Strandline Shells on Swansea Bay

Seashells on the beach at Swansea Bay

Shells drift lines on the beachSeashells in situ on Swansea Bay strandlines or drift lines are mostly tiny immature common cockle shells but there are many other species of bivalve and gastropod mollusc shells too. I noticed mussels, tellins, and oysters, winkles, top shells, netted whelks, sting winkles, slipper and common limpets, and I am sure there were many more types. There were seven drift lines of shells lying parallel to the water line and decreasing in the number of accumulated shells sequentially up the shore. Each line represents the highest reach of the sea on a series of subsequent falling tides that were decreasing in reach each time.

It was interesting to see that wave-worn pieces of black coal and dark clinker from industrial plants across the bay were scattered amongst the light coloured shells together with a fair number of burial-blackened periwinkles. Many of the shells were fragmented and the accumulations included the calcareous tubes of marine worms. It would be lovely next time to take a sample home and sort it through under a binoc. I am sure that it would reveal much more information.

Click on any image below to see the details in a larger version.

6 thoughts on “Strandline Shells on Swansea Bay

  1. I have never seen so many seashells. Do they blow in from the sea and end up on the beach? Just seem to be same places they end up on.

  2. All the bivalve shells like the baby cockles have been living in the softer muddier sediments lower on the beach and on the seabed further out in the bay. Thy have died out there for some reason and been washed in by the tide.

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