Article from Issue Number 12/1 February 2005

We all gathered on the Friday evening at the Beach Hotel, arriving by train to Taunton, bus and car. Those arriving at Taunton by train or bus were met by Eric and his son-inlaw to be ferried onto Minehead in two cars because our minibus had broken down. However, the minibus was quickly repaired and ready for us at 9 a.m. on Saturday morning, never to break down again during the weekend. We had all been wondering on the meaning of the name Minehead, thinking it had some relationship with a mine. However, Minehead Town Council’s website states that it was first mentioned in the Domesday Book of 1087, the name being Celtic, similar in origin to the Welsh mynydd (mountain), reflecting the prominence of North Hill just to the north west of the town.

Our hotel was opposite Minehead Station the terminus of the West Somerset Railway. We were greeted by the smell of coal smoke in the morning, so the first thing to do, after breakfast of course, was to go and look at the engine, which was in steam being polished for its first journey of the day. This engine was a 2-6-0 that had been “cannibalised” just recently. Its first outing had been in September (see photograph on www.lougs.org.uk). The railway was extended from Watchet to Minehead in 1874 and is now 22 miles long between Minehead and Bishops Lydeard although tracks do join with Taunton and, occasionally, Virgin Trains run a service called Somerset Venturer to Minehead. From 1860 onwards, under the auspices of the Luttrell family, new stone buildings were erected using local stone. For example, the Triassic red sandstone and Bath stone (windows) were observed in station buildings. After leaving the station we stopped at the War Memorial on North Hill, which gave a good, although misty, view of the topography of the coastline and the link with South Devon was postulated. The Hercynian folding and faulting had forced Exmoor and the Quantock Hills apart, which formed the source of material forming in the valleys of Permian and Triassic periods. With the view of Palaeozoic wooded hills and rounded hills of the New Red Sandstone we envisaged the Triassic monsoon drenching the landscape with the run-off eroding pebbles from the Palaeozoic beds, which tailed off into finer beds (Otter Sandstones). Below us was the Pleistocene inlet that had been drained by the Luttrell family; previously the sea had extended inland.

Our second stop was in Watchet by the Eastern pier of the harbour. We observed geology in action since when the tide comes in silt is deposited, which has to be dredged by suction across the sea wall. We observed the seaward dipping Mercia Mudstones, Rhaetian grey marls and black shales and the White and Blue Lias to the east of the harbour.

Coastal erosion was very marked at Watchet with its six metre tidal range. There has been an attempt to arrest this erosion with blocks of armour stone transported from the carboniferous limestone quarry at Frome. The Beach just east of Watchet harbour with seaward-dipping beds of mudstone, marl and shale and the armour can be seen in the third photograph on the LOUGS website.

The coast shows the passage from the warm climate with lacustrine and saline deposits of the Keuper Marls at the top of the Mercia Mudstone Group to chocolate and green layers of the Lias. Trace fossils were to be found here demonstrating the ecology of bivalves from freshwater to marine although evidence was hard to discern.

We walked back through the town, passing the Library, which had a number of interesting materials. These included sandstone pellets (nodules) in lime arid paler stone of Willaton. We also were impressed by the statue of the Ancient Mariner as we continued to walk across to Watchet West Beach. The first thing of note here were the cliffs, which had an inland dip compared to a seaward dip in the beds out to sea.

At the entrance to West Beach we observed the effects of the government ignoring the advice of the BGS. Sand had been extracted, which has led to ground being sucked away from elsewhere, demonstrating that you cannot isolate one part of the coast from another.

The Mudstone here had been deposited in water ponds during periods of semi-deserts that had been rich in salts. These evaporates had crystallised as lenticular deposits of gypsum (calcium sulphate) in the rocks. Later, when the rock was stressed and buckled during the Tertiary, fibrous gypsum formed that followed joints and bedding planes.

Lenses of gypsum (alabaster) had gone into solution and filled up the cracks. Examples of gypsum in fallen blocks and mudstones can be seen in the website photographs. The cliffs had good examples of faulting; the photograph below being an example of a “trap door” slump.

There was considerable evidence of splintering in the cliffs west of Watchet Harbour with fractures at point of impact.

We now walked back to Watchet where we had our packed lunch.

The last stop of the day was at Blue Anchor. After parking the minibuses we passed by an old brick kiln by side of road, which can be seen on the website. The beach between Blue Anchor and Watchet showed Liassic formation with inter-tidal bivalves in liquefied sand. Again, we saw Mercia mudstone (Keuper Marl). There were examples of small stresses that triggered landslips.

The photograph below shows a fault with the Penarth Group to the left and in the background, consisting of dark shales and sandy limestones of the Westbury Formation, which contain bivalves and fragments of fish. At the base of the cliff is the Blue Anchor Formation of alternating grey and green mudstones. The foreground consisted of Mercia Mudstone of red marls and mudstones.

