Block 6 (Processes Of Coastal Transport + Deposition + The Characteristics + Formation Of Associated Landforms + Landscapes)

Question 1

What are the 4 processes of marine transportation?

Answer 1

• Solution
• Suspension
• Saltation
• Traction

Question 2

What is the marine transportation process of solution?

Answer 2

Materials are dissolved in sea water (acidified by human waste) + carried along in solution

Question 3

What is the marine transportation process of suspension?

Answer 3

Fine sediment particles are carried by the water

Question 4

What is the marine transportation process of saltation?

Answer 4

Small sediment particles are bounced along the sea bed

Question 5

What is the marine transportation process of traction?

Answer 5

Larger sediment particles are rolled along the seabed

Question 6

What are the 4 littoral processes of transportation?

Answer 6

• Suspension
• Saltation
• Creep
• Long-shore drift (LSD)

Question 7

What is the littoral transportation of suspension?

Answer 7

Fine sediment is blown along the beach by the wind

Question 8

What is the littoral transportation of saltation?

Answer 8

Small sediment particles are bounced along the beach

Question 9

What is the littoral transportation of creep?

Answer 9

Large sediment particles are rolled along the beach

Question 10

What is the littoral transportation process of LSD?

Answer 10

Movement of material along the shore in a zig-zag motion

• Swash carries material onto beach at an oblique angle, in direction of prevailing wind
• Backwash carries material out to sea perpendicular to coastline
• Long term impact of this is the movement of material from one side of beach to the other

Question 11

What is the impact of LSD on the sediment budget in an area?

Answer 11

• Budget remains in equillibrium if sediment moved downdrift by LSD is matched by sediment input updrift
• If sediment is not matched, budget becomes negative + beach is starved

Question 12

What is deposition?

Answer 12

When material is dropped, as there is no longer sufficient energy to transport it

Question 13

What is Stokes Law?

Answer 13

Sediment deposited is directly proportional to the mass (size) of the sediment

• Larger material deposited first - requires too much energy
• Smaller material deposited later - can be transported further, needs less energy

Question 14

What is flocculation?

Answer 14

When particles aggregate together to form clumps of larger material (floc)

Question 15

How does flocculation affect Stokes Law?

Answer 15

Increases mass of smaller sediments, so they are deposited faster

Question 16

Where are flocculation beds often found?

Answer 16

In deltas - significant energy loss as river enters Sea

Question 17

What material commonly flocculates?

Answer 17

Clay - flocs naturally (others may require FLOCCULATION AGENTS)

Question 18

What process can Stokes Law trigger?

Answer 18

Sediment sorting

Question 19

What is sediment sorting?

Answer 19

On beach: largest calibre material deposited closest to Sea, as requires most energy to transport (exception - storm beach)

On seabed: largest calibre material deposited at bottom of seabed, as needs most energy so is deposited first

Question 20

What is a beach?

Answer 20

An area of deposited, unconsolidated sediment between the land and the Sea

Question 21

How can beaches survive rough conditions?

Answer 21

They are able to adjust their equilibrium (meta-stable)

-E.g. Summer/stable anticyclonic weather - beaches built up
Winter/unstable depressions + storms - beaches destroyed

Question 22

What are the three types of beaches?

Answer 22

• Swash aligned
• Drift aligned
• Zeta-formed

Question 23

What are swash aligned beaches? Give an example

Answer 23

Waves break parallel to shore 
- Little LSD
- Sediment movement is onshore-offshore
- Fairly closed system 
- ‘Normal’ beach formed
(E.g. in Rhossili Bay, Gower, South Wales)

Question 24

What are drift aligned beaches? Give an example

Answer 24

Waves break at oblique angle to shore
- Lots of LSD
- Sediment enters at one end, moved along, leaves at other end
- More open system
- Beach is thicker at one end + a spit may form
(E.g Spurn Head, Holderness coast)

Question 25

What are zeta-formed beaches? Give an example

Answer 25

Waves break at oblique angle to shore, but headland blocks sediment removal downdrift + causes wave refraction
- Lots of LSD
- Wave refraction around headland
- Beach wide next to headland, narrow other end
(E.g. Roches Beach, Tasmania)

Question 26

What are the three small-scale features on beaches?

Answer 26

• Berms
• Cusps
• Ripples

Question 27

What are berms?

Answer 27

Mounds of material found at tidal mark on beaches

• Mark deposition at each tidal mark
• Spring low, neap low, neap high, spring high

Question 28

What are cusps?

Answer 28

Crescent shaped indentations on the beach where waves move further inland

• Interspaced by ‘horns’ (ridges of courser material)
• Initially form due to beach geomorphology
• Grow in size through positive feedback - more waves in cusps - more erosion - get bigger

Question 29

What are ripples?

