Rhosydd Slate Quarry - West and East - May 2014

Rhosydd Slate Quarry - West and East - A Trip Report – May 2014

(with Peter Hamilton, Annette Price, Chris Crowley, Neil Montgomery and Siriol Richards of CCC, and a team from “Aditnow”)

Rhosydd Entrance
Above: - Siriol Richards stands at the portal of Rhosydd's mighty no 9 adit – possibly the longest tunnel in the Welsh slate mining industry


Rhosydd slate quarry lies on the north side of the Moelwyn range, 2 miles west of Blaenau Ffestiniog. Rhosydd means “moors” and is a medium sized quarry lying very high up and remote. Today the workings are not in particularly good condition due to numerous falls of ground over the years. It shares a boundary underground with its neighbour Croesor to the west, and when finally abandoned consisted of 14 floors numbered from 1, the highest to 14 the lowest. The chambers are lettered outwards to east and to west from the main underground inclines. Below floor 10 everything is flooded.

We started our long climb up to the quarry in terrible weather, past Llyn Cwmorthin, then up the rocky track at the end of the valley which eventually led up to the remains of surface buildings, and the mighty number 9 adit, which greeted us with its black maw, like a tunnel on the London underground, except that it was infinitely more inviting, set as it was in wonderful, yet forbidding surroundings. There it was, refreshingly ungated, and seemingly forgotten, high up on the mountain.

Into the Quarry

Haulage systemI was certainly glad to get out of the driving rain and begin the long walk underground towards Rhosydd's old vein workings, which this, probably the longest adit in the Ffestiniog area, was constructed to intercept. It is 2221 ft long from the portal to the inner sheave of the haulage system. Trucks were hauled along the adit via an endless wire rope which passed around horizontal sheaves at either end. The example positioned at the inner end is in good condition, (see photograph below), the powered one at the surface has however disappeared.


The trucks which journeyed back and forth along no 9 adit, did so by an ingenious means: they were hauled by a wagon called a megryn which had a adjustable gripper underneath that could be tightened up to grip the cable via a screw handle. A megryn was also stationed at the rear. The one at the front was attached to the rope, the rope then set in motion and when the couplings of the train were drawn tight, the back gripper was put into action.
A number of inventive transportation solutions were employed in Rhosydd, and we were to come
across these, or the remains thereof, during the course of our explorations.

Rhosydd side chamber

On its way into the mountain, 9 adit passes through the back vein where the slate was worked in a limited fashion creating a small area of chambering. These neat and tidy spaces proved ideal for our final preparations.

To the far west

Reaching the end of 9 adit, one reaches the main transport hub of the mine, from which both the east and west sides can be accessed. First we decided to head west to see the boundary with Croesor and look down into the “chamber of horrors” Thus we headed towards the 5/9 incline. This incline, unfortunately now run in part way up, employed an interesting haulage system whereby wagons were carried on a transporter shuttle called a trwnc, which consisted of a frame, triangular in elevation, (so the deck remained level), mounted on wheels. Its wooden deck carried three transverse tracks for waste and slab trucks. Two turntables allowed for loads to be swung round so as not to overhang the sides. Wagons could board this transporter shuttle from stone or wooden staging . On floor 9 the deck was brought level with the floor by the trwnc being run into a pit at the incline base. To prevent this pit from obstructing traffic coming from chambers on the western side, a wheeled bridge was installed to carry wagons coming from the westerly chambers across this pit. When the trwnc arrived on floor 9, the bridge was pushed back into a recess. Between the trwnc rails, another track was laid to serve the counterbalance truck which was known as a mochyn. This was made up of solid iron castings mounted on wheels and it was designed to be low slung enough to pass under the transporter shuttle at mid point.

At this point however, I noticed something I had not come across in a slate mine before. We climbed an incline a little way, then headed off through a small opening on the opposite side, to immediately gain another incline, which seemed to run in parallel to the first. Its presence came as a surprise to me, as I expected to find only one, as is more usual.

