22nd August 2016: Cheddar Gorge. NGR ST 475 543 [centre]
Perhaps one of the best known limestone karst features in the country with many excellent exposures of the Carboniferous Limestone, including Clifton Down Limestone, Cheddar Oolite, Cheddar Limestone, Burrington Oolite and Oxwich Head Limestone.
The cliffs have many valuable semi-natural habitats and are home to a wide range of plant species, many of them rare, for example the exclusive Cheddar Pink. There are, of course, lots of caves formed within the limestone during early interglacial periods.
Over the years the origins of Cheddar Gorge has been the subject of many debates and is now suggested to be a fine example of a gorge cut by a surface river, rather than a collapsed cavern. The gorge has long been left high and dry as the drainage went underground.
Although the gorge is dry now surface drainage occurred in the past particularly during the many cold periglacial periods over the last 1.2 million years. Meltwater floods during brief summers flowed on the surface carving out the gorge.
Reference:
Western Mendip: A walker’s guide to the geology and landscape of western Mendip. British Geological Survey, NERC 2008.
