A Geological Recce at Creswell Crags

 

Various cave entrances at the west end of Creswell Crags

 

After gathering enough information and taking enough photographs to illustrate A Geology Lesson at Waverley, for the Wave magazine, I quickly wrote my short article and spent the rest of March preparing for my “Let’s talk about the stones” walk at Boston Park and Moorgate Cemetery. 

 

A view from the east end of the lake

 

With this being successfully completed on the first weekend of April, the onset of a typical April showers weather pattern restricted my outdoor activities – except for another brief trip to Waverley with my next door neighbour Dan - and my next day out was to Creswell Crags, to provide geological input on a recce by Dave for the next Sheffield U3A Geology Group field trip. 

 

The Anston Stones Wood Geological Trail

 

I had visited Creswell Crags back in 2015, to meet the manager and to discuss the possibility of writing a guide to the geology of the gorge, along with my friend Mike who had co-written the Anston Stones Wood Geological Trail. We were given a free tour of the Church Hole Cave, where the rock art can be seen, which lasted just over half an hour but, except for the ibis, I thought that most of what was shown to us by the guide looked like natural features of the dolomitic limestone. 

 

The ibis

 

When this was proposed for the field trip itinerary, I emphasised the need to combine this with other sites in the area, such as Pleasley Vale and Robin Hood’s Cave but, very soon after meeting a member of staff at the visitor centre, it became obvious that Dave intended the group to spend the whole day there. At this point, I decided that I would show Dave the features that I thought were of interest, while we walked around the lake, but I would not be joining the group on the field trip. 

 

A view along the south side of the lake at Creswell Crags

 

Leaving the visitor centre and stopping at the east end of the lake, we stopped to look at the very distinctive buttress like features that are formed on its southern side. The gorge, which is cut into the upper Sprotbrough Member of the Cadeby Formation, is traversed by inclined joints that divide the buttress like features and in many places have been widened into caves. 

 

Undercutting at the base of the limestone outcrop

The geological memoir describes the crags as comprising about 18 metres of hard massive limestone that is crystalline and granular and contains many stylolites. Although the memoir does not mention it here, the lowest 2 metres are composed of pseudobreccia, which has resulted in undercutting and the entrances to some of the caves coincide with these beds. 

 

A view along the south side of Creswell Crags

 

There is well pronounced large scale cross-bedding at the east end, especially in the lower part of the crags, which the group has previously encountered during field trips to the Don Gorge, Warmsworth and Clowne. Cavities of various sizes are also very common, but I did not see many that are in the form of crystal lined vughs. 

 

Iron staining on a rock face

 

When first visiting Creswell Crags, in one of the rock faces that are set back from the lake, I vividly remember the iron staining that covers part of the joint plane and has been presumably washed down from a bed of red marl that occurs within the Sprotbrough Member or from the overlying Edlington Formation. 

 

A buttress like feature on the south side

 

In Braithwell, Stainton and Micklebring on the Doncaster/Rotherham border, a red ochre known as ruddle/raddle was mined from the Cadeby Formation that, amongst other uses, was used by farmers to mark their sheep. I know next to nothing about cave art, but the Cave of Altamira in Spain came to mind, where similar ochreous compounds were presumably used and I have wondered if the inhabitants of the caves at Creswell Crags ever thought about making use of this. 

 

A view of the north side of Creswell Crags

 

The caves at Creswell Crags have long since had their internationally significant Quaternary sediments and fossils removed and, with all of the 9 major caves gated and inaccessible - except Church Hole and Robin Hood for tours - and much of the rock faces thickly overgrown, the geological features aren’t that easy to see. 

 

A small cave with a sand filled fissure

 

Looking closely, in places it is possible to see that some of the fissures are filled with sandy deposits, which very often contain Quaternary mammal fossils. Also, in one place on the north side of the lake, I noted solution hollows, which I seen once before in the Magnesian Limestone at Warmsworth Park, when undertaking a survey for the Doncaster Geodiversity Assessment. 

