A Recce in Charnwood Forest

 

The Altar Stones in Markfield

In the first week of March 2019, I went to Charnwood Forest with Paul May of the Sheffield U3A Geology Group, to undertake a recce for the next field trip; however, the onset of the COVID-19 Pandemic and the subsequent lockdown prevented us from meeting up for another 16 months.

 

A geological walk around Cliffe Hill Quarry

We discovered that the British Geological Survey guide that we had used, published in 2004, was in many respects quite out of date and there were parts of our walk that needed revising. Although I thought that we had gathered enough information for our needs, with 19 months having passed since our recce, Paul wanted to go and have another look and so we set off again to Charnwood Forest on the day after my exploration of Fulwood and the Porter Brook. 

 

On Billa Barra Hill

We started again at Billa Barra Hill, where there are examples of volcaniclastic siltstone of the Bradgate Formation that are part of the Charnian Supergroup, which was laid down during the Ediacaran Period. After having another look at these rocks, we moved down to the lower quarry to check on the slickensides that we had uncovered and having noticed a soil horizon, which we hadn’t seen before, we returned to the car park. 

 

A soil horizon above the Bradgate Formation

Having decided to omit both the Old Cliffe Hill and New Cliffe Hill quarries from our walk, we then drove to the Altar Stones Nature Reserve where we considered that, with its ragged steeply dipping rocks and excellent views of the surrounding landscape, it would be a very good place for the group to have their lunch. 

 

The Altar Stones Nature Reserve

After having our own lunch here, we undertook a more detailed investigation of the rocks than we had during our previous recce and, with the sunshine highlighting the textures of the rocks, we were able to distinguish the Bradgate Formation, the Sliding Slump Breccia, the Beacon Hill Formation and the Park Breccia. 

 

The Sliding Slump Breccia

 

With the morning session successfully completed, we had a short drive to the car park on the outskirts of the village of Markfield and went to have a look at the quarry in the Hill Hole Nature Reserve, which extracted the very distinctive pink and green diorite known as markfieldite. 

 

Hill Hole Quarry

 

On our previous visit, due to the fact a few locals were using the quarry has a golf driving range, we didn’t go down into the quarry, but this time we found another entrance and had a quick look at the principal features of the rock, including its uniform colour and texture and the pattern of jointing. 

 

Markfieldite in Hill Hole Quarry

Continuing our walk, the last part of our itinerary was to explore the village of Markfield, where the mediaeval Church of St. Michael and All Angels, much of the vernacular architecture and various boundary walls are built with markfieldite. 

 

Markfieldite

 

While wandering around the churchyard, we noted that the headstones are not made of dense fine grained Carboniferous sandstone, as is seen in South Yorkshire and in many places all around England, but are Swithland slate. Comprising purple to grey meta-mudstones and greywackes from the Cambrian Swithland Formation, this was used mainly in Leicestershire, but was also used for the roof at St. Pancras railway station in London.. 

 

Swithland slate headstones

 

We finished our recce by having a walk around the old centre of the village, where we found several further examples of markfieldite in the houses along Main Street, often with red brick dressings, before returning to the car park.

 

Vernacular architecture in Markfield