Not many people make a link between geology and wildlife but the rocks and other geological deposits of an area dictate the landscape, the plant communities and how both surface and ground water behaves. Limestone and chalk are alkaline and can support unique plant communities but hard limestone can produce crags and gorges whilst softer chalk makes a gentle rolling landscape. By contrast, nutrient- poor, acidic soils are ideal for heathland.
Devon has some of the most varied geology in the UK, from the dinosaur-era sands and chalks of East Devon, to the much older limestones of Torbay and Plymouth, and the rocky tors and bogs of Dartmoor’s once-molten granite. Devon even has an entire geological era named after it – the Devonian – the only county in the UK to be commemorated in such a way!
Devon has a part of a geological World Heritage Site – the Jurassic Coast between Exmouth and Poole in Dorset – ranked in importance for its geology alongside the Grand Canyon, as well as other World Heritage Sites of global importance such as the Great Barrier Reef, the Taj Mahal and the Great Wall of China.
Traditional buildings often reflect the local geology with granite cottages on Dartmoor; desert pebble or ‘pobble’ walls in East Devon, and grand limestone buildings of Plymouth, Torquay and Newton Abbot all giving us a clue to local rocks.
Churches are often constructed of a variety of rocks, from the gravestones and the font to the construction materials and decorative features. But the walls themselves usually reflect the local rocks, including the volcanic lava churches of the Exeter and Crediton area and the famous ‘Beer Stone’ of East Devon, a band of shell-sand limestone in the otherwise soft chalk, so valuable for carving window frames and other features that it was extensively mined. Even where the geology has no hard bands suitable for building, subsoil (often including permafrost sludge deposits from the last ice-age) was dug and mixed with straw to be used for cob buildings. Elsewhere valuable deposits of china and ball clays have been used for manufacturing tiles and pottery, but now have a wide range of other industrial uses – such as for producing nice white shiny paper!
The quarries and cuttings from where these rocks have been excavated demonstrate much more than a cultural heritage, however, as they also reveal insights into 400 million years of Earth history – they are, in effect, windows through time. They record ancient seas, desolate deserts, fiery volcanoes and frozen wastelands – but just like any other aspect of our heritage, they need sensitive management to be able to continue to tell their fascinating stories. Left alone and forgotten these rocks exposures can become overgrown and inaccessible, they may become illegal dumping sites or simply filled in, often due more to a lack of awareness of their importance than any other motivation.
In looking after this heritage, local communities can play a major role, not just in direct management such as controlling vegetation, but also in educating others about why geological sites are important.
Possible community activities include:
- helping clear scrub and other vegetation from rock exposures
- maintaining fences and gates to manage access and activities such as tipping
- providing information boards or leaflets about the local geology
- developing safe access for schools to geological sites
- making notes on the geology found during building works – many temporary excavations reveal features never seen before – just as they do for archaeologists!
- creating a geology trail highlighting interesting geological features in local buildings, churchyards, churches, rocky banks or quarries
- finding out more about your local geology and its associated wildlife habitats
- producing a parish map or ‘audit’ recording your area’s geological heritage – both historically recorded and visible today!
- quarries and cliffs can be dangerous places – health and safety should be a paramount consideration
- always seek permission from, and work in liaison with, the appropriate landowners
- geological features can have important biological interest, too. If in doubt, seek advice before clearing vegetation.