 

Solution hollows

 

As at Anston Stones Wood and other gorges in the Magnesian Limestone escarpment, Creswell Crags is believed to have been formed by glacial meltwater flowing from an ice sheet to the west. When returning to the car park and looking across the field to the tip of waste material from the Steetley dolomite quarry, I noticed that the soil was full of quartzite and sandstone pebbles, which are remnants of much more extensive glaciofluvial deposits that once covered much of the Magnesian Limestone.

A few across a field strewn with glaciofluvial pebbles

A Geology Lesson at Waverley

 

Various rocks collected from the Waverley Estate (21mm coin)

Since living in Treeton, following the full remediation of the former Orgreave opencast coal mine in 2011, I have seen the Advanced Manufacturing Park and the Waverley Estate develop at a great pace and, on occasion, I have wandered around these sites to find various Coal Measures rocks that have differentially weathered – according to their physical and chemical composition. 

 

Bioturbated siltstone

 

After my last visit in December 2021, when I encountered further examples of these – as well as glacial erratics composed of basic migmatite in the play area and pebbly Millstone Grit to decorate the streets - I posted my photos on Facebook and had responses to say that these various rocks could be used as the basis of a simple lesson in geology. 

 

A basic migmatite glacial erratic

 

Knowing that Waverley Junior Academy had opened quite recently, I made a call to the editor of the Wave community magazine, who told me that his children attended this school and was very interested in my ideas; however, I didn’t get round to doing anything about this at the time but, after the Sheffield U3A Geology Group March 2023 field trip to look at the urban geology of Sheffield, I phoned the editor again and was surprised to learn he was still interested in a short article being written for the magazine.

 

A geological map showing the Orgreave opencast coal mine © BGS

The Orgreave opencast coal mine exposed the Pennine Middle Coal Measures Formation strata between the High Hazles Coal and the Aegiranum (Mansfield) Marine Band which, although containing a few thin minor sandstones, comprised mainly mudstone and grey siltstone with other coal seams and black shales. 

 

A section of the geology exposed in the Orgreave opencast coal mine © BGS

 

In the 12 years since the deep open pit had been refilled using the vast pile of waste, which prevented St. Mary’s church in Handsworth being seen from St. Helen’s church in Treeton, the lumps of mudstone and shale that were quite common in the landscaping have now mostly weathered to small fragments, but these and small pieces of coal can still be found. 

 

Blocks of grey siltstone

 

The large blocks of grey siltstone that were retained, however, have been used to block vehicular access to the site and have been moved around as the development has progressed. In these, carbonaceous and iron rich beds and rippled surfaces with bioturbation are often seen, which all provide interest to the geologist and, as I discovered when popping briefly into the school, the teacher that I met also seemed to be very interested. 

 

A band of clay ironstone nodules in a block of grey siltstone

In one of the blocks at the corner of Rivelin Way and Derwent Chase, a well developed bed of clay ironstone nodules is clearly visible and, one side of the block, the siltstone has crumbled away to reveal well preserved plant stems – a type of fossil that that I had never encountered before and which I think is well worth seeing. 

 

Fossil plant stems in a block of grey siltstone

 

Continuing my walk around to Cherry Wood Way, the developer that was now building on the land to the west of the River Rother had obviously been redistributing the landscaped rock waste, to accommodate their housing scheme, and I went to investigate a part of this that was easily accessible from the roadside. 

 

A view from Cherry Wood Way

 

In addition to a few ironstone nodules that had weathered out of the siltstone, I was very surprised to encounter a large number of pebbles of various sizes and composition that are very similar to those that I collected a couple of years earlier, when walking from South Anston to Kiveton Park and then from Todwick to Wales. 

 

An ironstone nodule

 

On that occasion, I had been crossing a small area that had been marked as Quaternary till on the geological map, even though it only consists of a scattering of various pebbles on the surface of the ploughed fields, which surround the public footpath that I was following. 

 

Pebbles of sandstone and quartzite

 

Along with glaciofluvial pebbles, which often include white vein quartz and purple quartzite, these are more commonly found on higher ground on interstream areas on the Magnesian Limestone and are not common on the Coal Measures, where the mudstones have been more easily eroded. 

