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| Weathered mudstone on Wallis Way |
My trip to Bowden Housestead Wood wasn’t very productive and, although I got to see Parkway Man and a few more houses built out of the locally distinctive ‘ginger nut’ hued sandstone, I didn’t improve my knowledge of the local geology.
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| An old brick wall on Waverley Lane |
Continuing from Waverley Cottages along Waverley Lane to the Advanced Manufacturing Park (AMP), I came across the remains of a brick wall that I presume is a relic from the old drift or the tramway running from Handsworth Colliery to the High Hazels Colliery No.1 and No.2 pits and coke ovens, which appear on the 1949 map but have long since vanished.
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| Graffiti on the railway bridge at Waverley Lane |
Briefly stopping to take a few photographs of the very colourful graffiti on the railway bridge, which brightens up an otherwise bleak area, I arrived at the southern edge of the AMP, which has been built on the site of these collieries – as with the adjoining Waverley Estate.
Scattered around both the AMP and Waverley Estate, large blocks of stone have been strategically placed on boundaries and at entrances to as yet undeveloped land, presumably to prevent access by travellers, and a long line of these can be found here.
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| A view towards the Advanced Manufacturing Park |
Although these blocks are no longer in situ, these provide a good introduction to the clastic lithologies – sandstone, siltstone and mudstone – that along with coal seams make up the bulk of the Pennine Coal Measures Group.
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| Siltstone with ripple marks |
Most of the blocks comprise grey laminated siltstone, with thin beds and flattened nodules of siderite and, in places, very fine layers of carbonaceous material and various bioturbation structures can be seen.
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| Siltstone with a thin bed of siderite |
The siltstones grade imperceptibly into both dark grey mudstone and buff coloured sandstone, with the latter being mostly fine grained and quartzofeldspathic, and their relative resistance to weathering can be observed here.
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| Siltstone with carbonaceous layers |
Various sedimentary structures and bedforms, which provide a subject for specialist study in their own right, provide clues to the depositional environments that existed during the Upper Carboniferous Period in the north of England.
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| Siltstone with bioturbation |
Individually, most of the blocks seen at the AMP show a limited range of features but, viewed collectively and put into context with field trips such as I have led before in Sheffield, they have good educational value.
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| A sample of carbonaceous siltstone |
Having had a good look at these rocks on the edge of the AMP, I came across further large blocks that contain various other interesting features on Whittle Way. The Coal Measures rocks typically contain large amounts of iron, which frequently appears as Liesegang rings in sandstones, dense accumulations of brown oxides on joint planes and concentrated along bedding planes.
One of the large blocks provides an example of this iron being in both the ferrous and ferric oxidation states. Here, the grey heart of the block is formed in reducing conditions but when exposed to an oxidising environment, as occurs during weathering at or near to the surface, a light brown rim is formed.
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| Siltstone with iron in different oxidation states |
Approaching Morrisons supermarket along Highfield Spring, I took a quick diversion up Wallis Way, where various other large blocks form the border to the premises of the TWI Technology Centre. I had come across these a few years ago and was stuck by the way that the siltstone has proved quite durable, but that the mudstone had deteriorated considerably.
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| Blocks of siltstone and mudstone on Wallis Way |
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