Category Archives: Industrial archaeology

Day Trip: The Grade II listed Pont Abermaw (Barmouth Bridge)

After walking up to Castell y Gaer hillfort in mid September, I drove to Morfa Mawddach railway station, a short drive away, and parked up.  This is a favourite route for cyclists of all sorts.  Some go there to do some serious peddling around the Mawddach on a marked out on the Mawddach Trail (following the route of the disused “Dolgelley Branch” of the Aberystwyth and Welsh Coast Railway line, which opened in 1869), others had hired bikes in Barmouth.  It’s the same with walkers – some are there to do the trail, others are just walking the bridge.  Fortunately, it was a very quiet day, at least on the bridge itself.  The views on a sunny day are great, and when the wind drops, the high-pitched sound of the oystercatchers is lovely.

The railway viaduct in c. 1869.  Source: Wikipedia

Barmouth Bridge, or viaduct, was built between 1864 and 1867 in  to carry the Aberystwyth and  Welsh Coast Railway, now the Cambrian Railway, across the Mawddach estuary, which it still does.  It cuts off an 18 mile trip around the estuary that would otherwise have had to be taken by the railway between Morfa Mawddach and Barmouth.  Designed by Welsh civil engineer Benjamin Piercy, and English civil engineer and architect Henry Conybearet, it has a span of c.800m, the longest wooden-framed viaduct in Britain.  It was grade II listed in 1988.

Although most have been replaced long ago, timber pile viaducts of the Barmouth bridge type were once common on the Welsh coastal railways.  Conybeare’s decision to choose timber as the main construction material was probably driven by much the same concern to save costs, rather than employing iron,.  Baltic timber could be brought to the site very cheaply by sea, and was a fraction of the cost that an iron viaduct would have been.  Although it was well known that Teredo navalis, a boring worm, could do considerable damage to vessels and sub-surface wooden structures, it was thought not to inhabit the Mawddach estuary, and may not have done when the viaduct was built.

The original design included a rolling drawbridge section that pulled back across the track and  enabled vessels to use the navigation channel into the estuary.  This was replaced by the twin-hogback steel lattice swing bridge in 1899, which, with a span of 41.5m, could swing open to let vessels pass, shown on a vintage postcard to the right.  The swing span was operated in March 1984 and April 1987, but permanent rails indicate that it is unlikely to be opened in the future.

After a number of repairs and renovations, the wooden elements supporting the span are composed of 113 timber pile trestles 5.5 metres apart, which are now encased in concrete sleeves reinforced by glass-fibre.

The viaduct has had quite an exciting life, with a number of challenges to its longevity.  It caught fire in 1892, and it was only thanks to a local boy, who raised the alert, that the fire was swiftly extinguished.  It had a lucky escape in 1946 when a live mine came in on the tide and touched one of the wooden pillars, but fortunately failed to detonate. In 1980, considerable dismay was caused by the discovery that Teredo navalis had eaten into 69 of the supporting pillars.  The bridge had to be closed, and restoration work was carried out over a six month period, during which a rail replacement service was run by the Cambrian Line between Barmouth and Tywyn.  In August 2015, there were real fears that the footbridge would be closed as part of a cost-saving exercise announced by Gwynedd Council.  The bridge had been a toll bridge, with a couple hired to collect small sums from users of the walkway, but with 90,000 visitors a year, these sums added up very nicely and contributed towards £38,000 that Gwynedd Council paid to Network Rail to keep the walkway open.   An online petition was immediately organized by a local resident, collecting over 20,600 names in support of keeping the bridge open.  A £1.00 honesty box system was implemented, but even on my one walk to Barmouth and back, it was amazing how many people didn’t contribute anything.  In October 2016 a fire broke out and the bridge had to be closed again, but only for a fortnight, with a rail replacement service also running between Barmouth and Tywyn.

On its 150th anniversary a celebration was held, and a special train was run from Shrewsbury to Pwllheli, pulling Riviera Trains Mark 1 carriages.  In March 2020 it was announced that the bridge was to receive a £25 million revamp from Network Rail to replace a large number of the timber and metal elements and install a new track along the entire span.

