Here we see a protective sea wall, with a path between it and the chalky cliff being protected. Running out into the sea are groynes, helping to prevent beach materials from heading, in this case, east. Photo: Malcolm Pemberton

OK, this is not a misspelling of the word you may think it is. Groynes are not covered by trousers, but are part of coastal defence systems, by which I mean protecting the coastline from erosion and damage by the sea. Seawalls parallel to the coast can prevent waves contacting the bottoms of cliffs, for example, thereby preventing undercutting and gradual collapse and retreat of the cliffs. This is particularly important along the famous white cliffs of the south coast of the UK. The cliffs are of chalk and extremely soft. The constant pounding of the waves hacks at the cliff-base, slowly undercutting the structure until, often quite dramatically, large sections of overhanging rock collapse. Groynes run out at 90 degrees to the coast and their function is to prevent beach material migrating down the coast by littoral drift. Groynes are particularly important if a coastal resort has fine sandy beaches, and the inhabitants don’t wish to passively donate this fine tourist attraction to the next town down the coast.