Landforms- formations and examples Flashcards
spit definition
is a long narrow feature that extends from the mainland at the end of a drift aligned beach
formation of a spit
the process of LSD will move material along a coastline determined by the prevailing wind
coastline changes direction so the finer material will continue to be transported out to sea
this will be upwards and outwards to develop into a permanent feature
won’t be able to extend across to meet the mainland due to the strong current in the estuary and deep water
wave refraction and a second dominant wind direction forces the material in a different direction, resulting in a curved end
low energy waves enter behind the spit where silt and mud is deposited, then colonised by vegetation=salt marsh
what is a compound spit
spits with barbs or hooks on their landward side
simple spits
a bar of sand without barbs or hooks
what is needed for a tombolo to form
drift aligned beach (waves approach beach at an angle so LSD can then happen) dominant wind prevailing wind supply of sediment low energy coastline an island
example of a barrier island
north Carolina – Cape Fear
example of bar/barrier beach
slapton sands devon
sand dune definition
sand dunes are accumulations of sand blown into mounds by wind (Aeolian landforms)
how to work out the age of a dune
look at the size of a dune
type of vegetation
amount of vegetation
luminescent dating
what do sand dunes need in order to form
ample supply of sand
strong prevailing wind
strong onshore wind
large inter tidal zone
how does a sand dune form
sand accumulates on the beach through LSD
at low tide the sand dries out and wind suspends the sand in the air when the wind reaches a certain level (fluid threshold velocity).
wind blows the sand up the beach and deposits it around an obstacle (as wind loses energy when it hits it- so is deposited). when debris on the beach traps sand this is called a strand line.
sand dunes take a long time to form but over time grass, mainly Lyme Grass, will form on the dunes and stabilise them
life cycle of a dune (the order they go in)
embroyo dune– fore dune— yellow dune– grey dune– dune slack- mature dune
examples of landforms on a submergent coastline
fjords
rias
examples of landforms on an emergent coastline
raised beaches
relict/fossil cliffs
example of a fjord
milford sound
example of a raised beach
isle arran
example of a fossil cliff
north west scotland
example of dalmation coast
along the coast of Croatia
example of rias
Kingsbridge estuary, Devon
example of marine platform
santa cruz marine terraces
description of the formation of a fjord
is formed when a glacier retreats after carving its typical U-shaped valley-sea fills the resulting valley floor
forms a narrow steep sided inlet (sometimes deeper than 1300m) connected to the sea
the terminal moraine pushed down the valley by the glacier is left underwater at the fjord entrance- so water at the neck is shallower than main body of fjord
description of the formation of rias
is a river valley next to the coast that has been ‘drowned’ as sea levels rise. a ria can be equal to the size of the valley that was submerged
a substantial rise in sea level can form a ria. a fall of landmass on a coastline can also permit water to entre a valley and form a ria
what they are and description of the formation of raised beaches
are areas of former wave cut platforms and their beaches which are left at a higher level than the present coastline
formed by sea levels dropping- their beaches are at a higher level
description of the formation of relict/fossil cliffs in scotland
the last ice age 10,000 years ago - land became depressed due to the weight of the ice (isostatic). when the ice melted it caused isostatic uplift- causing regression
what is a relict cliff
is an old cliff displaying features such as caves, arches and stacks. feature no longer experiences coastal erosion but are still weathered biologically and chemically.
where are marine platforms formed
where a sea cliff with a wave cut platform before it, is raised above sea level (often uplifted by large scale tectonic movements)
how are Dalmatian coasts formed
form in areas where valleys (especially glacial valleys) lie parallel to one another. when the valleys are flooded by the rise in sea level, the tops of valleys remain above the surface of the sea and appear to be a series of islands that run parallel to the coast
