Category: Geology

Coal Measures.

The lower coal measures.

The geology of the Yorkshire Coalfield is a story of working coal from the western edge of the coalfield in the Pennine lower coal measure starting at Walkley in Sheffield moving northwards to Bradfield, Bolsterstones, Stocksbridge, Crow Edge, East of Holmfirth, West of Huddersfield, to the north Western part of Halifax.

These coal seams were worked from the surface where they outcropped, and in shallow drift mines, and were situated in the foothills of the Pennines along this line.

The seams worked were the Pot Clay Coal seam, the Halifax Soft Bed or Coking Coal seam, the Halifax Hard Bed, The Black Bed, The Crow Coal and the Whinmoor Seam.

The Pot Clay Coal Seam was used for pipe manufacturing. The Halifax Soft bed was a very low sulphur coking coal mined in the Sheffield to Stocksbridge area using shallow drift mines. It was used for steel production and was mined as far north as the Halifax area on the outcrop.The Halifax Hard Bed was a coal seam used for local manufacturing and steam raising in mills and industrial installations. This seam had layers of fireclay and ganister, used for fire bricks and was worked from Sheffield, although not in great quantities, all the way to the north of Halifax. It was also known as the Ganister Seam. The Black Bed was a 24 to 30 inch seam used as house coal mined towards the north of the coalfield. The Crow Coal was a seam consisting of 20 inch of top quality house coal with a muck band of up to 12 inch and a further 7 inch of inferior coal at the base of the seam. It was mined mainly in the Leeds area. The coal from the Whinmoor Seam was a poor quality home coal and industrial coal.

I worked in the Whinmoor seam at Hayroyds Colliery, Clayton West, between 1998 and 2002. The seam varied between 4 feet 8 inch feet thick towards the north at Clayton West to 4 feet 2 inch going south towards Cawthorne, making underground conditions quite challenging. The seam had a muck band which thinned toward Cawthorne and was very wet. The coal was sold as power station fuel with the larger coal being sold as home coal from the pit as landsale.

The middle coal measures.

The middle coal measures are the group of coal seams which make up the majority of the coal mined in the Yorkshire coalfield. The middle measures make up a group of twenty five coal seams mined from east of Sheffield at Attercliffe moving north to Wincobank, Kimberworth, Greasbrough then north west to Thorpe Hesley, Pilley, Dodworth following a line north through Haigh, Netherton, Horbury, Ossett, Batley towards Morley then moving north eastwards towards Garforth via South Leeds. These seams provided the coal for the great Victorian Era and peaked in 1900 at 28,247,247 million tonnes and 100,826 miners before the final move eastwards in 1905 into the Doncaster coalfield. These pits were even deeper mines beneath the Permian layer, known as the Concealed Coalfield.

The seams worked in these measures starting from the surface are;

Shafton Seam: Pretty much worked around all the South Yorkshire area. A great steam raising coal and used during the railway era.

Swinton Seam: Poor quality coal.

Sharlston / Cudworth: Power station fuel.

Newhill / Castleford four foot Seam or Crown Coal: House and Power station fuel.

Meltonfield / Wathwood Seam: House coal.

Winter / Abdy Seam: House coal.

Beamshaw / Stanley Main Seam: One of the best house coals around.

Kent Thin Seam: House coal.

High Hazel Seam: Good house coal and Power station fuel.

Kent Thick / Mapplewell Seam: House coal, Power station fuel and sometimes a coking coal.

Warren House / Barnsley Rider Seam: Poor quality Power station fuel.

Barnsley Seam: The most important seam in the Yorkshire coalfield. It is world famous for the it’s thickness and quality and produced 50% of all the output in the area. It was up to 11 feet in thickness and was the main reason for sinking the pits in the Doncaster area and The Selby Coalfield. It has multiple beds with different uses. Used later as a perfect power station fuel.

Dunsil Seam: A dirty seam often used for blending with better quality coal for power station fuel. The seam sometimes combines with the Barnsley Seam, to the east of the area to create 14 feet of coal. South Kirkby Colliery, Markham Main and Rossington Colliery worked the combined seams.