I could not account for this set up, but information later gleaned from the study “Rhosydd Slate Quarry” by Lewis and Denton suggests the following: - An incline also serves the lower floors 9 to 14, the slate and waste being brought uphill to floor 9. This incline is thought to have been operated by a water balance system which run in an incline running roughly parallel to that of the 5/9. This is the 6/9 incline and it lies to the east of the 5/9, thus being the first of the inclines we encountered. Its roof is too low for it to accommodate a trwnc, thus it could never have been intended for ordinary traffic. Therefore it is thought that a truck filled with water on floor 6 would have been attached to a cable passing round a horizontal sheave positioned on this level. The weight of the full water truck descending the 6/9 would in turn haul loaded wagons up to 9 from the depths of the quarry.

The 5/9 incline sheave is still in good condition, but cut off by recent falls which now make it more difficult to reach, although some of our group made a detour to see it.

After crossing the two inclines, we scrambled upwards over large boulders to eventually arrive at the Western Twll, an opencast pit where chambers A, B and C west, terminated in large windows which opened onto a dismal grey sky.

Western Twll

The wan light of a rainy day penetrating into these lonely chambers high in the mountain gave the impression I had walked onto the stage set of a Wagnerian music drama, and one could well imagine magnificent harmonies echoing to silence among the brooding rocks.


Heading still further west involved more clambering and negotiating numerous falls until we gained floor 6 and thereafter the base of the 3/6 incline. The operation of this incline involved a similar transporter system to that mentioned previously. The photograph above clearly shows the wood and stone landing stages. The mochyn had ended up roughly half way down the incline, and the Trwnc was at the bottom.


Arriving at the top of the incline on floor 3 we found the horizontal sheave was in very good condition - a compact and even rather elegant piece of equipment which we took time to photograph. It is similar to that of the 5/9 incline sheave, with some minor differences and is actually considered to be a better design.


The above photograph shows the transporter shuttle (Trwnc) at the base of the 3/6 incline on floor 6. The pit into which it ran can be clearly seen. Its deck  accommodates two turntables for adjusting the position of the load. Here the tramway can bypass the Trwnc pit hence the absence of a wheeled bridge.

Chamber of HorrorsCrossing the 3/6 incline at its base, one enters a level which leads to the boundary wall between Rhosydd and Croesor , which was built to stop quarrymen leaving work early through either mine. Soon a short scramble down loose slate in a small chamber, led in turn to a tunnel which, after a little way, terminated abruptly in the “chamber of horrors” (of Croesor/Rhosydd through trip fame). To me it seemed a very eerie, remote, and echoing place, completely different in character from anything I had so far encountered in Rhosydd. But here of course, we were looking down into a different mine, and in my experience each has its own particular “feel.”
The deep lake, brooding silently between its steep slate walls was traversed by the sorry remains of a bridge, (or, to put it another way, one that had ceased to fulfil that exact function, a good many years back!).

The lost eastern workings

After our visit to the far west of Rhosydd, we turned back the way we had come and proceeded to the end of 9 adit from where we would continue in the opposite direction towards the so called "lost eastern workings."

Much of the south-east of Rhosydd was lost in a fall which occurred in 1900 around the East Twll which is now marked by a shapeless and treacherous pit. This event was thereafter known as "the great fall" due to its significant impact on the quarry. Only in recent years has it been discovered that a surprisingly extensive part of this area can be entered by negotiating unstable ground. This fall instantly transformed Rhosydd from a profitable enterprise, into one that was struggling to make ends meet, such was the extent of the damage to what was at the time, economically important workings.

Proceeding in a roughly easterly direction from the sheave wheels at the inner end of 9 adit, one enters a long somewhat meandering level (on floor 9). This passes
through an area which is "geologically messy" much of the rock being spoiled by a dyke (an intrusive band of quartzy material filing a large crack). Significantly, "impurities" like this may have been a contributing factor in the great fall itself (in addition to the more usual explanation of extensive pillar robbing leading to catastrophic failure of the roof).

