The Forest of Dean. Scowles, Sheep & Ancient Oaks.

The Forest of Dean is an ancient royal forest, and is now a popular tourist destination. For much of its history, the people of the area have been dependent on the coal and iron found within its rocks.
This article appeared in Vol. 9, No. 4 - 2014


The Forest of Dean became the UK’s first National Forest Park in 1938 and is the largest remaining oak forest in England. It now depends on rural tourism rather than industry but there are still many reminders of its industrial past, such as this chimney, built to ventilate the underlying iron mine. (Source: B. Cooper)

The Forest of Dean is found in Gloucestershire on the borders of England and Wales. The Forest of Dean in Gloucestershire is an area of great natural beauty with a distinctive character and history, covering over 100 km2 between the River Wye and the River Severn on the southern border of England and Wales. It was already reserved as a Hunting Forest for royalty before 1066, with a good supply of deer and wild boar, and was later a major source of oak timber for building warships.

Geologically it is an asymmetrical syncline (see the Virtural Field Tour below for more details), exposing the Old Red Sandstone and Carboniferous Limestone on its flanks and the Westphalian Coal Measures in its core. With a combination of outcropping ores from the Tournaisian Creace Limestone and coals from the Westphalian Coal Measures, this is probably the oldest area of iron and coal mining in Britain. The local people or ‘foresters’ have long combined the skills of mining, charcoal-making, forestry and iron-smelting with recreational poaching. They are very independently minded, with a strong sense of community. 

Scowles and Iron Mining

The outcrop of the Crease Limestone around the flanks of the Forest of Dean syncline is marked by a wide variety of naturally formed pits and cavities locally known as scowles, which are thought to be unique to the Forest. These are probably paleo-karst features developed in the outcropping Crease Limestone during Permo-Triassic uplift and erosion and range from shallow pits to irregular hollows several meters deep. The cave walls within the scowles are covered with massive or stalactitic brown haematites. The remaining cavities are frequently filled with fibrous goethite, and yellow, red, brown and purple ochres, much valued by artists ever since the Stone Age, are often found. Replacement red haematite is also present in the Crease Limestone. The haematite and goethite is thought to have been derived from solutions of pyrite and siderite from the overlying Westphalian sediment during acid conditions.

Some 14 named coal seams are present in the Westphalian, all of which outcrop. The thickest and most commercial seams were the basal (Westphalian C) Trenchard seam which is 1.3m thick. The Coleford High Delf seam is up to 1.5m thick and the Yorkley seam averages less than a meter. The latter are both Westphalian D of the Pennant Group, interbedded with thick sandstones.

The first use of Forest of Dean iron ore is thought to have been during the late Stone Age when ochre was used to dye cloth and glaze pottery. There was much more extensive iron mining during Roman times, although the mines remained relatively shallow.

The intensity of iron-mining appears to have increased after the Dark Ages. Medieval ironworks were relatively small and mobile, with charcoal for fuel and the use of foot-operated bellows. In 1217, during the reign of Henry III, so much of the King’s deer forest was being felled to make charcoal that private forges were banned and only those which could afford a Royal Charter remained. Some coal was being mined in the 1240s and, during the reign of Edward I (1272–1307), at least 59 small iron mines were operating in the Forest.

  • View from Symonds Yat Rock. 120m above the gorge of the River Wye, this is one of the best-known viewpoints in the region. (Source: Bernard Cooper)

  • Another view from Symonds Yat Rock of the gorge of the River Wye. (Source: Bernard Cooper)

  • Wooded hillsides flank the gorge of the River Wye. (Source: Bernard Cooper)

The Forest of Dean miners were much appreciated by the Crown as sappers and archers. They were often conscripted for military service in Edward I’s wars against the Scots and French and in 1296 were rewarded with ‘free mining rights’. Broadly speaking, any man over the age of 21 who was born within the Forest of Dean and had worked down a mine for a year and a day was then entitled to mine for coal, iron or stone anywhere in that location ‘without let or hindrance’. The individual mines were, and still are, called ‘gales’. The coal seams are ‘ delfs’ and the inclined roadways ‘dipples’. The Free Miners had their own court where disputes between them were settled. By the later Middle Ages the Crown regulated mining and mines in the forest through the Office of Gaveller or ‘keeper of the gale’, an office which still exists. 

During medieval times the Forest of Dean was a major center of the British iron industry but by the 18th century it was declining, with production dropping from 192,000 tons in 1860 to only 1,700 tons in 1921. Many iron mines closed between 1890 and 1900 although several re-opened during WWI and one in WWII. The last commercial iron mine closed in 1946.

Mining and Museums

Meanwhile the coal industry rapidly expanded and by 1787 the Forest had 90 working coal mines employing 662 Free Miners. The Industrial Revolution was a boom time when deeper coal mining predominated and probably more people were working underground in the forest than on the surface. There were disputes over the employment of ‘foreigners’ and over the boundaries of adjoining mines. The Miners’ Court decreed that mining in any gale was to cease when ‘mattocks clashed’!

Coal output rose from 145,000 tons in 1841 to 1,176,000 tons in 1898, by which time three-quarters of the coal mined in the Forest came from six deep mines with the Free Miners supplying local needs from smaller drifts and shallow pits. The coal industry was nationalized in 1946 but the rights of the Free Miners were preserved. Coal production declined due to the high cost of draining water from the deeper mines. Production increased during WWI and II but the last deep mine finally closed in 1965.

The long tradition of free mining continues in the Forest of Dean and there are thought to be about 150 Free Miners living today. In 2007 two small coal mines were still producing and two were in the course of development.

Cross Section

Additional Information

Rural Geology Trail - Soudley Valley, Forest of Dean

Phoenix & Hopewell Collieries

Clearwell Caves

Clearwell Caves leaflet

The Geomap Project


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