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| A detail of a coarse pebbly gritstone boulder on the roadside |
When I moved to Treeton in 1997, the view from St. Helen’s church to St. Mary’s church in Handsworth, set on higher ground to the west, was obscured by a vast pile of waste from the Orgreave opencast coal mine, which had replaced the Orgreave Colliery and Coking Works.
By 2010, the site had been regenerated and work was starting on the laying of the infrastructure for the planned Waverley Estate, so I decided to have walk around the area, starting at the site of the diverted River Rother, where the low water level revealed an exposure of shale and possibly the Haughton Marine Band.
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| A river bank exposure of shale on the River Rother |
Perhaps because it was intended to develop the site with very high density housing, no topsoil seems to have been used for the restoration which, although not good for growing plants, reveals a variety of Pennine Middle Coal Measures Formation (PMCMF) rocks – including fine sandstone, siltstone, mudstone and black shale – that have been weathered to varying degrees.
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| Various weathered rocks |
I had just started to use the black and white and red filter settings on my Canon EOS 400D camera and, with the typical April showers weather producing some spectacular skies, I went out a couple of days later to the Advanced Manufacturing Park (AMP), where I discovered several rough blocks of PMCMF rock forming the boundary of the TWI Technology Centre on Wallis Way.
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| Various weathered boulders |
Although I was no longer involved with any geological organisations that would appreciate the potential educational value of these various rocks, which demonstrate how sediments of different grain size and chemistry resist weathering processes – mirrored by the topography of the region – this made quite an impression on me.
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| Boulders of PMCMF rocks on Wallis Way |
On the very few occasions that I have since visited the Waverley Estate and the AMP, I have noticed various other large blocks of grey siltstone that exhibit various sedimentary structures, iron mineralisation and trace fossils, but I didn’t consider visiting it again until I read an article on the Sheffield Area Geology Trust (SAGT) website about various well preserved Carboniferous plant fossils that had been found in the red shale used for the footpaths on the estate.
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| An Article on the SAGT website |
The day after my exploration of Nether Edge and the Sheffield General Cemetery, I took advantage of a sunny December afternoon to go and take a look at the hard baked red shale, which is a product of the spontaneous combustion of fine coal dust associated with the oxidation of pyrite in colliery tips – as has occurred in the Treeton Colliery tip to the east of my house.
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| Various rocks collected from the Waverley Estate |
Having found a few pieces of fossiliferous shale amongst the handful of rocks that I collected using my Estwing hammer, I later talked with the finder of the plant fossils, who informed me that he had rummaged through piles of shale used for paths on the Waverley Estate several years ago and kindly gave some of them to me.
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| Various plant fossils from the Waverley Estate |
Whilst my search for fossils wasn’t that productive, I was interested to see that the foundations for the new back to back housing blocks were being dug into black shale and, in one place, I could see a very large piece of discarded coal beyond the heras fencing, which could easily grace the geology display in any of the museums that I know in South Yorkshire.
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| Black shale exposed by foundation works |
A couple of men were working on site within a short distance of this and, if I was still involved with these museums – who now just seem to expect their work to be done by volunteers – I would have given them a shout and slipped them a tenner for their trouble, to bring the lump of coal to me, with a very fair claim later made for ‘expenses’.
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| Glacial erratics used for landscaping |
The site is being rapidly developed, with much of the waste rock now being broken down by frost action, but I came across a children’s play area where several large boulders, which I presume to be glacial erratics, have been used for the landscaping.
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| Views of a migmatite boulder |
From a distance, I initially thought that they are granite but, when getting closer, I could see that that the rock has a distinct green tinge, with one of them containing quite large fragments of partially melted dark green metamorphosed rock.
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| A detail of a migmatite boulder |
I didn’t have my hand lens with me to closely examine the rocks, but they don’t look like a typical granite with well defined crystals or phenocrysts, with the dark green fragments forming xenoliths. I am not very familiar with high grade metamorphic rocks and I couldn't make a guess about its provenance, but it is probably a basic migmatite.
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| A block of siltstone |
Scattered around the estate, there are also a few blocks of grey siltstone, which display various sedimentary structure, including ripple marks and beds containing both carbonaceous material and concentrations of iron oxides/hydroxides – a characteristic of the softer beds in the PMCMF that is not generally seen in natural exposures, such as stream banks.
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| A detail of a block of siltstone |
Having spent less than 45 minutes wandering around the estate, I had already encountered several interesting geological specimens that, together with those that I had previously seen at the AMP, would make an interesting half day field trip. I finished my brief exploration of the Waverley Estate at Highfield Lane, where lumps of a very coarse pebbly gritstone from the Millstone Grit Group, laid out on the roadside, were glowing in the late afternoon sunshine.
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| A lump of gritstone on the roadside at Highfield Lane |
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