The Bellstone was originally located on the site of the NatWest bank at Mardol Head (Darwin Gate) but was moved to its present location. An annual toast is held at the Bellstone on Darwin’s birthday, 12 February.
In geological terms the Bellstone is known as a 'glacial erratic'. It is made of rock which is not native to this area.
It is not widely known, but Charles Darwin regarded himself as a geologist rather than an evolutionary biologist. Sadly, his geological field research activities were effectively terminated when a mystery illness started seriously to restrict his mobility, and after 1842 (when still only 33 years old) he had to curtail thoughts of any new fieldwork.
The Bellstone in Shrewsbury was Charles Darwin’s first introduction to geology. It was a Mr Cotton who pointed out the Bellstone to the young Darwin and he explained that this type of stone can only be found much further north in Cumbria or Scotland. Cotton went on to assure Charles Darwin that "the world would come to an end before anyone would be able to explain how this stone came where it now lay". It was only when he studied geology at Edinburgh that Darwin learned how it had travelled here. The world had not come to an end and he marvelled at the rapid progress of geology. He came to understand that this boulder was a glacial erratic.
Glacial erratics, or erosion-resistant boulders are transported by glaciers. Erratics can range in size, from small pebbles to large boulders. They key thing is that they are made of a rock which is different to that which is native to the area. Some erratics have been carried huge distances, like some Scottish rocks that ended up in southeast Ireland (a distance of 600 miles). The largest known erratic in the world is located in Alberta, Canada and weighs about 15 000 tonnes.
Erratics tell a story about where the glacier picked them up from their original bedrock. The local rock is red sandstone, a sedimentary rock, which is commonly used as a building material in Shropshire, having been used here in Shrewsbury for the castle and the abbey. This boulder is granite, an unmetamorphosed igneous rock, formed beneath the earth’s surface when a large magma body slowly cooled. Granite is not a native rock to Shropshire.
How rounded or angular the erratic is can also tell you how it was transported. A rougher, more angular boulder would have been subject to relatively little erosion – maybe it wasn’t transported near the base of the glacier. A smooth, rounded boulder indicates it was well-eroded, perhaps travelling a great distance.
Your tasks
To log this cache, you will need to complete the tasks below. Please message us with the info (rather than post it on your log). You can log a find once we have been sent a message. We may delete your log if your answer is way off the mark.
- Describe how the Bellstone differs in appearance to the native red sandstone rock which has been used to build the wall behind. (Colour, texture etc)
- What is the approximate volume of the boulder? (Approx width x height x depth = ?)
- How do you think that it is known that the Bellstone came specifically from Cumbria ?
- As an optional extra, post a picture on your log of yourself and / or your GPSr by the Bellstone boulder.