Sunday, 23 September 2018

A Trip to Alderley Edge - Part 2

The Sheffield U3A Geology Group on Stormy Point at Alderley Edge

During the Sheffield U3A Geology Group trip to Alderley Edge, the whole morning was spent examining Church Quarry in detail but, after lunch, the group set off to explore several other sites that relate to its history of mining. 

A scar left by mining along the Engine Vein

The first stop off point was to see the mine workings along the Engine Vein, which date back to the Bronze Age. The site is fenced off and it is not possible to look closely at the Helsby Sandstone, which contains most of the minerals here that consist of widespread occurrences of barytes and more localised copper-dominated polymetallic ore deposits; however, it is possible to see green coloured staining from the mineral malachite, which once appeared at the surface. 

A discussion about the geology that can be seen at Stormy Point

We then moved on to Stormy Point, an open space in the woodland where a large area of bare rock is exposed and which provides a good opportunity to examine the geology in some detail. 

A view towards the Peak District National Park from Stormy Point

The mineralisation is considered to be the result of the percolation of low temperature saline fluids through the porous Helsby Sandstone, with the faults in the region acting as conduits and also being associated with the concentration of minerals as veins.

An excavated mineral vein at Stormy Point

One of these mineral veins has been clearly excavated here and, although these have been worked out by generations of miners over the years, blue azurite and malachite can still be found in the rock fragments and barytes occurs as veins and clots in the bedrock here. 

Veins and clots of barytes at Stormy Point

Although the bedrock at Stormy Point essentially comprises conglomerate, in places these are underlain by beds of marl with green/red colouration, which are differentially weathered to leave the conglomerate standing proud. 

Triassic conglomerate and marl with a £1 coin used for scale

After a brief investigation of other  worked out mineral veins that are associated with faulting, we had a brief look at the large Old Alderley Quarry. Although the quarry faces were not readily accessible, from a distance a thick bed of marl is clearly distinguished from the sandstone above and below it – being differentially weathered to leave a deep linear scar in the quarry face. 

A view of the Old Alderley Quarry

The trip finished with an exploration of the area to the west of the B5027 road, to see one of the old minerals processing areas - where the land is still poisoned by the chemicals used in the extraction of the metals – and various capped old shafts and adits that are the only
 remains of the mining industry, which finished here in 1919.  

An old adit

As I had previously discovered with previous trips by myself to the Porter Valley and Ecclesall Woods, the industrial archaeology didn’t interest me that much – although I think that I would appreciate it much more if taking part in one of the organised visits down one of the old mines, arranged by the Derbyshire Caving Club; however, as a professional geologist, I won’t complain because I am a little bit wiser and my collection of rocks has increased significantly.

Various rocks collected from Alderley Edge

Thursday, 20 September 2018

A Trip to Alderley Edge - Part 1

Examining the quarry face in Church Quarry

In a year that has yet again been very barren for my professional work and spent near to home, I kept myself occupied for much of the time by focussing on the organisation of the Heritage Open Days for St. Helen’s church in Treeton. 

The Wizard Tearoom at Alderley Edge

I still made time for the occasional trip out to take advantage of the wonderful summer weather, however, with trips to Pontefract Castle and Saltaire by myself and on trips with the Sheffield U3A Geology Group. When the latter announced that the itinerary for 2018 included a trip to Alderley Edge, I put it in my diary straight away. 

The geology of Alderley Edge

Alderley Edge forms an uplifted area comprising Triassic conglomerates and sandstones, with subsidiary marl, which is surrounded by lower lying land that is covered in Quaternary till. I had seen examples of similar l during my previous U3A trip to the Churnet Valley, but the area around here has had a long history of mining, with both copper and cobalt being principally exploited since ancient times. 

An introduction to the geology by Chris Darmon

Our leader on the day was Chris Darmon, a very experienced geologist and field trip leader, and after we had all arrived at the Wizard Tearoom, we set off to Church Quarry, where we stayed all morning to closely examine the Helsby Sandstone Formation, which contains various separate members. 

