EQ 1: Why are coastal landscapes different and what processes cause these differences? Flashcards
(22 cards)
What are inputs in the coastal system?
2B.1.a
Inputs Marine -Waves, tides, storm surges Atmospheric - Weather/climate, climate change, solar energy Land - Rock type, geological structure, tectonic activity People -Human activity, coastal management
What are processes in the coastal system?
2B.1.a
Processes
- Weathering
- Mass movement
- Erosion
- Transport
- Deposition
What are outputs in the coastal system?
2B.1.a
Outputs
- Erosional landforms
- Depositional landforms
- Different types of coasts
What is the littoral zone?
How is it divided?
2B.1.a
The wider coastal zone including adjacent land areas & shallow parts of the sea just offshore. Divided into subzones: - Backshore - Foreshore - Nearshore - Offshore
What is the backshore?
2B.1.a
- Area of beach extending from limit of high water foam lines to dunes or extreme inland limit of the beach.
- Above high tide level
- Usually above the influence of the waves (only during exceptionally high tides & major storms.)
- Where greatest human activity occurs & physical processes of erosion, deposition, transport & mass movement largely operate
What is the foreshore?
2B.1.a
- Inter-tidal or surf zone
- where waves processes occur between high & low tide marks
- where human activity occurs, erosion, deposition transport & mass movement largely operate
What is the surf zone?
2B.1.a
The region of breaking water defines the surf zone. After breaking in the surf zone, the waves (now reduced in height) continue to move in and they run up onto the sloping front of the beach, forming an uprush of water called swash,
What is the nearshore?
2B.1.a
- Breaker zone
- Region of land extending between the backshore, or shoreline and the beginning of the offshore zone.
- Water depth usually less than 10m
- Often one of intense human activity (fishing & leisure)
- Forms part of the physical system of the coastline through transfers of sediment by currents close to the shore.
What does do coasts represent?
2B.1.a
where land & sea meet and both marine & terrestrial processes operate and interact.
What extreme events can coasts experience?
2B.1.a
- tropical storms
- cyclones
- tsunamis
Examples of human development on coasts
2B.1.a
- Ports
- Transport
- Coastal defences
- Industrial locations
- Residential & tourism land uses
Human development on coasts varies and is constantly changing.
How can coasts be classified?
2B.1.b
Long-term: geology & changes in sea level
Short-term processes: inputs from rivers, waves & tides
- Geological structure
- Level of wave energy
- Tidal range
- Relative sea level change
- Balance between erosion & deposition; formation processes
• Geological structure
Concordant, or Pacific coasts - generated when rock strata run parallel to the coastline.
Discordant, or Atlantic coasts - form when different rock strata intersect the coast at an angle, so geology varies along the coastline.
• Level of wave energy
Low energy sheltered coasts, with limited fetch and low wind speeds resulting in small waves.
High energy exposed coasts, facing prevailing winds with long wave fetches resulting in powerful waves.
• Tidal range
- Microtidal coasts (tidal range of 0-2m)
- Mesotidal coasts (tidal range of 2-4m)
- Macrotidal coasts (tidal range greater than 4m)
• Relative sea level change
Emergent coasts - where the coasts are rising relative to sea level e.g., due to tectonic uplift.
Or a coastline exposed by the sea by a relative fall in sea levels.
Submergent coasts - are being flooded by the sea, either due to rising sea levels and/or subsiding land.
• Balance between erosion & deposition - formation processes
Primary coasts - dominated by land-based processes such as deposition at the coast from rivers or new coastal land formed from lava flows.
Formed by more land driven processes than ocean-driven processes like plate tectonics, land erosion and sedimentation.
Secondary coasts - dominated by marine erosion or deposition processes.
Include marine-deposition coasts where sea movement causes accumulation of ocean sediments in a single place
What is offshore?
Beyond the influence of the wave
What can winter storms create?
Short-term high energy erosional environments
Examples of:
- Primary coastline
- Secondary coastline
- Emergent coasts
- River Nile delta, Hawaiian coast
- Great barrier reef Australia, Barrier-island Mexico
- Isle of Arran
High-energy environments in the UK
Cornwall & North-Western Scotland
Stretches of Atlantic-facing coast
High-energy environment erosional landforms
Headlands
Cliffs
Shoreline platforms/wave-cut platforms
Cornwall - UK’s most south-westerly peninsula
Peninsula - a piece of land that is surrounded on three sides by water. So, it is different from an island because it is attached to a larger landform.
o Similar to rest of Westerm Britain, mostly consists of older resistant rocks, resistant to erosive power of the sea, rain & wind
- igneous (basalt & granite), older, compacted sedimentary rocks (old red sandstone), metamorphic rocks (slates & schists).
o Exposed to bad weather from the Atlantic Ocean
o Due to its geology (rock type), Cornwall’s rocky coastline can withstand frequent winter storms w/o suffering rapid erosion.`
What are rocky coasts? • Where in the UK do they tend to be located? • How are they formed? • What sort of environment are they often in? • What landforms form? • Any sub categories? • Rate of erosion vs rate of deposition? • Examples?
Cliffs varying in height from a few to hundreds of metres.
High-relief cliffs tend to be composed of relatively hard rock.
Rocky coasts (high and low relief) result from resistant geology (to the erosive forces of sea, rain, and wind), often in a high-energy environment.
Transition from land to sea is abrupt.
Low tide, foreshore zone is exposed as a rocky platform (wave-cut platform).
What are Coastal Plains a.k.a Alluvial coasts?
• Where in the UK do they tend to be located?
• How are they formed?
• What sort of environment are they often in?
• What landforms form?
• Any sub categories?
• Rate of erosion vs rate of deposition?
• Examples?
Low-lying, low relief areas
Result from the supply of sediment from different terrestrial and offshore sources, often in a low-energy environment.
• Land gradually slopes towards the sea across an area of deposited sediment.
• Contain sand dunes, wetlands, salt marshes and mud flats.
Why?
Only just above sea level and poorly drained due to flatness of the landscape
How are they formed?
o A result of a fall in sea level exposing the seabed of a shallow continental shelf sea. e.g. Atlantica coastal plain in USA.
o Deposition of sediment from the land brought down to the coast by river systems can cause coastal accretion where the coastline gradually moves seaward e.g. in a river delta
• In many locations, they are maintained in a state of dynamic equilibrium by balancing the force of:
o deposition of sediment from river systems inland and deposition of sediment from offshore and longshore sources.
o erosion by marine action at the coast
What are sandy coastlines?
Sandy dunes fringe many coastal plains.
What are Estuarine coastlines?
Estuaries are found at the mouth of rivers.
o extensive mud flats cut by channels are exposed at low tides but inundated at high tide.
o closer to the backshore, mud flats are vegetated, forming a salt marsh.
o gradually transitions from land to sea (this type)
