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Author Topic: How much shingle is there in the Chesil Beach?  (Read 4057 times)

Offline antonymous

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How much shingle is there in the Chesil Beach?
« on: 01 March, 2014, 10:36:28 PM »
       

Folklore has it that it was formed during one major storm and the recent storms caused me to ponder on the power of the wind and sea and how much energy would be required to form such a prominent feature of the Dorset coastline - but to caclculate that one needs to know just how much stuff was moved, how far, and over what period. I've done some rough calculations.
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imfeduptoo

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Re: How much shingle is there in the Chesil Beach?
« Reply #1 on: 02 March, 2014, 10:04:30 AM »
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.

http://www.jurassiccoastline.com/jurassic_Info1b.asp?ID=115&AreaID=115


It took perhaps 10,000 years to form and if I've understood this correctly, was pushed into place by th Atlantic waves from the Lyme Bay area..

Chesil Beach initially formed from predominantly sandy deposits in Lyme Bay as water levels rose rapidly at the end of the last ice age 20,000-14,000 years ago. These deposits were eroded and the sand and gravel driven onshore as a barrier beach. As the barrier beach was driven further east by rising sea levels it overrode existing sediments and the Fleet was formed starting about 7000 years ago. The formation of the Fleet was virtually complete by 5000 years ago.

Sea levels stabilised 4000-5000 years ago and at that time Chesil Beach stood close to its present position. It was predominantly sandy with layers of shell and coarser material indicating over-washing by the sea.

At this time relict cliffs in East Devon, left stranded by falling sea levels during the ice age, were re-activated and the combination of re-working of extensive debris aprons and erosion of existing cliffs yielded large quantities of gravel. Estimates suggest that as much as 60 million cubic metres of gravel could have been supplied. This material was transported to Chesil Beach by longshore drift via a series of pocket beaches.

http://www.chesilbeach.org/chesil/formation.html

Offline antonymous

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Re: How much shingle is there in the Chesil Beach?
« Reply #2 on: 02 March, 2014, 10:44:54 AM »
Thanks Mrs Too - I did some very rough calculations and came up with 97 million tons - not bad eh?
BTW My sources limit its length to 15 kilometers! Which I used in my calculations. wve
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Offline P-Kasso2

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Re: How much shingle is there in the Chesil Beach?
« Reply #3 on: 02 March, 2014, 06:01:14 PM »
97 million tons or 100 million tons of shingle...where's it all gone?

Any chance of getting it back?
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imfeduptoo

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Re: How much shingle is there in the Chesil Beach?
« Reply #4 on: 02 March, 2014, 11:09:06 PM »
Thanks Mrs Too - I did some very rough calculations and came up with 97 million tons - not bad eh?
BTW My sources limit its length to 15 kilometers! Which I used in my calculations. wve
Not at all bad!
I've fished there several times so I had counted most of the pebbles!