Coastal Environments
Geography A2
, Why do coastal landscapes
vary?
• Lithology (Rock Type): Hard rocks (granite + basalt) give rugged landscapes such as Giants Causeway in
Northern Ireland, whereas Soft Rocks (sands + gravels) give low flat landscapes like the Nile Delta.
• Geological Structure: concordant (Atlantic) or accordant (Pacific) coastlines occur where the geological strata
lie parallel to the coastline. Whereas, discordant (Atlantic-type) coastlines occur where the geological strata are
at right angles to the shoreline.
• Processes: Erosional landscapes contain many rapidly retreating cliffs, whereas areas of rapid deposition
contain many sand dunes and coastal flats.
• Sea Level changes: interact with erosional and depositional processes to produce advancing coasts (those
growing either due to a deposition and/or relative fall in sea level) or retreating coasts (those being eroded
and/or drowned by a relative rise in sea level)
• Human impacts: some coasts are extensively modified whereas others are more natural
• Ecosystem types: such as mangrove, coral, sand dune, salt marsh and rocky shores add variety to coastlines.
, Lithology (type of rock)
• Some rocks have weak lithology and are not resistant to erosion, weathering
and mass movements
• The bonds between the rock particles a re weak so the coastal landforms are
not well defined or stable
• Others have strong bonds and interlocking crystals and are highly resistance
to erosion
• These will form cliffs, headlands and stable, well defined coastlines
• Different types of rocks will be susceptible to different things and create
different types of coastlines
, Coastal Zones
• The coastal zone includes all areas from the deep ocean (up to 320km
offshore) to 60km inland.
• At the coast there is the upper beach or backshore (backed by cliffs or sand
dunes), the foreshore (periodically exposed by the tides) and the offshore area
(covered by water)
• The coastal zone is a dynamic area with inputs and processes
from land, sea and atmosphere.
Geography A2
, Why do coastal landscapes
vary?
• Lithology (Rock Type): Hard rocks (granite + basalt) give rugged landscapes such as Giants Causeway in
Northern Ireland, whereas Soft Rocks (sands + gravels) give low flat landscapes like the Nile Delta.
• Geological Structure: concordant (Atlantic) or accordant (Pacific) coastlines occur where the geological strata
lie parallel to the coastline. Whereas, discordant (Atlantic-type) coastlines occur where the geological strata are
at right angles to the shoreline.
• Processes: Erosional landscapes contain many rapidly retreating cliffs, whereas areas of rapid deposition
contain many sand dunes and coastal flats.
• Sea Level changes: interact with erosional and depositional processes to produce advancing coasts (those
growing either due to a deposition and/or relative fall in sea level) or retreating coasts (those being eroded
and/or drowned by a relative rise in sea level)
• Human impacts: some coasts are extensively modified whereas others are more natural
• Ecosystem types: such as mangrove, coral, sand dune, salt marsh and rocky shores add variety to coastlines.
, Lithology (type of rock)
• Some rocks have weak lithology and are not resistant to erosion, weathering
and mass movements
• The bonds between the rock particles a re weak so the coastal landforms are
not well defined or stable
• Others have strong bonds and interlocking crystals and are highly resistance
to erosion
• These will form cliffs, headlands and stable, well defined coastlines
• Different types of rocks will be susceptible to different things and create
different types of coastlines
, Coastal Zones
• The coastal zone includes all areas from the deep ocean (up to 320km
offshore) to 60km inland.
• At the coast there is the upper beach or backshore (backed by cliffs or sand
dunes), the foreshore (periodically exposed by the tides) and the offshore area
(covered by water)
• The coastal zone is a dynamic area with inputs and processes
from land, sea and atmosphere.
