Blisworth Limestone
Encyclopedia
The Blisworth Limestone is a stratum
of limestone
of the Bathonian
stage, found in the Jurassic
ridge which extends north and south through England
. It was laid down in the shallows of the Jurassic sea and is part of the more widely defined Great Oölite Series. It is also known as the Great Oolite Limestone. From the Jurassic ridge it extends eastwards below the later deposits and in the North Sea terminology, it is part of the West Sole Group. (Cameron p. 74)
onto minute nuclei to form tiny spheres which together resemble hard fish roe. This is composed of eggs; hence the name oölite. The process goes on today in the seas off the Bahamas (Kirkaldy p. 59). Much of it also contains marine shells, notably of oyster. Subsequently, the site was submerged less deeply so that the overlying Blisworth Clay was deposited in brackish conditions. (Gallois p. 20)
The stratum is known as Blisworth Limestone because it was first studied at Blisworth in Northamptonshire
when the Blisworth tunnel
was being dug for what is now called the Grand Union Canal
. The tunnel finally opened in 1805.
district, it is a shelly oolitic limestone 1 to 2 m thick. At Wiggenhall it is around 190m below mean sea level (OD) and at Tydd St Mary, around 140m. (Gallois) At Bourne, Lincolnshire
, at the eastern edge of the Jurassic ridge, it is around 15m below OD. (BGS sheet 144) It is exposed at the surface around the valleys of the East and West Glen rivers (River Glen, Lincolnshire
) in which vicinity it is 2.4 to 4.8 metres thick. (BGS sheet 143). Its exposure continues southward in a similar relationship to the Jurassic ridge, to the west of Peterborough
. (BGS sheet 157) Around Towcester
it reaches a thickness of 9m. (Hains & Horton p. 85)
in Northamptonshire is made from Blisworth limestone.
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
of limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
of the Bathonian
Bathonian
In the geologic timescale the Bathonian is an age or stage of the Middle Jurassic. It lasted from approximately 167.7 Ma to around 164.7 Ma...
stage, found in the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
ridge which extends north and south through 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...
. It was laid down in the shallows of the Jurassic sea and is part of the more widely defined Great Oölite Series. It is also known as the Great Oolite Limestone. From the Jurassic ridge it extends eastwards below the later deposits and in the North Sea terminology, it is part of the West Sole Group. (Cameron p. 74)
Formation
The Blisworth limestone lies above the Upper Estuarine Series of strata. The latter was formed close to the coast where rivers flowed from the London-Brabant Island. The land sank a little in relation to the sea so the site lay a little further offshore. In the hot, shallow sea, the water partially evaporated so that the dissolved calcium carbonate (CaCO³) was precipitatedPrecipitation (chemistry)
Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...
onto minute nuclei to form tiny spheres which together resemble hard fish roe. This is composed of eggs; hence the name oölite. The process goes on today in the seas off the Bahamas (Kirkaldy p. 59). Much of it also contains marine shells, notably of oyster. Subsequently, the site was submerged less deeply so that the overlying Blisworth Clay was deposited in brackish conditions. (Gallois p. 20)
The stratum is known as Blisworth Limestone because it was first studied at Blisworth in Northamptonshire
Northamptonshire
Northamptonshire is a landlocked county in the English East Midlands, with a population of 629,676 as at the 2001 census. It has boundaries with the ceremonial counties of Warwickshire to the west, Leicestershire and Rutland to the north, Cambridgeshire to the east, Bedfordshire to the south-east,...
when the Blisworth tunnel
Blisworth Tunnel
Blisworth Tunnel is a canal tunnel on the Grand Union Canal in Northamptonshire, England between the villages of Stoke Bruerne at the southern end and Blisworth at the northern end.-Measurements:...
was being dug for what is now called the Grand Union Canal
Grand Junction Canal
The Grand Junction Canal is a canal in England from Braunston in Northamptonshire to the River Thames at Brentford, with a number of branches. The mainline was built between 1793 and 1805, to improve the route from the Midlands to London, by-passing the upper reaches of the River Thames near Oxford...
. The tunnel finally opened in 1805.
Occurrence
Blisworth limestone is a generally thin but widely spread deposit in eastern England. It becomes thicker as one progresses southward from north Lincolnshire or westward from Norfolk. In the King's LynnKing's Lynn
King's Lynn is a sea port and market town in the ceremonial county of Norfolk in the East of England. It is situated north of London and west of Norwich. The population of the town is 42,800....
district, it is a shelly oolitic limestone 1 to 2 m thick. At Wiggenhall it is around 190m below mean sea level (OD) and at Tydd St Mary, around 140m. (Gallois) At Bourne, Lincolnshire
Bourne, Lincolnshire
Bourne is a market town and civil parish on the western edge of the Fens, in the District of South Kesteven in southern Lincolnshire, England.-The town:...
, at the eastern edge of the Jurassic ridge, it is around 15m below OD. (BGS sheet 144) It is exposed at the surface around the valleys of the East and West Glen rivers (River Glen, Lincolnshire
River Glen, Lincolnshire
The River Glen is a river in Lincolnshire, England with a short stretch passing through Rutland near Essendine.The river's name appears to derive from a Brythonic Celtic language but there is a strong early English connection.-Naming:...
) in which vicinity it is 2.4 to 4.8 metres thick. (BGS sheet 143). Its exposure continues southward in a similar relationship to the Jurassic ridge, to the west of Peterborough
Peterborough
Peterborough is a cathedral city and unitary authority area in the East of England, with an estimated population of in June 2007. For ceremonial purposes it is in the county of Cambridgeshire. Situated north of London, the city stands on the River Nene which flows into the North Sea...
. (BGS sheet 157) Around Towcester
Towcester
Towcester , the Roman town of Lactodorum, is a small town in south Northamptonshire, England.-Etymology:Towcester comes from the Old English Tófe-ceaster. Tófe refers to the River Tove; Bosworth and Toller compare it to the "Scandinavian proper names" Tófi and Tófa...
it reaches a thickness of 9m. (Hains & Horton p. 85)
Application
Blisworth limestone is used as a building material, in particular as blocks of stone. Lilford HallLilford Hall
Lilford Hall is a Grade 1 listed stately 100-room home having a Jacobean exterior and Georgian interior with a floor area, located in the eastern part of the County of Northamptonshire in the United Kingdom, south of Oundle and north of Thrapston. A Grade 1 listed building is considered by the UK...
in Northamptonshire is made from Blisworth limestone.