Llanharan, near Llantrisant (SS 9962 8270)

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This South Pit of this mine was partly sunk in 1870 to just below the Six-Feet seam to a depth of 144 yards. It had limited workings in the Two-Feet-Nine seam which it called the Lantern seam (it was named the Lantern because it contained a band of cannel) but it was so wet and inclined that it had to be abandoned. Another pit a half-mile away – Llanharry was also abandoned in 1875 after it had proved all the lower steam coals.

In March 1882 this mine was offered up for sale at the Royal Hotel, Cardiff, but failed to reach its reserve price. In 1910, a nearby drift proved a seam that proved to be similar to the lantern. It had the same black shale roof, red fireclay floor and cannel band, but there was 800 feet difference in depth, although there was some speculation about this it was dismissed as a geological coincidence. In the early twenties Powell Duffryn decide to have another try, the South Pit was deepened and they put down the Llanharan North Pit. Once again there was an unresolved mystery – instead of eight seams, they found sixteen. Fortunately, they had sunk in the right spot. Had the new shaft been a quarter of a mile east or west they would have had to have gone through 150 feet of sand and gravel. Had it been a quarter of a mile to the north the sinking would have been through an area affected by a major geological thrust which, years later, was found to be the cause of the disruption and duplication of the seams. They did not realize at the time of sinking that they had driven through a ‘thrust’ and the same seams were being repeated 750 feet further down. The sinking was completed by the Powell Duffryn Steam Coal Company Limited in 1922.

The new sinking at Llanharan was to be a pilot project to help finance Llantrisant Colliery some three miles away. Llantrisant Colliery proved the No.2 and No.3 Rhondda seams and the lower steam coal seams. The former was too disturbed to be workable, but prospects in the lower steam coal seams were so good that, in 1939, Powell Duffryn sent mining engineer Jack Gregor to the Continent to study horizon mining methods. When he returned a start was made to organise Llantrisant.

In 1940 there was a violent explosion in the Llantrisant shaft which wrecked engine houses, fan drift and much of the pit-top installations and Gregor was among the four men killed. Replacing the destroyed equipment would have been difficult and costly, and the war-time need was for immediate output, so Llantrisant was abandoned.

But the company, and its general manager, David Griffiths, believed that horizon mining was the answer to the problems of the South Crop, and the first steps towards it were made at Llanharan. Progress was delayed by the war, but another important piece of work went ahead, this was the geological mapping of the area, in which Powell Duffryn and the geological survey co-operated.

Geologist Dr. A. W. Woodland supervised that work. One of his assistants was a young apprentice surveyor, Roy Piggot (later at 21, Roy was appointed surveyor at Llanharan, and planned much of the re-organisation made possible by this research).

They went into disused slants and other workings, collecting samples from marine and freshwater fossil shell bands. The geologists established that fossils from the Lantern and No.1 seams, 800 feet apart, were the same. The two were in fact the same seam displaced by a major upthrust fault running east to west through Llanharan. As well as causing duplication it had pushed the coalfield further south.

Further investigation gave, for the first time, a clear picture of what the situation was below Llanharan. There were really three areas of coal to be worked: One, south and east of the fault, contained some 26 million tons of coal, another to the north, and through the fault, contained 15 million tons; whilst the third consisted of the comparatively undisturbed upper seam above the upthrust fault.

From sketches on Powell Duffryn blotting pads, made in the days when many regarded the project as a dream, the scheme grew. Soon the new horizons, 15 feet wide, 11 ft 6 inches high roadways through the stone, were driven.

The South Pit was 15 feet in diameter and the upcast ventilation shaft and was sunk to the Gellideg seam which is found at a depth of 454 yards. The North Pit was 20 feet in diameter and the downcast ventilation shaft and was sunk to the Six-Feet seam which is found at a depth of 376 yards. The shafts were situated 1,000 yards from the southern outcrop of the Coalfield, with, 1,000 yards to the north of the shafts the east-west thrust area that made that portion of the Coalfield unworkable. The seams are so sharply tilted along the anticline set up by the south crop, that the only way to extract the coal was by the horizon mining method; the first time that this system had been fully employed in the U.K.

