Jackson, Ian. Cumbria Rocks — 60 extraordinary rocky places that tell the story of the Cumbrian landscape. Newcastle upon Tyne : Northern Heritage, 2022.
The richly illustrated and accessible book series of Cumbria, Northumberland and Durham Rocks are available to purchase from Northern Heritage.
Theme: Climate and landscape change
37 Great Asby Scar Orton — limestone pavement. A 4 kilometre walk eastwards from Orton village
Limestone pavements are rare in Britain and cover less than 2000 hectares in total. The best examples are in Cumbria and North Yorkshire. Those at Great Asby Scar are spectacular.
Limestone pavements are areas of bedrock which have been scraped bare by ice sheets. Limestone is a soluble rock and it has a natural system of grid-like joints and cracks. Water follows these and then dissolves the surface into blocks (called clints), separated by fissures (called grikes). While this natural ‘pavement’ is probably less than 15,000 years old, the limestone rock is much older. It was formed in a Carboniferous sea 335 million years ago. In some places you can see the fossils of corals in the rock, evidence that this sea was warm, shallow and clear and that at the time, what is now England, was very near the Equator. The rocks at Great Asby Scar are special and have given their name to rocks of the same geological age all over the world; they are called Asbian.
The plants which grow on limestone pavements take advantage of the different habitats the clints and grikes provide. Hart’s-tongue and rigid buckler ferns and dog’s mercury grow in the shadier grikes. These pavements are a very sensitive environment and pressure from grazing can seriously affect them; fortunately, a large part of the area is now a National Nature Reserve.