Saturday 16 January 2021

Geology in the Shire Brook Valley - I


An iron nodule in the Woodhouse Rock

The area around Hackenthorpe and Beighton is a part of Sheffield that I don’t know very well but, not that long after the A57 Mosborough Parkway opened here in 1988, I vividly recall the spectacular exposures of the Woodhouse Rock that could be seen in the road cuttings here.
 
An Ordnance Survey map showing Drakehouse Rocks

During my recent exploration of the Shire Brook Valley, having gleaned from fellow walkers that some rock exposures could still be seen, I decided to extend my walk by a couple of kilometres and went in search of them
 
Taking the underpass at the east end of the nature reserve, I followed the directions I was given to Moss Way and, having waited for what seemed like an age to cross this extremely busy road to the Crystal Peaks shopping centre, I followed the path and very soon arrived at an area called Drakehouse Rocks.
 
The Woodhouse Rock at Drakehouse Rocks

There is no sign of any quarries on old maps that I have access to and I am assuming that this is a cutting that was purposely made to provide a pedestrian link between Moss Way and Eckington Way, which were built at some time after 1950.
 
An ironstone nodule in the Woodhouse Rock

I stopped only long enough to take a few photographs of the Woodhouse Rock, but it is an excellent safe and easily accessible exposure for study and it has in fact already been used as a field trip location by the Sheffield Area Geology Trust (SAGT), with members of the Open University Geological Society.
 
A general view of the Woodhouse Rock

The massive, wedge-bedded and medium grained nature of the rock contrasts strongly with the laminated sandstone that I had seen earlier on my walk at Normanton Hill and this indicates deposition in a river channel rather than a crevasse splay deposit, which is formed when a river bursts its banks.
 
Thin basal beds of ironstone

As with very other sandstones from the Pennine Middle Coal Measures Formation, it has a high concentration of iron and this is apparent as lenses, nodules, thin basal beds of ironstone and as dense brown accumulations on joint planes.
 
A lens of ironstone in the Woodhouse Rock

Crossing Eckington Way, which is also very busy with traffic, I made my way up the public footpath and, instead of following this towards Beighton, I made my way to another path that runs round the edge of the field.
 
A view west along the A57

Looking back to the west along the line of the A57, the dip slope of the escarpment that I followed down Normanton Hill can be made out in Richmond Park to the right, with an angle of 9 degrees to the east-north-east. To the left, the high ground beyond which is Ridgeway Road – the ring road to the south-west of Sheffield – is formed by Parkgate Rock, which dips 5 degrees to the north-east. 
 
Carrying on in search of a place where I might get a view of the road cutting between the Eckington Way and Beighton roundabouts, I stopped to photograph the views of the Parkgate Rock on the skyline to the south-west and a panorama of the Mexborough Rock to the north-east, before finally arriving at a footbridge over the A57.
 
A panorama of the Mexborough Rock on the skyline

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