Rock Armour

Parts of the coast are defended by boulder piles known as rock armour. The boulders were brought from as far away as the English Midlands, Norway and Scotland, introducing exotic stone types to local beaches. Fragments are adding to the variety of pebbles you can find. As well as the large blocks which you can see - and should not climb on - there are many fragments on the beach where bits broke off as the blocks were craned off barges.

Rock defences behind earlier wooden defences at Overstrand in a picture from 2009. There had been a major land-slip caused by water lubricating the boundary between clay and sand in the cliff, and a large section was dug out and stabilised.

Exploring granite fragments on Cromer west beach. It's a coarse-grained granite, with a 'salt and pepper' appearance and large feldspar grains.Boulders of Larvikite brought from Norway are often used as rock armour. They have shimmering, blue-tinted feldspar crystals.Boulders on East Runton beach originated from a quarry in Leicestershire. They are examples of Precambrian volcanic breccia, over a half a billion years old.

The rock defences on Cromer west beach and on Mundesley beach came from a quarry near Oban, in Scotland. The video below starts in 2023, to show Cromer west beach as it was before work began. Through the summer, day and night, rock was brought by ship to an anchorage off Cromer, it was then transferred to a barge, and brought in at high tide. The barge would off-load and when the tide went out, mechanical diggers were able to shift the rocks into position in front of the sea wall.

As Alfred Savin correctly stated to the Cromer Protection Commissioners at the end of the 19th century, when they were about to extend the promenade, any protection must sit on the chalk below the sand. This involved digging down to the chalk in front of the sea wall, inserting a membrane on the chalk and dropping the boulders on top of it.