limestone

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Page 2: Limestone
Page 3: Limestone

This is a map to show the location of the Yorkshire Dales National Park. Map courtesy of Ordnance Survey.

Map on the right shows the location of Malham.

Page 4: Limestone

Limestone pavements are large areas of exposed limestone. When the overlying rock was eroded the pressure release on the limestone below caused it to crack even more. Hence limestone pavements are characterised by large gaps between the rock, called grikes. The remaining blocks of rock are called klints.

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Swallow holes and sink holes are where rivers flow down into the rock. Sink holes are relatively small, whilst swallow holes are larger. Both have been formed either by the constant chemical attack of the water on the joints in the limestone, or by the collapse of a cavern below.

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When a stream disappears it travels underground through caves and eventually works its way down to a level of impermeable rock .The stream travels along the surface of the impermeable rock until it reaches the surface as a spring. Where limestone lies on top of impermeable rock along a valley there can be several springs which tend to form along the intersection of the two rocks.

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This is an example of a dry valley in the Yorkshire Dales national park. This has occurred from the limestone freezing to great depths. After this the ice melting and then carved out valleys over the frozen rock. As the limestone then thaws out the surface water makes its way down through the rocks and the dry valleys were left with no surface water.

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The cove face is noticeable for its horizontal ledges, due to variations in the hardness of the limestone layers, and the dark vertical stripes, which are formed by the growth of lichens and mosses as water seeps down the face of the rock. The addition of soot and dirt in the air gets caught on the growths, further changing the colour.

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The sides of this gorge overhang to a considerable extent, this is saying that there was once a great cavern, the roof of which has collapsed over the years.

On close observation remains of this roof can been found to the right above the first waterfall. The left side of the cavern is to be seen for its close and intimate vertical jointing dividing the limestone into thin plates this is less than an inch in thickness.

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The land in the Yorkshire dales national park is used for farming. Tourism to come and visit the park and be able to park there cars and have a luck around. For people to go and have a walk with the stunning scenery next to them. It is also used for holiday homes so people can come and buy a house to stay in at the park. The Dales offers excellent opportunities for caving, cycling, climbing and many other outdoor activities. The nature of limestone pavements is very popular for people to come and see. The land is also used for Quarrying limestone in the area.

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The underground features in the Yorkshire dales National park are:

• The cave system

• Caves

• Subsurface drainage

• Water table

• Ground water

• Stalactites

• Stalagmites

• Underground streams

• Columns

• Curtain

• And impermeable rock

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