Just off the level, one can enter the compressor room where bases for the compressor can be seen. At this point, I was curious about a cool draft coming from the entrance to a small chamber or cavity containing water, leading from the back of the compressor area. I had a feeling this lead somewhere significant, hence the passage of air. But it probably only led into the great fall itself at its western extremity, with the air being channelled from elsewhere in the mine through cavities
and gaps in an avalanche of fallen boulders. Anyhow, no one seemed keen on pursuing this lead, so I left it alone. One of those funny little places that you get a nagging feeling about, as if you somehow know something nasty will happen if you proceed....... like exceeding critical welly depth perhaps?

Thereafter, we continued on our way, crossing the base of a number of chambers, until an inclinelike slope of loose material was reached leading off the level to the right. Up this we climbed, then proceeded to clamber under and over a nice selection of (thankfully, well wedged) slate blocks. I understand that the chambers we bypassed on the way to this upward slope are, to all intents and purposes, extensively, if not totally filled with collapse material, so now in effect, we where beyond what appeared to be the main area of the fall.

After more scrambling, sliding, damp bits etc (and, NO, by some miracle, I didn't find myself upside down, back on floor 9, or wherever I'd end up if I took a tumble), we soon gained what was a more obvious incline, which we then ascended to a well preserved winding gear. This incline, I later discovered, is between floors 7 and 6 (chamber I east). Looking further still up the chamber from this point, one has a very good view of the ground effected by the great fall, or subsequent ones, which probably continued on and off down the years. Massive boulders, many of which seemed to me to be the size of cars or vans (you get the general idea!) were jumbled and tumbled down the chamber: – a very sketchy area.

Some members of our group traversed up and over this collapse, to gain still more remote workings containing artefacts. I politely declined this experience, fearing that these lurking "not so little" slate blocks would suddenly come alive and head enthusiastically in a downward direction!
Here quartzy material was much in evidence, and this could have contributed to a fatal weakening of the rock, which combined with the aforementioned pillar robbing, may have served to bring vast tracts of it down. It was amazing that entry into these working can be gained at all, and indeed any exploration of this area should be done with great care. Yet, there is compelling evidence that the quarry men attempted to regain this area for what was probably a short while before finally abandoning it for good.

For example the presence of at least 2 inclines: -floor 6 down to 7 in I east and 7 down to 8 in G east in different chambers and going down only one floor each, seem to indicate an attempt to win good rock, or take out fallen material in the eastern workings after the great fall. It looks as if they had to fit the inclines in where they could, in order to salvage what they could: - at this point the quarry was struggling to survive.

Significantly, and in support of the above theory, these inclines show no evidence of the more sophisticated technology employed on the main established inclines in the west, thus suggesting they where makeshift affairs installed after the fall,the inclines that have so far been discovered here employing comparatively simple wooden winding drums of a double winding type. Oddly however, although this was an important part of the quarry before the fall, inclines like those in the
western workings with their associated equipment have not so far come to light, unless they are buried without trace. This is pure speculation, and probably unlikely, as I have come across nothing in the available literature to suggest they were originally here.

Incline Head

The well preserved incline head of the chamber I floor 6/7 incline in the largely shattered eastern workings

Rhosydd artifactsThe photograph shows artefacts in the eastern workings somewhere up and over the fallen blocks. Near the 6/7 incline head we found the characteristic spindle shaped weight that once belonged to the lower part of a jwmpr which is a weighted metal rod once used to make shot holes by pounding the rock. (once commonly used in the Welsh slate mines in Victorian times, complete specimens are now hardly ever found, and then usually only in very remote and untouched workings)
Up here on the eastern side, hob nail boot prints and the fragment of a newspaper dating from the 1920's have also been discovered.

I wonder if there are also many artefacts lost forever in the flooded lower reaches of the quarry - stairways, complete Jwmpers, more evidence of the interesting mechanisms they used on the inclines for example? A veritable “Lost World” lying locked in water beneath the high and lonely moor.


I wish to express my thanks to those Aditnow members who made us welcome and showed us around this intriguing slate quarry.
(Note: - All photographs by Peter Hamilton and Siriol Richards – some photos were taken on a previous trip)


Rhosydd Slate Quarry, M.J.T. Lewis and J. H. Denton, The Cottage Press 1974...A detailed field study in industrial history.
http://www.aditnow.co.uk/ Includes many more photographs of Rhosydd and plan of the workings

Siriol Richards