Saturday, 16 March 2019

Further Surveys of the Greenmoor Rock

Spheroidal weathering and Liesegang rings at Heeley Retail Park

During my brief exploration of Totley, I discovered an escarpment of the Greenmoor Rock that I had never seen before. Although I didn’t see any rock exposures, and had to rely on the vernacular buildings to give me an idea of its physical characteristics here, it provided further insight into its importance - in contributing to the landscape and economy of Sheffield. 

The outcrop of the Greenmoor Rock between Norton and Brincliffe Edge

Having encountered the Greenmoor Rock many times when exploring Sheffield in the last couple of years, I thought that it might be possible to base a future field trip with the Sheffield U3A Geology Group on the sites that I had visited. 

Sites visited to examine the Greenmoor Rock

When visiting the church of St. James the Great in Norton, roughly following the route of the Sheffield Round Walk, I walked through Graves Park a couple of times and was interested to see that several spring fed streams converge here, before flowing down through Cobnar Wood. At the end of October 2018, I decided to go and take a closer look. 

Entering Cobnar Wood in Graves Park

Knowing already that the nearby Morrisons supermarket in Meadowhead occupies an old quarry, with accessible rock faces, I was interested to see how much rock was exposed and if it had potential as a field trip location. 

Mudstone exposed along the stream bank in Cobnar Wood

The strata between the Grenoside Sandstone and the Greenmoor Rock are composed of mudstone and siltstone, which the various streams in Graves Park essentially follow; however, after converging, a single brook runs down through a spectacular steep sided V-shaped valley that has been cut into the similar softer rocks beneath the Greenmoor Rock. 

A detail of mudstone

Although extensive rocky exposures of flaggy sandstone are rare, in many places where the banks of the brook have not been lined with stone walls, it is possible to see outcrops of the finely bedded mudstone and siltstone. 

A general view of Cobnar Wood

Leaving Graves Park at the Cobnar Road entrance, the brook disappears beneath a built up area before reappearing 150 metres further down the road, to the west of the steeply falling ground at the rear of the Big Tree public house.

An ouutcrop of flaggy sandstone in Cobnar Wood

I had previously walked down the A61 through Woodseats down to the Homebase/Dunelm site, which sits in another large old quarry – exploited for making bricks - where there are good exposures of the Greenmoor Rock and underlying strata, so I decided to try and follow the course of the brook down to the River Sheaf and see what I might find. 

A walk into Sheffield from Graves Park

Discovering that the brook largely flowed through underground culverts, I quickly made my way down to Abbeydale Road and headed back to Sheffield, but not before coming across the site of an old quarry that I had passed by many times in a car or on the bus. 

An old quarry face on Marden Road

Occupied by a petrol station as long as I had known it, and now the site of a car wash, the old quarry faces visible from Abbeydale Road are covered by concrete blocks that form a retaining wall. Turning into Marden Road, however, an extensive exposure of flaggy sandstone can clearly be seen, which I later discovered was another exposure of Greenmoor Rock. 

A detail of the quarry face on Marden Road

From here, a walk up and along the escarpment formed by Brincliffe Edge connects with several locations where the Greenmoor Rock is exposed in old quarries, which once supplied vast amounts of the local variety known as Brincliffe Blue, for general building, kerbs and setts and for high quality memorials. 

Greenmoor Rock at Quarry Lane on Brincliffe Edge

With my walk from Graves Park to Marden Road revealing two good sites for a potential field trip, my exploration of the Greenmoor Rock in Sheffield in 2018 finally came to an end in the week before Christmas, when I unexpectedly discovered another old quarry that is now occupied by the Heeley Retail Park – which I visited to buy a new DVD player in time for the holiday. 

An old quarry face at Heeley Retail Park

In the car park, in addition to exposures of flaggy sandstone there is an excellent example of spheroidal weathering and Liesegang rings, with an angular spur of sandstone being rounded off by the delamination of sheets of sandstone parallel to its exposed surfaces. 

An exposure of Greenmoor Rock at Heeley Retail Park

Also, at the junction of beds of sandstone with underlying mudstone, an artificial spring line has developed, where permeable and impermeable rocks meet. It makes a good stopping point between the exposures at Homebase/Dunelm and Marden Road and, with a short diversion along the way, to Meersbrook Park, a natural spring can be seen too.

A stream fed by a spring in Meersbrook Park

Tuesday, 12 March 2019

Historic Stone Architecture in Totley

A view of the interior of All Saints church in Totley

In December, the Sheffield U3A Geology Group have a social event held at one of the members’ houses, instead of a field trip, and this year this was held in Totley – a place that I driven through several times on my way to the Peak District National Park, but had never explored on foot. 

