Limestone rocks are sedimentary rocks (one of the three main rock groups) that are made from the mineral calcite. Limestone rocks are formed at the bottom of lakes and seas with the accumulation of shells, bones and other calcium rich goods.
For thousands, even millions of years, little pieces of our earth have been eroded, broken down and worn away by wind and water. These little bits of our earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of each. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock. The heat and pressure causes chemical reaction at the bottom and the rock turns into solid stone, the limestone.
Limestone is especially popular in architecture, and many landmarks around the world, especially in North America, Europe, and the pyramids in Egypt are made of limestone. In the 19th and 20th centuries, limestone became very popular in the architecture because limestone was readily available and relatively easy to work with. It is also long lasting and stands up well to exposure. However, it is a very heavy material, making it impractical for tall buildings, and relatively expensive as a building material.
Physical Properties of Limestone
3 to 4 on Mohs Scale (out of 10)
2.5 to 2.65 Kg/m3
1800 to 2100 Kg/cm2
Less than 1%
Stepping pyramid build of limestone
Limestone landscape also called Karst is a unique landscape formed by the underground erosion of rocks such as limestone and marble that dissolve in water. Rainwater, made acidic by carbon dioxide from the atmosphere and soil, slowly infiltrates cracks in limestone and marble, dissolving the rock and enlarging the openings. If these openings become large enough for humans to enter, they are termed caves. Caves, however, form only a tiny part of most karst areas. Karst openings support unique ecosystems that include plants, bacteria, crickets, spiders, fish, and small mammals adapted to this dark but little changing environment. Caves and karst develop slowly over tens of thousands of years or longer. Areas of karst landscape require careful management, as sensitive underground features can be damaged by surface activities such as road building or logging which alter the underground flow of water and air.
The subsurface component of the karst system under natural conditions is a stable environment that has developed over thousands of years, with consistent temperatures and humidity all year round. Unusual fauna that develop in this light deficient environment range from bacteria, crustaceans, spiders, fish and small mammals. These ecosystems are very sensitive to change. Changes in water percolation and airflow can significantly alter these stable environments effecting both life forms and the rates of bedrock dissolution. Karst offers opportunities for scientific study and education, allowing us a window into past environments that may not have changed for thousands of years.
The River Dove is named after the old English word dubo meaning ‘dark’. It rises on the gritstone moors of Axe Edge between Buxton and Leek, and flows south through Beresford Dale, Wolfscote Dale and Milldale before reaching the gorge of Dovedale. It meets the Manifold just east of Thorpe village, some 8km north of Ashbourne; and from there it meanders through farmland to its confluence with the River Trent at Burton-on-Trent in Staffordshire.
The power of the river to erode and transport material is dependent on the volume of water and its rate of flow. Erosion occurs far more slowly now than it did several thousand years ago when the glaciers were melting. However, in the winter, when rain and snow are frequent, the river floods its banks and washes away soil and rocks, fences and footpaths, often causing extensive damage. However, this action by the river does create a dynamic river valley, with where the river is not contained, shingle spits, eddies, islands and pools being created. This form of river creates habitats favorable to invertebrates and the water birds that depend on them, such as the Dipper. Arguably, this wild river is a richer river in terms of nature conservation value that the sections of the river which have been changed by the installation of weirs and revetments which favor a game fishing river. The National Trust is working with the fishing clubs and Environment Agency to formulate a conservation plan for the river; this should ensure a river for all for the future.
The Peak District National Park is one of the most visited areas in the world because it has a beautiful and wild countryside. Most people who visit the National park attend Dovedale. Dovedale is a very good place to do science because the environment is natural and the karst system is one of the world’s oldest natural systems to study. However most people visit Dovedale to enjoy the spectacular landscape and also because of the peace and quiet they find there.
The tourism in Dovedale provides an income and a livelihood for many local people. Visitors bring in an income to farmers with caravan and camping sites in their fields, to local villagers offering Bed & Breakfast in their homes and to hotels. The tourism provides an increased income for local shops, and there are also many more people working in shops and other service industries near to the park, whose jobs are related from the tourism in Dovedale.
The large number of tourists and visitors brings also problems. 90% of visits to the Park are made by car. Resulting in overcrowded car parks, blocked roads and pollution. The most popular paths in the park have led to considerable erosion of vegetation. The wildlife of some animal has been disturbed by the level of crowed.
To Limit problems at the park the National Trust lined up some idea’s :
1. To provide for those seeking quiet enjoyment of the Park – through promoting quiet active recreation, such as walking, cycling etc.
2.To reduce the number of visits made by car – in all parts of the Park, efforts are being made to encourage greater use of public transport with extra bus services and special routes serving popular honey pot areas.
3. To achieve a more even spread of visits over the year – the tourism market is very seasonal and many places are overcrowded in the summer and very quiet in winter.
4. To increase the number of staying visitors (who stay one or more nights) – as they spend more money and so help support the many small businesses which depend on tourism.
5. Keep the park clean by placing more bins.
The graph on the next page shows that most people who visit Dovedale never wander further than the Thorpe Cloud and the Stepping-stones. This is because most people drop out there because the distance from the car park to park is far so many people with health problems get tired.
Many people are likely more interested in the stepping stones and the outlook from the Thorpe Cloud.
Dovedale from the slopes of Thorpe Cloud
The Stepping Stones from the slopes of Thorpe Cloud
G.C.S.E. Geographical Investigation Landforms, Processes and Tourism in a River Valley : Dovedale, Derbyshire.