What type of weathering causes caves

Dissolution occurs when rocks are dissolved. Caves are formed when dissolved particles are washed away and leave hollow spaces behind.

Solution caves are formed in limestone and similar rocks by the action of water; they can be thought of as part of a huge sub- terranean plumbing system. After a rain, water seeps into cracks and pores of soil and rock and percolates beneath the land surface.

Examples of mechanical weathering include frost and salt wedging, unloading and exfoliation, water and wind abrasion, impacts and collisions, and biological actions. All of these processes break rocks into smaller pieces without changing the physical composition of the rock. Caves are formed by both chemical and mechanical weathering. The water sinks underground into holes known locally as 'swallets' or 'slockers'. The streams reappear at the base of the limestone outcrop at large springs, for example at Cheddar and Wookey Hole.

Over time, the water finds new lower routes leaving some caves high and dry. Some of these have been dug out by cavers. The dipping Carboniferous limestones have produced a particular style of cave.

A typical Mendip swallet cave is developed where a stream sinks underground at the contact between the Avon Group and the Carboniferous Limestone. Initially the cave descends steeply, often down dip or along joints, via a series of small cascades or pitches.

These dissolve in the water, and then are washed away, weathering the rock. Some types of rock are not easily weathered by chemicals. For example, granite and gabbro are hard rocks that are weathered only slowly. However, some of their minerals do react with the acids in rainwater to form new, weaker substances that crumble and fall away.

Coal, oil and natural gas are fossil fuels. The equation is as follows:. Limestone also dissolves at relatively shallow depths underground, forming limestone caves. This is discussed in more detail in Chapter 14, where we look at groundwater. The main processes of chemical weathering are hydrolysis , oxidation , and dissolution.

Complete the following table by indicating which process is primarily responsible for each of the described chemical weathering changes:. Skip to content Chapter 5 Weathering and Soil. Exercise 5. Complete the following table by indicating which process is primarily responsible for each of the described chemical weathering changes: Chemical Change Process? Pyrite to hematite Calcite to calcium and bicarbonate ions Feldspar to clay Olivine to serpentine Pyroxene to iron oxide.

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