Limestone Pavement
The Formation of Limestone Pavements
Transcript:
Limestone, is a sedimentary rock that was historically used in buildings such as the Sphinx in Egypt. It also can create some dramatic scenery
Most of the limestone found in Britain was formed three hundred and fifty million years ago, when what would become Britain was under warm shallow seas south of the equator. It was formed with the bones of dead sea creatures and coral, compressed over long periods of time. It is laid down in beds separated by bedding planes. Cracks in the limestone are known as joins. As the earth moved, the limestone rose to form mountains.
During the ice age, a relatively recent three million to ten thousand years ago, all the soil and other rocks were worn off the top of the limestone by glaciers, leaving it open to chemical weathering.
Rain water, as it passes through the atmosphere, reacts with Carbon Dioxide forming a weak Carbonic Acid (H2CO3). As it lands on the Limestone an alkaline rock, mostly made of Calcium Carbonate (CaCO3) there is a reaction that produces a salt solution, water, and carbon dioxide. The rock appears to effervesce and the limestone is worn away by the reaction and the solution running off the surface creating runnels: slightly deepened channels.
The chemical weathering widens the joins helping water get below the surface to create caverns deep underground.
The flat weathered surface is known as a clint and the gaps between them are called grykes.
This is how a limestone pavement is formed.
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