Sources

Barmouth Railway Viaduct. Coflein.  https://coflein.gov.uk/en/site/34918/details/barmouth-railway-viaductbarmouth-bridge-cambrian-coast-line

Barmouth Viaduct. Engineering Timelines
https://web.archive.org/web/20141015015046/http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=1340

Closing Barmouth Bridge will have ‘big effect’ on economy warns charity.  North Wales Live.  20th August 2015
https://www.dailypost.co.uk/news/north-wales-news/closing-barmouth-bridge-big-effect-9841952

20,000-name petition to keep Barmouth Bridge open to all. 21st August 2015.  BBC.
https://www.bbc.co.uk/news/uk-wales-north-west-wales-34010645

Fire shuts Barmouth Bridge until next week.  North Wales Live. 4th October 2016
https://www.dailypost.co.uk/news/north-wales-news/fire-shuts-barmouth-bridge-until-11978355

150th Anniversary of Barmouth Bridge Celebrated with Special Train Service.  Forwarder Magazine. 10th October 2017
https://forwardermagazine.com/150th-anniversary-of-barmouth-bridge-celebrated-with-special-train-service/

Barmouth Bridge £20m plan on its 150th anniversary.  BBC News. 10 October 2017
https://www.bbc.co.uk/news/uk-wales-north-west-wales-41568248

Barmouth Viaduct to get £25m revamp. BBC News.  26 May 2020
https://www.bbc.co.uk/news/uk-wales-52807338

A walk up to Craig yr Aderyn (Bird Rock) #1 – the route and the scenery


I have divided my Craig yr Aderyn (Bird Rock) walk into two posts, of which this is the first.  The first focuses exclusively on the Iron Age hillfort.  This one looks at the walk itself, how to approach it, incidental information about the environment and views from all the parts of the walk that I did.  This has to be one of the most magnificent walks in the area.  You might want to drive on to the 13th century ruins of Castell y Bere if you have energy left afterwards.

Chough. Source and more details: RSPB

As well as a destination for some of the most fabulous views in the area, it is also well known as the nesting site of cormorants (the furthest inland nesting ground for cormorants in Wales) and red-billed choughs (the latter on the endangered list).  It is also houses a two-phase Iron Age hillfort.  The hill used to be inhabited by feral goats, which were introduced in the 1960s, but slowly died out.  In the more recent past the hill has been used as a quarry for road stone, but this has now been stopped.  Today it is protected as a Site of Special Scientific Interest and a Special Protection Area.  As the birds nest on the north face, they are undisturbed by walkers, and climbers are only allowed to scale that face outside the nesting season.

Map showing the parking area and the footpaths up Craig yr Aderyn. Source: Protected Landscapes of Wales

Craig yr Aderyn is a highly visible local landmark in the Dysynni valley (SH643068).  A narrow road skirts its base, unfortunately not identified with a number on the Ordnance Survey map. If you are familiar with Happy Valley, where you can usually squeeze two cars past for most of the way, halve that.  If you don’t like reversing, this may not be for you.  From all directions, it is a single track road with occasional passing places, and I had to reverse three times for quite a way, once around some steep corners.  From the west Craig yr Aderyn is best approached along the road from Bryncrug; from the east it can be approached from the B4405 from Abergynolwyn or via the very narrrow road through Abertrinant.

There is a small grassy parking area by the roadside at the foot of the hill, sufficient for about six or seven cars, and marked on the map above right, but not shown on the Ordnance Survey map.  There is a farm gate here that opens onto a public footpath, a rocky farm track that starts off quite steeply before levelling out for a bit, although it inevitably rises again.  After about 10 minutes,  the track carries on beyond a gate across a field, just before which the footpath veers right, a grassy break in the bracken heading up the slope.  If you find yourself pondering whether to go through another gate once out of the car park, you have gone too far.  This fork is not signposted, just has a 2ft tall post on the right of the track to mark its presence, so look out for it.

The path up from the car park

The gate in front of a track heading over the field, and the small post at the centre right of the photograph, where you turn up onto the hillside.

The public footpath that leads from the track up the hillside

The path from here is good, but climbs a lot more steeply, and doesn’t let up much.  In winter it is likely to be very wet, as even in Monday’s high heat, after two very dry days, it was distinctly soggy in places. Don’t forget to keep turning round to enjoy the fantastic views.  There’s almost no sound up there except for the tiny birds that nest in the long grass, and some crows.

 

When you have been walking for perhaps another 15 minutes there is another fork, which is not signposted in any way, but is clearly visible on the ground as wide turf tracks that make their way through low bracken.  One track leads to the hillfort on Y Pallis Bach (the low stockade) and the other leads to Col Crag, the foot of a small crag that sits on the saddle that connects Craig yr Aderyn (Bird Rock) with the main line of the hill behind.

