Croesor Quarry

Croesor Quarry in 2007, showing the remains of the fan house by the main adit and the site of the mill

Final and most awkward crossing in the Croesor to Rhosydd through trip

Croesor Quarry is a large underground slate mine in north Wales which was served by Croesor Tramway. It has a single adit in the hillside and ceased operation after a hundred years in 1930 having produced 11,000 tonnes of finished slate annually at its peak.^[1]

Features

Croesor Quarry is notable amongst Welsh slate quarries for being almost entirely underground, with no significant surface workings. It was rare in its extensive use of forced air ventilation instead of the more common natural ventilation used in most slate mines. It also generated relatively small external waste tips compared with the volume of finished slates produced; this was largely achieved by back-filling underground chambers with waste once they were exhausted.^[2]

History

Croesor Quarry was initially worked from 1846 until 1878. From 1864 onwards, the quarry was connected to the slate wharves at Porthmadog by an incline to the head of the Croesor Tramway. After a hiatus, it re-opened in 1895 and continued in production until 1930.^[2]

In the 1960s the quarry was operated by Cookes Explosive, a local firm who used its underground chambers to store explosives. In the early 1970s it was purchased by the Ffestiniog Slate Company with a view to reopening it as a working slate quarry. Planning permission for this was not granted and in the later 1970s most of the remaining mine infrastructure was removed for use in the Oakeley Quarry, also owned by the Ffestiniog Slate Company.

Current conditions

The whole mine is largely shattered and not in particularly good condition. Chamber 1 East was possibly the biggest underground chamber in the slate industry, being several colossal chambers worked into one void – so big in fact the roof couldn’t support itself any longer and it collapsed. The top third of the chamber remains intact.^[1]

Croesor Quarry is connected to the nearby Rhosydd Quarry by a tunnel that was built to aid surveying and settle boundary disputes.^[1]

In spite of a series of collapses, the Croesor to Rhosydd through trip is still possible and has long been considered a classic trip for mine explorers.^[3][4][5] Fixed ropes, home-made suspension bridges, zip wires, and inflatable boats have been installed which make it possible to complete the journey in comfort although not necessarily in safety.

Mine Status as of July 2010

Several of the fixed ropes have been replaced; however the first pitch rope is worn to the core a few meters from the bottom. Using your own ropes for a pull-through is recommended. The zip line is in good condition with a new safety rope along side it. The suspension bridge no longer exists (and hasn't for around 18 months) so a boat normally has to be used for this crossing. The various bridge crossings have also had new ropes and the status of the steel cables remains good. The final bridge before the long boat crossing now only has a single rail for the first section; however this has now been secured in the middle by rope. The boat pull-cord is in good condition and works well. Many of the old damaged boats have been removed and there are a couple of good ones (but take your own anyway). Rhosydd mine is still in good condition

Mine Status as of March 22nd 2011

The suspension bridge has been repaired and was still in place on the date above. There is a rigid hulled open canoe in the final lake that can hold up to 3 people. The pulley system is still working well.

References

1. ^ ^{a b c} http://www.mineinfo.co.uk/mines/Croesor_195/Croesor_3308.pdf
2. ^ ^{a b} Richards, Alun John (1999). The Slate Regions of North and Mid Wales. Carreg Gwalch. ISBN 0863815529. 
3. ^ Photographs of Croesor Rhosydd Through Trip 27 10 2006
4. ^ Photographs of Croesor Rhosydd Through Trip 13 01 2007
5. ^ ukBouldering.com

Coordinates: 52°59′27″N 4°00′08″W / 52.9907°N 4.0023°W / 52.9907; -4.0023