SHROPSHIRE ROCKS!

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The Hermitage, Bridgnorth

The Hermitage The Hermitage is a series of caves cut into the weak red sandstone that is found all around the town of Bridgnorth.

This sand was formed during the Permian era, when Shropshire was around 25° North of the equator and conditions were very similar to the present day Sahara desert. Imagine enormous sand dunes tens of metres high marching across a barren rock landscape being blasted by a never-ending wind.

These dunes have been preserved in the rocks that you can see at the Hermitage and in the cliffs at Low Town in Bridgnorth. You can see sweeping curves in the rock that cut across one another and these are the remains of the once active sand dunes.

It was a barren and desolate place, inhospitable to life and very few fossils are found in these red sandstones. If you pick up a piece or touch some rock you’ll feel how crumbly it is, sand grains come loose on your hands really easily. That’s because the glue that holds the grains together is nothing more than rust, iron oxide. It’s this rusty coating that gives the rock its bright red colour.Dunes 2

If you look at the roofs of the caves at the Hermitage, you might notice that these rocks appear very different. They’re not quite so bright red in colour and have got lots of pebbles in them of all different shapes and sizes. This dramatic change in rock type tells us that there was a sudden change in the environment, that Bridgnorth was no longer a desert.

These thick pebble beds are a type of rock called conglomerate, a kind of natural concrete. Conglomerates can be made in different ways, slowly, with the pebbles being sorted, in water like rivers, by size and then sand and mud filling in the gaps later, or rapidly, where an enormous flash flood just picks up all the material lying in its path and then dumps it all randomly.

The pebble beds at the Hermitage were made by both these methods. Rivers encroached onto the desert, cutting down into the soft dunes with occasional violent flash floods tearing down these channels scouring the land and bringing pebbles from as far away as Brittany in France.

This sudden change happens at the end of the Permian, the time when the Earth nearly died and may be related to the serious climate changes that had happened.

You might like to start your visit to Saharan Shropshire around the pretty town of Bridgnorth. You can see how local people have incorporated the rock into their houses, using it as walls in some cases. Look at the dune bedding in the cliffs of low town and follow the old Wolverhampton road up to the Hermitage.

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