The Chalk Beds

Sheringham from west (Chris Taylor)

KEY FACTS

  • Thought to be the longest chalk reef in Europe, possibly the world.
  • The chalk beds include spectacular ridges, gullies and arches up to 20 metres high.
  • The chalk was originally laid down tens of millions of years ago by the gradual accumulation of the shells of tiny marine creatures.
  • The chalk occurs in a mosaic with flint cobbles and patches of sand and other sediments. The areas of exposed chalk change as waves, currents and storms move sand around.
  • The reef supports a huge variety of marine plants and animals.
  •  The importance of the reef was recognised in 2016 by designation as a Marine Conservation Zone (MCZ), aimed at protecting the best marine habitats around the coast of England.
  • The designated area extends about 30 kilometres along the coast from Weybourne to Happisburgh, out to about 10km offshore and a depth of about 25 metres – a total area of about 320 square kilometres.

More about what makes the chalk beds special…

Most of the bed of the North Sea is composed of sediments (sand, mud and gravel). The North Norfolk Chalk Beds are different and special – one of the best examples of marine chalk beds in the North Sea.

A large area of exposed chalk and cobbles in shallow water up to 10m depth extends for almost the entire length of the site from east to west.

The gullies and arches were formed by meltwater at the end of the last Ice Age, thousands of years ago.

The rock provides a stable surface on which a great variety of seaweeds and animals that attach themselves to rock can flourish. These, in turn, provide a sheltering habitat for many types of mobile marine creatures such as fish, crabs, lobsters, cuttlefish and starfish.

In deeper water, the lower light penetration means fewer seaweeds but more animals associated with the reef.

In the eastern part of the site, large populations of the Ross worm form tubes composed of shell fragments and coarse sand cemented together with mucus. In high densities, these form areas of a different type of reef, known as a biogenic reef (i.e. one that is formed by living animals).

The variety and changing mosaic of habitats, particularly those that are rare in this part of the sea, give rise to a rich mixture of marine plants and animals, including some that are rare for this part of the world.

Over 350 species of marine animals and plants have been recorded. These include sponges, sea-squirts, sea anemones, fish such as bass and bib, starfish and brittlestars.

Some of the species are rare or even unique – a purple sponge was previously unknown anywhere and  a sea slug, a sea-anemone and a goby (a type of small fish) have not been recorded before on the east coast. More may remain to be discovered!