There’s a very well-timed bench at this fork in the path, dedicated to Nick (I don’t know who he was, but I love him), which is at the perfect point for taking a much-needed breather on a seriously hot day and admiring the views.  I flopped with enthusiasm.  Once you have enjoyed a slurp of water and enjoyed the scenerey, you simply follow the right hand fork beyond the bench to reach the hillfort, which you can see from the bench, or you can head left to go to Y Pallis Bach.  I do recommend the views from Craig yr Aderyn.

Thread your way up through the main entrance of the Iron Age hillfort, which is flanked by two great banks of local stones.  This is the second phase entrance (see my post about the hillfort if you’re interested).  Keep heading upwards for a couple minutes and you will very soon reach the summit.  Pause and enjoy.  The world is your thoroughly fantastic oyster – the whole of the western Dysynni valley rolls out before you, a truly astonishing sight.  Head a little way down from the summit, nearer to the edge, and the view is even better.   I plonked down on a convenient rock and was only sad that I hadn’t brought a picnic.  This has to be the ultimate picnic spot.  Next time.

After a very lazy sit in the sun and loving the view, I retraced my steps to the hillfort.  I had an archaeological site plan for the hillfort and try to match up the plan with what is left on the ground.  As I came down I bumped into a lovely couple who had left their car in Dolgellau and were on a six night camping hike, looping back to Dolgellau at the end of their holiday.  Now that’s serious walking!  Very impressive.  They were looking for a way down the other side of the hillfort rather than retracing their steps.  I didn’t see them again, so perhaps they found a route.

Having sorted out the hillfort features to my own satisfaction, I walked below the bottom wall towards the west to have a look at the view from there.  It’s better from the top, but still very fine.  If you’ve chosen to go to Craig yr Aderyn first and afterwards decide to go to Y Pallis Mawr, you can take a short cut by crossing towards it following sheep tracks rather than going back to the fork in the official footpath.  The marsh symbols on the above map aren’t kidding, and there are big patches of beds of spiny rush (Juncus acutus) and a large pond surrounded by small birds enjoying a bath and a drink, so stay above the dark spiky tell-tales, following the sheep tracks, and you’ll hopefully retain dry feet.  You rejoin the footpath and find yourself at the foot of a smaller, more conical peak between Craig yr Aderyn and the main hill’s peak.  The public footpath stops here, but if you feel inclined to walk up to the high crag of the hill behind, be aware that it is steep and is a scramble over rocks alongside a barbed wire fence, with a fairly convincing drop immediately to your right.  It convinced me to give it a miss.

Instead, I turned to walk down the side the hillside where there is a huge rockfall, which I was guessing was the main source of stone for the stone-lined ramparts.  These are enormous chunks of rock, with a lot of bright white quartz in amongst the dull grey.  I rounded the base of the conical peak and returned back towards the footpath, heading down the hill to the carpark.  The views were just as good on the way back.  Bliss!

Craig yr Aderyn from Castell Mawr:

 

A walk to the top of Tonfanau to explore the Tal y Garreg Iron Age hillfort

Tonfanau from the southwest. Tal y Garreg is immediately above the quarry

Ordnance Survey map showing the route taken up the hill, and the location of the two hillforts, marked by red dots. These two sites are also marked on an aerial photograph below.

I have wanted to see the Tal y Garreg Iron Age hillfort at the top of Tonfanau quarry, on Mynydd Garreg (rock hill), for some time, so on Sunday (9th August) I packed my rucksack and went along the route I had scoped out on Saturday, which had been made so enjoyable by the verges filled with wild flowers.  I parked the car on the road leading up to the Tonfanau footbridge, as before and followed exactly the same route, but this time instead of stopping at the gate into the field at the end of the bridlepath, I followed the faint track of the footpath up the hill.  The route is marked in dark green on the map to the left.  There are two hillforts on Tonfanau, both of which are marked with red dots, Tal y Garreg at the summit overlooking the quarry, and Llechlwyd on a lower promontory to the east of the quarry.   On this post I will talk about Tal y Garreg, but I covered Llechlwyd on another post, and the map above and an aerial shot below show the geographical relationship between the two.  The walk up the side of the hill is very beautiful, and the views from all around the top of the hill are breathtaking.  I should, however, make a couple of health and safety notes about this walk before I recommend it as a great one to do

