Beacon Hill

Limited parking is available along the roadside on Beacon Hill.

Beacon Hill [60] [ST 63835 45906] is the highest point on eastern Mendip, and forms a broad north-west-trending ridge. From this ridge there are many spectacular views across much of Somerset, and east to the Chalk downlands of Salisbury Plain. Two Roman roads cross the ridge: the Fosse Way running north–south, and the road from Charterhouse which runs along the ridge.

Beacon Hill is a pericline with Devonian Portishead Formation and older Silurian volcanic rocks (Coalbrookdale Formation) outcropping in the core and forming the elongate ridge stretching from Maesbury east to Cranmore Tower and Downhead. Carboniferous Limestone flanks both sides of the pericline, and is locally buried beneath younger rocks.

At the top of Beacon Hill is a narrow strip of woodland [60] [ST 63835 45906] that is managed by the Woodland Trust. This beech- and pine-dominated plantation has been woodland for over 200 years, and has a carpet of bluebells in the spring. A few patches of the original heathland vegetation occur in the wood. It lies at the junction of two Roman roads, and occupation that long predates the Romans is indicated by the numerous barrows in the woods, which form part of a 4000-year- old burial site. The Beacon, from which the hill takes its name, was located at the centre of a group of barrows and is marked by a standing stone.

The Portishead Formation is visible at several small outcrops in the woods. The rocks consist of a sequence of conglomerates and sandstones. The conglomerates contain far-travelled, well- rounded quartz pebbles with some rhyolite lava and granite pebbles set in a red-coloured sand matrix. These are overlain by red sandstones. The sandstone from this site was quarried and used at nearby Roman sites.

To the south, the Fosse Way descends steeply down the hill. South of the wood, there is a prominent break of slope, which marks the margin of the Lower Jurassic Downside Stone outcrop. This rock is draped over the older Carboniferous and Devonian rocks, and forms a gently sloping plateau between here and Shepton Mallet. To the east, the Silurian volcanic rocks outcrop along the ridge.

They consist of andesite and rhyodacite lavas, tuffs (consolidated volcanic ash) and agglomerate (volcanic conglomerate) sandwiched between ash-rich, fossiliferous siltstone and mudstone. These rocks are the remains of an ancient volcano that erupted into a shallow sea around 425 million years ago. They are the oldest rocks in the Mendips, and are the most southerly outcrop of Silurian strata in Britain. Fragments and pebbles of these rocks can be seen in ploughed fields and stone walls across the outcrop.

Silurian rocks have been quarried at Moon’s Hill Quarry, south of Stoke St Michael [61] [ST 66286 46061]. Quarrying has taken place here for about 120 years. This site comprises two large pits situated on either side of the road and clearly visible. The two quarries are now operated as a single entity by John Wainwright & Co Limited, an independent, family-run firm. The company employs around 30 full-time staff together with a slightly smaller number of contract hauliers. The quarry supplies both local and distant markets with a range of materials principally for road construction. The andesite lavas in particular are used for high grade, skid resistant roadstone. Around 500 000 tonnes of crushed stone are produced annually. The site is a working quarry, so access is only by prior arrangement.

The East Mendip Study Centre, an educational centre for school groups run by a consortium of local quarry companies is planned to be based here. The volcanic rocks were also quarried just south of Tadhill.

Just over a kilometre south of Moon’s Hill Quarry is the disused Waterlip Quarry [62] [ST 66047 44584]. Opened in 1899, this quarry worked the Carboniferous Black Rock Limestone. The rock was transported to the railway at Cranmore Station by a tramway, which also served Moon’s Hill Quarry and Downhead Quarry, 3 km to the north-east. The quarry was closed in 1946, and is now full of water.

To the south-east of Stoke St Michael lies Cranmore Tower [63] [ST 67682 45054], a folly visible from the surrounding roads rising above Cranmore Wood. The tower was built by local landowner Sir Richard Paget in 1863 and overlooks East Cranmore. The tower and the attached cottage are now a private residence and are not open to the public, but Cranmore Wood is accessible via public footpaths. This is a mixed woodland that contains some notable Somerset species and is underlain by sandstone.

From here there is a good view of the surrounding region and the underlying rock spans over 300 million years of geological history. In the foreground is the Torr Works quarry, excavated in Carboniferous Limestone. To the south-east, beyond the clay lowlands is the wooded Postlebury Hill, an outlier of the Cretaceous Upper Greensand, which also forms the escarpment beyond.

To the east is the conspicuous knoll of Cley Hill, topped by an Iron Age fort. This is an outlier of Upper Cretaceous Chalk, with the main Chalk mass of Salisbury Plain beyond. To the north-east, the Westbury White Horse sits just east of the conspicuous chimney of the Westbury Cement Works.

Images

(Figure 66) Aerial photograph of the Beacon Hill area.

(Figure 67) Conglomeratic sandstone of the Portishead Formation, Beacon Hill.

(Figure 68) Schematic cross-section of a volcano similar to that which produced the Coalbrookdale Formation volcanic rocks.

(Figure 69) A modern day volcano on Montserrat, producing pyroclastic ash-fall deposits similar to the Moon’s Hill volcano.

(Figure 70) Silurian volcanic rocks exposed in Moon’s Hill Quarry. Courtesy Somerset Geodiversity Audit.

(Figure 71) Locomotive on the Waterlip railway at Cranmore, operated by Roads Reconstruction Ltd, circa 1936. Courtesy National Stone Centre, F Davies collection.

(Figure 72) Cranmore Tower.