Reprinted by kind permission of the author from:

The Mines of the Forest of Dean

by Tony Oldham


  The Forest of Dean, lies, between the two famous rivers of the Welsh Borders - the Severn and the Wye. In its original extent it never passed beyond these two natural boundaries, but it can scarcely be described now as covering a breadth of territory so extensive.
  As far back as the reign of Henry the Second, the Forest did actually comprise all the land that these two boundaries encompassed. Then, if you wished to perambulate the Forest boundary, you would have had to have started where the Wye empties its waters into the Severn, just below the ancient town of Chepstow, and paced along the Severn side until you reached the city of Gloucester, you would have had to turn westward from the busy city, and followed the winding course of the Leadon river to Newent, you would then have passed on through Herefordshire until the old castle at Goodrich stopped your westward progress; thence turning due south, and following closely the banks of the Wye, you would again have found yourself at Chepstow.
  From this it will be seen that in olden times the Forest was almost completely surrounded by a natural water boundary; for, with the exception of the Herefordshire land, which was then included in the forest, the three rivers already named flowed round the hills and dales of ancient Dean.
  But this is not the Forest I have to describe. Since the reign of Henry the Second many changes have taken place, both in the extent and condition of this district. When Edward the First came to the throne the Forest boundary, as it was known in Henry's time, had been greatly reduced. On the north side the rich lowlands of Herefordshire and Gloucestershire, and on the south the fair spreading pastures that lie between Chepstow and Lydney had been gradually cut off. By Royal grant, or by private purchase, these tracts of soil had been secured for purposes of cultivation: and thus the first inroad was made upon the original extent of the Forest of Dean.
  During the reign of Edward the First the encroachment which his accession to the throne had found complete, was still further repeated. For as it happened, previous to his reign, the north and south extremities of the Forest had been curtailed; in like manner it happened during his reign that the east and west sides of the Forest were similarly treated. Once more it was the land best adapted for agricultural purposes that was cut off from the Forest territory, but from that time to this the boundary has remained nearly unchanged.
  This process of curtailment has reduced the range of Dean Forest to the central hills which occupy the district now lying between Newnham and Coleford, on the east and west, and Mitcheldean and Bream, on the north and south.
  Many of the iron mines in the Forest are associated either with natural caves or are in the Crease Limestone. Consequently the book "The Caves of the South Eastern Outcrop and Caves and Mines in the Forest of Dean" [= COSEO] has become a little unwieldy. This present tome hopes to over come this problem by dealing solely with mines: coal, iron and even a gold mine!


  Extensive iron mining dates from Roman times, although there is some evidence to show that outcrop ores were worked in the Iron Age, e.g. iron slag was found in the Iron Age hill-fort at Llanmelin near Caerwent. Scowles or scowle holes, the depression left by outcrop workings, have taken their name from either the Welsh 'ysgil', which means recess, or the old English 'crowll' or cave. The bulk of ore was taken during the Roman Occupation, although mines only reached a maximum depth of 100 feet. Slag heaps, containing up to 50% of ore due to the crude smelting techniques, were said to be up to 100 feet high and to reach as far north as Worcester. During the nineteenth century Roman slag was re-cycled and mixed with a small proportion of newly-mined ore in the improved furnaces of the time.
  A revival of iron mining took place after the Dark Ages, and it is recorded that there were at least 59 mines operating during the reign of Edward the First. Geraldus, describing a tour though Wales in 1188, speaks of the "noble Forest of Dean, by which Gloucester was amply supplied with iron and venison". In 1220 King Henry the Third ordered all forges to be removed, except for those having a Royal Charter.
  Prior to this time the Monks of Flaxley Abbey suddenly discovered the mineral wealth of this area. For a period of nearly five centuries the iron trade was carried on in different parts of the Forest, at almost any spot where there was a flowing stream, a dense wood and a good supply of ore.
  In the early 1600's, iron mining became much more economical, due to improved forges, and the use of charcoal, but by 1650 Parliament had become concerned about the rise of power in the Forest, and the amount of oak needed for ship building. All but a few forges were closed and by 1674 the industry was in decay. Iron was still being mined but had to be smelted outside the Forest incurring, crippling transport costs. The Laws of the Free Miner are described on pp 15 - 17. The gale or boundary of each mining concession is allotted by the King's representative - "the keeper of the gawle" or "gaveller". Even today the Gavellerís permission is needed to visit abandoned mines in the Forest of Dean. The Gavellerís Office in Coleford is also the legal depository for abandoned mine plans.
  Improved blast furnaces in the 1800's made mining economical once again, although pumping was needed to reach the remaining ores at lower levels.
  Most of the mines closed between 1890 and 1900 because of the thinning of the ore with depth, the problems involved with deep pumping and also increasing competition from cheaper Spanish ore.
  During the First World War, Wigpool, Easter, New Dunn and Old Sling Pit amongst others were re-opened, but most had closed again by 1926. New Dunn, however, remained open and was taken over by the Ministry of Supply during the Second World War and closed in 1946 after more iron had been put in (rails, supports etc.) than was taken out!


