Croesor Rhosydd Through Trip

From Ukcaving.com wiki

Introduction

Questions are often asked about this trip on the forums. To prevent having many similar forum topics, information regarding the trip will be kept here.

This popular and exciting mine trip connects the disused slate mines of Croesor which lies high on the slopes of Cwm Croesor, and Rhosydd which is situated on the watershed of Bwlch Rhosydd between Cwm Croesor and Cwm Orthin.

The normal direction is to enter Croesor and traverse to (and exit from) Rhosydd. Although the traverse would be possible in the opposite direction, this is not to be advised. There are several abseils that would need to be reversed and it would be impossible to inspect the state of the fixed ropes (if indeed they are in place) before using them. As there are many sharp slate edges in this sort of mine using a fixed rope without pre-inspection would be extremely foolhardy.

Due to the dangerous and fragile state of both the mine itself and some of the fixed aids, it must be assumed that parts of this route may become impassable or may change at any time. Past roof collapses have necessitated changes in the route on more than one occasion. That said, over the years the route has become increasingly popular which has led to many of the dangers being sanitized and the quality of many of the fixings such as the zip-wires is excellent.

It is essential that all party members are well-prepared for this trip. All members will need:

A reliable light source. The trip will last several hours and your light may become submerged.
Warm clothing. The mines can draught strongly and become very cold, especially if you're wet.
A helmet
SRT knowledge and equipment. You should carry the appropriate equipment and have the knowledge to both descend and ascend ropes. It is not enough to only know how to abseil. You may find your route blocked and need to reverse your path to the entrance.
Some means of buoyancy and the ability to swim. At times you may need to swim across flooded chambers and you may fall in from the traverses or from a boat.

Before embarking on this trip you should leave details you trip and a proposed exit time with a third party who will be able to summon the rescue services if you become stranded in the mines.

It is worth noting that if you exit Rhosydd via the upper Twll exit you end up on high terrain. In bad weather it can be difficult to navigate back into Cwm Croesor. It is recommended to take a map and compass/GPS to help you find your way.

Parking

Cwm Croesor

Croesor Village car park at SH632447.

Cwm Orthin

At the end of the road above Tanygrisiau village at SH683455.

Approach

From Cwm Croesor

From the car park, go back to the crossroads then turn left and follow the tarmac road along the bottom of the valley. Eventually this becomes a 4WD track and climbs diagonally up the southern (right) side of the valley to bring you out at the Croesor workings. The grilled adit entrance is obvious and to your right behind some old buildings. Unless you are familiar with the area, a map will be required to make sure you choose the correct ascending track. Map.

From Cwm Orthin

The simplest route is to follow the 4WD track up through the slate tips into Cwm Orthin. Follow this main track all the way alongside the western (left) side of Llyn Cwmorthin. This track then climbs diagonally up the head of the valley into the Rhosydd slate tips bringing you out at the abandoned Rhosydd mine barracks. The Rhosydd adit entrance is obvious to the left and behind the old buildings. It is at the foot of an incline and usually has water running out from it. The route onto Croesor mine from here is less obvious and follows a footpath across the open mountain, crossing the outflow of Llyn Croesor. This section will require the use of a map and compass/GPS unless you are familiar with the area. Map.

There is a direct route up from Tanygrisiau to Croesor without passing the Rhosydd adit, however, the early section of the footpath is really not obvious on the ground and climbs very steeply indeed. The route takes you over some high ground where the visibility and weather is likely to be worse before you drop down past the Twll entrances and on to the Croesor workings. This route will require the use of a map and compass unless you are very familiar with the area. This route is not recommended. Map.

The Through Trip

Croesor entrance at SH657457

Through the grilled Croesor entrance, head straight along the adit. After a short while an incline is reached. Climb up the incline all the way to a sturdy grill across the passage. At this point turn left along a level to reach the top of a pitch. After carefully checking the state of the fixed ropes, abseil down ensuring that the rope proectors are in place.