 

A gritstone pebble

 

In this part of Rotherham, the geological memoir records that grave diggers in Moorgate Cemetery encountered 3 metres of greyish-brown mottled clay with rounded pieces of quartzite and blocks of sandstone and a much larger expanse occurs either side of the Bawtry Road in Brinsworth. 

 

Outcrops of glacial till in the vicinity of Waverley

 

It is therefore conceivable that such sporadic deposits existed on the land that has been mined away, only to turn up again on the surface in a very random way, as part of the subsequent redistribution of the landscaped heap of coal waste. 

 

A block of conglomerate

 

Having found numerous pebbles that I thought must have a glaciofluvial origin, I was even more surprised to discover a large piece of what looks like a conglomerate, which appeared amongst large lumps of concrete, a pile of limestone aggregate and blocks of grey siltstone. 

 

Views of the conglomerate from the top and side

 

Composed of an unsorted mass of imbricated subangular to subrounded clasts of sandstone, it reminded me very much of a similar cemented glaciofluvial deposit at Constitution Hill (grid reference SK 51713 99601), north of the River Don at Conisbrough railway station, which I had highlighted in the Doncaster Geodiversity Assessment (pp.55-60) and was one of the key sites for a proposed field trip with the Sheffield U3A Geology Group. 

 

A Geology Lesson at Waverley

 

Now having plenty of varied specimens of rock from Waverley, with numerous photographs of the large blocks of rock that I had encountered, I returned home and immediately set about writing a short article for the April/May 2023 issue of the magazine.

 

The front cover of the April/May 2023 issue of Wave

An Urban Geology Field Trip in Sheffield

 

Applying an acid test to volcanic green slate in the Peace Gardens

 

My brief stop on Ecclesall Road, when on the way to finalise the Sheffield U3A Geology Group field trip itinerary for 2023, added to my knowledge of the use of the Brincliffe Edge/Greenmoor Rock – as seen in the late Victorian and Edwardian terraced houses - and I was interested to see the relief sculptures by Richard Watts at the Church of St. William of York. 

 

The Building Stones of Sheffield - Part 1 by Peter Kennett

Two weeks later, my next day out was to lead the group around Sheffield City Centre to look at its building stones – a field trip that other members of the group had organised going back to 2009, which was presumably based on the Building Stones of Sheffield written by Peter Kennett back in 1999. As a member of the Sheffield Building Stones Group, Peter had consulted me about this and I walked around Sheffield with him to add my comments - particularly the cleaning of the terracotta and polished  granite at the former Laura Ashley building with strong hydrofluoric acid.

 

The Building Stones of Sheffield - Part 2 by Peter Kennett

As a geologist with specialist stone identification and matching skills, which I first learned as a building restoration contractor in London, I had previously written several articles about the Heart of the City developments in Sheffield for Natural Stone Specialist magazine, which continued with the Stone Plus and Stein stone trade magazines in Germany. 

 

Articles for various stone trade journals

In February 2018, I was asked to lead a walk to look at the building stones of Sheffield and my extensive preparation for this is recorded in a series of four Language of Stone Blog posts – starting with The Building Stones of Sheffield – Part 1. 

 

A planter in Tudor Square

 

Our walks typically start at 10:30 a.m. and finish at 3:30 p.m. and Peter Kennet’s leaflet is completely inadequate for this, but I had no problem devising a walk that would include newer developments such as Tudor Square, The Moor and Sheaf Square, where we started our day – as well as a good look at the interiors of Sheffield Central Library, the Town Hall and City Hall, where a wide variety of decorative stones from the UK and Europe have been used. 

 

Kilkenny limestone seating on the Moor

 

Since my first walk around Sheffield city centre with the Sheffield U3A Geology Group, whilst investigating the Sheffield Board Schools, I had travelled all around Sheffield and, when photographing very many historic buildings for the British Listed Buildings Photo Challenge, I encountered very many buildings in the Sheffield City Centre Conservation Area that were designed by Sheffield’s leading Victorian architects. 

