I will enhance this post by adding photos as appropriate.
Up Among the Preseli Crags
Carn Afr (093302)
Grid Ref SN. This is a very beautiful tor on the southern flank of the Preseli ridge, only a couple of kilometres away from the hamlet of Rosebush and almost due south from Foelcwmcerwyn summit. Its name can be translated as "the cairn of the goat". It is a hillside tor (rather than a summit tor) at an altitude of 380m, and it looks down upon a shallow depression and then over the "step" of Mynydd Crwn. The main feature of the tor is a prominent double pinnacle of rock which is visible from a great distance. Around it there are small vertical cliffs, grassy steps and clean slabs of rock, with a litter of massive boulders especially to the west. There are several perched boulders near the pinnacle. The rock is for the most part rhyolite, but there are also other foliated or layered volcanic rocks including tuffs and trachyte lava. This is the only substantial tor on Preseli which is made of volcanic rocks belonging to the Sealyham Volcanic Formation; all the others are made of rocks belonging to the Fishguard Volcanics. There is only a little scree, at the foot of the lowest of the cliffs. The tor is reminiscent of Plumstone Rock, and it is deeply weathered. It look as if it has been battered by the elements since the beginning of time....... But the lower part of the rocky slope has abundant ice-smoothed outcrops indicative of ice action, with an upper edge around 365 m.
Carn Alw (138338)
Grid Ref. SN. The largest and most spectacular tor in the whole of the Preseli area, standing in glorious isolation above the sweeping grasslands on the northern flank of the main upland ridge. Translated, its name is "echoing rock" or "calling rock". Its summit is only about 240m above sea-level. It is most easily reached from the roadside south of Glynmaen Farm. Its northern and eastern faces are high, shadowy and forbidding, but the approach is easy from the west and south. It is made of light-coloured volcanic rocks including dolerite, rhyolite, felsite and various others with complicated names. Look at the glassy texture and "flow structures" in some of the rock outcrops, formed while the rock was cooling from the molten state. About 400 million years ago this was clearly a major centre of volcanic activity; perhaps it developed as a subsidiary eruption cone on the flank of the much larger Foeldrigarn volcano. Some pieces of rock from here were assumed by HH Thomas to have found their way to the "bluestone circle" at Stonehenge; probably they were eroded by ice moving along shear-planes in the Irish Sea Glacier as it crossed the upland ridge, and were later dumped when the ice melted not far from the famous and enigmatic monument. (Note: Thomas's work has been questioned by more recent geological research.)
Carn Arthur (135323)
Grid Ref SN. Alt 300m. This tor is perched on the mountain side at 300m, looking down on the open depression of Cors Tewgyll and across to the crags of Carnmeini. The local rock here is coarse dolerite, and there are some outcrops which show the large while felspar crystals which are characteristic of spotted dolerite or bluestone. The rocky outcrop is easily approached from above, where there is a grassy platform close to a huge perched boulder. This massive block -- and possibly one or two others lower down on the outcrop -- were assumed by the locals to have been placed there by King Arthur or some other mighty hero. Less romantically, we now know these rocks to be nothing more than large glacial erratics left by retreating ice. The tor is in an advanced state of decay, with a great litter of broken blocks and scree banks on its lower part. Not far away is Bedd Arthur, reputed to be the burial place of the mysterious king.
Carn Bica (129326)
Grid Ref SN. This little tor would be called "pointed carn" or "peaked carn" in English, in recognition of its conical shape. Its altitude is about 380m. It is not a very prominent feature, and has suffered from a great deal of frost shattering in the Ice Age, and also from comprehensive rearrangement by the Bronze Age folk who built a large burial mound on its flank. The mound of loose stones has since been further rearranged by various members of "Dad's Army" who manned a lookout post here during the Second World War; and by assorted boy scouts and cadets trying to make shelters from the wind and the rain in this bleak and exposed spot. Note that the rock here is classic spotted dolerite -- the rough surface texture of boulders is characteristic, and on broken fresh surfaces the large white feldspar crystals are very noticeable. This cairn is close to the route of the Bronze Age "Golden Road", and about 100m to the east you can see the strange stone arrangement referred to by the locals as Bedd Arthur or "the grave of King Arthur." The wooden posts close to the carn mark part of the route of Ras Beca, the tough fell trace which takes place in these hills in August each year.