First, the track starts to climb fairly easily, as in the photo on the right, but as you near the top, where the bracken gives way to open ground, it becomes steep.  When you turn around to admire the view, the ground seems to drop sharply away beneath you, and falling would result in an unimpeded roll downhill.  I am very sure-footed, but instead of tacking to reduce the effort, I went straight up, leaning forward, to reduce the risk of tripping.  The views are stunning, just be careful. There are other public footpath approaches marked on the map, which might be easier.  Second, the hillfort of Tal y Gareg sits above the quarry.  Indeed, the quarry has removed a big part of the hillfort.  When you climb to the brick monument on the summit of the hillfort you are getting near to the edge of the quarry, and at the edge there is almost nothing to prevent you falling the steep drop into the quarry should you lose your footing – just fence poles with a single run of wire to mark the edge.   Perfectly okay if you’re aware of it, but do not let children loose up there.

Access over two sets of steps to the ridge at the top of the hill

The top of the hill is a ridge that extends 1.5km to the northeast, with terrific views either side.  The ridge is enclosed today by a long, winding drystone wall that extends as far as the eye can see.  A short wooden ladder on either side of the wall allows you to cross the wall easily, but take care – two of the steps on the ridge side are rotten, one completely broken.  The inside of this drystone perimeter is divided up into separate enclosures by more drystone walling, but all of them have gates or are open so you can wander freely across the top.  To the southwest is the river Dysynni, at the eastern end are views over the hills flanking the valley, including Craig yr Aderyn (Bird Rock).

I was up there partly for the views, but mainly because I am on a hillfort mission at the moment and wanted to check out what was left of one of two small Iron Age hillforts.  In the area between the Mawddach estury and the Dyfi estuary are fifteen known hillforts.  These fall into two distinct geographical groupings, a northern and southern group.  Eight of the fifteen are in the southern group and I am hoping to walk all of those that are accessible by public footpath.

When the first hillforts were excavated during the late 19th Century, it was assumed that all hillforts were defensive, and some southern hillforts certainly were, but it is by no means clear if all hillforts were built as a response to conflict.  Because so few hillforts have been excavated in northwest and mid Wales, it is impossible to establish exactly what they were designed to do, and most of them probably had multiple functions.  I’ll be talking more about the roles of hillforts in this area on a future post.

It is almost impossible to photograph a hillfort sensibly at ground level, although some banks and ditches can usually be captured.  Aerial photographs and excavation plans are the best ways of of visualizing individual hillforts.

 

Another view of the quarry. Source: Gwynedd Archaeological Trust

In fact, Tal y Garreg hillfort was very easy to spot from the ground, as the builders made use of a rise in the local topography and natural escarpments that face north.  Tal y Garreg means “end of the rock/cliff” and probably refers to the rocky ridge on which it is built. It lies at the southwest end of a 1.5km ridge at c.170m OD.   The natural lift in the land, shown on the above photograph at far right makes the hillfort highly visible from the ridge behind it.  The composite image above (click to enlarge if required) shows Tal y Garreg hillfort from the air with the 1967 site plan (upside down in terms of the photograph – Bowen and Gresham 1967) and a view of it from the middle of the ridge.  Another plan to the left offers a different view.  Today, massive piles of rock from the quarrying activity are left lying around, so it is not immediately easy to see the structural features and it helps to have the plan to hand to locate them.  There are two sets of banks and ditches, referred to as bivallate on the northeastern and southwestern sides.  The banks, or ramparts, were probably pallisaded to make it even more impressive from a distance, and to make it easier to protect if needed.  These ramparts contain an area around 45m long by 22m wide, small in hillfort terms.  Still, it was clear that although the space it contained wasn’t large, it had been built on an impressive scale.  The entrance was simple, inturned, and cut through the scarp to the north, facing the ridge.  It’s worth walking along the the edge of the drystone wall that runs behind the fort so that you can get a feel for the banks and ditches shown on the far left in the aerial photo, but be careful how near you get to the quarry edge.  One of the banks and ditches, cut into bedrock, is shown below, with the sea in the background.  Tal y Garreg overlooks the Dysynni valley rather than establishing a good line of sight with hills to the east or the coast to the north, although a short walk along the ridge on an averagely clear day provides those views.  The views have been radically changed by quarrying, but there were clearly good lines of sight across the sea, down into the Dysynni valley and back along the ridge.

