Mendips header
 Overview maps
 Locality areas
  Cheddar Gorge
 Burrington Combe
 Shipham & Rowberrow
 Crook Peak & Axbridge
 Banwell to Churchill
 Harptree & Smitham Hill
 Draycott & Westbury-sub
 Wookey Hole & Ebbor
 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
 Rocks of Mendips
 Geological timescale
 Ancient environments
 Geological structure
 Minerals and mines
  Minerals and mines
 Industrial archaeology
  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
  Flora and fauna
 Typical Mendip habitats
 Special Mendip habitats
 Horseshoe bats
 Appendix of names
 Biodiversity of western
 Biodiversity of eastern
 External links
 Detailed site information
  Coal mining
  Mendip quarry companies
  East Mendip quarries
 Biodiversity of eastern
  West Mendip quarries
 Biodiversity of western
 Site map
Geology and biodiversity
Vegetation communities, and the species that they support, reflect a complex interaction between a wide range of environmental variables. These frequently include soil type, structure and pH, availability of nutrients, aspect, altitude, degree and type of grazing or management, and available soil moisture.

The nature of the bedrock fundamentally influences its overlying soil, and many plant and animal species are typical of certain soils that in turn are associated with a certain underlying rock. A good example of this are the rich downland habitats typical of thin rendzina soils over chalkland in southern and eastern England.

The Mendip Hills supports a wide range of soil types, ranging from thin alkaline soils over well-drained calcareous bedrock, through more neutral to acidic silty wind-blown loessic soils on flatter ground, to well-drained acidic podzols over Devonian sandstone on the highest ground. With some minor differences, a remarkably consistent suite of species can be found wherever these soils are present in many of the wildlife sites on Mendip.

Calcicolous (lime-loving) plants are strongly associated with poor mineral soils over limestone and other strongly calcareous rocks. Shallow rendzinas and other dry calcareous soils are typically high in free calcium carbonate, usually have an alkaline pH and are very low in the major plant nutrients nitrogen and phosphorus, as well as certain other trace elements. They are also usually freely draining, and become parched in summer. This environment therefore strongly favours plants that can tolerate these conditions, and the plants are often very diminutive as a result. Typical calcicoles of unimproved Mendip limestone grasslands include salad burnet (Sanguisorba minor), fairy flax (Linum catharticum) and sheep's-fescue (Festuca ovina).
  Thin limestone soils Crook Peak

Limestone heath and lead mining

Map of biodiversity

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