Carn Breseb (137333)
This carn (translated as "manger rock") is a substantial outcrop of spotted dolerite on the northern flank of the upland ridge, at an altitude of about 300m. In reality there are several stepped outcrops here, all of them very much degraded because of frost shattering and the downslope movement of blocks and scree. The tor does not look much like a manger, but the name may indicate that the local farmers once used to feed their animals here. The most prominent feature of the carn to be seen from a distance is the flat slab which looks like a gigantic needle when seen end-on. There is a large area of broken rock (and some solid rock) here, and it is fascinating to explore the nooks, crannies and crevices and to discover the sheltered and nutrient-rich "micro-environments" which provide homes for lichens, liverworts, and higher plants in this otherwise hostile and open terrain. There are traces of very ancient stone walls on the north-eastern flank of the carn, suggesting that it may have been used by the Iron Age inhabitants of nearby Carn Alw.
Carn Ddafad-las (147330)
There is not much left of this little tor, which can be named "the cairn of the blue sheep" in English. Goodness knows where its name comes from; perhaps there was once a prehistoric sheep farmer here who marked his sheep with blue dye made from bilberries! It is one of a group of little tors at about 325m just to the north of the Golden Road track and close to Carn Gyfrwy. Frost shattering, and possibly the action of overriding glacier ice, have damaged the tor so badly that it now consists simply of a rickety pile of massive boulders. One feels that the whole thing could collapse at any moment, so if you explore this tor and climb on it, please employ great caution.
There are no tors worth the name to the west of the Haverfordwest - Cardigan road, but there is a small one just to the east of the road as it drops down from Bwlch-gwynt towards Tafarn y Bwlch. In fact there are several small crags here, made of flinty and slightly speckled dolerite. This was one of the locations used in the making of a TV series called "Homeland", featuring Anthony Hopkins.
This is a small tor south of Foeldrigarn and the Golden Road. It is on private land and like Carn Sarn is therefore difficult to visit; but there are similar small tors (Carn Goi, Carn Pant-teg, and Carn Bwdcyn being the only named ones) in the coniferous woodland to the west. They are made of dolerite and other volcanic rocks. Before the woodland was planted there were two smallholdings in the neighbourhood, now reduced (like many others around the flanks of the uplands) to tumbled cottage walls and a few traces of paddocks and kitchen gardens. When you approach Carn Gaseg from the north you may feel that it does not look very interesting; but you would be mistaken, for when you drop down over the brow of the hill you encounter several splendid rock bastions up to 6m high. When seen from downslope the tor is very spectacular, and very beautiful. Most of the dolerite rock faces overlook a grassy terrace of bedrock slabs with patches of gorse and heather. Some of the slabs appear to have been smoothed by the action of overriding ice. The dolerite here is fine-grained and in places flaky. There are a few elongated stones which have been broken from the solid rock by frost action, and the tor is still breaking down, with long deep cracks, gullies and perched blocks.
Carn Goedog (128333)
This is one of my favourite Presely tors, partly because of its impressive size and partly because it is a tranquil place, seldom visited by hill walkers. Located on the northern flank of the upland ridge, it is adjacent to the old drover's route used by many thousands of animals en route from Pembrokeshire farms to the meat markets of the Midlands and London in the 1700's and early 1800's. The up-slope flank of the tor (at about 300m) is not very prominent, but on the downslope side there is a wilderness of huge dolerite blocks, banks of scree, little grassy platforms, solid rock outcrops, crevices and caves. The rock is very coarse, with some spotted dolerite. One or two small trees have managed to survive here in places inaccessible to grazing animals; but the name ("woodland cairn" in English) indicates that there must once have been an extensive woodland here after most of the upland ridge had been cleared by burning, felling and grazing. Recently the tor has attracted attention following the suggestion by geologists Richard Bevins an Rob Ixer that many of the Stonehenge spotted dolerite monoliths have come from here. Prof Mike Parker Pearson and colleagues claim that there is a Neolithic "bluestone quarry" here; but intensive investigations (reported on this blog) have revealed no unequivocal signs of quarrying in prehistoric times.