The Six-Feet seam was called the No.4 seam at this colliery and was extensively worked and had a thickness of between 75 inches to 84 inches. The combined Yard and Two-Feet-Nine seams were extensively worked and had a thickness of between 66 inches to 75 inches. Also worked as the ‘Thick’ seam which comprised of the Pentre Rider, Pentre and Lower Pentre seams which had merged in this area. It had a thickness of:

  • Coal 32 inches
  • Dirt 1 inch
  • Coal 11 inches
  • Dirt 1 inch
  • Coal 21 inches
  • Dirt 9 inches
  • Coal 11 inches
  • Dirt 3 inches
  • Coal 24 inches

The manager in 1925/7 was W. Thomas.

On the 4th of March 1929, Rhys Jones aged 53 years and an assistant repairer died when he was run over by trams.

In his annual address in March 1930, the chairman of Powell Duffryn remarked that at Llanharan the seam that had been opened up was of good quality but had presented many mining difficulties. They were then trying to open up another seam with better conditions,

In 1934 the Powell Duffryn Company was based at 1, Great Tower Street, London with the directors being; Edmund Lawrence Hann, Sir Leonard Brassey, Charles Bridger Orme Clarke, William Reginald Hann, Norman Edward Holden, Lord Hyndley, Sir Stephenson Hamilton Kent, Sir Francis Kennedy McClean and Evan Williams. The company secretary was Alfred Read. At that time it employed 15,260 men working in sixteen collieries who produced 4,780,000 tons of coal.

In 1935 the colliery employed 60 men on the surface and 550 men underground and produced 200,000 tons of coal with the manager being J. Gregory while in 1938 there were 707 men working underground and 148 men on the surface, the manager was still J. Gregory. In 1943/5 the manager wasH.C. Bisp and this colliery employed 643 men working underground in the Nos. 1, 4 and 7 seams and 152 men working at the surface of the mine.

The Coal News reported in 1948;

History was made at Llanharan, South Wales, on a bright autumn day last month, when horizon mining, an entirely new principle in the British coalfields, was launched. This method, used hitherto on the Continent, consists, broadly, of driving level roadways from the shafts through the measures instead of following the undulations of the coal seam. It marks a vital stage in the development of technique in this country, a milestone in the progress of mining.

For years the South Crop of the South Wales coalfield has been a hard nut to crack. Heavy faulting and steeply inclined seams have presented a challenge to mining engineers. Now comes horizon mining, literally cutting straight through the problem with level roadways.

Llanharan where the new system has been inaugurated is between Llantrisant and Bridgend, and right from the start, the colliery has not been an easy one to work. The first shaft was partly sunk in 1870 and then abandoned. A new one was sunk in 1922 which was intended to be a pilot undertaking at Llantrisant, three miles away, but geological difficulties stifled the Llantrisant project.

Today there are 760 men at work at Llanharan, producing 4,000 tons a week; by 1956, it is hoped output will have soared to 2,000 tons a day, or 10,000 tons a week, for by that time the whole colliery will have been converted to horizon mining. Of course, this will not come at once, the initial output from the district to be worked by horizon mining will be 500 tons a day, or 2,500 tons in a five-day week. But eventually, in eight years time, the whole output of the colliery will be from the area now being opened.

Years of hard thinking have gone into this project, Powell Duffryn grappled with the problem for a long time. It was Mr. David Griffiths, a former general manager for Powell Duffryn, and new Deputy Production Director for the South Western Division, who took the first steps, ten years ago, towards the re-organisation of Llanharan on the basis of horizon mining.

His first consideration was a completely effective and mobile underground haulage system; level roadways were the answer, Llanharan has seams that tilt at high angles – sometimes they double back on each other – so the old system of haulage slows down production seriously. Now Mr. Griffiths has brought his schemes to fruition and the National Coal Board has carried on from the point where Powell Duffryn left off.

The stone drives to win the coal in the present area were started in October 1946, 1,177 yards of level stone drivage have been made on the coal mining horizon and 460 yards on the upper, or return horizon, to give good transport for the coal lying between these two horizons.

