Limestone Scenery Limestone scenery is mainly found in England, in areas such as the Yorkshire Dales and the Peak District. Limestone is a sedimentary rock, laid down in horizontal layers. It is a resistant rock, and so forms high, level areas called plateaux
The most common type of limestone found in Britain is carboniferous limestone. Carboniferous limestone is made up almost entirely of calcium carbonate and so it is very susceptible to chemical weathering.
What are the landforms? • Limestone Pavements • Swallow Holes • Pot Holes • Caves • Stalagmites, Stalactites and Pillars • Gorges • Dry Valleys • Springs
Limestone Pavements Where there is an area of bare limestone ie no vegetation cover. The surface is made up of deep fissures called grykes running at 90 degrees to each other, leaving slabs of limestone called clints.
Limestone has been left bare because during glaciation, the ice scraped it clear of any soil, and soil takes a very long time to form. Grykes form because rainwater enters joints in the limestone; by the processes of carbonation, Hydrolisis and oxidation, the cracks are widened and deepened. Freeze-thaw also widens these cracks into grykes.
Rainwater contains a weak carbonic acid that reacts with the limestone, causing it to dissolve. RAIN CLOUD CLINTS GRYKES
Over time, the grykes become wider as the processes of carbonation, Hydrolisis, oxidation and freeze-thaw have affected them.
Stalagmites, Stalactites and Pillars • These are columns of calcium in a limestone cave. • Rainwater passes through limestone dissolving much calcium carbonate. • As the water trickles through the layers in the limestone it picks up larger amounts of calcium carbonate. • As the water reaches the cave it drips slowly from the ceiling of the caves. Some water evaporates leaving behind the calcium carbonate. • These deposits frow upwards and downwards very slowly, approximately 7mm per year. • The calcium carbonate forms needles shaped columns on ceilings, stalactites, and on the cave floor, stalagmites, where they meet together, limestone pillars form.
Rainwater trickles through the layers of limestone, picking up calcium carbonate. Stalactites Limestone Cave Stalagmites
As the water evaporates it leaves behind the calcium carbonate, forming stalagmites and stalactites
Task The picture below shows an area of carboniferous Limestone Draw a labelled sketch to help you describe the main surface and underground features associated with this type of landscape. (Use your notes to help you)
For any two features marked on your sketch, outline the main processes which were involved in their formation, ie. Limestone Pavement Limestone Cave Gorge Stalagmites and Stalactites (Pillars) Use your notes to help you, limestone features on pages 13 – 15, Processes on pages 2 - 4