The South Wales Coalfield is a pear-shaped area extending from St. Bride's Bay in the west to Abersychan in the east, a length of around 90 miles. The coalfield as a whole is in a basin of the formation geologically known as the Old Red Sandstone, onto which the coal measures were deposited. From North to South the coalfield measures around 16 miles in Glamorgan, narrowing to just 2 miles in Pembrokeshire. Some of the coalfield lies beneath the sea in Swansea Bay and Carmarthen Bay.

 

The carboniferous layers of rock in the coalfield are in descending order:

Supra-Llantwit series

Llantwit series - containing some coal seams

Pennant series - containing coal seams only in the Swansea area

Steam Coal series - containing most of the workable coal seams

 

Below the coal series are layers of rock known as the Millstone Grit and carboniferous limestone.

There were distinct types of coal mined in South Wales dependent on the part of the coalfield you found yourself, for the following reasons.

The strata dip gently from the North of the coalfield (Aberdare, Ebbw Vale, Blaina, Brynmawr and other Heads of the Valley towns), but are steeply tilted on the South (Bedwas, Risca). Earth movements over time faulted the seams of coal, in some cases throwing the strata up hundreds of feet above where they would otherwise be found. In the centre of the coalfield on a line broadly running East to West, coal seams are thrown much nearer the surface than would be expected. The great fault running North to South down the Neath Valley also splits the coalfield into two parts. The Western part contains the Anthracite coals, whilst the Eastern part where Bedwas is situated, has the steam and bituminous coals.

For our purpose of exploring the history of Bedwas, we are concerned with the South-east of the coalfield, where steam coal was mined. There was a huge demand in the late nineteenth up to the middle of the 20th century for steam coal. Such coal powered the boilers of the Royal and Merchant Navies, the railways around the World and those powering the mills of the textile industry.

Th remarkable heat-producing properties of many Welsh steam coals lie in the fact that they combine a high proportion of fixed carbon with well-developed "cauliflowering" tendencies when under heat. This allows rapid generation of steam under conditions of draught. This cauliflowering or swelling effect of steam coal allows the passage of air through the coal whilst it remains undisturbed, rather than having to use poking to maintain an adequate passage for the air.

Collieries which mined steam coal aimed at the lucrative markets of the World's navies. Colliery owners often gave their collieries nautical names in a bid to attract naval custom. Some of the names of steam coal collieries were set out in the South Wales Coal Buyer's Handbook.

 

Britannic,

Ebbw Vale Marine Waunllwyd,

Graham's Navigation,

Great Western,

North's Navigation,

Britannia,

Ocean,

Cilely,

Deep Navigation,

Oriental Merthyr,

Marine,

Bedwas Navigation.

 

The naval connection is how Bedwas Navigation Colliery received its name. Navigation Street in Trethomas which leads to the colliery site is named after the colliery, maintaining to this day the naval connection.

 

 

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