Last Thursday saw me pulling on my walking boots to join a group of geology enthusiasts on a tour of three sites in the Black Country, chosen to illustrate the geological diversity of the area. The sites were Barr Beacon, Barrow Hill and Dudley’s’ Limestone Mines.
Although I have lived on the edge of the Black Country for almost 25 years I ‘ve never visited Barr Beacon or Barrow Hill before. Actually if I’m honest I’d never even heard of them until a few weeks ago when Graham Worton, Keeper of Geology at Dudley Museum Service, suggested they were important places to learn about the geology of the Black Country. As a non-geologist, I had no idea what to expect when Graham described them as old aggregate quarries – my first question was “What is an aggregate?”; not just some simple sand and gravel as I later found out.
But back to last week’s field trip…
Our first port of call was Barr Beacon, near Walsall. Travelling on the coach I was surprised how we suddenly turned off the typical busy Black Country road onto a narrow country lane – not the sort of surroundings conjured up by the name “Black Country”. Barr Beacon is actually in the middle of the countryside with amazing views across Walsall, Wednesbury and West Bromwich. We didn’t have long to admire the views as Graham led us down the hillside until we eventually found ourselves standing below a sheer sandstone cliff. Graham told us that the lower part of the cliff was made from red Permo-Triassic sandstone with pebble beds, topped by a mixture of glacial sand and gravels. The pebbles ranged in size from under a cm to fist size. These pebbles come in lots of colours – brown, red, cream, white, but they all had one thing in common…they were all round and smooth from weathering and erosion.
Graham explained that the sand’s colour and layering tells us that it formed somewhere hot. Graham then went on to tell us that when the rocks formed they weren’t where the Black Country is now, but near the equator. Slow movements of the Earth’s crust over geological time meant that it ended up here where we live today; which takes some thinking about! I did know that the Earth’s landmasses had moved around and the continents we know today didn’t exist in the past, but it’s one thing to read about it and another to be standing somewhere that was originally on the equator.
Next stop Barrow Hill, another place with amazing views; from the top you get a 360⁰ panorama of the Black Country. Again Graham led us off down the hill to an entrance that took us to the centre of the volcano – for that is what Barrow Hill is, an extinct volcano. The rocks here were completely different from Barr Beacon, not red but black, not soft and crumbly but hard with vertical fissures. The rocks at the centre of Barrow Hill were originally the molten core of the volcano which cooled and solidified over millennia. At the base of the quarry cliff we could see mounds of this rock which had been broken into sharp, angular fragments; quite different to the smooth stones of Barr Beacon.
Our final stop was underground inside Dudley’s Limestone Caverns to see yet another different type of rock; the cream coloured limestone which was mined here. We also found out about the renowned Victorian geologist, Sir Roderick Murchison who visited the area in the early 19th Century (you can find out more about Sir Roderick by watching the video blog on this website).
I hope I got all my geological facts correct but if I haven’t please leave a comments below.
If you want to find out more about the Black Country Aggregate sites please visit the Black Country Atlas online or for more information about local sites of geological interest visit the West Midlands Geodiversity Partnership website.
Wolverhampton Art Gallery