coasts

• Geology of Holderness coast

  • Consists of boulder clay, which is structurally weak and has little resistance to erosion
  • Produces shallow sloping cliffs between 5 and 20 meters high
  • Chalk band surrounding the boulder clay has created a headland at Flamborough Head
• Fetch


  How far the waves have traveled, which affects wind energy and wave size/power
• Low pressure weather systems and winter storms passing over the North Sea produce locally strong winds and waves
• Longshore drift


  The tide flowing southwards transports sand south, leaving the cliffs at Holderness poorly protected
• Beaches at Holderness


  • Narrow, offer little friction to absorb wave energy
  • Never enough sand to stop waves reaching cliff base at high tide
• Sub-aerial processes affecting Holderness cliffs

  1. Chemical weathering relatively ineffective except on chalk cliffs

  2. Mechanical and biological weathering more significant

  3. Freeze-thaw and wetting/drying of boulder clay causing cracking and slumping
• Coastal defences, groynes at Hornsea

  Interrupt longshore drift, starving beaches to the south and exposing cliffs to wave attack (terminal groin syndrome)
• 200 homes and several roads predicted to fall into the sea between Flamborough Head and Spurn Point by 2100
• 7,000 homes nationally predicted to disappear due to coastal erosion by 2100
• East Riding Coastal Change Fund


  Offers limited financial assistance and advice for residents affected by coastal erosion, including relocation, demolition, and adaptation packages
• Eustatic change


  Global change in sea level due to a volume change in ocean water, usually caused by climate change
• Eustatic fall in sea level

  Glacial period where ice sheets form and water is locked on land, leading to a global fall in sea level
• Eustatic rise in sea level

  Interglacial period where ice is melting, returning water to the sea and causing thermal expansion, leading to a global rise in sea level
• Isostatic change


  Local land level changes causing a rise or fall in local sea level
• Emergent coastline


  • Produced by post-glacial adjustment, with features like raised beaches, elevated marine platforms, caves, and arches
• Submergent coastline


  • Coastal zones where the littoral zone is inundated with rising sea levels, with features like rias, fjords, and dalmatian coastlines
• Climatic change


  Leads to eustatic sea level rise through melting of glaciers and thermal expansion of ocean water
• Holderness coast


  • Rapid erosion rates due to soft, porous, and heavily jointed rock type, as well as high fetch, destructive waves, and longshore drift
• Nile Delta


  Increased coastal recession due to the Aswan Dam holding back sediment, starving the coastline
• Weathering and mass movement at Holderness coast


  Mechanical weathering like freeze-thaw, marine processes like hydraulic action and abrasion, leading to rotational slip of the soft boulder clay cliffs
• Factors controlling coastal recession at Holderness

  • Wind direction and fetch, seasons, tides, isostatic change, and storms
• Onshore winds


  • Long fetch range
  • Produce destructive waves
  • Increase rates of coastal recession
• Tides at the Holderness coast

  • Rapid high and low tide
  • Greater energy and impact on the shoreline
• There is a high level of isostatic change on the Holderness coastline, which means higher erosion overall and local sea level changes
• Storms (low pressure events and depressions)

  • Produce high energy destructive waves
  • Increase erosion rates
• Many coastline areas are well populated, have beaches that attract large amounts of tourists, have ports where lots of poorer cities are based, are generally extremely fertile with a lot of agricultural land, and have rivers and deltas and estuaries where people trade through
• Tuvalu


  • Low-lying, with most places 1-2 meters above sea level
  • No more than 5 meters above sea level across the whole of its islands
  • Population of 11.5 thousand
  • Suffers from sea water encroachment
• Subsidence in Tuvalu


  • Caused by human activity, such as the weight of buildings and compression of sediment
• Vegetation issues in Tuvalu

  • Removal of vegetation in the past has removed the structure of the sand and soil, which binds it together
  • Recent replanting of vegetation can reduce the risk of flooding and stabilize the sand
• Storm surge


  A temporary rise in sea level produced by a storm or depression or tropical cyclone
• The IPCC 2014 report projected a high confidence that delta flooding will increase by 50% in some of the world's major deltas
• Constructive waves


  Low energy, generally flat, long wavelength, low frequency, strong swash pushing sediment up the beach, weak backwash, deposition occurs on the beach
• Destructive waves


  High energy, large wave heights, short wavelength, high frequency, little energy is lost, strong backwash carrying materials back down the beach
• Erosional processes

  • Hydraulic action
  • Abrasion
  • Attrition
  • solution
• Hydraulic action


  The force of the water itself causing rocks to break away, weakens the structure of rocks
• Abrasion


  Waves picking up rocks and throwing them against other rocks, chipping away rock structure
• Attrition


  Transported material in the sea bashing against each other, rounding and reducing the size of rocks
• solution

  Rocks dissolving due to their minerals in the sea, turning into solution
• Wave cut platform


  • Kimmeridge Bay, Dorset
• Wave cut platform


  • Flat area in front of a cliff where the cliff has retreated over time due to erosional processes chipping away at the bottom of the cliff