T3 2B.1: Characteristics Flashcards
(25 cards)
Define the littoral zone
Littoral zone: the coastal zone in which sediment is moved along the shore and subject to erosion
Intertidal zone definition
Intertidal zone: refers to the difference between high tide and low tide where in high tide, it is submerged and in low tide it is exposed
What are the different zones of coasts in order (sea to land)
- Offshore
- Nearshore (breaker, surf)
- Foreshore (swash zone)
- Backshore
Dynamic equilibrium definition
Dynamic equilibrium: refers to the state of balance of factors of inputs/outputs at a coast and how this relationship is adapting but still remains the same over time.
Outline the features of offshore
Offshore: deep water before waves break
- waves are not breaking
- lower ocean depth but is decreasing
- long fetch
- Offshore bar
Outline the features of the nearshore:
Nearshore: before low-tide mark where the sea-bed and waves are close causing friction to break waves.
Breaker zone:
- before the low-tide mark
- friction begin seabed and waves cause —> waves break
Surf zone:
- waves begin to swash
- rip currents
Outline the features of the foreshore
Foreshore: the intertidal zone between the low and high tide marks
- beach
- larger coarse material but becoming smaller
- backwash drains back into the water
Outline the features of the backshore:
Backshore: the area above the high-tide mark which is exposed and holds the majority of the beach
- berms — ridges of sediment
- limited vegetation
Suggest ways that coasts can be classified
- Emerging/ submerging
- Depositional/ erosional
- Material/ sediment (rocky, sandy, salt marshes)
- level of relief
What are the three types of coast and characterstics?
rocky - high relief, resistant geology, high energy environment.
sandy - low relief, sand dunes and beaches, flatter
Estuarine - low relief with mudflats and salt marshes near estuaries and river mouths
Features of a high energy coast (WPLG - waves, processes, landforms, geology)
High energy coast:
Waves: destructive, long fetches and storm conditions
Processes: erosion and transport of eroded sediment, mass movement
Landforms: cliffs, wave-cut platforms, cave-arch-stack-stump
Geology: varies
Features of a low-energy coast (WPLG - waves, processes, landforms, geology)
Low energy coasts:
Waves: constructive —> calmer conditions, short fetches and less powerful
Processes: deposition and transport of sediment —> LSD
Landforms: beaches, spits, bars, sand dunes, salt marshes
Geology: varies
Concordant coastline definition
Concordant coast: occur when the strata is arranged parallel to the beach and coastline which alternates between soft and hard rock.
Discordant coastlines:
Discordant: occur where the strata runs perpendicular/90 to the coast and shoreline with alternating strata where these are exposed to the coast.
Discordant coastlines (WPLG)
Waves: vary
Processes: erosion occurs of soft rock at faster rates and hard rock at slower rates
Landforms: headlands* and bays with cave-arch-stack-stump
Geology: 90 so varies and causes *differential erosion
Concordant coastlines (WPLG)
Waves: vary
Processes: erosion and transportation but at a more uniform/ similar rate
Landforms: Haff coastlines, Dalmatian coasts and coves
Geology: parallel to coast
How does longshore drift occur and what landforms does it occur
LSD:
1) swash comes up the beach at direction of *prevailing wind**
2) backwash at 90 to the coast takes away sediment
3) moves swash along and down and repeats
Landforms: barrier beaches, spits, recurved spits, double spits, tombolos, salt marshes
How do coves form?
differential erosion at concordant coastlines
1) Hard rock is slowly eroded in one area over time
2) Allows water to access next band of soft rock
3) Soft rock erodes fast and wide —> Cove
What are the four types of dip in order of fastest to slowest erosion
Dip: refers to the angle of tilt lag the rock when compared to the horizontal. There are several types of dip influencing erosion rates.
Seaward
Vertical
Horizontal
Landward
Define differential erosion
Differential erosion: this refers to erosion but at varying rates along a coastline due to different factors (WPLG).
What can impact differential erosion
- cracks, joints and weakness
- permeability
- condition —> sub-aerial
- geology
Psammosere succession
1) pioneer species settle along the coast
2) Sand is blown and trapped so accumulates near plants
3) Forms embryo dune which are above high tide
4) Plants add nutrients and reduce evaporation helping stabilise dunes
5) These become —> foredunes/ yellow dunes —> grey dunes —> climatic climax
What are halophytic and xerophytic plants?
Xerophytic: adapted to live in low-water environments group retaining moisture
Halophytic: adapted to live in high salinity environment
Explain how pioneer species stabilise coasts with examples
1) Pioneer species help stabilise salty or low water conditions
2) They add moisture, stabilise using their roots and consolidate sand
3) This dries the sand out —> wind blows it and it gets trapped to form dunes
4) This absorbs waves and forms dunes
Ex:
- Marram grass at sand that withstands gale-forces
- Cordgrass —> muddy helps build up muddy substrate
