliff profiles?
Rock type and resistance, the dip of rock strata in relation to the coastline, faulting to expose rocks to erosion, and natural cracks in the rock (joints and fissures)
Describe igneous rock
Crystalline, strong and resistant, very slow recession (less than 0.1cm a year)
Give an example of igneous rock
Granite
Describe metamorphic rock
Generally resistant, some may have crystals oriented in one direction, rocks may be folded or faulted so have weak areas, slow recession (0.1-0.3cm a year)
Give an example of metamorphic rock
Slate
Describe sedimentary rock
Rocks are clastic (stick together in layers), less-resistant, rocks have natural bedding planes, fast recession (0.4-10cm a year)
Give an example of sedimentary rock
Sandstone
Describe unconsolidated rock
Very weak material, easily eroded, rapid recession (2-10cm a year)
Give an example of unconsolidated rock
Boulder clay
What are permeable rocks?
Rocks that allow water to pass through (sandstone and limestone)
What are impermeable rocks?
Rocks that don’t allow water to pass through (clay, most igneous and metamorphic rocks)
Why is vegetation useful when strengthening coasts?
The roots bind sediments together, when submerged they protect the surface from erosion, they protect sediment from wind and rain due to friction on the leaves
Describe how sand dunes are formed
Sand is deposited by the sea under low-energy environments, the wind moves the sand to build sand dunes further up the beach, these become colonised by stabilising plants
