5 Benacre Broad

Grid reference [TM 530 830]

Benacre Broad is one of the best places in Britain to see coastal erosion at work, and also one of the most beautiful. The Broad and nearby cliffs are eroding at a rate of over 3 m (10 ft) per year, but it has been known for 25 m (75 ft) of land to disappear overnight. The effects are dramatically visible at Boathouse Covert and Long Covert, where the trees on the cliff top are undermined with each new storm, and their sea- bleached and sand-blasted remains can be seen on the beach.

The Broad itself is a lagoon of brackish water fringed by woods and reedbeds, and has a strong wilderness feel. It is separated from the sea by a shingle bar, which — like the cliffs — is steadily retreating inland, and gives the Broad its fragile identity. On occasions this barrier is breached and sea water floods into the Broad; the water flows out again when the tide falls, turning it into a forlorn expanse of mud. Moving shingle soon restores the breach, and the lagoon can begin to reform. The shingle bar is usually roped off during the spring, to encourage species such as ringed plover to breed, and there is a small public hide overlooking the Broad. The area is part of the Benacre National Nature Reserve.

The cliffs at Benacre are easily-eroded sands and clays of the Norwich Crag Formation, deposited in shallow marine conditions about 1.8 million years ago. (For more information see the Covehithe and Easton Bavents pages.)

The area of Benacre Broad was formerly a coastal inlet; it became closed off from the sea about 300 years ago by the growth of a shingle barrier. The valley here is underlain by layers of freshwater peat and marine alluvium. These beds extend offshore and they are being eroded as the coast rolls back. This is the origin of the lumps of compacted peat scattered on the beach, some of which may be several thousand years old.