Friday 14 August 2020

Wharncliffe Crags


A view across the Don Valley from Wharncliffe Crags

My day out to Chatsworth House, in October 2019, concluded 8 months of extensive travel by bus and train from Treeton to more than 40 places in the counties that surround South Yorkshire - very many of which involved 2 changes in transport each way.

At the Lowood Club

This memorable year of exploration ended with a geology field trip with the U3A to Wharncliffe Crags, followed by a visit to Wortley Top Forge in the afternoon - places that I had passed by many times since living in South Yorkshire but had never visited.

A map of Deepcar and Wharncliffe Crags

Gathering at the Lowood Club on Station Road in Deepcar for our usual 10:30 start, we began with an introduction by our leader of the day, Dr. Gareth Martin of the West Yorkshire Geology Trust, and a short talk about the mining of ganister in the area.

A bat sleeping beneath a railway bridge

We then made our way up the lower slopes by a track that passed under two railway lines, one of which housed a bat, and carried on until we reached Wharncliffe Crags, a prominent rocky outcrop of the Wharncliff Rock - a medium grained massive sandstone in the Lower Pennine Coal Measures Formation.

Wharncliffe Crags

The rocks at the north-western end of Wharncliffe Crags have been quarried to produce quern-stones as long ago as the Iron Age, continuing into the period of the Roman occupation of Britain, and it is protected as a Scheduled Monument.

Blocks of Wharncliff Rock

Along the crags, two principal sandstone beds are exposed. The lower one, around 10 m thick, has well developed cross-bedding, typical of river point-bar sediments and is interpreted as the remains of a meandering river channel. The upper bed is thinner, up to 2 m, but shows interesting soft-sediment deformation structures.

Deformation structures in the Wharncliff Rock

These sections afford one of the best preserved examples of a fluvial meander belt in the  Pennines, of considerable importance for sedimentological investigations of the Coal Measures of this region and was designated as a SSSI in 1988.

Deformation structures in the Wharncliff Rock

We stopped off at several places to examine various sedimentary structures, including examples of deformation structures and sand volcanoes, which are considered to be a good indication that earthquakes occurred in the area.

An exposure of Loxley Edge Rock in an old quarry

Having looked at these unusual structures, we then retraced our steps back to the River Don, where there is an exposure of the Loxley Edge Rock in a disused quarry. Positioned at the rear of the group and some way from our leader, I just took a few photos before we returned to our cars and headed off to Wortley Top Forge.

A detail of weathering in the Loxley Edge Rock

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