Carn Gwr (142330)
This name means "husband's cairn" or something similar. The name suggests that from a distance, a man might be standing on the summit. There are really five separate small tors here, scattered about on a broad saddle or col in the upland ridge at an altitude of c 315m. There are no steep slopes, and it is easy to stroll between one tor and another on the heather and bilberry moorland. Here you are right at the heart of "bluestone country", with tors all around you. Carn Bica, Carn Breseb, Carn Alw, Card Ddafad-las, Carn Gyfrwy, Carn Meini and Carn Arthur are all within easy walking range. As you walk around this area, with skylarks above and sheep and mountain ponies grazing on the moorland, you can feel the timeless serenity of Presely; and you can also see traces everywhere of human occupation of this landscape over 3,500 years or more. Slight ridges in the turf, pits, elongated hollows, fallen stone walls and small stone cairns may date back to Bronze Age or Iron Age times. An old cart track runs across the moorland here, linking the rock outcrops with the farming community to the north which used the area as a handy quarry for gateposts and other "special stones". The cart track, in places deeply entrenched, runs downslope between Carn Breseb and Carn Alw and then to the west of Carn Alw down towards Mirianog Ganol.
Carn Gyfrwy (147327)
One of the most prominent features on the Presely ridge, this cairn is more of a rock bastion than a tor. It is made of spotted dolerite or bluestone, and has a steep cliff face at its northern end, immediately overlooking the route of the ancient Golden Road. Its summit is about 365 m above sea-level. On the OS 1:25,000 Outdoor Leisure Map the place-name is incorrectly located; the name means "saddle cairn" in English, and there is no doubt which cairn has the saddle-like appearance. There is another error in the labelling of the so-called "sheep-fold" beneath the cliff face. This crude stone-walled enclosure has also been referred to in the literature as a "drover's hut." However, it is far too small to contain sheep, and it is some way from the old drover's route. It is more likely to be a simple shepherd's shelter used during bad weather. It is still used for this purpose by weary hill walkers caught out in the wind and rain.
Carn Meini or Carn Menyn is the one Presely cairn whose name is known to people from all over the world, since it is reputed to be the source of some of the famous Stonehenge spotted dolerite bluestones. (Its reputation is largely undeserved, since recent geological work suggests that the said bluestones have probably come from other locations.) The single name is used to describe a cluster of seven or eight distinct tors arranged in an arc around a spur on the upland ridge. They are very spectacular indeed, and from a distance they give the skyline a jagged or "cock's comb" appearance. The name is interesting. In English the name Carn Menyn (used on recent OS maps) would be "butter cairn", but this is a nonsense name in this geographical setting, and it is much more likely that the alternative Carn Meini ("cairn of the stones") has the better historical claim. Also, the words "maen" (singular) and "meini" (plural) are used in the context of shaped or dressed stone, as in "maenhir" ("long stone") used by the old archaeologists as a word for a standing stone. We may speculate therefore that the name was first used to describe a place of special elongated stones; and indeed there are many elongated stones here as a result of columnar jointing in the spotted dolerite. The massive tumbled blocks which are characteristic of this area indicate that there has been large-scale frost shattering here during periods of prolonged cold climate; but there are also some wonderful ice-smoothed surfaces at the southernmost edge of the rocky spur, with deep gullies and cliffs which indicate that over-riding glacier ice has "plucked" or dragged away large quantities of broken rock. The rock fragments, some of them weighing several tonnes, were carried up into the body of the glacier along shear-planes as it flowed southwards and south-eastwards, to be dumped hundreds or even thousands of years later on the fringes of Salisbury Plain. There are a number of possible man-made features among the Carn Meini tors. For example the flat stone referred to as the "altar stone" may be a sub-Neolithic burial chamber or cromlech, and there are a number of traces of very old stone walls that may date back to the Iron Age. An ancient cart-track is cut into the hillside between two of the eastern tors; it runs down to the road near Glanrhyd, and was used by farmers who were collecting convenient elongated stones from the mountain for use as gate-posts, lintels, steps or sills.