Answer 29

Backwash flowing back to Sea in channels

• Symmetrical ripples - when waves have similar velocities
• Asymmetrical ripples - when flow is pronounced in one direction

Question 30

What is a spit? Give an example

Answer 30

Finger-like extension of beach into the Sea, as coastline changes but LSD continues

• Spurn Head, Holderness Coast (4 miles long, into Humber Estuary)
• Homer Spit, Kenai Peninusla, Alaska (4 miles long, into Kachemak Bay)

Question 31

What characteristics are needed for a spit to form?

Answer 31

• Good sediment supply
• Drift aligned coastline (LSD)
• Abrupt coastline change
• Limited tidal range of usually less than 3m (common for depositional landforms)

Question 32

How does a spit form?

Answer 32

• Sediment transported by LSD in direction of prevailing wind
• At coastline change, transportation continues
• Deposition of larger calibre, heavier sediment first
• Further deposition extends beach into estuary - spit
• Change in prevailing wind direction may cause spit to curve (RECURVED END)
• Silt deposited in sheltered area behind spit - mudflats form
• Veg grows in mudflat - forming salt marsh

Question 33

What is a bar? Give examples

Answer 33

An elongate deposit of sand + shingle, usually parallel to shore

• Onshore = across bays, attached to land
• Offshore = on seabed, unattached to land

(E.g. Slapton Ley, Devon - extension of Slapton Sands beach to leave the lagoon behind)
(E.g. Hordle Cliff, Hampshire)

Question 34

What characteristics are needed for an onshore bar to form?

Answer 34

• Area where spit is forming across a bay

Question 35

What characteristics are needed for an offshore bar/barrier island to form?

Answer 35

• Gently sloping offshore gradient
• Relatively high wave energy - to provide sediment
• Limited tidal range often less than 3m (common of depositional landforms)

Question 36

How do onshore bars form?

Answer 36

• Spit forms
• Continues across bay
• Cut off bay forms lagoon - slowly infilled by deposition

Question 37

What are the two ways that onshore bars/barrier islands are said to form?

Answer 37

1) Waves approach gently sloping coast, friction occurs, causing deposition
2) Sediment cell’s rip currents move material off beach, then sideways, so energy is lost, causing deposition

Question 38

How do offshore bars change seasonally?

Answer 38

Summer - starved (to build beach)

Winter - grow (plunging, destructive waves remove beach material)

Question 39

What are the 3 ways that barrier islands are said to form?

Answer 39

1) Bar grows until it is no longer submerged at high tide
2) High energy waves breach spit, cutting it off into an island
3) Sea level rise after last Ice Age, ridges remain, rest flooded

Question 40

How can the structure of barrier islands change?

Answer 40

Tidal inlet migration

• Inlets between islands (for tides to move between)
• Inlets can shift downdrift, due to LSD
• One side is gaining sediment + the other is losing it

Landward migration

• Most material deposited onshore side
• Slow migration of the whole island inland

Question 41

What are barrier islands? Give an example

Answer 41

Large scale offshore bars that are NOT submerged at high tide

(E.g. Frisian Islands - 14 islands in the North Sea, off the Dutch coast)

Question 42

What is a tombolo? Give an example

Answer 42

A strip of sediment connecting an island to another island or the mainland

E.g. UK - Chesil Beach, Dorset coast - 18 miles long, connects Portland Island to the mainland

E.g. Abroad - Tombolo di Orbetello, Tuscany

Question 43

What characteristics are needed for a tombolo to form?

Answer 43

• A spit forming over an area that is close to a new section of land

Question 44

What are the two ways a tombolo can form?

Answer 44

1) LSD continues until island reached

2) Wave refraction causes ‘shadow area’ of low energy behind island, causing deposition here

Question 45

What is a cuspate foreland? Give an example

Answer 45

Triangular-shaped projection attached to the mainland, with its apex pointing out to Sea

• E.g. UK - Dungeness, Kent - 30km long, 15km wide, product of converging swells from English Channel + Straits of Dover
• E.g. Abroad - Cape Hatteras, N.Carolina, USA - 150km long

Question 46

How do cuspate forelands form?

Answer 46

• LSD occurs in two opposite directions

- Equilibrium reached + sediment deposited (not enough energy)

Question 47

What is the term for an island connected to the mainland/another island by a tombolo?

Answer 47

Tied island

Question 48

What is the name for the curved end of a spit?

Answer 48

Recurved end

Question 49

What is the name for a spit with multiple recurved ends

Answer 49

Compound spit

Question 50

What are the 6 landforms of deposition?

Answer 50

• Beaches
• Spits
• Bars
• Barrier islands
• Tombolos
• Cuspate forelands