Saturday, 30 June 2012

Bath in Stone Walk

At ASE west we use the expertise of Elizabeth Devon from the Earth Science unit a lot. Her training sessions are always excellent and her knowledge is vast.

We found out that she does walks around Bath looking at the rocks and explaining their geology. As it was a walk for science teachers we could do it for free!

Elizabeth gave us all hand lenses and we started with a brief description of the geology of the area. She used a sponge with the layers represented in colour and a removable chunk to represent the way the river had worn away the layers to form the bowl Bath is in. The top layer is the famous Bath stone.

Then we set off around Bath to find examples of different kinds of stone.

The Podium in Bath is built from Bath stone from two different quarries. You can see the different colours.

Bath stone is a limestone and was formed in the Jurassic era when the British Isles were very much further south than they are now. The same conditions exist in the Caribbean today. We examined the Bath stone on the obelisk in Queen Square and saw the tiny round holes that once contained ooids.

This paving stone shows that it was formed in a river bed. The asymmetrical ripples show there was water and it was moving in one direction. It is known as Pennant Sandstone.

These curb stone are igneous rock as you can see the crystals. It is granite.

The light mark in this cobble stone is known as a devil's toenail and is a little fossil.

You can see from this image where cobble stones have been replaced with a different type of stone.

It is fair to say that I had never considered the paving stones as telling us much about Geology.

Besides the sedimentary Bath stone, there is also a lot of good examples of igneous rocks to be found in Bath.

These stones have been made from volcanic ash, although it is hard to tell as it is too fine to see any crystals. The marks are known as volcanic bombs and the shape indicates the stream it was formed in.

Light coloured, large crystals, means we have an igneous rock formed from the continental plate and it is granite.

These images of granite show that there has been two rates of cooling. It is known as shap granite and is from Cumbria.

The talk was so interesting, but I didn't have to make note as Thematic Trails have published a guide which we were able to buy. Below is an image of the walk you can do. We did a big section, but not all in 1.5 hours. It felt like 20 minutes.

What was fantastic is that Elizabeth was modelling the types of questioning we could use with students. For example: "Can you see the crystals? What colour is it? What conclusions can you draw?"

I would recommend anyone to have a look at the local geology and use it as a teaching tool when approaching earth science units.

A great evening!

- Posted using BlogPress from my iPad


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