Ditch at Tal y Garreg, excavated through the bedrock. Ramparts on the bank at this point would have given views over the Dysynni valley and Cardigan Bay.

The site has never been excavated, so any thoughts on its date or the number of phases involved in its construction are purely speculative.  On both plans a 10m diameter “tower” is marked, and this was a circular structure, in front of which is a rock-cut ditch now full of stone, which may be the remains of the tower, suggesting that it was quite a substantial feature.  One proposal is that the small primary bivallate hillfort may have been overlain by a smaller and later fort that made use of the earlier features, and that the tower may have been part of this later re-use, dating to a Roman or post-Roman/Early Medieval re-occupation.  In fact, there is so little evidence of Roman presence in the area that it seems rather unlikely that a Roman fort was located here, so it is more likely that any second phase was post-Roman.

The Tal y Garreg hillfort is so small that I am not sure that it really qualifies for the title “hillfort,” when compared with more massive and impressive examples, that contained a number of other structures within their ramparts.  It does, however, feature typical hillfort characteristics. It took advantage of strong strategic position that could be partially barricaded with banks and ditches on vulnerable sides, using steep sides to provide natural barriers to attack.  Like most hillforts, although not all, it is on high ground overlooking good farming land or pasture.  Although there are no known settlements in the area, farmsteads were almost certainly dotted around the landscape much as they are today, and the hillforts probably overlooked some of these in the valley.  The ridge itself may have been used for grazing livestock, just as it is today. In the photograph below, the sheep were on top of the ridge and the horses were just outside the drystone wall at the top of the approach to the ridge.

The hillfort had no water supply other than rainfall.  This small defended enclosure could not have sheltered large numbers of people against hostilities, and could not have been reached in a hurry from the valley below, so it was either designed to shelter a privileged few;  to store important resources in a relatively inaccessible location;  to segregate certain centralized activities in a single location;  to be a visible symbol of territorial tenure – or a mixture of various roles.

Located both on the edge of the Dysynni valley and on the coastal plain, lines of communication could have extended both on a north-south axis and along the Dysynni valley, past Craig yr Aderyn (Bird Rock) hillfort, and into the Tal y Llyn valley heading northwest towards the hillforts near Corwen and Ruthin.  The ridge itself would have provided a high-level route alongside the Dysynni valley for c.1.5km.  At the other end of the ridge is another hillfort, Castell Mawr, which appears to have had a large annex that could have been used as a livestock corral.

Tal y Garreg is only a short walk from Llechlwyd hillfort, which also sits on the side of Tonfanau quarry, and I will be posting about in the future.  Both are poorly understood, and it is not known if they were related to each other or were chronologically separate.  They could have been contemporary but they may have been separated by anything from years or decades to one or more centuries. Until they are excavated this relationship will not be clarified.

I wanted to see if there was a clear line of sight from Tal y Garreg to the hillforts of Llechlwyd, also at the southwestern end of the ridge at the top of Tonfanau, Craig yr Aderyn (Bird Rock) c.8km to the east and Bwlch hillfort on the next hilltop, 2km to the north, Foel Llanfendigaid.  As none of these sites have been excavated it is not known whether they were contemporary, but in the event that they were, having a clear line of sight might have had many benefits, irrespective of whether the occupants of the hillforts were friends or enemies. The nearest hillfort, Llechlwyd, is visible from Tal y Garreg, which has a view down into the much lower promontory fort.   Craig yr Aderyn is visible from Tal y Garreg, although in the distance.  If required, it would have been easy enough to set up a signal on a clear day.  Bwlch is very easily visible, and looks like the perfect location for a hillfort.  Between the two, a near-flat piece of coastal plain is divided today into fields and used for pasture.

Craig yr Aderyn (Bird Rock) c.8km from Tal y Garreg

View from Tal y Garreg to Foel Llanfendigaid, on top of which is the hillfort Bwlch

It was useful to see what could be viewed when outside the hillfort, but still along the ridge, and it was impressive how many broad views were available from the ridge beyond the hillfort, some of which are below, all overlooking good quality pasture, currently being grazed by sheep and cattle, and far into the distance in all directions including the sea.  It was a hazy day so the views weren’t quite as spectacular as they might have been, but they showed enough to indicate that Tal y Garreg was a good site for watching movements for many miles around.

View from one side of the ridge to the other, taken from the stile.

