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Coastal Landscape Development (workbook 3a) (more coastal landforms…
Coastal Landscape Development (workbook 3a)
Different Landforms
Created by erosion
stump
stack
bay
headland
arch
wave-cut platform
wave-cut notch
cave
Created by deposition
shingle beach
sand beach
spit
bar
tombolo
offshore bar
mudflat
saltmarsh
sandunes
cuspate foreland
Created by sea level change
raised beach
marine platform
Fjord
Dalmation Coast
Rias
BLOWHOLE- vertical erosion (marine processes) exploit weaknesses in rock. Water forces itself upwards and can emerge at the surface
GEO- when rock collapses and forms a steep-sided inlet
longshore drift and deposition are fast- minute by minute
erosion and weathering are slow- years
Timescales for formation
INSTANTANEOUS- affected by changes that operate within a single cycle (e.g waves or tides). Ranges from seconds to weeks e.g beach
EVENT- time span from an individual event through to seasonal variations. varies from a few days to many years e.g a sand dune
ENGINEERING- fluctuations take place over longer periods of time. from years to decades to centuries e.g stack
GEOLOGICAL- from decades to millenia as changes take place in sea level and climate e.g spit
OREGON COAST- made up of many distinctive landforms formed by erosion and deposition over varying time periods
GEOLOGY- significant factor in change at the coast as it can determine the speed of erosion and the supply of sediment
other factors include prevailing winds, fetch, wave type, tides, wind and the moon
Sea level change
the last ice age ended around 11,500 years ago and we are now in a period known as the holocene
Transgression- rising sea levels- coastline retreating
Regression- sea levels fall as ice is trapped in glaciers and ice sheets
tectonic movement where crustal plates move and land is submerged and emerged may change sea levels
coastal landscapes
OLD HARRY- stack- shows how a landscape changes over time
KIMMERIDGE, DORSET- wave cut platform, headland and a cliff
ETRETAT, NORMANDY, FRANCE- bay, headland, cliff, stack, arch
DOVER, KENT- cliff, wave cut platform
SANTA CRUZ ISLAND, CALIFORNIA- cave
BAJA CALIFORNIA, MEXICO- arch, stack
ALGARVE COAST, PORTUGAL- stack
CAPE COD, MASSACHUSETTS- sands dunes, sand beach
CAPE HATTERAS, NORTH CAROLINA- barrier island
CHESIL BEACH, DORSET- tombolo
NEW YORK STATE- offshore bar
CHAMPAGNE BAY, VANATU- sand beach
FAREWELL SPIT, NEW ZEALAND- spit, saltmarsh
formation of a stack
1) sub-aerial processes occur on top of the cliff
2) weaknesses are created by weathering e.g solution
3) erosion occurs at the cliff foot
4) creates weaknesses in the rock
5) wave-cut notch formed by erosion e.g wave pounding
6) cave formed by further erosion e.g wave quarrying
7) arch formed by undercutting by erosion e.g hydraulic action
8) stack formed from weathering causing the arch to collapse
9) cliff recession by erosion and slumping
10) wave cut platform exposed at low tide
formation of a spit
e.g Dawlish Warren, Devon
1) longshore drift carries a supply of sediment along the shore
2) where the coast changes direction, material is deposited in open sea by longshore drift
3) material accumulates over time so that it lies above the level of the water and a spit develops
4) vegetation begins to grow, helping colonise the spit
5) the end of the spit is shaped by waves from other directions so that it forms a hook
6) if sediment continues to be supplied, the spit may grow beyond the hook
more coastal landforms
TOMBOLO- a spit joining an offshore island to the mainland e.g Chesil beach or Tombollo Di Orbitello, Italy
LAGOON- the lake behind a spit
BARRIER ISLANDS- found in seas with shallow gradients, close to the shore away from deep water. Formed as a result of deposition from constructive waves. Form parallel to the shore e.g North Carolina/ Outer Herbrides Scotland
reasons for formation
accumulation of material transported by swash or wind blown sand
isolation of the shore when sea levels rise, higher storm beaches and sand dune ridges are left isolated
the emergence of previously submerged offshore bars as sea levels fall
spits being heavily built up by storm waves, then being breaches
OFFSHORE BAR- describes a spit that has formed across the bay to join two headlands. They can reduce erosion by reducing energy
processes
OVERTOPPING- shingle and water thrown landwards onto the ridge
CUT BACK- erosion of the seaward face of the shingle ridge due to wave action
CUSPATE FORELAND- a low-lying triangular area where sediment has been deposited e.g Kent
reasons for formation
waves from different directions create 2 converging spits
deposition of fluvial material
changes in direction of the coast
Slapton Sands
made of flint
developed 6,000 years ago due to sea level change
in 2004, storm waves overtopped the barrier and deposited shingle onto the road
road destroyed due to flooding
RUNNEL- dip in sand at right angle direction to the maximum fetch
RIDGE- collection of sediment by the shore
BERM- ridge of material running across the back of a beach, found at the highest point on a beach that a wave has reached
BEACH CUSP- crescent shaped indentation on the seawards edge of a berm, related to swash distance
STORM BEACH- material deposited from a storm found at the upper shore
MUDFLATS/ SALTMARSH- form in low energy environments where wave action is weak. vegetation colonises mudflats to form saltmarshes. This vegetation must be tolerant of saline conditions if at coast
The Sundarbans, Bangladesh- Mangrove forests on mudflats
sand dunes
Dunes of Flanders, France
example of an aoelian feature
form when:
large supply of sand
large tidal range so sand dries out
flat surface gradient
sufficient space
when there is a stabilising agent
wind transports grains by:
SALTATION- the main form of transport. sand grains are picked up by the wind then bounced along
SUSPENSION- lighter, smaller grains can be picked up and carried in air by the wind
SURFACE CREEP- traction type process where grains are rolled along by the wind
EMBRYO DUNES- take 10-20 years to develop, less high as no input of sand
VEGETATION- grows on the dunes and slows down wind speeds. Marram grass stabilises the dunes
BLOW OUT- u shaped hollow where sand in the centre has been removed
