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 CHESIL CHALLENGE

THIS IS A PERSONAL CHALLENGE AND NOT A RACE!
YOU MUST BE SELF SUPPORTED OR HAVE A CREW THAT KNOW WHAT THEY'RE DOING.
*CHALLENGERS WILL GET A MEDAL UPON FINISHING*

CHALLENGE TO BE TAKEN ON BETWEEN OCTOBER 1ST AND APRIL 30TH EACH YEAR DUE TO BEACH RULES. PLEASE READ BELOW IN ORDER TO PREP FOR YOUR CHALLENGE.

Chesil Beach is 18 miles (28 kilometres) long and 160 - 200 metres wide and it rises between 12 and 15 metres in height. It is a pebble and shingle tombolo connecting Portland to Abbotsbury and then continuing north-westwards to West Bay near Bridport. It is the largest tombolo in the UK.

The pebbles are graded in size from fist-sized near Portland to pea-sized at Bridport. The pebbles are mainly a mix of flint and chert, with some quartzite pebbles from Buddleigh Salterton.

The origin of the beach continues to be argued over with some proposing it is actually two beaches. The stretch from West Bay to Abbotsbury appears to have different characteristics to the stretch from Abbotsbury to Portland.

Chesil Beach shelters Weymouth from the prevailing wind and waves and prevents the area being eroded by wave action. Evidence suggests that the beach is no longer being replenished by natural means.

The beach forms part of the Dorset and East Devon World Heritage Site, known as the Jurassic Coast.

Chesil Beach is a linear shingle storm beach stretching from Portland in the south to West Bay in the North-West.

The seaward face of the beach is steeply shelving and this continues below the sea level until it gradually levels off at around 18 metres below sea level some 300 metres offshore in the southern part of the beach. Further north the offshore depth is around 11 metres.

There is a clear southern limit to the beach where it meets the limestone of Portland, but the northern limit is less distinct and depends on the definition used. Various limits have been proposed from Abbotsbury to West Bay. Geologically there is some merit in these arguments, but for practical purposes the limit is taken as the pier at West Bay. The pier is an effective barrier to longshore drift into or away from Chesil Beach.

The beach stabilised close to its present position some 5000 years ago. Since then it has been advancing slowly towards the mainland. Current estimates suggest that at the southern end this rate of advance is around 15cms per year, with a slower rate further north. This advance occurs under storm conditions and is caused either by over-topping waves or by can action where the water comes through the beach pushing quantities of pebbles out into the Fleet. This advancement is slowly causing increasing isolation of the various segments of the beach between Abbotsbury and West Bay.

Under storm conditions large quantities of pebbles can be removed from the beach onto the seabed. For severe storms the quantities can exceed 3 million tonnes. Subsequent wave action then replaces these pebbles on the front of the beach.

There appears to be two types of storm conditions that affect Chesil Beach. The majority of storms are deep depressions approaching from the south-west where the combination of strong winds and low barometric pressure can produce storm surges in the English Channel combined with high local waves. A rarer type, but potentially more dramatic in impact, occurs when large storms out in the Atlantic generate huge, long-period swell waves that travel up the Channel and impact the Beach. Such waves can have a period of up to 20 seconds, compared with the 5-10 second period of local storm waves. Two such events are known to have occurred in 1904 and 1979.