Carn Pant-teg (153327)
Literally this means "causeway cairn", and indicates an alignment of rocks. This little tor is almost due south of Foeldrygarn and is on private land to the south of the Golden Road. Access is not encouraged by vhe lndowner! The causeway or route remembered in the name may be the Golden Road itself, since it has been used by traders and local inhabitants over a period of at least 4,000 years. The tor is part of the same volcanic complex as Carn Meini and Carn Gyfrwy; and other small tors are now lost in the coniferous plantation of Llethyr-mawr. The tor is not very spectacular, consisting of little more than a few dolerite outcrops on the hillside and a few small pinnacles up to 3m high. There are broken boulders scattered across the slope, over an area of about 50m x 50m. There are grassy banks and patches of gorse and heather, and this is a pleasant sunny place sheltered from westerly and northerly winds.
This little dolerite tor, almost in the centre of the Talfynydd upland spur, is named after someone called Sian or Jane. It is unremarkable as tors go, but well worth a visit since the walking is easy hereabouts, and there are fine views towards Carn Meini and Foeldrygarn. The land surface in the vicinity of the tor has been greatly modified by the hand of man. If you look carefully you will see the traces of old stone walls and enclosures which probably date back to the Bronze Age or Iron Age. There are many elongated hollows which show us the routes of ancient trackways. And the turf is pock-marked with long-abandoned peat cuttings, reminding us that large parts of the upland were used as turbaries by the commoners who owned the farms and smallholdings on the flanks of the mountain.
Cerrig Marchogion (112323)
Here, on the crest of the upland ridge at an altitude of about 400m, the strange craggy outcrops of Cerrig Marchogion make a lasting impression on all who pass by on the nearby Golden Road. They are really small tors and rock outcrops made of dolerite, surrounded by a litter of broken boulders affected by frost action and moverd about by glacier ice. There is a magical quality about this place, especially when it is raining, or when low cloud or mist is drifting across the mountain ridge. Literally, the name means "the stones of the knights". The explanation for the name can be found in the ancient book called "The Mabinogion", in the story of Culhwch and Olwen. This is adjacent to Cwm Cerwyn where, according to legend, King Arthur and his knights fought a pitched battle with the wicked black boar Twrch Trwyth and his cohorts. So bloody was the battle that eight of Arthur's knights were killed, and the rocks are supposed to be their petrified remains.
Craig Talfynydd (130314)
This is a series of rock outcrops with banks of scree and broken slabs on the eastern flank of the Talfynydd spur. Literally, the name means "crag on the end of the mountain". This is a beautiful sheltered spot when the wind is in the west or north-west, with many gullies, dolerite outcrops and grassy banks to explore. Some small trees have managed to survive in the rocky wilderness. Because the slope is quite steep in places, some of the rock slabs and scree banks are still moving periodically but inexorably downslope; they are therefore quite unstable, and great care is needed when you clamber across them. There is a very large rabbit warren here, and you are certain to see rabbits of all ages scuttling about among the rocks. The spring below the crags is used to supply water to the cottage of Dan-y-garn in the copse of trees.
Craig y Cwm (096313)
This rocky outcrop high above the hollow of Cwm Cerwyn is not really a tor, but a series of crags and cliffs created by a combination of glacial action and frost shattering. The name means "the rock of the valley". Located quite close to the Presely summit of Foelcwmcerwyn, the altitude here is about 490m. The crags are made of slates and other rocks metamorphosed close to the dolerite intrusion which outcrops on the mountain summit. Down below there is a small and very old slate quarry with pits, cuttings, a trial tunnel, spoil heaps and a cart track running southwards around the end of the spur. The quarry excavations have made Craig y Cwm quite dangerous, especially when the grassy slopes are wet or when visibility is bad; this is one of the few places on Presely where a serious accident can happen if you are lost in the mist. A few years ago there was a fatal air crash here when a light aircraft en route from Swansea to Dublin flew into the side of the mountain in poor visibility. The cwm was probably the site of the last small glacier in Pembrokeshire; morainic traces and exposures in stream cuttings suggest that there was a small glacier here around 10,500 years ago.