From the base of the pitch, walk and scramble straight across a massive chamber to reach the second pitch. Again, carefully check the ropes/rope protectors and descend. Shortly, a descending Tyrolean/zip-wire across a lake is met. Carefully check the condition of the wire. It is essential to employ some kind of braking on the crossing to prevent hitting the far side at high speed. A line can be attached to the caver on the crossing to act as a brake and this can be used to pull back the pulley or other equipment. Across the lake is a short section of dry passage before another lake is met. The suspension bridge that used to span this lake now lies on the bottom following a roof collapse sometime in 2007. A dinghy or a cold swim is now required.

From here, follow the obvious passages along the level until an almost horizontal zip-wire is met. Carefully check the condition of the wire. Cross this and continue to another wire traverse along the ruins of a crumbling bridge (the so called "Bridge of Death"). This wire is belayed in the middle so it is necessary to pass a join. Shortly after this is a short pitch down into another lake. Carefully check the condition of the rope. It is necessary to abseil straight into a dinghy and paddle across this so called "Chamber of Horrors". At the far side of the lake is a short pitch to prussick up on fixed ropes.

Crossing a low wall takes you from the Croesor workings into Rhosydd. Route finding now becomes more complex. It is possible to find the way through collapses to the adit exit, though daylight coming in from above may tempt some to scramble up and tackle the rather exposed climb out of the Twll.

Rhosydd adit at SH665461

The Twll entrances are at SH666453 (no photo)

Return

To Cwm Croesor

If exiting from the Twll, a walk across the open mountain down to the Croesor entrance is best, a map and compass/GPS will be required for this. Then follow the main 4WD track down into the valley. Map.

If returning from the Rhosydd adit, it is possible to turn left and follow a lower footpath into Cwm Croesor without passing the Croesor adit. A map will be required to ensure you hit the top of the path. Map.

To Cwm Orthin

If exiting the Twll, a walk over open mountain and down the inclines to the Rhosydd adit is best. A map and compass/GPS will be required for this. From the Rhosydd adit, follow the main 4WD track to the right and down into Cwmorthin. Follow along the lakeside back to Tanygrisiau. Map.

It is possible to take the direct route from the Twll and over the ridge to Tanygrisiau, however, the lower slopes are extremely steep and the path non-existent in places. A map and compass will be required for this. This route is not recommended. Map.

Other alternatives

Main Shaft Entrance

Suggested Equipment

For the cable Tyroleans and traverse lines, a dedicated tandem pulley for use on wires is recommended, such as the Petzl Tandem Cable. If a party has two of these they can be shared and dragged back across the traverses with a tail rope.
Every party should aim to carry some spare rope and rigging kit to enable them to complete the trip or escape if the fixed aids are in a bad way or if things go wrong.
Although there are usually serviceable dinghies in situ and lots of string to pull them back across the Chamber of horrors, it is probably essential to take your own just in case (and take it out with you - don't abandon it in the mine!).
Wearing gloves is recommended as broken slate can be sharp.
A map and compass/GPS is probably essential for finding the entrances and your way home if you're not extremely familiar with the area. This is proper Snowdonia Mountain terrain and is often completely covered in cloud!

Rubbish

It goes without saying that you should not leave any litter in the mines, but if you replace any fixed equipment then please take the old gear out with you. This includes things like inflatable boats.

Local accommodation

Lancashire Caving and Climbing Club have a hut in Tanygrisiau right by the walk up to Rhosydd and also Cwmorthin. Well appointed and reasonably priced.

http://www.lccc.org.uk/huts/index.html

Somewhat further away is a Bunkbarn and campsite in Tremadog owned by the legendary Eric Jones.

http://www.ericjones-tremadog.co.uk/

References

"Rhosydd Slate Quarry" by MJT Lewis and JH Denton, ISBN 0 9522979 0 6 contains full surveys of Rhosydd. Although the 5/9 incline has collapsed since the book was published, making the trip from the West Twll to the 9 adit slightly more exciting.

Trip write ups/descriptions

Video clips

There are now numerous video clips of the through trip on YouTube.