We observed the Septarian nodules (see photo on website) formed by shrinkage of clay minerals, a from of dewatering under water when ion exchange occurred. The cracks formed in the process were later filled with minerals precipitated.

We all had a marvellous day looking at the many features of this coastline, looking for and finding fossils of ammonites and bivalves that illustrated life in late Triassic and early Jurassic times. It is an area that is worth revisiting.

Laurie Baker

Today was also rather overcast, and after a start made more leisurely by the change of clocks to GMT, we proceeded in convoy to the former Woolston Quarry, situated in a valley inland where New Red had infilled the Plaleozoic, and the terrain had subsequently been moulded by Pleistocene drainage.

The disused quarry had been billed in the notes as an accessible outcrop of the stone that underlies the valley. Some of the party were rather alarmed to discover that the “access” involved negotiating a particularly muddy lane serving a cow byre. Access was somewhat easier for the mini-van party whose parking arrangements enabled them to join the lane higher up the hill, but one or two members of this party got fairly well covered in deep mud. They had clung to the side of the lane only to discover to their chagrin that the centre was much firmer than it looked. The party was, however, well rewarded after leaving the lane, crossing the West Somerset railway line and walking up the meadow to the quarry exposures. The remains of the quarry well illustrate the varied debris which had buried the original landscape - part of a fault graben between the rial from that facies. The ramp had been eroded away and the whole area subsequently carved away to form the Bristol Channel in the Pleistocene, leaving only the islands of Steep Holm and Flat Holm, which displayed limestone of the same facies. The abundance of limestone material within the sandstone explains the presence of tufa-like material in joints in the quarry, which may have resulted from stresses subsequent upon deposition, in the Kimmeridgian or the Tertiary. The presence of the limestone pebbles also explains the former abundance of lime-kilns in local villages within the valley, where the limestone pebbles had been burned. Eric’s masterly exposition (drawing rapt attention from the party - interrupted only by the passing of two steam trains on the West Somerset line - the first drawn by a GWR tank engine and the second by the hybrid locomotive we had admired raising steam the previous day at Minehead station) mourned the passing of quarrying skills, and concluded in an attack on the Welsh Gorsedd for replacing the traditional stone circles with plastic pebbles. After negotiating the muddy lane, the party went in convoy to St George’s (parish) church of the nearby Sampford Brett, a hamlet once dominated by two great landed estates, and reflecting the violent streak in the Somerset character, which had produced one of the team that had murdered Thomas a Beckett. The church, in large part covered by rendering, nonetheless demonstrated the versatility of the different materials from quarries, like Woolston, for use in church building. Pointing to a window of Upper Lias limestone (weathered with characteristic “vents”) from Ham Hill - quite a distance from here - Eric said the stone was probably easily transported by river (via Sedgemoor) before being carted the final stretch. He also gave us a disquisition on the various gravestone materials and the symbolism of the memorial carvings. The convoy returned to the road and took an uphill route onto the Palaeozoic, through misty woods with yellow autumnal leaves, stopping at Raleighs Cross Inn for lunch, where we could sample Golden Hill Brewery Exmoor beer and other real ales. After lunch, passing the Beulah Chapel which had been built by Welsh miners, we drove a short distance into the Brendon Hills to visit the remains of haematitic iron ore workings, near the Naked Boy Stone - a boundary stone at the junction of three parishes, which drew its name from the hallowed Anglican practice of beating choirboys along the parish boundaries so that they would remember them well. Walking along the line of the disused West Somerset Mineral Railway - to where Metropolitan Line transport trains were “pensioned off” - we came to the remains of a Cornish engine house at Barrow Farm, built largely of Mort Slate (the local Devonian country rock through which the disused railway had run). The beam engine here had provided power both to pump the mine and raise the ore, which was then transported along the ‘Incline’ - Mineral Railway to Watchet - to go by sea to South Wales. In return, SouthWales provided steam coal for the engine, as will as miners to work the iron ore, in the latter part of the nineteenth century, because it had the right content in phosphorus for the Bessemer process then being developed in South Wales. However, in contrast to the pocket deposits found in Llantrissant and Rubaina (and also at the Clearwell Caves in the Forest of Dean), the ore here, found in quartz veins, was very difficult to work. In the 1880s, due to the competition of cheaper ores from Spain and Sweden, the quarries closed (although an abortive attempt was made to revive them just before World War 1). We picked up samples of the ore and ore-veined quartz from the nearby spoil heap, which has been exposed by the activity of sheep. As we returned to the road, Eric drew attention to a stile footrest, made out of a slab of the local Treborough slate, which was extensively used in the area for building and monumental purposes. The party then disbanded, with the minibus hurrying back to Taunton for bus and rail connections. All in all, this was a most enjoyable weekend, for which the participants are greatly indebted both to Eric, and also to Marilyn Carter who worked so hard to organise it.

Richard Trounson

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