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‘A love letter to the scenery of the Jurassic Coast’ – the geology of Broadchurch

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“East Cliff Westbay – geograph.org.uk – 1234069” by Pam Goodey. Licensed under CC BY-SA 2.0 via Wikimedia Commons

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Broadchurch Detective Show – Image Credit: Licensed under Fair use via Wikipedia

Did Joe kill Danny? Do we care about Sandbrook? What’s with all the bluebells? Will Alec make it through those super tense court scenes alive?

On Monday, at least some of these questions should be answered as the slightly topsy-turvy second series of Broadchurch (or so says the press…) comes to a close, and the nation begins twiddling its thumbs waiting to hear about a third series.

Those iconic cliffs, however, as rocks always do, will LIVE ON through good Broadchurch and bad, as well as everything else (with the exception of heavy storms and sea level rise.)

The show’s famous cliffs play host to many key plot points. They are where Danny Latimer meets a grizzly end, and Susan may or may not have seen her son Nigel carrying the body of (you get the picture).  In real life, they are the stunningly beautiful, endlessly instagrammable cliffs at East Cliff, West Bay in Dorset, and we thought the closing of the series would be a good opportunity to find out more about them….

East Cliff forms part of West Bay, a small town and resort in Dorset, part of the Jurassic Coast World Heritage Site. West Bay is also within the Dorset Area of Outstanding Natural Beauty and East Beach (the beach below East Cliff) is a Site of Special Scientific Interest.

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Chesil Beach in Dorset by Jim – Flickr: Chesil Beach – Dorset.. Licensed under CC BY 2.0 via Wikimedia Commons

East Beach (where much intense character contemplation occurs) forms the most westerly end of the famous Chesil Beach, a barrier beach which continues on another 18 miles out towards the Isle of Portland. A barrier beach is defined as a sand ridge that rises slightly above the surface of the sea and runs roughly parallel to the shore, from which it is separated by a lagoon. This kind of feature is formed by longshore drift. The feature is thought to have been initially formed from sandy deposits in Lyme Bay that were eroded and driven onshore. It is now considered a closed system with no replenishment, so the beach is very sensitive to changes in environment. 

The West Bay area sits within the Dorset coastline; one of the most visited and studied coastlines in the world. Through 95 miles of coastline, it exposes rocks from the beginning of the Triassic all the way through the Jurassic and up to the end of the Cretaceous, spanning the entire Mesozoic era with amazingly well preserved fossils.

The famous cliffs themselves are made up of the Bridport Sands, formed in the Toarcian Age (183 million years ago) of the early Jurassic. The prominent bands are caused by the alternating hard and soft layers of rock, which represent a major rhythm in sedimentation. The distinctive yellow colour is formed by the oxidation of fine pyrite grains in the rocks, causing the formation of limonite, an iron oxide-hydroxide caused by weathering.

The cliff is capped by a thin layer of inferior oolite composed of predominantly calcium carbonate formed from ooids – grains made of up concentric layers. These rocks were formed in a warm, shallow Jurassic Sea.

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The many moods of Broadchurch… Image Credit: “East Cliff, near West Bay – geograph.org.uk – 1234062” by Roger Cornfoot. Licensed under CC BY-SA 2.0 via Wikimedia Commons and “East Cliff, West Bay, Dorset – geograph.org.uk – 1288467” by Stacey Harris. Licensed under CC BY-SA 2.0 via Wikimedia Commons

 

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Wellsites M and F, oil wells on the Goathorn Peninsula in the Wytch Farm oilfield – Image Credit: by Pterre – Own work. Licensed under CC BY 3.0 via Wikimedia Commons

These rocks have also been faulted, which has led to some interesting structures in the area. The Epe Mouth fault, which occurred during the Cimmerian Orogeny (200-150 million years ago) is aligned east west and can be seen at West Cliff, with a vertical displacement of around 200 metres.

The Bridport Sandstones have been faulted below sea level and form part of the Wytch Farm Oil Field in nearby Purbeck. Wytch Farm is largely concealed by the coniferous forest on Wytch Heath and has remaining oil and gas expected to last until 2020-2025. The Bridport reservoir was the first discovered in the area and is located in the same Jurassic sands that we see at East Cliff in West bay. For this reason, the area is also used for educational trips to give students a first-hand opportunity to study oil reservoir rocks.  

The cliff, as the show frequently reminds us, is not the most stable. Every now and then it suffers from failure due to storms and adverse weather, which can result in episodic rock falls. With continued climate and sea level change, this coastline as we know it won’t be with us forever.

If you need any more convincing about how wonderful this area of Dorset is, then you can read all about what the cast and crew had to say about working in West Bay. Suffice to say that Chris Chibnall, creator and writer, described the choice to film Broadchurch there as “a love letter to the scenery of the Jurassic Coast”.

The idea for this post came from our Director of Finance, Jonathan, just one of many GSL Broadchurch fans!

  • This post was amended on 24.2.2015.

One thought on “‘A love letter to the scenery of the Jurassic Coast’ – the geology of Broadchurch

  1. Pingback: Door twenty four | Geological Society of London blog

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