The seas around Gunwalloe are home to the wrecks of the Santo António, a Portuguese ship wrecked during a storm almost 500 years ago, and the San Salvador, a Spanish ship wrecked over 300 years ago. Inspired by recent stormy weather I headed down to Dollar Cove at Gunwalloe to see if anything interesting had been washed up (although note I was neither expecting or hoping for a ship). Before I even got down to the beach I noticed that sea foam had been blown up to the footpath. Sea foam is created by the agitation of seawater, which is why it is often associated with stormier sea conditions.
Dissolved organic matter, derived from the breakdown of algae for example, can act as a foaming agent (surfactant). As the seawater is churned around in the surf zone as the waves hit the shore these surfactants can trap air, forming persistent bubbles. Surface tension causes these bubbles to stick together creating foam, which is often then be blown up onto the beach as a result of onshore winds.
People often mistake sea foam as an indication of polluted or dirty water. Sea foam does not rely on polluted water for its creation and is probably far more commonly unpolluted.
As for if anything had been washed up onto the beach; I didn’t get that close to the water and am waiting for a calmer and drier day for a proper exploration. [Dollar Cove looking south west image here]
Published: Feb 2016
Author: Charlotte Marshal (Marine Lead Adviser, Natural England)