A general view of Church Quarry

This medium sized quarry was worked in the 19th century for building stone and exhibits dipping strata, with the lowest metre or so of the principal quarry face consisting of a uniform medium grained sandstone separated from the conglomerate above it by a distinct unconformity

Conglomerate above sandstone at the unconformity

The conglomerate in particular provided the group with the opportunity to observe cross bedding, scour structures, variations in grain size and other features, which indicate that the sediment had been formed in a river channel, whose extent and direction could be worked out approximately from field evidence. 

A section through the main quarry face

As with other Triassic sandstones that I had seen in the Churnet Valley, Alton Towers, Nottingham and around Doncaster, the distinctly rounded pebbles found in the conglomerate are mainly quartz. It is thought that these are Devonian in age and have been reworked from rocks of this age that were found in the area that is now Budleigh Salterton in Devon and brought by a north flowing river into the area now occupied by the Cheshire basin, as a flash flood. 

Examining the unconformity

In one corner of the quarry, a short man made tunnel provides evidence of the mining activities in the area. The appearance of cobalt mineralisation of the sandstone here was investigated for its economic potential, but further investigation soon discovered that it was worthless and the tunneling ceased.

A view along the aborted tunnel

Wednesday, 12 September 2018

Heritage Open Days - A Review

An examination of 'honest repairs' to the chancel

When deciding to open up St. Helen’s church in Treeton for the Heritage Open Days this year, the Friends of St. Helen’s Church Trust made a conscious decision to choose the weekend that coincided with the Rotherham ShowAfter all, it had severely declined in recent years in our opinion and, considering that Sunday has always been the most popular day, our marketing strategy was to try and encourage everyone to visit us on Saturday.

The welcome to St. Helen's church on the Heritage Open Days

The Thursday opening was planned as an extension of the regular Coffee Morning and the posters and other publicity material – including posts on Social Media – was primarily intended to encourage more residents of Treeton to visit the church, although we were hoping that we would attract visitors from our listing on the HOD website

Setting up the bunting and balloons to the entrance steps

When setting up the banners, bunting and posters in the morning, having noticed the enthusiasm of the other volunteers who were helping out, I said that “even if we don’t attract a single new visitor, we should just be content to have another day of fun amongst ourselves”, which we did; however, our visitor counter reached 46 and, although we were a bit disorganised in this respect – and included volunteers - everyone agreed that it had been a very successful day. 

Help given to visitors by a member of Treeton Local History Group

In addition to the expected visitors from Treeton and nearby, we had several visitors from Sheffield and further afield and the display stand and the slide show of old photographs produced by the Treeton Local History Group was much appreciated. 

A visitor from Scunthorpe taking photos for her website

For the Saturday, one of my concerns had been that the Rotherham Advertiser and the Rotherham MBC communications team didn’t provide the help in publicising the event that we had asked for. I needn’t have been worried because, despite the weather that changed from light drizzle at the time of opening to a downpour at the finish, a steady stream of people came through the doors all day. 

A general view of visitors in the nave

The Thursday had been a ‘trial run’ in many respects, catering mainly for the local community, but we all had to step up a gear on the Saturday and I didn’t stop for a moment all day. The many tours of the exterior of the church proved to be very popular, and the ‘two tone’ tower and other architectural features - described by Sir Nikolaus Pevsner as “very confusing” - were discussed. 

A display by Trevor Spencer from the Sheffield Indexers

Inside St. Helen’s church, the presence of the Sheffield Indexers was an added bonus and the homemade cakes and other refreshments proved to be very popular, with £106 received for the Friends of St. Helen’s Church Trust – as well as other donations being made towards the Treeton Local History Group and to the badly needed maintenance of this Grade I Listed church. The visitor count for the day was 52 but, with no one specifically delegated to this duty, and with the counter being passed around, this was considered to be an underestimate. 

Cakes and scones

All in all, it was considered to be by far the most successful Open Day that the Friends of St. Helen’s Church Trust had organised, and all those that took part said that they thoroughly enjoyed the day. If I had to express an element of disappointment, it would be that we had all hoped for a dry and sunny day, so that the village stocks could have been opened up to provide some great family entertainment and photo opportunities; however, the rain didn’t stop the sense of fun for a few people that left school very many years ago.

Having fun in the village stocks (Photos provided by Diane Thurman)