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 Overview maps
 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
Ancient environments
Silurian l Devonian l Carboniferous l Triassic l Jurassic

The Carboniferous, 359 – 299 million years ago

Tropical reefs
At the end of the Devonian the sea spread across the Mendip area, marking the beginning of a long phase of limestone deposition. Initially, muddy sediments accumulated (Avon Group) in shallow, turbid waters, but gradually the reef limestones that are characteristic of the Carboniferous Limestone (Pembroke Limestone Group) became predominant. The environment in which these rocks formed was analogous to the Bahamas today, with tropical, warm, clear shallow water conditions covering the Mendip region in the early Carboniferous.

Sandstone deltas
Deposition of the Carboniferous Limestone was abruptly terminated by the southward spread of sandy sediment that today forms the Quartzitic Sandstone Formation. This sandstone formed part of a delta complex, built out by rivers that drained a landmass (St George's Land) to the north of the Mendip region.

Coal swamps
Throughout the Upper Carboniferous the river deltas that now covered the Mendip region were densely colonised by lush forests of giant tree ferns, horsetails and club mosses. River channels meandered through the forest and periodically the delta was flooded by the sea. Thick peat deposits formed in this tropical swamp, eventually becoming buried and transformed into coal.

  A reconstruction of the paleogeography in the early Carboniferous.
A reconstruction of the paleogeography in the early Carboniferous.

Life in the early Carboniferous

Life in the late Carboniferous
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