This KS3 Geography quiz takes a second look at limestone scenery. Limestone is a sedimentary rock composed largely of the minerals calcite and/or aragonite, which are different crystal forms of calcium carbonate (CaCO3). Sedimentary rocks are deposited in layers on the beds of oceans, seas, lakes and occasionally on dry land. The breaks between the layers are called bedding planes. They are usually areas of weakness in a mass of rock. Carboniferous limestone is no exception, but not only does it contain bedding planes, it also contains a lot of vertical joints.
Rainwater is slightly acidic and, as you should have learnt in your science lessons, calcium carbonate will dissolve in acids. Rainwater slowly dissolves the vertical joints, widening them and creating a limestone pavement. As the water travels deeper underground, it can still dissolve the limestone, particularly along the bedding planes. This is how caves and caverns are formed. A cave or cavern that is close to the surface of the earth can suffer from a collapsed roof, creating a deep and steep-sided limestone gorge.