coastal systems -landscape development (depositional landforms -spits, tombolos, offshore bars)

Question 1

what are spits?

Answer 1

.long, narrow ridges of deposited sediment which are joined to the mainland at one end and stick out into the sea or across an estuary or bay

Question 2

what are the 2 types of spits?

Answer 2

.simple
.compound

Question 3

what is a simple spit?

Answer 3

.straight or recurved (curved backwards) but do not have minor spits or recurved ridges along their landward edge

Question 4

what is an example of a simple spit?

Answer 4

.spurn point -into the Humber estuary on the East Yorkshire coast

Question 5

what are compound spits?

Answer 5

.series of minor spits or recurved ridges along their landward side which may show their former position

Question 6

what is an example of a compound spit?

Answer 6

.hurst castle spit -located on the stretch of water that lies between the south coast of England and the isle of wight

Question 7

how do simple spits form?

Answer 7

.material is moved along the coast due to longshore drift but a direction change of the coastline causes sediment to build up in the sheltered area of the headland to begin to form a spit
.finer material continues to be moved along the spit via longshore drift and into deeper water of the estuary/bay where energy is lost so sediment is deposited which extends the spit further
.the end of the spit may become recurved due to wave refraction and secondary winds -so waves carry and deposits sediment round the end of the spit

Question 8

how is a compound spit formed?

Answer 8

.if the end of the spit recurves enough this causes another change in coastline direction so the spit may continue to grow in the original direction -happen a number of times creating a compound spit.
.salt marsh can form behind the spit

Question 9

what landform is associated with spits?

Answer 9

.tombolos

Question 10

what is a tombolo?

Answer 10

.an island connected to the mainland by a mound or ridge of sediment

Question 11

how do tombolos form?

Answer 11

.as a result of Longshore drift where a spit grows out and connect an island to the mainland

Question 12

what is an example of a tombolo?

Answer 12

.chesil beach on Dorset -links the mainland to the isle of Portland 30km long

Question 13

how else can a tombolo be formed?

Answer 13

.by wave refraction

Question 14

how is a tombolo formed by wave refraction?

Answer 14

.waves move toward the coastline and are slowed down as they enter the shallower water -they reach the islands that are close to the shore first -because these waves are moving at a slower pace than normal
.when the waves meet on the side of the island facing the coast, energy falls and sediment is deposited, sediment build ups until it creates the sandbar that connects the island to the beach

Question 15

what is an example of a tombolo formed by wave reafrction?

Answer 15

.st ninians, Shetland isles in Scotland

Question 16

what are offshore bars?

Answer 16

.long stretches of sediment deposited off the coast
.remain submerged offshore beyond the breaker zone so vegetation cannot grow on them

Question 17

how do offshore bars form?

Answer 17

.formed from sediment deposited by coastal currents that deposit sand off-shore