3.1.3.3 Landforms Of Depositiom

Question 1

Outline the role played by wave energy and sediment in the development of
deposition landforms.

Answer 1

Deposition occurs in coastal areas where waves are low energy or where there is a large supply of sediment which the waves lack the energy to transport.

Question 2

where does the sediment come
from for beaches

Answer 2

Offshore bars, longshore drift, wind-blown from up the coast, mass movement, sediment brought down to the coast by rivers.

Question 3

Beaches form between which two ‘lines’?

Answer 3

The highest point reached by storm waves and the lowest tide.

Question 4

Outline the main differences between sand and shingle beaches.

Answer 4

Sand = gentle gradient (<5o), small sediment size, less percolation, lots of swash/backwash
Shingle = steeper gradient (10-12o), larger sediment size, more percolation

Question 5

Storm berm description

Answer 5

Flat, raised area of coarser sediment at the back of the beach

Question 6

Formation of storm berm

Answer 6

High energy storm waves transport heavier sediment to the back of the beach, beyond the reach of tides and regular waves.

Question 7

Description of cusps

Answer 7

Line of cresent shaped depressions formed on the lower foreshore, with sand in front and shingle behind

Question 8

Formation of cusps

Answer 8

Form where sand meets shingle on a beach where swash and backwash are equally strong. Waves are split in two directions by the horn of the cusp, then break in the back of the cusp, depositing coarser material here.

Question 9

Description of ripples

Answer 9

Wavy ripples of sand on the lower foreshore on gentle, sandy beaches

Question 10

Formation of ripples

Answer 10

Formed by tidal wave action and reform at each tide.

Question 11

Description of ridges

Answer 11

Raised areas of sand, parallel to sea on the lower foreshore on gentle, sandy beaches

Question 12

Formation of ridges

Answer 12

Formed by tidal wave action and exposed at low tide.

Question 13

Description of runnels

Answer 13

Depressions behind ridges that can trap water when the tide goes out. Form on the lower foreshore on gentle, sandy beaches

Question 14

Formation of runnels

Answer 14

Formed by tidal wave action and exposed at low tide.

Question 15

Outline the main differences between swash-aligned and drift-aligned beaches.

Answer 15

Swash aligned beaches occur where waves arrive parallel to the shore, meaning the swash and backwash occur at the same angle meaning no longshore drift and a build up of beach sediment over time.
Drift aligned beaches occur where waves arrive at an angle to the shore resulting in longshore drift, meaning beach sediment is transported along the shoreline resulting in a narrower beach.

Question 16

.Describe the key features of spits, including the difference between simple and compound spits.

Answer 16

Long, narrow ridges of deposited sediment, joined to the mainline at one end and sticking out into the sea or across an estuary.
Simple spits are straight or with one recurved end. Compound spits have a series of minor spits or recurved ridges along their landward side (showing spits former positions).

Question 17

Formation of a spit

Answer 17

1) Longshore drift occurs along drift-aligned coastline (waves arrive at an angle to coastline).
2) When the transported sediment reaches a change in direction of the coastline sediment is deposited out to sea, e.g., in the lee of a headland.
3) Over time the sediment accumulates to form a narrow ridge of sediment joined to the land at one end.
4) Deposition increases in the sheltered water behind the spit where a salt marsh may form.
5) The length of the spit depends on changing currents or rivers which may prevent sediments form being deposited e.g., a spit cannot extend across an estuary.
6) Wave refraction and a secondary wind direction cause the end of a spit to curve (simple spit). Over time multiple curves may form (compound spit).

Question 18

Give a named example of both a simple and compound spit.

Answer 18

Simple = Spurn Point, Humber Estuary, east coast Compound = Hurst Spit, Solent Estuary, south coast

Question 19

Outline the formation of a tombolo from a spit due to longshore drift.

Answer 19

Tombolos can form due to longshore drift, where a spit grows out and connects an island to the mainland.

Question 20

Name an example of a tombolo formed in this way.

Answer 20

St. Ninians Shetland Islands Scotland

Question 21

Outline the formation of a tombolo due to wave refraction.

Answer 21

• Tombolos form on swash-aligned coastlines with a beach and an island near the shore.
• Wave refraction causes waves to bend around the island, slowing in shallower water.
• As waves meet on the opposite side, energy drops, leading to sediment deposition.
• Over time, sediment accumulates into a sandbar, connecting the island to the mainland.

Question 22

Identify the main features of barrier islands.

Answer 22

A series of long, narrow depositional islands, made of sand or shingle, running parallel to the shore. They can be up to 100 miles lang and are separated from each other by narrow inlets. Over time vegetation succession occurs.

Question 23

Outline the likely formation of barrier islands

Answer 23

• Sediment was initially deposited along the coast at the end of the last Ice Age.
• Currents carried sediment onshore, forming beaches.
• Rising sea levels from melting ice caused coastal flooding, separating beaches from the mainland.
• Further sediment accumulation and vegetation succession stabilized the islands.
  Barrier islands typically form in areas with low tidal ranges and shallow, gently sloping coastlines.

Question 24

Name an area where there are barrier islands

Answer 24

West Frisian Islands, the Netherlands

Question 25

.What are offshore bars and how do they link to sand dunes?

Answer 25

Long stretches of sediment (sand) deposited offshore (beyond the breaker zone) and running parallel to it. These sand bars remain submerged or semi-submerged.

Question 26

Identify three conditions needed if sand dunes are to form along a coastline

Answer 26

a. Wide sandy beaches with a gentle gradient. b. Large tidal range – large exposes of sand exposed at low tide so dry out c. On shore winds able to transport sand up the beach through saltation

Question 27

Formation of sand dunes overtime

Answer 27

Sand accumulates on the storm berm, trapped by seaweed and driftwood. More sand forms embryo dunes, colonized by salt-tolerant plants like sea couch and marram grass. Roots stabilize the dunes, and organic matter aids water retention, creating 5m-high yellow dunes with 20% exposed sand. If the water table reaches the surface, dune slacks may form. Continued sand accumulation and plant growth create grey dunes (10% exposed sand), with grasses replaced by woody plants like gorse. Over time, the climax vegetation develops, including trees like birch and shrubs like gorse and brambles.

Question 28

Name and locate an area of sand dunes in the UK.

Answer 28

Studland Bay, Dorset Coast

Question 29

Identify three features of estuaries that encourage the deposition of sediment.

Answer 29

They are low energy environments as tidal currents are slowed down when sea water meets the fresh river water. Spits may form across part of the estuary creating a sheltered area of ‘slack’ water behind. Rivers entering an estuary carry a large amount of suspended load, including clay particles. Flocculation occurs when the salt water is reached and the particles aggregate (join together), becoming heavier, causing them to sink.

Question 31

outline the formation sequence of mudflats and then salt marshes in an estuarine environment over time. Name specific species for each stage of the vegetation succession.

Answer 31

- Deposition in sheltered estuary waters forms mudflats, aided by flocculation. Over time, vegetation colonizes them, creating salt marshes. - Eelgrass grows first, slowing currents and increasing deposition. - Pioneer species like cordgrass bind mud, trapping sediment until the area is submerged less often, forming a salt marsh. - More complex plants, like sea lavender, establish. - Eventually, the climatic climax is reached with shrubs and trees growing above the spring high tide.

Question 32

Vegetation succession in salt water

Answer 32

Halosere succession

Question 33

Name a location in the UK where mudflats and saltmarshes are found.

Answer 33

Behind Spurn Point Spit in the Humber estuary