1.1.6 - processes of coastal transport and deposition, associated landforms Flashcards
what are the four transport systems to transport sediment?
traction, saltation, suspension, solution
define traction?
where grains/sediment slide along the seabed, if strong current - larger materials
define saltation?
where sediment is bounced along the seabed, often used to transport sand.
define suspension?
sediment and sre held suspended and supported by turbulence
define solution?
particles dissolved in the salt water are carried out by the sea.
define longshore drift?
- material moved along the shoreline in the direction of the prevailing wind, through angular swash
- in a zig-zag movement, backwash moves sediment back into the sea at a right angle
- carries sediment from one side of the beach to the other
- system remains in equilibrium
define deposition?
when the energy of the transporting wave becomes too low to transport sediment.
define flocculation?
- clay particles form a clump where the mouth of a river and the sea meet, due to their opposite charges
- increases the amount that sediment is deposited.
what are the characteristics of beaches?
loose, unconsolidated sand/pebbles that survive storms due to it’s ability to adjust to dynamic equilibrium.
what are the three aligned beaches?
swash-aligned - waves break parallel
drift-aligned - waves break at an angle to shore
zeta-aligned - waves break at angle, but sediment builds up at headland
what are spits?
- deposits of sand attached to the land at its PROXIMAL end, but free at its DISTAL end
what conditions do spits need to occur?
where coastline has abrupt change of direction like, estuary
ready supply of sediment
longshore drift where waves deposit material
how do spits occur?
longshore-drift move sediment along the shore-end, and where the coastline changes direction the sediement continues to be deposited by LSD, into the sea, creating spits.
these form: protected salt marshes/lagoons
what is a barrier island/bar?
deposits of sand parallel to the coastline, known as islands when very long
where is an example of a barrier island?
Loe bar in Cornwall
what is a tombolo?
where longshore dirt connects an island to the mainland
where is an example of a tombolo?
tombolo di orbetello in Tuscany
what is cuspate forelands?
sediments pointing out to sea, 90º to the shore, triangular
how do cuspate forelands occur?
where sediment gets trapped on the shore when equilibrium is reached, between the sandy inputs and the energy to move it - so it moves out
what is sediment sorting?
where the size of sediment grains within a deposit becomes more uniform
why does sediment sorting occur?
waves with a weak backwash can only transport smaller, finer sediment and hence only transport the smaller sediment
