Coastal Landforms

Question 1

Describe the formation of a cliff and the process of it collapsing due to weathering and erosion.

Answer 1

Cliffs are common coastal landforms- they form as the sea erodes the land. Over time, cliffs retreat due to the action of waves and weathering. Weathering and wave erosion cause notch to form at high water mark. This eventually develops into a cave. Rock above the cave becomes unstable with nothing to support it, and it collapses.

Question 2

Describe a wave cut platform?

Answer 2

Wave cut platforms are flat surfaces left behind when a cliff is eroded.

Question 3

How are headlands and bays formed?

Answer 3

They are formed where there are bands of alternating hard rock and soft rock at right angles to the shoreline. The soft rock is eroded quickly forming a bay. The harder rock is eroded less and sticks out as a headland.

Question 4

How are caves, arches and stacks formed?

Answer 4

Weak areas in rock are eroded to form caves. Caves on the opposite sides of a narrow headland may eventually join up to form an arch. When an arch collapse, it forms a stack.

Question 5

How are beaches formed?

Answer 5

Beaches form when constructive waves deposit sediment on the shore- they are a store in the coastal system

Question 6

What are berms?

Answer 6

Berms are ridges of sand and pebbles found at high tide marks

Question 7

What are runnels?

Answer 7

Runnels are grooves in the sand running parallel to the shore, formed by backwash drainage to the sea.

Question 8

What are cusps?

Answer 8

Cusps are crescent shaped indentations that form on beaches of mixed sand and shingle.

Question 9

Where do spits tend to form?

Answer 9

Spits tend to form where the coast suddenly changes direction across the river mouths.

Question 10

How are simple spits formed and what causes them to have a curved end?

Answer 10

Longshore drift continues to deposit material across the river mouth, leaving a bank of sand and shingle sticking out into sea. A straight spit that grows out roughly parallel to the coast is called a simple spit. Occasional changes to the dominant wind and wave direction may lead to the spit having a curved end.

Question 11

How are compound spits formed?

Answer 11

Over time, several recurved ends may be abandoned as the waves return to their original direction. A spit that has multiple recurved ends resulting from several periods of growth is called a compound spit.

Question 12

What forms behind the spit?

Answer 12

The area behind the spit is sheltered from the waves and often develops into mudflats and saltmarshes.

Question 13

How are bars formed?

Answer 13

Bars are formed when two spits join two headlands together. This can occur across a bay or across a river mouth. Bars can also form off the coast when material moves towards the coast.

Question 14

What is a tombolo?

Answer 14

A bar that connects the shore to an island.

Question 15

What forms behind the bar?

Answer 15

A lagoon.

Question 16

What are barrier islands?

Answer 16

Barrier islands are long, narrow islands of sand or gravel that run parallel to the shore and are detached from it.

Question 17

Where do they normally form?

Answer 17

They tend to form in areas where there’s a good supply of sediment, a gentle slope offshore, fairly powerful waves and a small tidal range.

Question 18

Describe two theories on how barrier islands are formed?

Answer 18

scientists think that they probably formed after the last ice age ended, when ice melt caused rapid sea level rise. The rising waters flooded the land behind beaches and transported sand offshore, where it was deposited in shallow water, forming islands. Another theory is that the islands were originally bars, attached to the coast, which were eroded in sections causing breaches in the bar.

Question 19

Describe the formation of sand dunes?

Answer 19

Sand dunes are formed when sand deposited by longshore drift is moved up the beach by the wind. Sand trapped by driftwood or berms is colonised by plants and grasses (marram grass). The vegetation stabilises the sand and encourages more sand to accumulate there, forming embryo dunes. Over time the oldest dunes migrate inland as newer embryo dunes are formed. These mature dunes can reach heights of up to 10m.

Question 20

Where do mudflats and salt marches develop?

Answer 20

Mudflats and salt marshes form in sheltered, low energy environments. As silt and mud are deposited by the river or tide, mudflats develop.

Question 21

How are salt marshes formed?

Answer 21

The mudflats are colonised by vegetation that can survive the high salt levels and long periods of submergence by the tide. The plants trap more mud and silt, and gradually they build upwards to create an area of saltmarsh that remains exposed for longer and longer between tides.

Question 22

How are channels created in the mudflats and saltmarshes?

Answer 22

Erosion by tidal currents or stream forms channels in the surface of mudflats and saltmarshes. These may be permanently flooded or dry at low tide.