A geological map of Totley

Planning my journey so that I would arrive nearly an hour before the allotted meeting time, I had a quick walk around the Conservation Area in the village to look at the various Grade II listed buildings that can be found here, and which are mainly built out of the local sandstone – the Greenmoor Rock

Greenmoor Rock used as walling for terraced cottages along the A621

I had encountered this rock formation several times before in Sheffield - at Brincliffe Edge, the Upper Don Valley and during visits to Norton and Chancet Wood – and further afield at Green Moor, the type locality, and at Castle Hill near Huddersfield. It forms a distinct escarpment wherever it outcrops and, at Totley, this is found in the part of the village to the north side of the A621, where the land falls sharply to Totley Brook

Greenmoor Rock used as a walling stone for a cottage on Totley Hall Lane

On the main road, several cottages are built with roughly squared and coursed blocks of Greenmoor Rock that are generally thinly bedded. A large proportion are stained brown/red due to the high iron content – as I previously noted in former agricultural buildings near to Beauchief Abbey, which is overlooked by the Greenmoor Rock escarpment. 

A late Victorian commercial building on the corner of the A61 and Totley Hall Lane

For the quoins, Greenmoor Rock is also often used for the older vernacular housing, but with more massive sandstone of unknown provenance used for the lintels, cills and jambs and as a general building stone in late Victorian buildings that are found in the Conservation Area. 

A late Victorian house on Totley Hall Lane

On Norton Hall Lane, the Grade II listed old School House, dated 1827, and the Totley Hall Farmhouse and outbuildings – as well as the older cottages – are also built out of the Greenmoor Rock, but the whereabouts of the quarry source for the village is not known. 

The old School House

Carrying on down the hill, following the dip slope of the Greenmoor Rock, Totley Hall – dated 1623 - is set back from the Totley Hall Lane on higher ground, but it can be seen that the general walling here is also iron stained Greenmoor Rock, with more massive sandstone used for the quoins and large lintels, cills, transoms and mullions in the windows of a typical Jacobean style. 

A general view of Totley Hall

Having quickly seen the building of architectural merit in the southern part of the Conservation Area, I walked back up Totley Hall Lane and then went to have a look at All Saints church - dated 1923 and designed in a Neo-Norman style - which had caught my eye when looking on Google Earth before my trip. 

A view of  All Saints church from the north-west

Walking very quickly around its exterior, it is unusual for its modern style of rubble walling, with hand tooled ashlar dressings and, although I didn’t have the time to closely examine the stone, it is very different to that seen in the vernacular architecture of Totley – particularly the very distinct red colouration of very many of the stones. . 

A view of All Saints church from the north-east

Unexpectedly, the church was open and the abundance of round arches in its interior continues the Neo-Norman theme, although the piers and columns are square in profile and not round, as seen in the original Romanesque churches. 

A view of the nave in All Saints church

A very quick exploration of the Conversation Area to the north of the A621, revealed only the modest Grade II listed Bryn and Moor Cottages, which was originally a single house built in 1704 with an L shaped plan and again using the local Greenmoor Rock.

A general view of Bryn and Moor Cottages

Sunday, 10 March 2019

St. James the Great Revisited

A view of the nave at the church of St. James the Great

After the Sheffield U3A Geology Group visit to the Porter Valley, on 21st November, I thought that the extended period of exploration that I had enjoyed since the Heritage Open Days at St. Helen’s church in Treeton would at last come to end. 

The lopsided Early English Gothic tower arch

With the record breaking summer of 2018 having turned into an Indian summer, I had more than made up for a year of relative inactivity compared to my investigation of mediaeval churches in and around South Yorkshire, back in 2016. 

A view of the arcades from the north aisle

My next day out coincided with a coffee morning at the church of St. James the Great in Norton. I had visited this church twice before, once when it was closed and I was only able to survey its exterior and a year later to see its interior, which coincided with one of the Farmers' Markets that are regularly held here. 

The chancel

On this occasion I had the opportunity to look a bit more closely at the various details, especially in the Blythe Chapel, where Magnesian Limestone has been used as general walling stone for its external fabric and dressings in its interior – particularly for the piscina

The piscina is carved from dolomitic limestone

Here, I was also able to take a better look at the details of the alabaster tomb to William and Saffrey Blythe and to the finely inscribed grave slabs that can be seen on its floor, including the memorial to William Selioke and his wife Joyce. 

The memorial to William Selioke and his wife

Without closely investigating the various stones with tools that I normally use when employed as a professional geologist – hydrochloric acid, a steel knife and a hand lens – I could only make an educated guess as to their provenance. 

A detail of the tomb of William and Saffrey Blythe

In hindsight, I have discovered that many Norman fonts that I have seen, and which I had assumed to be made of Magnesian Limestone, are actually made from Caen stone – a soft, easily carved Jurassic limestone from Normandy, which was imported in vast amounts to build cathedrals and abbeys after the Norman Conquest in 1066. 

A detail of the font

The font dates to c.1190 and judging by its pale colour, which contrasts with the yellowish Magnesian Limestone used in the walling of the chancel, this could easily be made of Caen stone and I will investigate further on my next visit.