 

A detail of stone carving by Frank Tory on Carmel House

 

Very many of these made great use of the eminent sculptor Frank Tory, whose work can be seen at Carmel House on Fargate, Parade Chambers on High Street and on the gateposts at the south-east corner of the old churchyard at Sheffield Cathedral. Again, another series of my Language of Stone Blog posts, starting with Historic Architecture in Sheffield – Part 1, records the observations of these buildings that I had made the year before. 

 

Historic architecture in Sheffield city centre.

 

I like to get the group members to look up to see these wonderful examples of architectural sculpture, rather than stop at every bank building to examine granites and other igneous rocks from Scotland and Scandinavia, such as larvikite and Rapakivi granite, which were widely used by Victorian and Edwardian architects and can be seen in most cities and towns throughout the UK. 

 

Pound's Park just before its completion

 

One of the newer members of our group, Andrew, had made the seating for the Peace Gardens and had worked as a part time Public Arts Officer for Sheffield City Council. He worked with their design team and was able to give us an insight into this and other developments at Pound’s Park and Charter Square – where he selected the enormous pieces of Crosland Hill sandstone and supervised their installation. 

 

A view of Charter Square

 

As usual, when leading ‘urban geology’ walks such as this, I don’t get much time to stand back and take photographs as I would normally do on other trips, so I rely on other members of the group to do this and Paul and John H supplied most of the photos that I used for the report, which records the events of the day. 

 

The report on the field trip

 

The Church of St. William of York

 

Clothed in Glory

When having a quick walk up Ecclesall Road, to look at the Brincliffe Edge/Greenmoor Rock used for some of the late Victorian and Edwardian terraced houses, I was surprised to come across three relief sculptures on the west front of the Roman Catholic Church of St. William of York - a modern church that I had not taken much notice of before. 

 

The Chucrh of St. William of York

 

As a photographer that had been once commissioned by the Royal Commission on the Historical Monuments of England (RCHME) to photograph as many examples of post-war architectural sculpture that I could find – at £10 per 7” x 5” black and white print supplied - I am sure that I would have noticed these, when making occasional use of the supermarket that stands on the site of the John Gregory brickworks. 

 

Relief sculptures by Richard Watts

I only had a few minutes before I had to catch the next bus to join Paul and Dave of the Sheffield U3A Geology Group, to finalise our field trip itinerary for 2023, so I didn’t get a chance to have a good look at the stonework. I wasn’t familiar with the reddened sandstone for the dressings and walling stone and I just took a few record photographs.

 

Saved From the Deep

 

When I got home and undertook some research on this, I was interested to discover that the sculptor was Richard Watts, who worked as a landscape architect at Sheffield City Council. Along with his colleagues Ric Bingham and Zac Tudor, he had been very helpful when I wrote several articles about the Peace Gardens, Sheaf Square, Tudor Square and other Heart of the City developments for Natural Stone Specialist and the Stein and Stone Plus magazines in Germany. 

 

Various articles describing Heart of the City developments in Sheffield

 

After he had left Sheffield City Council, I encountered Richard during an event organised at the Millennium Gallery in Sheffield, where he was working on a small piece but I never realised that he had been working as a sculptor and letter cutter alongside his job as a landscape architect. 

 

Washed and Healed

 

Looking at his website, I was interested to discover that he learned his craft from his father, who was influenced by the work of Eric Gill. This came to mind when I first saw the relief sculptures - Washed and Healed, Saved From the Deep and Clothed in Glory. As a geologist with specialist skills in stone matching, I also noted that these sculptures are made from Woodkirk stone, which is still quarried from the Thornhill Rock in Morley.

 

Sessile Oak by Richard Watts

 

Although not related to the church, while looking at his website I noted that he had also carved Sessile Oak, a sculpture that I had been very impressed with when visiting Bowden Housteads Wood a couple of years earlier. 

 

A statue of St. William

 

On the north elevation of the church is a statue of St. William, which is not by Richard Watts but was retained from the original chapel of ease - built on the site in 1904 by the architects C and C.M.E. Hadfield, who designed several Roman Catholic churches in Sheffield. The latest extension to the church, which also incorporates a plaque that is inscribed in Latin, was added in 1971 by John Rochford and Partners.

 

An inscription in Latin