Coastal landforms Flashcards
What is strata
Layers of rock
What are bedding planes
Horizontal, natural breaks in the strata, caused by gaps in time during periods of rock formation.
What are joints
Vertical fractures
What is the dip
Angle at which rock strata lie
Formation of a WCP
When Waves concentrate erosion at small area of rock, this leads to cliff becoming undercut. Forming wave cut notch, increasing shear stress of on cliff. Cliff retreats leaving WCP. Example of negative feedback.
What is differential erosion
Rocks erode at different rates, due to weaker beds and more resistance rocks
Flamborough head overview.
Cliff height- 30-100 m
Geology- Chalk, with horizontal bedding planes-resistant
Marin processes- Hydraulic action, solution
Mass movement- Rockfall, 1-2 cm per year
Landforms- WCP, caves, notches
Aldbrough overview
Cliff height-5m-10m
Geology- Unconsolidated boulder clay, low shear strength.
Marine processes- Wave quarrying, hydraulic action, cavitation.
Mass movement- Very regular slumping so no caostal landforms -1-2 per year retreat, due to undercutting.
How was Selwicks bay created
Tectonic movements folded and faulted the chalk layers, creating cracks. This enlarged the surface area making rock more vulnerable to weathering, erosion and retreat. Creating Selwicks bay.
What are Geos
Steep- sided inlet, due to erosion excavating enough material along a fault.
What is the building up of a beach called
Accretion
What is the storm beach
Ridge of pebbles pushed up by storm waves
What are berms
Lower ridges parallel to the storm beach , ridge of material left by HT.
What are swash- aligned beaches
Form in low energy environments when waves arrive roughly parallel to the shore.
What are drift aligned beaches
Form where the waves approach the coast at an angle. LSD moves the sediment along the beach
How are simple spits different to compound spits
Simple spits do not have minor spits or recurred ridges along their landward edge.
exmple of spit
Spurn head, Dominant wind direction from NE, creates LSD, sediment moves southwards.
Humber estuary provides change in direction of coastline.
When does a bar form
When the sediment from a spit reaches to the other side of the bay.
What is an offshore bar
When destructive waves erode sand from the beach with their strong backwash and deposit it offshore. - They absorb wave energy.
What is a Tombolo
Where ridges of sand and shingle link the coast to an island.
What is Xerophyte
A plant adapted to living in a dry arid habitat like a sand dune.
Sand dune development
-Dry sand is transported landwards by onshore winds.
-Wind velocity drops when it encounters an obstacle and sand is deposited
-The sand accumulates to form embryo dunes
Pioneer species colonise
-Sand is anchored, wind flow is further disrupted, deposition continues and sand dune grows into foredunes ort yellow dunes.
-Sand is blown off the top and sand dune slowly migrates landwards.
-A new dune is formed at the strand line.
-Wind weep down the leeward side of the dune and scour the dip until the wet sand is reached and a dune slack is formed.
-Removal of vegetation will result in the sane dune being eroded and forming a blowout.
Embryo dune conditions
-Saline environment.
-Windy- sand mobile
-Arid- little freshwater
-PH8, harsh
therefore only specially adapted plants can survive-pioneer species-xerophytic plant.
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Foredune+ yellow dune conditions
Established 50 years ago
-Less saline
-Windy, sand is less mobile
-More minerals due to marram grass decomposed.
-PH7 more acidic due to organic acids from decomposition.
Grey dunes conditions
-Rain washed away salt
-Higher organic matter content- decomposed material = acidic ph6
-Cation exchange capacity of soil- displaces minerals and makes available for plant uptake.
Formation of a slat marsh
A salt marsh begins when mud and silt are depositied along a sheltered part of coastline, this is because rates of deposition are greater than transportation due to lack of wave energy.
Some plants then colonise the mud flats, called pioneer species. usually eelgrass. It is tolerant to seawater and long roots help hold sediment together. The decomposition builds up over time meaning that the mud breaks the surface to form mudflats, allowing new plants to colonise.
Due to The sediment and material accumulating, it gets covered by the tide even less. The rain will leach some of the salt. As the salt is now lower in concentration, it means more plants can start to grow in more fertile soil.
What are mudflats
Develop in estuaries where the sea water flows into the river mouth with each HT and out with each LT.
Formation of a mudflat
Where the saltwater flow gently into the estuary it brings large amounts of fine sediments; this meets the equally slow moving river which is also carrying its own sediment.
The meeting of fresh and salt water causes the clay particles to aggregate together, making them heavier and sink. This is known as flocculation.