A detail of the salamander on the font

Tuesday, 5 March 2019

A Return to the Porter Valley

Peter Kennett with a geological map of the Porter Valley

At the beginning of spring 2017, as part of my exploration of the Sheffield Round Walk, I planned to walk from Ringinglow down the Porter Valley into Endcliffe Park, stopping off at various points of interest highlighted in the leaflet – The Geology of the Porter Valley

Due to problems with the bus service, which resulted in me having to walk from Whirlow up to Ringinglow via the Limb Valley, beforehand, I didn’t have the time or inclination to stick to my plans; however, I got another chance to look more closely at the Porter Valley, when Peter Kennett himself led the Sheffield U3A Geology Group there on the last field trip of 2018.

A discussion of Carboniferous flora and fauna

Meeting up on a cold November morning, more than 20 of us convened at Forge Dam, where we were given an introduction to the geology of area, using various maps, 3D models, photographs and maps that Peter had accumulated when teaching geology at the nearby High Storrs school. 

The group stops to look at a monocline in the river bank

We then followed the meandering Porter Brook downstream to a point where the sandstone in the Rough Rock has been folded into a monocline that can be seen in the river bank, before walking further along the brook to another exposure of the Rough Rock, where large scale cross bedding is evident in the river bank. 

An example of large scale cross bedding in the river bank

Like Ecclesall Woods and other locations on the Sheffield Round Walk, none of the rock exposures were very spectacular, but the various dams, goits, weirs and iron stained tributary springs and streams record some of Sheffield's industrial history, which was very dependent on the geology and geomorphology. 

A fossil mould of a Lepidodendron root

Walking further downstream, we stopped to look at a small exposure of the Rough Rock which contained fossil moulds of the roots of a primitive tree from the Carboniferous PeriodLepidodendron

An exposure of Rough Rock at Porter Bridge

Continuing past Porter Bridge, more flaggy sandstone in the Rough Rock could be seen in the bank where branches of the Porter Brook merge here and, less than 100m from this point, the boundary between the Millstone Grit and the Lower Coal Measures has been determined. 

A river bank exposure of the Pot Clay and associated strata

The Rough Rock is succeeded by the Pot Clay, which is described in detail on page 36 of the Geology of the Country Around Sheffield memoir (1957) but, at the time of our visit, the water level was far too high for us to see the various strata mentioned. 

An electric transformer on Highcliffe Road

From here we walked back to Porter Bridge before walking up Highcliffe Road on the south side of the Porter Valley, where we encountered an old electric transformer, before being told about the various shallow coal workings that are found around here - including drift mines and bell pits

An explanation of the mining of coal with a bell pit

After what proved to be a very short day out, compared to the last field trip that I had undertaken with the Sheffield U3A Geology Group, we then made our way back down to Forge Dam – making various observations and comments on points of interest that we all saw on the way.

Modern sculpture

Sunday, 24 February 2019

Manor Top to Manor Lodge – Part 2

A memorial at City Road Cemetery in Sheffield

During the first part of my walk from Manor Top to Manor Lodge, I encountered various sculptures by Tom Clark, Thomas Kenrick and Ben Leach, which had been commissioned by Sheffield City Council in 2009 – as part of the City Road Project. 

Sculptures outside the Gatehouse at Sheffield City Road Cemetery

Walking down from the entrance to Manor Fields Park, there are two more large sculptures in this series – again carved in Crosland Hill sandstone – which flank the entrance to the City Road Cemetery, which has an impressive Grade II listed gatehouse.

Carrara marble and Hopton Wood stone

I had briefly visited the cemetery a couple of times before but I had never been inside the Halls of Remembrance, where I was interested to see that that the niches used to inter the ashes contain inscriptions that are carved into panels of grey veined variety of Carrara marble - known in England as ‘Sicilian’ - and Hopton Wood stone

Various stones used for monuments in City Road Cemetery

Walking up past the crematorium, there are numerous large monuments with obelisksurns, crosses and statues made in various granites and white Carrara marble, which were very popular during the Victorian period, and these provide an opportunity for students at all levels to study the mineralogical and physical characteristics of a wide range of stones. 

The Cross of Sacrifice in City Road Cemetery

Exploring the cemetery further, I came across a war memorial c.1920 designed by Sir Reginald Bromfield. The Commonwealth War Graves Commission style Cross of Sacrifice, together with its accompanying inscribed all, is made out of Portland stone and this monument is protected with Grade II listed status. 

The Belgian war memorial in City Road Cemetery

Making my way quickly to the north entrance, I paused to look at the dilapidated Roman Catholic Mortuary Chapel, which was at last being repaired, and there I noticed another war memorial c.1920 in the form of a calvary – this time in memory of soldiers of the Belgian Army and of the refugees who died in Sheffield during the Great War.

A detail of the calvary at the Belgian war memorial

Arriving at Manor Lodge, I had hoped to take another look around this interesting Tudor ruin – which is situated on high ground formed by sandstone of the Pennine Lower Coal Measures Formation but, I found it closed.

A view of  Manor Lodge from Manor Lane

Making my way down Manor Lane to the Manor Oaks Studios, where I briefly talked to a few of the artists, I carried on to the low ground upon which the Sheffield Parkway has been built, before catching the tram back to Sheffield city centre at Cricket Inn Road. 

A view to the east from Manor Lane in Sheffield