The roadways are 15 feet wide at the base and 11 feet high, lined with steel arches and double tracks. First-class conditions are then provided, not only for the transport of coal but also for the passage of air. These roadways will be extended to provide for new coalfaces – extended rapidly too, for under the intensive methods now used in driving a roadway 30 yards can be completed in a week.

The seams to be worked are on average 6 feet thick. Wherever possible electricity will be used and all cutters and conveyors will be electrically driven. Where the coal has been extracted the waste will be pneumatically stowed so that slag, instead of accumulating at the surface, will be scientifically stored underground.

All underground haulage will be by diesel locomotives, of which three have already been delivered – the first in the South Western Division.

The horizon mining development is at present confined to the east side of the colliery. Ultimately the main field of operations will be to the north, where the reserves are calculated to be sufficient to last for 150 years at an output of 500,000 tons a year.

The North pit is the main intake and coal winding shaft. It is 20 feet in diameter and sunk to a depth of 376 yards, winding being done from a depth of 332 yards. The South Pit is the upcast 15 feet in diameter and sunk to a depth of 449 yards.

The North field is separated from the remainder of the taking by an Overthrust fault which repeats the seams on the South side. All the seams on the under the limb of this overthrust fault outcrop to the surface south of the pits. These are the seams it is proposed to work on the East side. The dip is in a northerly direction and reaches an inclination of 35 degrees on the Eastern boundary. The seams in the North field also dip in a northerly direction but average only about 10 degrees.

After examining the geological structure of the two fields, it was found that the present coal winding level at 332 yards would be the most suitable coal haulage horizon for working the seams on the North field, and that an upper horizon would be in the South pit at 232 yards would be suitable for the import of rubbish and material for working the North field coal lying between this horizon and the coal winding horizon.

Having decided on the horizon for the North field, it was found that considerable reserves of coal on the East side would be undermined and made difficult to work in the future if work was confined to these two horizons. A further upper horizon was fixed at a depth of 115 yards in the South pit, which would give a maximum cover of 60 yards at the lowest surface level on the East side. Thus, there would be two horizons for working the North field coal, and three horizons for working the East field coal.

The vertical distance between the top and bottom horizons is 674 feet, and all the coal that lies between these two flat planes will be extracted and eventually loaded into mine cars on the bottom horizon.

In 1951 a multi-million-pound development scheme was introduced at this colliery, and 87 men from Wern Tarw Colliery were transferred to Llanharan to help man it. In June 1951 over 1,550 men from the collieries nearest to Werntarw came out on strike in support of the Werntarw lodge’s decision not to transfer 97 men to Llanharan as the NCB wanted. The two pits were six miles apart. The NUM Lodge at Wern Tarw Colliery were outraged at this and tried to, but failed, to obtain an official Area Strike over the loss of these men. Eventually, Wern Tarw Colliery outlived Llanharan.

The Coal News again in 1952;

It is now four years since a ten-ton diesel locomotive arrived at Llanharan in No.2 (Maesteg) Area. The first-ever to roll away underground in the South Wales coalfield it was also the first to be used in a re-organisation of a British pit by horizon-mining principles. Today the re-organisation is more than halfway through and should be completed before the scheduled date of 1956. Daily output has gone up from 800 tons (in 1948) to 1,200, and the increase will quicken as other seams are developed from the main drifts – or horizons. There are three of these – major, level roadways driven through the solid stone. No.1 is at a depth of 111 yards from the surface, No.2 at 231 yards, and No.3 at 335 yards. Lateral roadways driven from them will tap the inclined seams. Coal from the upper horizons will travel via spiral chutes down staple shafts to the lower horizon and thence locomotive-hauled to the shaft.

All this is plain and simple enough when Llanharan’s manager and agent, Stanley Hughes, patiently leafs through his big portfolio of plans and sections or explains progress on the Perspex model of the pit. Yet to obtain the data for the plan of re-organisation took years of sustained research and costly effort.

In 1925 when Stanley Hughes started work as a collier at Llanharan, coal getting in the South Crop was a hit and miss business. Little was known about the lay of the measures, and lack of knowledge prevented effective planning. As an old collier remarked “you followed the seam – and you hoped it would stay put.”