Swallow Wood / Top Haighmoor and Low Haighmooor Seams: House coal, gas coal and second class steam coal. Top Haighmoor was often used for coke production.

Lidgett Seam: Good quality house coal.

Joan Seam: Poor quality general use coal.

Flockton Seams: House coal and Coking coal.

Fenton Seam: A gas and coking coal seam. Sometimes splits into two seams, High and Low Fenton also known as the First and Second Brown Metal seams.

Middleton Little Seams: The West Yorkshire version of the Parkgate and Fenton Seam. They are also known as the Brown Metal group of three seams.

Parkgate Seam: A very good quality coking, gas and industrial coal. It was heavily mined in South Yorkshire and only second to the Barnsley Seam. It was known as the Old Hards Seam in the North of the area.

Thorncliffe / Middleton Main Seam: A good quality coking, gas and industrial coal. It was known as the New Hards or Swilley Seam in the north of the area.

Silkstone Fourfoot / Wheatley Lime Seam: General purpose coal.

Middleton Eleven Yards Seam: General purpose coal.

Silkstone / Blocking Seam: High quality coking, gas and house coal.

Beeston Seam: Two beds of coal make the Beeston and can be up to 9 feet in thickness in central and East of Leeds. It was used as power station fuel. This is the final seam in the middle coal measures.

Coal seams in Yorkshire

Having worked in coal mines in South Yorkshire, West Yorkshire and the Selby Coalfield and my own research, it is obvious that coal seams are all different. ‘Dry’, ‘dusty’, ‘wet’, ‘gassy’ and ‘fiery’ are some of the descriptions you may use for the seam you are working in at the time. Gassy and fiery often mean the problem of spontaneous combustion is a major problem associated with these seams. As you can see below, Yorkshire has it’s fair share of these seams.

  • Shafton
  • Stanley Main
  • High Hazels
  • Barnsley Bed
  • Dunsil
  • Parkgate
  • Thorncliffe
  • Silkstone
  • Beeston

The South Yorkshire and West Yorkshire coalfields and seams are very different. Coal seams vary not only by thickness and quality but even in name. Below is a section of all the coal seams in Yorkshire, starting with the Shafton seam nearest the surface.

Yorkshire Coal Seams

The Yorkshire Coalfield is made up of two quite distinct areas. The world famous, Barnsley Bed Seam, also known as the Main Seam in South Yorkshire, was the prime seam in the South Yorkshire area. Collieries sunk to work the Barnsley seam were called Main, e.g. Cadeby Main, Wath Main, etc. The Barnsley seam changes character and splits to the north of the coalfield. It becomes the Warren House with a poor seam called the Barnsley Rider above the Warren House.

The Barnsley seam was discovered in the Selby area very much later in the 1960s, which started the Selby Coalfield development in the 1970s

The coalfield is split in an East / West line running from Woolley, in the West, to Askern in the East. This line was the dividing line of of two distinct coal swamps formed around 320 / 300 million years ago in the Carboniferous era.

The northern edge of the Yorkshire coalfield is situated North of Leeds and also has an East / West fault line. With the movement eastwards, victorian mining engineers encountered problems with the increasing depth of pits. in addition, a major geological problem was to cause more mining problems, vast expense and huge financial risk. This problem was the Magnesian limestone or as it is also known, The Permian Layer. This layer of rock is from the later Triassic and Jurasic geological era, from 130 million years ago.

This unbroken layer of Permian Limestone starts on the western outskirts of Nottingham and continues northwards up to Durham. The first pit to be sunk to work beneath this layer of limestone, which was also the deepest at the time was Denaby Main Colliery, mid way from Mexborough and Conisborough. The pit was sunk in 1867 to 457 yards to work the 108 inch Barnsley bed seam by the Pope and Pearson company, who sank the West Riding Colliery in Altofts, near Castleford. This layer of limestone, along with it’s water, was one of the major problems to be overcome when the Selby Coalfield was planned.