  Coal mining undoubtedly pre-dates the Roman occupation, but there is scant evidence. The Romans used Dean coal in their villas near Gloucester but charcoal was employed for their iron smelting. In 1282 it is recorded that "the Earl of Warwick takes likewise some seacoale [=coal as distinct from coale which was charcoal] in his wood of Lidney [sic]". Outcrops were exploited in the 13th century, but deeper mines were opened up in the 17th century.
  The rights and customs of the Forest are set out in the Book of Dennis and this covers both iron and coal mines. The Free Mining Rights were established in the reign of Edward I (1272-1307) in a record entitled "The Laws and Customs of the Miners in the Forest of Dean" as a reward for the part played by the Forest miners in the Siege of Berwick-on-Tweed. Between 1668 and 1777 a Court of Mine Law met at intervals in the Speech House, to deal with disputes amongst the miners. It was presided over by the Constable of St Briavels Castle, with the Gaveller and Clerk of the Court attending and verdicts were given by a jury of 12 Free Miners.
  To become a Free Miner a man had to be born within the Hundred of St Briavel and to have worked a year and a day in an iron or coal mine within the hundred. Even today a Free Miner has to apply to the Deputy Gavellor with a signed and witnessed document. Eventually the Court of this Society fell into disuse, disputes concerning ownership of the gales were frequent and an Act of Parliament became necessary to clarify the position. Acts 1 and 2, Vict Cap 43 established the Dean Forest Mining Commissioners who issued a Report (Sopwith 1841) which re-defined the rights of the Free Miners.
  These rights lead to a proliferation of small coal pits: in 1787 there were 121, by 1856 there were 221. In 1904 the Gaveller was empowered to amalgamate the gales and 44 were grouped into 7 large areas for coal mining. By 1920 most colliers were employed in the 20 or so big or deep pits. Here water was a problem and stories of "pumping 100 tons of water per ton of coal" were not uncommon.
  In 1948 the National Coal Board nationalised all the larger pits, but this period of modernisation was short lived as the last NCB pit closed at Christmas 1965. Today, only the Free Miners work the small drifts and levels, whilst above ground open cast mining by outsiders is set to raise its ugly head.


  From Chepstow, the Carboniferous limestone extends northwards through St Briavels, Clearwell, Coleford, and Symonds Yat where it veers to the east through Joyford, Westbury Brook, Buckshaft and Lydney and forms a basin, underlying the Coal Measures and Millstone Grits which lie unconformably upon them. An undulating plateau is deeply incised by the River Wye which exposes the limestone at many points. This is shown in Fig 1.

The coal measures are naturally divided, as will be seen from Fig 2, into three distinct series.