Llanharan men soon adapted themselves to the new technique of mechanised drifting, and speeds of 30 yards weekly have been attained. They are now going ahead with the driving of stone drifts at the rate of 3,000 yards per year.

The first staple pit is now in use, bringing coal down from No.2 to No.3 horizon. This shaft, 116 yards deep, and 12 feet in diameter, was sunk in five months. It was the last job to be tackled by Tom Dutton, foreman sinker, before his retirement. His first at Llanharan was the sinking of the North shaft.

There have been setbacks, in 1948, for instance, the lower horizon met the plane of the upthrust fault some 300 yards from the shaft. It was a mass of rubble wreckage from the series of cataclysms that formed the mountains and valleys of South Wales, and it was full of gas, the boreholes blowing off at a pressure of 50lbs to the square inch. The heading stood for two years while the gas bled off and a scheme to go through the fault was worked out in conjunction with the inspectorate.

When work at the heading was resumed the drills were equipped with stuffing valves to prevent the gas from escaping. In spite of these precautions the gas emerged, and rescue men wearing breathing apparatus had to go in to retrieve the drills.

When the gas was exhausted the heading went ahead. Today it is some 800 yards beyond the fault, No.2 horizon will also go through it. Both horizons will connect up with the old Meiros Collieries, and the shafts there may be used again.

Joe Pascoe, once a cutterman at the derelict colliery, now a leading stone drifter, is looking forward to seeing familiar workings again and maybe ascending the old shaft.

Up at the old South shaft, the trams are now coming up to the surface loaded with stone for the crushing plant. Every week 1,500 tons of stone are sent out from the headings which are penetrating the South Crop. Crushed, much of it returns as stowing material for the first longwall faces won from the cross measure roadways branching from the lower horizons. Already more than 50% of the pit’s output comes from these new workings. Conveyed down the steep faces on troughed pans fitted with retarding discs, it is transferred to gate trunk conveyors which deliver it to No.3 horizon.

Coal also travels down the first spiral chute where an underground winding engine has been installed to provide quick travel between the two horizons.

The major elements of this first horizon mining reorganisation are taking shape. Supplemented by the best in modern machinery and equipment, they will eventually bring about the conquest of the once-unpredictable seams of the South Crop.’

In 1954 there were 181 men employed on the surface of the mine and 786 men were working underground. In 1955, 430 men were employed at the coalfaces, 392 men were working at the coalfaces in 1956, and in 1958 there were only 312 men working at the coalface. Llanharan Colliery immediately encountered difficulties in their attempts to work this geologically disturbed area, out of the seven seams planned to have been worked, only one was worked successfully. In the late 1950s attempts were made to drive into the area of the closed Meiros Colliery, however, this also proved fruitless.

Through 1,200 feet of vertical ground at this colliery, there were eighteen coal seams totalling 97 feet 6 inches in thickness. This averaged out at a seam thickness of 5 feet 5 inches, with an average distance between the seams of 75 feet.

An inspection was carried out to assess the conditions at the colliery and also to consider future prospects for successful development. The summary of the report is below:

The general condition of the mine at present is very poor, many of the service roads were in a deplorable condition. This condition arises out of the considerable maintenance problems in the areas which had not been scheduled to be worked. Road formation was not of a good standard and much of the support of the main roadways consisted of arches with close strutting in the webbing, but little or no effective support to the ground.

Work in these conditions has been persevered with due to lack of face room. The development position is critical at the colliery, not due to the lack of effort or work output, some 3,000 yards of development drivages is done each year. The amount of drivage done to establish short duration faces is unreasonable and certainly uneconomic but has to be undertaken to keep the mine in production until a workable area can be found and developed. The existence of the colliery depends upon the coal being found and developed within a period of about a year. The hope of achievement lies only in the Meiros area. The tests have been disappointing up to the present, and whilst it would appear almost certain that workable reserves will be found, the condition of the lower seams in the area from the history of the seams in adjacent mines, may not be easy. To this is coupled the fact that development commences 1.25 miles from Llanharan shafts. Meiros worked mainly the upper seams as follows:

    • No.2 Rhondda: 400 x 600 yards approximately.
    • No.3 Rhondda: 1,800 x 2,200 yards approximately
    • Hafod: 400 x 400 yards approximately.
    • Pentre (Thick Seam):1,200 x 2,000 yards approximately
    • Two-Feet-Nine (No.1 Seam): 300 x 400 yards approximately.
    • Six-Feet (No.4 Seam): 300 x 400 yards approximately.

