Magnesian Limestone
Encyclopedia
The Magnesian Limestone is a suite of rocks in north-east England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 dating from the Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

 period. The outcrop stretches from Nottingham
Nottingham
Nottingham is a city and unitary authority in the East Midlands of England. It is located in the ceremonial county of Nottinghamshire and represents one of eight members of the English Core Cities Group...

 northwards through Yorkshire
Yorkshire
Yorkshire is a historic county of northern England and the largest in the United Kingdom. Because of its great size in comparison to other English counties, functions have been increasingly undertaken over time by its subdivisions, which have also been subject to periodic reform...

 and into County Durham
County Durham
County Durham is a ceremonial county and unitary district in north east England. The county town is Durham. The largest settlement in the ceremonial county is the town of Darlington...

 where it is exposed along the coast between Hartlepool
Hartlepool
Hartlepool is a town and port in North East England.It was founded in the 7th century AD, around the Northumbrian monastery of Hartlepool Abbey. The village grew during the Middle Ages and developed a harbour which served as the official port of the County Palatine of Durham. A railway link from...

 and South Shields
South Shields
South Shields is a coastal town in Tyne and Wear, England, located at the mouth of the River Tyne to Tyne Dock, and about downstream from Newcastle upon Tyne...

. The term has now been discontinued in formal use though it appears widely in popular and scientific literature on the geology of northern England.
The Magnesian Limestone is now incorporated within the Zechstein Group. In the southern part of its outcrop, the former 'Lower Magnesian Limestone' is now referred to as the 'Cadeby Formation'. Overlying this it is the 'Edlington Formation' (formerly the 'Middle Permian Marl') and above this the Brotherton Formation (formerly the 'Upper Magnesian Limestone'). In the north, the Lower Magnesian Limestone is now referred to as the Raisby Formation and the Middle Magnesian Limestone as the Ford Formation. The Upper Magnesian Limestone is replaced by the Roker Formation (in its lower part) and the Seaham Formation (in its upper part) with the Edlington formation between them, though in the Durham area this last is replaced by the Fordham Evaporite Formation and the Seaham Residue.

Much of the Magnesian Limestone is dolomite
Dolomite
Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....

, i.e. calcium magnesium carbonate, and has been for many years the main source of dolomite-rock in Britain. It is used in connection with the production of refractory bricks but also for aggregate for road-building and other construction purposes. It is also used in the production of agricultural lime.
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