Introduction to Cornwall's Sand Dunes

Cornwall's ever-changing sand dunes contrast greatly with the high cliffs bordering most of the county. Sand dunes cover approximately 2% of the area of Cornwall (approximately 3050 hectares) and are important both as natural sea defences and special places for wildlife and history.

How dunes form

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There are a number of conditions necessary for sand dunes to develop. There generally needs to be:

  • A significant distance between the high and low water mark, exposing a vast supply of sand.
  • Strong onshore winds.
  • A gently sloping shoreline.

The wind blows sand up the beach, until it meets an obstacle, such as seaweed, driftwood, pebbles or marine debris on the strandline, which slows down the wind, causing it to deposit the sand it is carrying. Sand begins to pile up behind the object, allowing specialist plants to colonise, trapping more sand and beginning the process of dune formation. 

What dunes are made of

Sand dunes, as the name suggests, are mostly made of sand. The mixture of different types of sand can have a huge influence on which plants and animals can be found on the dunes.

Sand can be a mixture of different things:

  • Shell sand - is made when marine animals with shells, like snails and cockles. When they die the waves grind up the empty shells to create shell sand. Shell sand has lots of calcium carbonate in it (the stuff that your teeth and bones are mostly made of). It is highly alkali and called calcareous. Shell sand is usually yellow or white.
  • River sand - when hard rocks are slowly broken down or eroded by running water rivers carry the sand to the sea where it eventually ends up on the beach where it can create sand dunes. River sand is usually grey and more acidic than shell sand.
  • Crumbling cliffs - eroded by the power of the sea can contribute to sand, this is called lithic material.

Most of Cornwall dunes are made of wind-blown calcareous sand.

The shape and size of the dune system depends on:

  • The quantity of sand supply.
  • Direction and strength of the wind.
  • Shape of the shore.

There are different types of dune systems found in Britain including:

  • Most of those in Cornwall are Bay Dunes e.g. Towans, Penhale, Par, which as the name suggests, form at the back of bays;
  • Rock and Crantock are Estuary Dunes and have formed along the estuary mouth, where the river meets the sea and;
  • Other types of dunes in Britain include Spit Dunes, Offshore Island Dunes and Prograding Ness Dunes.

Sand dunes can be found along the length of the Cornish coastline and can be seen at the following locations;

  • Summerleaze, Bude
  • Widemouth Bay, nr Bude
  • Rock Beach
  • Harbour Cove, Padstow
  • Harlyn Bay
  • Constantine Bay
  • Porthcothan Bay
  • Mawgan Porth
  • Crantock Beach
  • Holywell Bay
  • Penhale Sands
  • Porthtowan
  • Hayle/Gwithian Towans
  • Lelant
  • Sennen
  • Marazion
  • Praa Sands
  • Church Cove
  • Kannack Sands
  • Pendower Beach
  • Par

Follow the links below for more information:

Plants of the Dunes: Provides information on dune succession and plant adaptation to survive in dune habitat.

Animals on the Dunes: Provides information on animals that can be found on dunes.

People and the Dunes: Provides information on a range of human activities that occur on dune systems and the potential impact these activities have.

The Management of Cornwall's Sand Dunes: Provides information on factors that must be considered when managing sand dunes.