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Long Mynd

Pipe WalkToday the Long Mynd can seem a place of barren beauty, with its open expanse of heather and bilberries and sculpted valleys, but beneath the thin soil lies an even more dramatic scene recorded by the rocks 565 million years ago.

Imagine yourself on a desolate muddy shoreline, a bare rock continent rising behind you in the distance, the sea lapping at your toes. Out to sea you can make out the plumes of ash from far away volcanoes, the ground trembling beneath you as the earth moves along buried rips in the crust. There is no other life around, no green plants, maybe a little algae in the sea and a few other soft sea creatures, but the land is an alien place for life at this point in the history of the earth.

Stay where you are for a few million years and you will see the continent behind you being worn down slowly, ground into mud and silt and sand, and carried by rivers to the sea and onto the very mudflats where you are standing. This is how the layers of sediment were made building up to some 8000 m thick. Later, those faults or breaks in the earth’s crust would squeeze and fold these layers bending them over on themselves, creating the vertical rocks that you can see lining the valleys of the Long Mynd.

Although we don’t generally find fossil animals in the rocks we can find fossils of a different kind – trace fossils. These are marks or impressions left behind on the surface of the mudflat or beach, wherever the sediment is being deposited. These could be made by an animal, like footprints or in the case of the Long Mynd, the weather.

There are certain layers in the rocks of the Long Mynd that have perfectly preserved little craters. These were once thought to be raindrop marks recording a passing April shower, made when rain fell onto a layer of firm dry mud leaving behind a tiny crater, like a miniature asteroid crater. These little pits were then covered by another layer of mud, which filled them in and preserved them for the last 565 million years. However, recent research by carefully slicing through a number of these features shows that many of them were in fact formed by escape of gas from rotting algae, buried by mud on the sea floor. Yet others may be fossilised seaweed!

You can also find desiccation cracks, which show a very different type of weather – extreme heat. When mud dries out it bakes and cracks in an odd, almost hexagonal pattern and this texture has been preserved on the slopes of the Long Mynd.

Transport yourself back to the present. When you visit the Long Mynd, remind yourself that you are walking through time, through vertical layers of rock. You might like to start your tour at the nearby town of Church Stretton, or from the Cardingmill Valley a little way outside the town. The Society has prepared a Wonder as you Wander guide to help you.

 

 

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