2B.2ab

• what are concordant coasts?

  coastline where the bands of alternating hard and soft rock run parallel to the shoreline
• which landforms form at concordant coasts?

  coves, dalmatian coastlines and haff coastlines
• how do coves form?

  1. powerful and erosive waves create a small fracture in the hard, resistant rock
  2. this creates an opening in the rock causing the less resistant rock behind it to be exposed
  3. waves erode the softer rock at a faster rate so it recedes quickly until they reach the next layer of hard rock, this hard rock slows the growth of the curve further inland
• how do dalmatian coastlines form?

  • tectonic folding creates anticlines (ridges) and synclines (troughs), which run parallel to the shoreline. sea level rise submerges the synclines, leaving islands parallel to the coast
  • e.g. Adriatic Sea in Croatia
• how do haff coastlines form?

  where deposits of sand run parallel to the coastline on top of offshore bars. lagoons form in between the bars and the shoreline

  e.g. Baltic sea
• what are discordant coastlines?

  bands of alternating hard and soft rock run perpendicular to the shoreline
• which landforms form at discordant coastlines?

  headlands and bays
• how do headlands and bays form?

  differential erosion - the less resistant rock is eroded quicker forming a bay. the more resistant rock is eroded less quickly and sticks out as a headland
• what happens to the headland?

  once it has formed, it will erode at a quicker rate due to the exposure and due to wave refraction --> process by which wave direction changes
• headlands also experience higher wave heights compared to bays:

  • at a headland, waves slow down. water builds up behind the wave crest (the highest point of the wave), increasing the height of the wave and giving it greater erosive power
  • this means headlands have steep cliff faces and arches and caves can develop
  • the shape of the bay dissipates the wave energy which reduces their height, overtime, the difference between the headlands and the bays may become less significant as the headlands are eroded faster