           After Sopwith 1841
 nb Coleford = Coleford High Delf

  The upper series consists of four thin seams of coal called the Woorgreen Delfs, none of which have proved hitherto of sufficient thickness to be worth working.
  It is from the middle series that the great supply of coal was drawn from the extensive collieries in the neighbourhood of Parkend and Cinderford. These veins are:- The `Smith Coal', or `Twenty Inches'; the `Parkend High Delf', or `Lowrey'; the `Starkey'; the `Rockey'; the `Churchway High Delf', and the `Brazilly'. These veins were worked on the long wall system and, as in most cases, there is a good holing above, or under the coal, very little is lost by waste in working.
  With the exception of the coal that was made into coke for the use in the Iron Furnaces in the Forest; all that was raised from these seams was sold for household purposes for which its large size, hardness and good burning properties make it especially suitable.
  The intervening strata of the upper and middle series consists almost exclusively of argillacious shale, with only here and there thin beds of sandstone. Below the Brazilly vein the character of the measures undergoes a decided change and instead of the softer ground of the upper and middle series, we find hard sandstone which continues with little variation down to the Coleford High Delf vein.
  The coals of the lower series are the `Nags Head'; the `Whittington'; or `Yard Delf'; the `Coleford High Delf', or `Hill Delf'; and the upper and lower `Trenchard' veins. Of these the first two have been worked to a small extent on the western side of the Forest, where also the Coleford High Delf vein has been chiefly worked. This vein extends a considerable distance beyond the general line of the coal basin on the Western side of the Forest, and that the outlying portion of the vein is divided by a fault called `The Horse' a tract of barren ground varying in width from 200 to 300 yards.
  It has been surmised, by some geologists, that this fault occupies the bed of a river, which is thought to have cut away and removed the soft vegetable matter forming the seam of coal, and afterwards been filled up by the sandstone which overlies it. Two smaller faults called the `Lows' have also been considered as tributary streams. This theory however does not appear to be borne out by the evidence afforded by recent drifts through `The Horse'. The coal has been found to thin out gradually on both sides towards the middle of `The Horse'; in some places as a single vein; whilst in other places it is split up into number of veins, each becoming thinner until all traces of coal are lost in the compact sandstone of which `The Horse' is formed.
  The Coleford High Delf vein is worked on the pillar and stall system; the absence of sufficient material for packing prevented the adoption of the long wall system. It is remarkably clean and free burning coal, and is largely used for forge and steam purposes.
  The Coleford High Delf is the most prolific seam. Due to faulting and surface topography it is found at varying depths from 400 feet to 600 feet. It varies in thickness, on average from 3.5 to 5 feet but its chief characteristic is the variation in thickness from seams less than 2 feet to other over 7 feet and in one freak case to 20 feet thick. Because the mines are comparatively shallow they are consequently very wet. The deeper mines of say, Yorkshire, are protected by layers of impervious rocks and tend to be dry and dusty. Consequently the working faces have to be constantly sprayed with water to keep down the coal dust which is inflammable and injurious to health causing pulmonary silicosis. The mines of the Forest are a startling contrast, being extremely wet. They are also free of fire damp or methane and for many years carbide and other naked flame lamps were used.
  The Farewell rock, or Millstone grit, which underlies the coal measures throughout the Forest, contains a bed of iron ore in its lower bed, which has been worked extensively since Roman times.
  In the Forest many of the caves appear as iron mines. In Triassic times iron bearing solutions filled these caves with iron ore such as haematite, goethite and lepidocrocite. Other sediments were formed in situ by the oxidation of iron sulphides and other iron bearing compounds. Iron compounds are highly insoluble, so that these materials tend to form crusts and coatings in caves. Another theory suggests that a mixture of acidic iron-bearing solutions corroded cavities in the limestone and in so doing were neutralised, causing precipitation of iron compounds which filled the newly formed voids. These `churns' often contained many thousands of tons of ore, for the most part soft and easily worked. The quality of the ore varies considerable from the `Brush' ore, frequently containing 60 to 65% iron, to the poorer kinds being mixed with calcite yielding only 15 to 25% iron.
  Mining operations from Roman times to the 1930's have left a complex network of phreatic tubes connected by chambers which are locally called `churns'. The iron ore is mainly found in the Crease and Lower Whitehead limestone beds and one way of finding the ore-bearing levels was to follow the obvious boundary between the two limestones. As the map shows (Fig. 1), most of the mine entrances are to be found round the edge of the limestone. The dip angle in the east of the Forest is steep. Here, the iron can be found as deep as 1000 feet and most of the mines in this area require tackle for exploration. However, in the west the dip angle is shallow, the iron deposits are not found below about 500 feet and the workings are consequently nearer the surface. Minor, localised pockets of iron ore have been found in the lower part of the Limestone Shales, the Lower Dolomite and the Drybrook Limestone. This explains why many iron mines fail at depth. Outcrops of iron ore appear to encourage the growth of Yew trees and it is thought that this is the clue which first attracted the early miners to the area. 

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