IT’S hard to believe when visiting the huge sandy beach at Carlyon Bay in Cornwall that it didn’t exist 200 years ago.

The white sands stretch for more than a mile along the coast near St Austell and cover a massive area, particularly when the tide is out.

I must admit I was unaware of the story of the beach until I was looking into my family history which on the paternal line includes the Olvers from the St Austell area who were involved with farming and mining.

The beach is basically made up of silt, grit and sand created by the extraction of tin and china clay in the St Austell district. But how it got there is not straightforward.

In the early days of tin working, cassiterite ore was taken from streams and rivers and their banks for its tin content. The silt from the extensive digging was washed downstream.

In the St Austell area, the Sandy River, as it is now known, took silt from various workings out to the sea at Par. There the material largely added to the beach at Par Sands.

As tin mining become more industrialised at Carclaze, above St Austell, so significant amounts of waste flowed to Par.

However, when Joseph Treffry built a harbour at Par in the 1830s, so he could transport mined products to other markets, he soon realised the silt posed a problem for shipping.

Then he came up with a radical solution – he had a tunnel built through the ridge and cliffs at Carlyon Bay to divert the river out to sea there.

At the time, high tides reached to the bottom of the cliffs and there were only small beaches when the tide went out.

With the rise of the china clay industry, enormous amounts of sediment flowed down the river to make up the Crinnis, Shorthorn and Polgaver beaches.

Steps were taken on environmental grounds to reduce the disposal of sand via the river in the second half of the 20th century and since the 1970s little material has reached the bay. However, today a vast sandy expanse still remains.