Coasts Flashcards
What is the Littoral Zone?
- The wider coastal zone including coastal land areas and shallow parts of the sea offshore
What are the essential features of the backshore?
- Usually above high tide level and only affected by waves during exceptionally high tides and major storms
What happens at the foreshore?
- Inter-tidal zone or surf-zone
- Wave processes occur here between high and low tide
Describe the essential features of the nearshore?
- Shallow and usually submerged underneath water
- Used extensively for fishing, coastal trade and leisure
What is the offshore?
- Area beyond the influence of the waves
What are three different criteria that might be used in classifying coasts?
- Headlands and Bays
- Sediment Movement
- Erosion Rate
What are subaerial processes?
- Processes that cause erosion that are caused by the weather
Describe the essential features of coastal plains?
- Low energy
- low Lying
- A lot of deposition occurs
- Has weaker waves
What is a concordant coast?
- Rock runs parallel to the coast
What is a discordant coastline?
- Rock runs adjacent to the coastline
What is an example of a concordant coastline?
- Lulworth cove, Dorset
What is a Haff coastline?
- When long sediment ridges that are topped by sand dunes run parallel to the coast.
- Create lagoons between the ridges and the shores
What are the micro-features of a cliff?
- Caves
- Cracks
- Wave cut notches
How are cliff micro-features formed?
- Expansion of joints and faults in a cliff
What is rock strata?
- The layers of the rock
What are bedding planes?
- Natural breaks in the strata (Often horizontal) caused by gaps in the rock formation
What are rock joints?
- Fractures (Often vertical) caused without displacement either by contraction as sediments dry out, or by earth movements during uplift.
What are rock folds?
- When rock buckles and crumbles due to pressure during tectonic activity
What are rock faults?
- Fractures caused when stress of pressure to which a rock is subjected, exceeds its internal strength.
What is rock dip?
- The angle at which a rock strata lie
What are Igneous rocks?
- Erosion rate?
- Examples?
- Very hard that forms 95% of the earths crust. Formed through solidification of lava or magma. No layers.
- ER: Less than 1mm a year
- Examples:
+ Diorite
+ Granite
+ Obsidian
+ Basalt
What are Metamorphic rocks?
- Erosion rate?
- Examples?
- Rocks formed through the transformation of older rocks . Able to change. may or may not have layers. Relatively harder.
- ER: 1mm a year
- Examples:
+ Slate
+ Quarzite
+ Hornfels
+ Marble
What are Sedimentary rocks?
- Erosion rate?
- Examples?
- Rocks formed through compaction of sediment. Very permeable. Easy to crumble. Distinctly layered.
- ER: 1cm - 1M a year
- Examples:
+ Sandstone
+ Iron ore
+ Coal
+ Limestone
What is morphology?
- Combination of ‘Morph” = Shape or form and “Ology” = the study of something
How do plants protect the coastline?
- Roots: Bind sediment together
- Sheltering from water: When submerged plants provide a protective layer for sediment.
- Sheltering from wind: Plants slow wind speed and act as protection for sediment.
What are halophytes?
(Not essential)
- Plants that can tolerate salt water both around their roots and by their leaves
What are Xerophytes?
(Not essential)
- Plants that can tolerate very dry conditions like these found on coastal sand dunes where very little water is retained.
What are the 5 stages of sand dune formation?
- Embryo Dune
- Fore Dune
- Yellow Dune
- Grey Dune
- Dune Slack
What are embryo dunes:
- Youngest dunes
- Formed from new sand pushed up from the beach.
Stabilised by pioneer plants with their roots.
What is a fore dune?
- Second stage of dune creation.
- Sand stabalises and new species begin to grow
What is a yellow dune?
- The third stage dune
- The highest dune
- may form a ridge with
Marram grass
What is a grey dune?
- 4th stage dune
- Formed when there is a plentiful supply of sand
- Well established and mature
What is a dune slack?
- Last stage dune
- Right at the back of all of the dunes
- oldest and furthest away from the sea
Apart from colour, what distinguishes yellow dunes from grey dunes?
- Yellow dunes are usually bigger and steeper
How are waves formed?
- Action of the wind dragging on the surface of the sea creating friction
What is the fetch?
- The distance the wind blows over water with similar speed and direction
What is wind duration?
- The time for which the wind has blown over the water without disruption
What are wind waves?
- Waves generated by the immediate local wind.
- Not self-sustaining and will die out when wind stops
What are swell waves?
- Self-Sustaining waves generated by energy beneath the ocean’s surface.
- No longer needing local wind
What is a constructive wave?
- Shallower waves with much less energy
- Deposit sediment on beaches