Beach Sand

For a long time we wondered what the sands of West Ardamurchan's beautiful white beaches were made of, until Rachael did a Highers Geography project in which she looked at the profiles of the beaches, which change constantly with storms and tides, and their composition.

We had assumed that most of the beach sand came from the erosion of the local rocks by the fast-running burns, and therefore that they would largely be formed of bits of eroded rock and minerals such as quartz and felspar.  We were wrong. When Rachael studied them under the school microscope she found they are formed almost entirely of the smashed remains of millions upon millions of shells.

This picture shows a sample of the sort of sea creatures which contribute: tops, cockles, mussels, winkles, sea urchins, the calcerous tubeworm serpula, limpets, oysters, cowries, and numerous other species of bivalves and snails.

We also tried to work out why there are sandy beaches in some places, particularly along the north coast and at Sanna, and pebble beaches elsewhere, but we came to no firm answers.