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Geography - B - Coastal Landscapes > Block 6 (Processes Of Coastal Transport + Deposition + The Characteristics + Formation Of Associated Landforms + Landscapes) > Flashcards

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

1
Q

What are the 4 processes of marine transportation?

A
  • Solution
  • Suspension
  • Saltation
  • Traction
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2
Q

What is the marine transportation process of solution?

A

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

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3
Q

What is the marine transportation process of suspension?

A

Fine sediment particles are carried by the water

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4
Q

What is the marine transportation process of saltation?

A

Small sediment particles are bounced along the sea bed

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5
Q

What is the marine transportation process of traction?

A

Larger sediment particles are rolled along the seabed

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6
Q

What are the 4 littoral processes of transportation?

A
  • Suspension
  • Saltation
  • Creep
  • Long-shore drift (LSD)
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7
Q

What is the littoral transportation of suspension?

A

Fine sediment is blown along the beach by the wind

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8
Q

What is the littoral transportation of saltation?

A

Small sediment particles are bounced along the beach

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9
Q

What is the littoral transportation of creep?

A

Large sediment particles are rolled along the beach

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10
Q

What is the littoral transportation process of LSD?

A

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
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11
Q

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

A
  • 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
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12
Q

What is deposition?

A

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

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13
Q

What is Stokes Law?

A

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
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14
Q

What is flocculation?

A

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

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15
Q

How does flocculation affect Stokes Law?

A

Increases mass of smaller sediments, so they are deposited faster

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16
Q

Where are flocculation beds often found?

A

In deltas - significant energy loss as river enters Sea

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17
Q

What material commonly flocculates?

A

Clay - flocs naturally (others may require FLOCCULATION AGENTS)

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18
Q

What process can Stokes Law trigger?

A

Sediment sorting

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19
Q

What is sediment sorting?

A

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

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20
Q

What is a beach?

A

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

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21
Q

How can beaches survive rough conditions?

A

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

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

22
Q

What are the three types of beaches?

A
  • Swash aligned
  • Drift aligned
  • Zeta-formed
23
Q

What are swash aligned beaches? Give an example

A 
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)
24
Q

What are drift aligned beaches? Give an example

A

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)

25
Q

What are zeta-formed beaches? Give an example

A

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)

26
Q

What are the three small-scale features on beaches?

A
  • Berms
  • Cusps
  • Ripples
27
Q

What are berms?

A

Mounds of material found at tidal mark on beaches

  • Mark deposition at each tidal mark
  • Spring low, neap low, neap high, spring high
28
Q

What are cusps?

A

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
29
Q

What are ripples?

A

Backwash flowing back to Sea in channels

  • Symmetrical ripples - when waves have similar velocities
  • Asymmetrical ripples - when flow is pronounced in one direction
30
Q

What is a spit? Give an example

A

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)
31
Q

What characteristics are needed for a spit to form?

A
  • Good sediment supply
  • Drift aligned coastline (LSD)
  • Abrupt coastline change
  • Limited tidal range of usually less than 3m (common for depositional landforms)
32
Q

How does a spit form?

A
  • 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
33
Q

What is a bar? Give examples

A

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)

34
Q

What characteristics are needed for an onshore bar to form?

A
  • Area where spit is forming across a bay
35
Q

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

A
  • Gently sloping offshore gradient
  • Relatively high wave energy - to provide sediment
  • Limited tidal range often less than 3m (common of depositional landforms)
36
Q

How do onshore bars form?

A
  • Spit forms
  • Continues across bay
  • Cut off bay forms lagoon - slowly infilled by deposition
37
Q

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

A

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

38
Q

How do offshore bars change seasonally?

A

Summer - starved (to build beach)

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

39
Q

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

A

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

40
Q

How can the structure of barrier islands change?

A

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
41
Q

What are barrier islands? Give an example

A

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)

42
Q

What is a tombolo? Give an example

A

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

43
Q

What characteristics are needed for a tombolo to form?

A
  • A spit forming over an area that is close to a new section of land
44
Q

What are the two ways a tombolo can form?

A

1) LSD continues until island reached

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

45
Q

What is a cuspate foreland? Give an example

A

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
46
Q

How do cuspate forelands form?

A
  • LSD occurs in two opposite directions

- Equilibrium reached + sediment deposited (not enough energy)

47
Q

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

A

Tied island

48
Q

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

A

Recurved end

49
Q

What is the name for a spit with multiple recurved ends

A

Compound spit

50
Q

What are the 6 landforms of deposition?

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

Geography - B - Coastal Landscapes (10 decks)

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