8.2 The characteristics and formation of coastal landforms

Question 1

Inter-tidal zone

Answer 1

The zone on the beach between the mean low tide and the mean high tide level.

Question 2

Backshore zone

Answer 2

The upper part of the beach above the mean high tide level but affected by spring tides and storm waves/

Question 3

Springtide

Answer 3

Once a fortnight, when the sun and moon are aligned, there is an unusually high tidal range.

Question 4

Breakpoint bar

Answer 4

A long thin ridge of sediment on the seabed, running parallel to the coastline, at or below the level of the lowest spring tide. They form at the point where waves begin to break.

Question 5

Barrier beach

Answer 5

Long, sandy beaches, detached from, but parallel to, the coastline.

Question 6

Barrier island

Answer 6

Long islands running parallel to the coastline. Probably started as barrier beaches, but sand dunes formed on them and vegetation then built them up above high tide level.

Question 7

Beach cusps

Answer 7

Semi-circular, scalloped depressions cut into the lower edge of the storm beach.

Question 8

Foreshore

Answer 8

Sometimes called the inter-tidal or surf zone, the zone of the beach between the mean low tide and the mean high tide level.

Question 9

Tidal range

Answer 9

The difference in height between the low and high tide levels.

Question 10

Nearshore zone

Answer 10

Sometimes called the breaker zone. The lower part of the beach below the mean low tide level but uncovered by spring tides.

Question 11

Offshore zone

Answer 11

The zone below the level of the lowest spring tides, never uncovered.

Question 12

Swash aligned beach

Answer 12

Beaches that are aligned parallel to the crests of the prevailing waves.

Question 13

Drift aligned beach

Answer 13

Beaches that are aligned at an angle to the crests of the prevailing waves. As a result, LSD takes place.

Question 14

Cuspate forelands

Answer 14

Low features which extend outwards from the shoreline in a triangular shape. They are formed by the deposition of sand and shingle at the point where two streams of LSD sediment meet.

Question 15

Simple spit

Answer 15

Spits occur when LSD extends the beach part of the way across an estuary, bay or inlet. Simple spits are sometimes straight but more usually have curved ends.

Question 16

Compound spit

Answer 16

Compound spits form like a simple spit but they have a narrow base attaching them to the mainland and they widen into a broad, recurved end, consisting of a series of ridges which have grown successively over time.

Question 17

Offshore bar

Answer 17

Long thin ridges on the seabed, running parallel to the coastline below the level of the lowest spring tide. They are produced when the circular movement of water in the waves starts to touch the seabed.

Question 18

Bar

Answer 18

A ridge of sand or single that extends right across a bay or inlet.

Question 19

Tombolo

Answer 19

Outwards beach extension that joins an offshore island. e.g. Chesil beach in Dorset.

Question 20

Cuspate tombolo

Answer 20

When wave refraction causes LSD to operate in opposite directions either side of an offshore island, the beach extends out to the island, joining it to the mainland at low tide. When two beaches extend to the same island, a cuspate tombolo forms.

Question 21

Sward zone

Answer 21

A zone of saltmarsh where grasses dominate the ecosystem. It may only be covered by the sea for an hour a day.

Question 22

Creek

Answer 22

A small channel in a saltmarsh along which the receding seawater drains as the tide goes out.

Question 23

Storm surge

Answer 23

A rush of water driven onto land by strong winds when the sea surface is raised, either because of expansion caused by heating or because a low-pressure system with its rising air takes a weight off the sea surface, allowing it to rise.

Question 24

Eustatic

Answer 24

A global change in sea level.

Question 25

Isostatic

Answer 25

A local change in sea level, usually produced by movements of the land relative to the sea.

Question 26

Isostatic rebound

Answer 26

During a glacial period the land is pushed down by the weight of the ice sheets. At the end of the glacial period the ice sheets melt and the land slowly rises back to its former level.

Question 27

Ria

Answer 27

A drowned river valley

Question 28

Fjord

Answer 28

A drowned glaciated valley

Question 29

Dalmatian coastline

Answer 29

A drowned coastline with long narrow islands running parallel to the coastline. The islands were the ridges of hills when sea level was lower in the past.

Question 30

Raised beach

Answer 30

An old beach which is now above the current sea level. Produced by a fall in sea level relative to the land.

Question 31

Emerged coastal plains

Answer 31

In a part of the world with a wide, shallow continental shelf, a fall in sea level can produce a wide coastal plain, backed by a relict line of cliffs which represent the old coastline.