Yorkshire Dales, England
'Beautiful limestone pavement and vertical curved cliff face.'
From Joel Gill on Facebook.
'The spectacular limestone pavement & curved crag of Malham Cove'
From @Jamie_Woodward
Nominated by: @Jamie_Woodward(Twitter) Mark Godden, Joel Gill (Facebook)
Malham Cove is a spectacular natural limestone formation which comprises a curved limestone cliff at the head of a valley. The limestone pavement at the top is a superb example of later karst weathering.
Rock Formation
The limestone was formed during the early Carboniferous (Dinantian, 359-331 Million years ago), when sea levels rose and northern England was flooded by warm, tropical seas. At this time the area was about 10⁰ south of the equator.
Sedimentation in the north of England was influenced by structurally controlled blocks of Lower Palaeozoic basement which, due to extensional rifting, produced a set of basins and troughs. The Malham area lay near the southern edge of the Askrigg Block, a stable submarine plateau, underlain by granite, and overlain by shallow, clear, marine lagoons. Over this area beds of pure, pale grey 'shelf' limestone were deposited.
In the Malham area this limestone is known as the 'Great Scar Limestone' and can be seen at Malham Cove, Gordale Scar and on the plateau to the north. The distinct horizontal lines between the beds of limestone (bedding planes) indicate pauses in deposition. The bedded limestones contain many fossil corals, crinoids (sea-lilies) and shells. The latter are mostly brachiopods, a group of animals that are rare today but more common in Carboniferous seas.
Limestone deposition ended gradually with sediment brought from the north by huge rivers, deposited
by a Mississippi-like delta.
Ice Age
The features seen today are a legacy of the action of ice and melting of this. It was the last of four ice advances within the last sixty thousand years, which had most significant effects. A large waterfall flowed over the edge of the cove as the glacier melted and eroded the lip to form a curve. Today underlying cave systems have a large enough capacity to swallow any water before it reaches the fall, and the stream now disappears into a ‘sink’ about a mile from the edge. The last record of water flowing over the fall in an appreciable volume was in the early part of the 19th century.
Eroding ice also scoured the limestone plateau north of Malham to create the bare limestone exposing it to water action. Since then the rain has been quietly dissolving the limestone and widening the fissures and also forming many of the caves in the area. The rain continues to slowly dissolve the limestone today. Above Malham Cove, the Great Scar Limestone forms a spectacular limestone pavement with grykes (fissures) formed by the solvent action of rainwater on joints in the limestone.
Text courtesy of Lesley Dunlop