coastal 2
- Created by: parker123
- Created on: 28-12-17 18:24
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- coastal erosion
- beaches
- formation of beaches
- sandy beaches
- 1--in sheltered bays, low energy constructive waves transport material onto the shore.
- 3--when tide has gone out there is more material on beach than before
- pebble beach
- 1-- exposed beaches sometimes have large fetch.
- 2--the plunging nature of destructive waves along with backwash means pebbles aren't moved far up beach, making beach profile steep
- 3--a storm beach may form when wild, stormy weather and waves hit boulders and large pebbles to the back of beach.
- a beach is a landform of coastal deposition that lies between the high & low tide levels, most beaches formed of sand & shingle or pebbles as fellas mud & silt.
- a beach that forms in a bay is crescent-shape, but shape is distorted by longshore drift so the beach is narrower updraft than downdrift
- sandy beaches
- characteristics
- sandy beach
- gradient generally shallow, almost flat
- waves mostly constructive
- back of beach are sometimes sand dunes & beach stretches inland a long way
- at low tide wet sand may have rippled appearance
- pebble beaches
- gradient is generally steep
- waves are normally destructive
- back of beach, (storm beach) large pebbles & beach stretches inlands not far.
- sandy beach
- formation of beaches
- sand dunes
- formation of sand dunes
- 1--are large leaps f sand that form on the dry backshore of a sandy beach
- 2-- they need large flat beach, large supply of sand, onshore winds to move sand to the back of the beach & obstacles scubas driftwood to form against
- 3-- sand continues t more up the windslope
- 4--heights builds up until the structure becomes unstable
- 5-- sand then slips down the leeward slope
- characteristics of sand dunes
- gentle slope on windward side
- crests height vary up to approx 15m
- unstable steep slip slope (30-34') on sheltered leeward slope
- formation of sand dunes
- spits
- formation of spits
- 1--a sipit is a a sand & shingle beach that sis joined to the land but projects downdrift into the sea. spits form where coastline suddenly changes or at mouth of estuary.
- 2-- where a coastline changes shape the waves begin to lose energy so there is proxominal end & the spit begins to grow out to sea
- 3-- prevailing wind makes the swash at an angle to the shore. backwash is at right angle because of gravity. longshore drift therefore moves material in a zig-zag manner to beach
- 4-- shingle or pebble spit the pebbles become smaller more rounded towards the distal end due to attrition. they becomes smaller as longshore drift becomes weaker.
- 5-- a dominant wind causes the distal end to hook towards the land& olde recurve (hook) marks a former env of spit.
- characteristics of spit
- proximal end (large pebbles)
- hooked distal end (small pebbles)
- mudflats, salt marshes & lagoon & recurves
- formation of spits
- bars
- formation of bars
- a bay bar (barrier beach bar)
- is a ridge of sand or shingle that stretches from one side of bay to other forming a lagoon behind it
- beach barrier formation is due to longshore drift transporting sediment from one side of bay to other
- submerged bay
- form in shallow waters where there is a lot of sediment on a beach, formed by transport of sediment off then back onto beach.
- offshore bars
- bar raised area of a seabed that lies a little offshore, in stormy weather destructive waves drag the beach material out to sea to form an offshore bar.
- a bay bar (barrier beach bar)
- characteristics of bars
- bay bar
- at least some part of the barrier beach bar is visible at all times
- submerged bars
- often completely detached from land, can be serval metres long
- offshore bars
- completely detached from shore, it has salt marshes, sand dunes and mudflat
- bay bar
- formation of bars
- beaches
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