Dysynni valley, looking east

A final though on the views available from the hillfort and visibility from below is that a couple of days later I went to walk along the Dysynni from Tonfanau bridge to Ynysymaengwyn, skirting the broadwater, and found that the entire of the top of Tonfanau was under a cloud, just where Tal y Garreg was built.  It was impossible to see its location, and it would be impossible to see anything at all from the hillfort down into the valley.  This could have been a distinct disadvantage in its location!  The second hillfort, Llechlwyd, which is on the lower promontory at 70m OD, was not shrouded in cloud, so although it had no visibility of the ridge behind it, it did have the advantage of being less prone to cloud cover.

There’s a modern structure on top of the hill at this point, which is an Ordnance Survey trig pillar.  There are also the foundations of an old shipping signal.  Ordnance Survey trig pillars (or points) are part of the history of mapping in the UK.  Trig is shorthand for triangulation, and in 1936 the first of c.6500 trig pillars were built as part of the project to retriangulate Britain.  Most of them made of concrete but the Tal y Garreg trig pillar was made  of local stone, and is shown on the right.  The OS is still responsible for maintaining the pillars, of which around 6000 remain at similar locations. The project was designed to improve the accuracy of mapping, and although it has been surpassed by modern techniques and technologies, it revolutionized map-making in Britain.  Here’s an excerpt from the Ordnance Survey page on the subject of the trig pillars:

Triangulation works by determining the location of a point by measuring angles to it from known points at either end of a fixed baseline and in this case, those known points were the 6,500 + trig pillars erected across the country. In practice, a theodolite would have been secured to the top mounting plate and made level. It would then be directly over the brass bolt underneath the pillar. Angles were then measured from the pillar to other surrounding points. For the highest accuracy primary points in the retriangulation, many rounds of angles would have been measured with the observations taking several hours.

I was expecting to have the hill to myself, but there was a group of around 10 people up there enjoying the view.  We exchanged cheerful greetings, and when they left I noticed that they took the  wide quarry track that runs on a shallow incline alongside the quarry scar.  Out of curiosity I took the same route down, and it runs into the quarry yard, which is the same as the access point to the Wales Coast Path.  A farm gate opens out onto the B-road.  The quarry track is not a public footpath, but it is not barred in any way, is safe, and as the quarry is out of use it seems okay to use it.  It’s a much easier, much shallower incline than the steep path that I took up.  Although not as attractive, it gives remarkable and safe views over the quarry itself.

The quarry track

When you reach the quarry yard, you’ll find that it is a piece of industrial archaeology in its own right, with an abandoned control panel in a small building, and various bits of abandoned heavy-duty hardware lying around, plus various shallow concrete water holders, presumably for filtration purposes.  One of them had a healthy population of bullrushes growing out of it.  Gwynedd Archaeological Trust reports that the quarry was first used for extracting granite, which is unusual in this area:

The ridge has been quarried since at least the nineteenth century. A narrow-gauge link to the Cambrian Railways was put in c. 1898, superseded by a standard-gauge siding in 1906, around the time it was taken over directly by John Corbett of Ynysymaengwyn, working as Tonfanau Granite Quarries. In 1965 this became a subsidiary of Penmaenmawr and Welsh Granite Co., and operated as Kingston Minerals from 1965 to 1981. It was thereafter worked by Mr G.C. Evans of Aberllefenni.

The report goes on to say that latterly the quarry was used to exploit a sill of coarse dolerite and gabbro that is suitable for use as road surfacing material.  Here are a few snaps of the quarry as I was on my way out, but I will be going back to explore in more depth.

Sources:

Bowen, E.G. and Gresham, C.A. 1967.  History of Merioneth, volume 1.  From the earliest times to the Age of the Native Princes.  The Merioneth Historical and Record Society.

Gwynedd Archaeological Trust 2009.  A visitor guide to the main Iron Age hill forts of Meirionnydd.  Project No. G1770. Report No. 839

Sjöberg, K.S. 2014.  Hidden possibilities.  Possible uses of hillforts in southern Gwynedd, north-west Wales. Unpublished Masters thesis, Uppsala University, Department of archaeology and ancient history. http://www.diva-portal.org/smash/record.jsf?pid=diva2%3A799381&dswid=8151

Websites:

Coflein
https://www.coflein.gov.uk/

Gwynedd Archaeological Trust (no date).  Historic Landscape Characterisation: The Dysynni
http://www.heneb.co.uk/hlc/dysynni/dysynni2.html