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| Rough Rock on the River Don at Oughtibridge |
After spending a day looking around Worrall, investigating the geology of Hagg Stones and photographing historic architecture in Oughtbridge, I finished off my day by taking a walk along the bank of the River Don, from Oughtibridge to Birley Wood.
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| The River Don at Oughtibridge |
Taking the footpath from Station Road, which follows the Upper Don Trail on the east bank of the River Don, I continued past the cricket ground until I reached an old weir. The 1894 Ordnance Survey map marked this as being connected to a large goit that ran south-east for about 600 metres to the former Middlewood Rolling Mills, which has since been filled in.
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| A weir on the River Don at Oughtibridge |
Continuing south along the river bank for a short distance, I was very interested to discover a few small outcrops of a thinly bedded flaggy sandstone, approximately 2 metres thick, which contained some irregular massive beds.
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| An exposure of the Rough Rock |
The sample of fine/medium grained sandstone that I took with my Estwing hammer is light brown/grey in colour, with iron banding and sporadic flakes of muscovite mica. As such, it looks no different to several other samples of sandstone that I have obtained from various strata in the Pennine Lower Coal Measures Formation.
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| Samples of Rough Rock |
Neither the British Geological Survey online 1:50,000 map or GeoIndex Onshore map viewer enable me to pinpoint the rock formation in question, but given that the outcrop is on the edge of the floodplain of the River Don, it looks likely that this belongs to the Rough Rock and not the Crawshaw Sandstone.
On the opposite west bank, I was rather intrigued to see a section of retaining wall along the water’s edge, where thick ochreous deposits appear to be flowing from the river embankment. In my experience, these are usually associated with the bacterial breakdown of pyrite in exposed river bank coal seams or the flow of such deposits from shallow coal mines along adits into rivers and streams or rivers.
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| Ochreous deposits along the bank of the River Don |
Although no coal seams are specifically marked on the geological map, the Pot Clay Coal seam does sometimes occur in the region between the Rough Rock and the Subcrenatum (Pot Coal) Marine Band. I could only see from a distance on the wast bank of the river but, at the same level as the ochreous deposits, black deposits that look suspiciously like coal can be seen falling from large voids in the retaining wall.
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| A possible exposure of the Pot Clay Coal |
Continuing downstream, the retaining wall disappears and, where the bank has been eroded, a thick deposit of water worn boulders are exposed, which presumably records a previous position of the main river channel.
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| A riverbank deposit of water worn boulders |
Whilst the potential identification of the Pot Clay Coal seam was quite speculative, the underlying Rough Rock is exposed in the streambed and the west river bank a little further downstream. Unlike the coarse pebbly varieties seen in West Yorkshire, the Rough Rock found in the Sheffield district is mainly a flaggy variety – as I had seen in Whinfell Quarry Garden and along Limb Brook.
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| A riverbank exposure of the Rough Rock |
Carrying on further downstream, I got talking to a fisherman who was interested in my Estwing hammer. Although I can’t ever recall seeing him in the village, he told me that he also lived in Treeton and often came up to this to part of Sheffield to fish for grayling, which he would keep in rock pools that he made with a circle of boulders.
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| The riverbed of the River Don |
Having had a good day out, I finished my day by walking down the river into Beeley Wood, where various ganister quarries and mines once operated, which would supply the Oughtibridge Silica Firebrick Company, and then past the remains of a dismantled weir.
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| Part of a dismantled weir |
I eventually found the footbridge over the River Don at Abbey Forge Products, which would take me to the Middlewood Road. From here, I went photograph the gate piers to Middlewood Hall and a milepost for the British Listed Buildings website, before walking back down to the Middlewood Park and Ride – to catch a tram back to Sheffield.
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| A view north along the River Don |
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