Coast Outputs (Depositional Landforms) Flashcards
Outline the formation of coastal sand dunes
Accumulation of sand shaped into mounds by wind
Outline ridges on sand dunes
Parallel to coastline - decrease i height inland as sand supply diminishes
How are sand dune ridges separated?
Depressions - reach down to the H2O table to separate dune ridges
Outline the windward & leeward slopes on sand dunes
Dunes have a steep windward slope & a less steep leeward slope - sand eroded on windward slope is deposited on leeward slope
Outline 5 conditions needed for the development of Coastal Dunes
- High range between high & low tide to expose a large area of sand
- Abundant supply of sand
- Gentle beach profile
- Prevailing offshore wind
- Vegetation that’ll stabilise sand in mounds
Outline the sequence of sand dune development
Sand deposited by LSD is moved up the beach by prevailing wind and the process of saltation
Outline the height and % of exposed sand in embryo dunes
Height = up to 1m
Exposed Sand = 80-99%
Outline embryo dune formation
Sand trapped by driftwood/berms colonised by plants & grasses
Veg stabilises sand encouraging more sand accumulation forming embryo dunes
What type of plant is suitable to live on embryo dunes? Why?
Halophytic plants - they can survive in highly saline areas
Outline a plant that can survive in embryo dunes and why it can survive (3 reasons)
Marram Grass
1. Long roots to reach H2O table
2. Leaves silvery to reflect heat + folded to retain moisture
3. Accumulate sand by growing in a clump
Outline the height and exposed sand % of fore/yellow mobile dunes
Height = up to 5m
Exposed Sand = 20%
Outline how fore/yellow mobile dunes are formed
Follow from embryo dunes.
Initially yellow - lack of organic matter
Colonisation = plant growth + humus to soil -> increase H2O retention & reduces salinity
Outline the height and % of sand exposed in grey fixed dunes
Height = up to 10m
Exposed sand = 10%
Outline the formation of grey fixed dunes
Follow from yellow/mobile
Plant litter stains sand grey & shallow soil develops fixing dunes
More fixed organic layer develops increasing nutrient supply & H2O retention
More plants grow - red fescue > marram
Outline the formation of Dune Slacks
Develop where wind speeds increase at the bottom of slopes causing erosion
Define Blow outs
Large bare areas due to erosion caused by destruction of veg by grazing, human activities
Outline the threat of global warming to sand dunes
Frontal erosion of sand dunes by waves in storms
Rising sea levels - increasing threat in 21st century
Outline the formation of dune heaths
Sand supply behind yellow/grey dunes is cut = smaller dune features
Main veg = heather, gorse, broom
Define Succession
A plant community develops overtime
Each stage = certain species evolve - exploit & alter conditions
New SUCCEED old
Outline the name of a plant succession that occurs on the sand
Psammosere
Outline the conditions required for the formation of mudflats
Need sheltered shorelines
Low lying areas of shore - submerged at high tide - slit & clay
Outline the location where mudflats form
Estuaries where rivers meet the sea
Flow of fresh H2O from river meet salt H2O from sea
Both flows meet - flocculation - individual clay particles form large particles - sink
Low tide - inter tidal areas of mud exposed
Outline the creation of Salt Marshes
In quiet environments - flocculated mud caught by the roots of halophytes. Builds up & dries out
Outline 5 conditions needed for salt marsh development
- Low-energy sheltered environments
- Large supply of fine material from rivers
- Mix fresh & salt H2O causes chemical settling of clays
- Tidal change spring & neap = veg & height change
- Veg root hold sediment