 The conditions obtained are not those which should readily be tolerated, but there is a serious struggle taking place in order to save the mine. The present workings are uneconomical and cannot be otherwise, but the circumstances are worthy of some tolerance in order that continued employment for the men in the locality can be made secure. A very serious situation has developed at this colliery due largely to the fact that out of seven seams available for exploitation, only one can be exploited. The other six had been tried and it was found that they were in a very disturbed condition. The present seam that is being exploited is fast being exhausted and physical conditions in that seam are such as to call for great care in its exploitation.

The roadways are in a poor condition and it is very difficult to traverse them and to bring coal over them. However, they are safe. Normally speaking I would not be pleading for the continued working of this particular seam; however, the life of this colliery is at stake and everything should be done that can be done to win the coal in this seam pending the development of the Meiros Take at this colliery. Two drivages have been driven towards the Meiros Take and driven in the hard ground at the rate of 20 yards per week. However, they have not as yet struck any seam despite the fact that it was anticipated that they would have done so some time ago. If they do not strike the coal before long there would be the possibility of the heavy withdrawal of men from the colliery prior to the Meiros Take being available to absorb them. The coal seams at this colliery were numbered:

    • No.1 Seam: Two-Feet-Nine.
    • No.2 Seam: Upper-Four-Feet.
    • No.3 Seam: Lower-Four-Feet.
    • No.4 Seam: Six-Feet.
    • No.5 Seam: Caerau.
    • No.6 Seam: Red Vein.
    • No.7 Seam: Upper-Nine-Feet.
    • No.8 Seam: Lower-Nine-Feet.
    • No.9 Seam: Bute.
    • No.10 Seam: Yard.
    • No.11 Seam: Seven-Feet.
    • No.12 Seam: Five-Feet/Gellideg.

Despite an investment of £9,000,000, Llanharan Colliery closed on August 25th 1962 due to its coal being unworkable. Its men were transferred to Coedely, Cwm and Werntarw collieries.


Some Statistics:

  • 1923: Manpower: 192.
  • 1925: Manpower: 300.
  • 1926: Manpower: 410.
  • 1927: Manpower: 376.
  • 1928: Manpower: 474.
  • 1929: Manpower: 442.
  • 1930: Manpower: 376.
  • 1931: Manpower: 228.
  • 1932: Manpower: 397.
  • 1933: Manpower: 801.
  • 1934: Manpower: 787.
  • 1935: Manpower: 610. Output: 200,000 tons.
  • 1937: Manpower: 912.
  • 1938: Manpower: 855.
  • 1940: Manpower: 988
  • 1941: Manpower: 969.
  • 1942: Manpower: 842.
  • 1944: Manpower: 834.
  • 1945: Manpower: 775.
  • 1947: Manpower: 663.
  • 1948: Manpower: 760.
  • 1949: Manpower: 749. Output: 194,833 tons.
  • 1950: Manpower: 776.
  • 1954: Manpower: 967. Output: 184,000 tons.
  • 1955: Manpower: 861. Output: 202,494 tons.
  • 1956: Manpower: 926. Output: 197,030 tons.
  • 1957: Manpower: 892. Output: 196,895 tons.
  • 1958: Manpower: 874. Output: 190,599 tons.
  • 1960: Manpower: 667. Output: 119,112 tons
  • 1961: Manpower: 571. Output: 94,654 tons.


Llanharan 997825.

One of the most southerly mines in the Coalfield, it attempted to work the difficult geology near the southern outcrop of the South Wales Coalfield. In this area, the coal seams are badly faulted and in some places almost vertical. South Llanharan Colliery closed in 1895. It was the upcast shaft for Llanharan Colliery.


This information has been provided by Ray Lawrence, from books he has written, which contain much more information, including many photographs, maps and plans. Please contact him at welshminingbooks@gmail.com for availability.

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