Pebble Size and Longshore Drift

The stones that make up the Chesil Beach are mainly derived from East Devon, consisting of Metaquartzites of the Ordovian and Devonian Age, Chert and Flint. A unique feature the Chesil Beach is how the pebble size changes from one end to the other. Large cobbles are found at Chesil Cove, Portland, while West Bay has fine grit and gravel. It is thought the bigger heavier stones have a larger surface area and are therefore carried further to the east by the powerful prevailing south westerly waves hitting the beach at an angle, while the smaller lighter stones are carried back to the west by the less powerful waves approaching from the south east. In effect the stones zigzag their way along the coastline, carried by this longshore drift, accounting for the size graduation. The harbours at Lyme Regis and West Bay are both obstacles to the longshore drift, and the reduction in quantity of stone being delivered through coastal erosion in East Devon is diminishing. The long-term future

The Chesil Beach (Chesil Bank)

Consisting of a 100 million ton bank of pebbles, the Chesil Beach stretches for 28 km to West Bay. The beach varies between 36 and 200 meters wide and also in height, being 14 meters at Portland and just 5 meters at West Bay. The bank of pebbles separates the sea from Britain’s largest tidal lagoon, the Fleet, an important wildlife habitat for all manner of extraordinary flora and fauna. The beach is marching inland at a rate of 5 meters every century, reducing the size of the Fleet Lagoon in the process. The Chesil Beach is by no means stable. Storm waves have breached its pebble bank several times in the past, flooding the Fleet Lagoon, the land behind it and Portland to a depth of several meters. In one great storm the beach was swept away, exposing the underlying Kimmeridge Clay, in which were coins, jewelry and all sorts of artifacts that had been lost between the pebbles throughout the centuries.

Vegetated Shingle

Growing along the shore of the Fleet and on Chesil Bank are a multitude of plants, all especially adapted to growing in this harsh coastal environment. The plants are particularly prolific around Bum Point, the Fleet and Chesil Visitor Centre and they can also be found alongside the causeway beside Portland Harbour.

The Chesil Beach and Smugglers

Folklore says that a local fisherman or smuggler could tell exactly where he was on the beach at night or in fog simply by looking at the size of the pebbles. This aided him in sneaking ashore, away from the customs men and their patrols.

The Royal Adelaide

It was late in the evening of the 25th of November 1872 that a crowd of over 3000 people came to watch as one of the new breed of huge iron passenger and cargo sailing ships, the 235 foot (71.5 meter) long Royal Adelaide, was pushed onto the Chesil Bank during a south westerly gale. Held firm as the pebbles washed around her hull, all but 5 on board were successfully rescued by breeches buoy, and it wasn’t long before some of the first items of cargo, caskets of Dutch gin, began to wash ashore as the vessel broke up. Seized by wreck fever the crowd went mad, punching holes into the barrels, and all, men, women and boys drank long and deep. By morning, the true extent of the Royal Adelaide’s loss became apparent, as lying on the beach were 20 corpses. All had succumbed to exposure after falling into a drunken sleep upon the cold, wet pebbles. The iron carcass of the Royal Adelaide remains 14 meters down on the seafloor at the foot of the beach providing a home for all manner of marine life.