Rotherham The Unofficial Website An unofficial website about the Town and Borough of Rotherham

Geology of the Coalfield

The coal-bearing strata underlay large parts of South Yorkshire, Derbyshire and Nottinghamshire. They were laid down in what are now known as the coal measures during the Upper Carboniferous period of the Paleozoic era which ran from 360 to 299 million years ago. The period is called Carboniferous because of the worldwide occurrence of coal and limestone (calcium carbonate or CaCO3) that was formed during this time.

At that time all the land on Earth formed a supercontinent called Pangaea which reached from pole to pole with one vast ocean covering the remainder. The area that is now Britain was in the tropics and covered by giant tropical swamps of club moss trees. Over long periods of time these trees died, fell to the ground and were covered by later deposits which fossilised and compacted them. In this same period the shells of countless billion sea creatures fell the beds of the ocean to form limestone. Ages of time passed, the Earth changed, continents drifted, mountains rose, seas were formed. The bit of Pangea that became Britain eventually ended up where it is now.

The coal measures were covered by later deposits, compressed and folded by tectonic movement over millions of years. Some measures are narrow bands of difficult to exploit coal, some are hopelessly fractured but in this area there were many thick, rich seams. Some of the coal ended up close to the surface around here with stream beds are made of coal in the undulating countryside (for example between Kiveton and Harthill).

There are many seams of coal underlying South Yorkshire and the East Midlands. Some have been eroded in some parts of the coalfield but can be found in other areas. This a very complicated subject beyond the scope of this page, especially as the same seams of coal had different names in different places and I've been left scratching my head trying to work it all out. These are some of the coal seams mined and exploited in the Borough of Rotherham:-

• The Aston Common seam produced household coal and coal used for coke making. Also called Meltonfield, Wath Wood, Wakefield Muck, or Clowne coal. 209/190
• The Barnsley seam, also called the Top Hard seam. This dips from west to east and is reached at about 745m below the surface at Thurcroft. The coal mined is high quality coal that is excellent for boilers.
• The Flockton seam was mined at Waleswood and Orgreave. There are two seams of Flockton coal, the Flockton Thin which is the lowest and is generally too thin to work and the Flockton Thick which lies above it. A good household and coking coal.
• The Furnace seam was mined near Catcliffe.
• The Haigh Moor seam was mined at Dinnington, Thurcroft, Treeton Manvers Main and Wath Main.
• The High Hazels seam at about 270m from the surface. High Hazel was a very good quality house coal.
• The Kent's Thick seam was mined at Aldwarke, and previously at Kent's Main presumably.
• The Lidget seam was mined at Barley Hole near Thorpe Hesley, also Aldwarke.
• The Low Fenton seam was mined at Barley Hole near Thorpe Hesley.
• The Meltonfield seam was mined at Silverwood, Dalton.
• The Parkgate Seam was mined for good quality industrial coal used for gas manufacture. It is a three part seam consisting of Tops, Bottoms (used for gas manufacture) and Middle Hards (a good steam generating coal). and Swilley or New Hards Seam are probably associated with the Parkgate seam. Thorncliffe Thin Seam produced a good quality low ash coal that was used for steam raising, gas and house coal and the smalls were used for coke manufacture. Coal mined from the Swilley or New Hards Seam was very variable and worked south of Barnsley i.e. in the Rotherham area. The coal was suitable gas and coke production. The seam consists of "tops" and the "bottoms" split by a dirt parting.
• The Silkstone Seam was mined at Barley Hole near Thorpe Hesley..
• The Swallow Wood seam mined near Rawmarsh. The quality of this coal seam varied but it generally provided a household and gas coal and was some times used as second class steam coal. Also called Netherton or Top Haigh Moor Seam.
• The Swinton Pottery Seam was a poor quality coal, used for brick making. Also called Wheatworth or Castleford 4 foot coal or Bateson's Bed.
• The Thorncliffe seam found at a depth of about 600 metres in the Rotherham area. It is approx 1m thick and apparently good for coke only. It was mined at Brookhouse.
• The Wathwood seam was mined at Treeon.