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 Locality areas
  Cheddar Gorge
 Charterhouse
 Blackdown
 Burrington Combe
 Shipham & Rowberrow
 Crook Peak & Axbridge
 Banwell to Churchill
 Priddy
 Harptree & Smitham Hill
 Draycott & Westbury-sub
 -Mendip
 Wookey Hole & Ebbor
 Gorge
 Wells
 Great Elm & Vallis Vale
 Mells & the Wadbury Valley
 The Vobster area
 The Whatley area
 Torr Works & Asham Wood
 Beacon Hill
 Stoke St Michael & Oakhill
 Holwell & Nunney
 Shepton Mallet & Maesbury
 Gurney Slade & Emborough
 The Nettlebridge valley
 Geology
 Rocks of Mendips
 Fossils
 Geological timescale
 Ancient environments
 Geological structure
 Minerals and mines
  Minerals and mines
 Industrial archaeology
 Quarrying
  Stone as a resource
 Employment & the economy
 Quarrying & geodiversity
 Quarrying & the environment
 History of quarrying
 Caves and karst
 How caves form
 Dry valleys and gorges
 Dolines and sinkholes
 Mendip caves
 Going caving
 Hydrogeology
 Biodiversity
  Flora and fauna
 Typical Mendip habitats
 Special Mendip habitats
 Horseshoe bats
 Appendix of names
 Biodiversity of western
 Mendip
 Biodiversity of eastern
 Mendip
 External links
 Detailed site information
  Coal mining
  Mendip quarry companies
  East Mendip quarries
 Biodiversity of eastern
 Mendip
  West Mendip quarries
 Biodiversity of western
 Mendip
 Acknowledgements
 Site map
Banwell to Churchill
The northern flank of Mendip between Banwell and Dolebury is formed by a narrow discontinuous ridge of Carboniferous Limestone. This forms the steeply dipping northern limb of the Blackdown Pericline. The limestone ridge was initially formed during Triassic times and then buried beneath the Triassic Dolomitic Conglomerate and Mercia Mudstone infilling the Lox Yeo valley. Only in the last few million years has erosion exhumed the hard limestone beneath, in effect recreating the former Triassic landscape.
  Aerial view of Banwell to Churchill (click to enlarge view)

Aerial view of Banwell to Churchill (click to enlarge view).

Overturned limestone
The Carboniferous Limestone is well exposed in quarries alongside the A38 at Churchill Batch. Here, the graffiti covered slabs of Burrington Oolite has been so severely folded that rocks have been overturned, and strata appear to dip to the south.
  The transition from overturned rock to vertically bedded and then upright, northerly dipping strata can be seen in the cliffs further south along the A38. The fossiliferous Black Rock Limestone outcrops in the many crags and scree slopes on the south side of Dolebury Warren which is dominated by the Iron Age hill fort. The rocks here are very steeply dipping or even vertical.

Ochre and potato stones
Evidence for old ochre workings can be seen in many places along the margins of the ridge between Banwell and Dolebury, particularly around Sandford. In places, small pits, spoil heaps and adits can be seen and specimens of ochre and quartz crystals, or 'Bristol Diamonds' can be found on the old spoil heaps. These quartz geodes, known locally as 'potato stones' are formed by the replacement of halite nodules by quartz. The halite (rock salt) nodules were originally deposited in ephemeral salt lakes during the Triassic, and evidence of these salt and gypsum deposits can still be found in the Mercia Mudstone.
  Quartz crystals ('Bristol Diamonds') from a geode, Sandford Hill.

Caves
At the western end of Banwell Hill are two caves; Banwell Bone Cave and Banwell Stalactite Cave. Miners broke into Banwell Stalactite Cave in 1757, but the entrance collapsed and the cave was largely forgotten about. In 1824, an attempt to reopen the Stalactite Cave led to the discovery of Banwell Bone Cave. This cave consisted of a large chamber almost filled with sediment and containing many thousands of bones. The bones includes many cold climate species such as reindeer, brown bear, wolverine and arctic fox dating from the early part of the last glaciation about 80 000 years ago. The Bishop of Bath and Wells, George Henry Law, who owned the land, took the bones as wonderful evidence for Noah's Flood. Both caves are on private land but are occasionally open to the public. On Sandford Hill are several small caves and mine adits including Mangle Hole which intercepts the underground river feeding the springs in Banwell.
  Banwell Bone Cave, with a collection of stacked bones

Quarrying
At the eastern end of Sandford Hill is the disused Sandford Quarry, which is developed mostly in the Burrington Oolite. In 1884, the quarry was a few small pits on the south side of the hill, but over the next 100 years expanded considerably into the western side of the hill. The quarry was closed in the 1990s as part of an arrangement to extend Whatley Quarry near Frome and parts of the site are now used for climbing and abseiling.
  Steeply dipping limestone, Sandford Quarry.

Flora and fauna
The nature reserve at Dolebury Warren is owned by the National Trust and managed by the Avon Wildlife Trust. This is an area of contrasting flower-rich limestone grassland and heathland, developed on acid loessic soils. Butterflies and insects are plentiful, especially on south-facing slopes where the conditions tend to be warmer.
  Gorse and anthills developed on limestone grassland, Dolebury Warren
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