- One of the largest areas of limestone in the UK is found in the Yorkshire Dales National Park, near Malham and Ingleton.
- Limestone is a sedimentary rock made of calcium carbonate.
- It dissolves slowly in carbonic acid (carbon dioxide and rainwater) creating a range of distinctive landforms.
- The structure of limestone is like building blocks, with joints (vertical) and bedding planes (horizontal) separating the blocks.
- Most weathering takes place between the blocks where the acidic rainwater can penetrate: limestone is a perviousrock.
- Due to the pervious nature of the rock, drainage is usually underground and can only be seen where the limestone meets an area of impermeable rock. This process can be seen in the appearance of natural springs and is known as resurgence.
(Limestone cavern in the Peak District)
- Swallow holes or sink holes. This is where the acidic rainwater has dissolved and widened a joint in the limestone, and surface streams disappear underground, eg Gaping Gill near Ingleborough.
- Limestone pavements. Where limestone has been exposed at the surface due to erosion, the joints become widened to leave dips between the blocks of rock called grikes. The blocks are calledclints. There is an excellent example of limestone pavement above Malham Cove in North Yorkshire.
- Dry valleys. These were eroded by fast flowing surface streams towards the end of the last ice age when the ground was either frozen or saturated with glacial meltwater. The streams flow underground today, eg The Dry Valley of Watlowes, near Malham.
- Gorges. If the roof of an underground cave system collapses due to extensive limestone solution, it leaves a stream flowing at the base of a deep narrow valley.
- Caves. These are found when a stream flowing down a swallow hole has dissolved a large area underground. Deposits of limestone hanging down from the ceiling are called stalactites; those found rising from the floor of a cave are called stalagmites.
(Watlowes dry valley near Malham)
- Quarrying. Limestone is quarried in the Yorkshire Dales and is very important for the local economy. Limestone is used for building, cement and fertiliser. Limestone is also used in the steel industry, eg Castle Bolton quarry in Wensleydale, North Yorkshire.
- Tourism. Tourists visit the area for walking, camping, climbing, pot-holing, caving, educational visits and for the distinctive scenery. Over 8 million visitors provide employment and an important boost to the local economy, where farming has become less profitable.
- Farming. Sheep farming is common, as the soils are thin and unsuitable for any other type of farming. Some farmers diversify into camping and bed and breakfast accommodation.
(Malham Cove, Yorkshire)
- ‘Honeypot’ sites, such as Malham, become congested with cars and tourists, causing conflict with the local people.
- Ramblers can cause conflict with farmers – eg by dropping litter and leaving gates open.
- Some tourists buy second homes, pushing up property prices to the point where local people can’t afford them.
- Environmental damage to frequently used footpaths.