Here are some really unusual rocks that are incorporated in sea walls around Lyme Regis in Dorset, UK. I don’t know what they are. Perhaps you do. I’d love to know what they are. I’m uncertain whether they are local in origin – maybe picked up from the beach – or whether they have been imported from elsewhere. Some of the rocks used in the construction of The Cobb sea defence and harbour were quarried on the Isle of Portland further east along the Dorset coast. Other Cobb rocks were shipped in from much further afield – Norway, I think.
I’m struck by the honey-comb appearance of these sea wall rocks, the networks of cavities and intricate partitions in the stone – almost bubbly and volcanic. I am wondering whether the holes in the rock are an integral part of the rock’s formation or whether they represent the effects of years of driving rain and pounding seas dissolving softer areas of the stone and leaving harder parts relatively unaffected. It’s a bit of a puzzle.
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13 Replies to “Curious sea-wall rocks at Lyme Regis”
The Cobb was reconstructed in 1820 using Portland Admiralty Roach, a type of Portland stone.
Thanks, Ian. However, Portland Roach typically is fossiliferous including many marine molluscs such as the long pointed gastropod known as the Portland Screw. You can easily see these in the blocks of stone used in the building of the Cobb. There were no fossils at all in these holey stones in the sea wall. I have some photographs on my other site of rocks on the Cobb, for example, http://jessica-winder.artistwebsites.com/featured/rock-on-the-cobb-01-jessica-winder.html
and more similar pictures in the ROCK Gallery: http://jessica-winder.artistwebsites.com/art/all/rock/all
I really think there should be a ‘real ale’ called Portland Screw.
What an excellent idea. I think you should pass the suggestion on to a local brewery for them to produce the ale to coincide with the olympic sailing events off Portland next year.
Hall & Woodhouse maybe? I’ll let you do it, as you are local.
I’ve done it. If they take up the idea and send me a crate of the product, I’ll be sure to share it with you.
You are so kind!
Not at all. It was your idea. Let’s see what happens.
Yes, let’s. But I was inspired by your post.
In a short while, I’ll post the new revised versions of the posts about the Cobb that I published last year. I’m slowly working through the backlog of revisions as well as adding new articles and photographs.
I was searching your blog to see if you had posted any images of ”honeycomb weathering’. I discovered it for the first time a few days ago at Caerfai Bay near St David’s. There are a few references online and a Wikipedia entry but all in all it’s a bit of a mystery. The effect however is quite something.
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There are quite a few posts in this blog that feature images of honeycomb weathering in rocks. The phenomenon is fairly common where rocks that are mainly of a softer sedimentary type such as sandstone, mudstone or limestone, have veins of hard material within them. The softer rock is more easily eroded by rain, wind, and water, especially on the coast, leaving a network of the harder material standing out on the surface. Here are links to a few posts showing pictures of rocks like this: