• Water in cracks and crevices in limestone, freezes and expands. This action had its greatest effect during the ice ages as the land froze and thawed again and again, over many hundreds of thousands of years. Fragments of rock were gradually broken off and formed scree at the foot of the cliffs.
  
  
• The steep dales have been carved out by swift-running water - from melting glaciers during the ice ages as well as from rivers. Water continues to dissolve limestone, forming caves and washing away fragments of rock. Where layers of shale become waterlogged under layers of gritstone, landslips occur.
  
  
• wind blows dust against the rocks and over thousands of years particles are broken off and the surface worn down.
  
  
• Vegetation plays an important part in protecting the land from excess soil erosion. Grass roots build up fine soil particles into large crumbs that are not easily eroded. Roots and leaves of plants decay in the soil and form a sticky substance (humus) that has the same effect. Intensive cultivation keeps the soil bare in winter and tills the soil to fine particles which are then easily eroded by wind and rain. Fortunately most of the Peak District’s farmland is used for grass production, though some is ploughed up and reseeded every few years.
  
  

Erosion in the Peak National Park is a problem in two main areas - on the moorland in the Dark Peak and on the footpaths that cross both the moors and the farms and dales of the White Peak.
Reservoirs in the moorland area are also affected by erosion. Peat and soil particles washed into the reservoir from the surrounding land, gradually reduce the water storage capacity and reduce drinking water clarity to below the accepted EC levels.

• the destruction of the vegetation cover and the prevention of the regeneration of the plants
  
  
• the removal of the exposed material, especially peat, by water and wind. Peat was formed from the remains of vegetation which haven’t decayed because of acidity and lack of oxygen.
  

The first step is to identify the size of the problem and then to find ways to deal with it. The Moorland Erosion Project was set up in 1979. In a study of 13 moorland parishes in the Peak National Park, extensive erosion was found, particularly in the North-west. A number of factors were identified as contributing to the destruction of the vegetation and the subsequent erosion of the peat:-

1. Sheep have grazed the moors for hundreds - even thousands - of years. The numbers of sheep have gradually increased. Since 1950 the number has increased by 300%. Large numbers of ewes graze the moorland right through the winter. This overgrazing removes the vegetation (mainly heather and grasses). As flowers are eaten so the seeds which would have allowed regeneration are lost and the effects of overgrazing become long lasting.

moorland fire

2. Accidental fires during spells of dry weather kill off both the living plants and the dormant seeds in the soil. Vegetation is removed and regeneration is prevented. Severe fires can burn peat away.

3. The Climate with its high rainfall and low temperatures, means a very short growing season. This also makes it hard for seeds to grow into viable plants before winter frost lifts them out of the peat. The highest moorland, which has the lowest temperatures and is the most exposed, has the highest level of erosion. When ground is left bare, normal weathering is intensified by the high rainfall and the freeze-thaw effect of the low temperatures.

4.Heavy trampling by visitors to the moorland areas of the Peak National Park kills off the vegetation on some areas of deep peat, which is highly ‘trample sensitive’. A few thousand footsteps per year may be enough to cause erosion. This can cause a very marked localised effect but makes a relatively minor contribution to the major peat erosion.

5. During the 19th century a high concentration of sulphur dioxide (SO2) was given off by factories around the edges of the Peak District. These gasses caused Acid Rain which killed lichens and mosses such as sphagnum. Sphagnum acted as a giant sponge, protecting the surface of the peat. The levels of smoke and sulphur pollution have declined during the 20th century but pollution from nitrogen oxides (from vehicle emissions) and hydrocarbons has increased; the peat remains extremely acid and sphagnum is still confined to springs.

Erosion of the moorland has economic effects for the farmer and landowner. Loss of vegetation means that sheep and grouse (which feed on heather) have less to eat and so fewer can live on the moor. In some soils, damage to grass and heather can encourage bracken to spread.