Depositional landforms Flashcards
what does deposition form?
beaches
where are depositional landforms most common?
lowland coasts, beaches are the most common depositional landform
what are beaches?
beaches are accumulations of sand and shingle deposited by waves and currents
where does the sediment on a beach come from?
cliff erosion but most is brought down to the coast by rivers
what are the two different types of beaches?
-swash aligned
-drift aligned
swash aligned
beaches where waves approach parallel to the shore and break with swash moving directly up the beach and the backwash returning directly back, these form wide beaches with an even shoreline
how do you identify a swash aligned beach on a photograph?
the lines are parallel to the coastline (berms)
what’s an example of a swash aligned beach?
chesil beach
drift aligned
form when waves approach the beach at an angle resulting n swash moving diagonally up the beach and the backwash returning though gravity, these beaches have an uneven profile especially when groynes have been used to slow the long short drift
how do you identify a drift aligned beach on a photograph?
most likely a straight coastline
what is an example of a drift aligned beach?
west wittering
why are pebble beaches steep?
A strong swash and a weak backwash causes deposition, on a pebble beach the water goes through the gaps in the rocks and goes back to the sea under/through the rocks. This means lots of material is put into the beach but very little is pulled back into the sea which causes it to be very steep.
nearshore
the breaker zone where waves break
backshore
an area that is not usually affected by waves, so the sand is usually dry
foreshore
the inter-tidal zone repeatedly covered, then uncovered by changing tides
offshore
fairly far out to sea where the waves do not break
beach profile`
shows the gradient from the back of the beach to the sea
what kind of bay is a sandy beach formed in?
a sheltered bay as low-energy constructive waves transport material onto the shore
what is the main type of transportation used to form sand dunes?
saltation
how are sand dunes formed?
- wind pushes sand grains along by saltation
- sand grains start piling up as something has trapped the sand at the back of the beach (e.g. seaweed or driftwood)
- more sand piles up
4.the dune stops growing at the high water mark, this is where the highest tide reaches - the dune becomes stabilised by grasses such as Marram or Lyme growing on the new dune
- as the dune is growing another embryo dune is forming in front of it (closer to the sea) over time the new dunes get closer and closer to the sea