The Lilstock Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

. It preserves

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...

and other invertebrate

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

, as well as fossil fish of '' Agkistracanthus mitgelensis'' and the basal theropod dinosaur '' Newtonsaurus cambrensis'' dating back to the

Rhaetian The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest ...

of the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

White Lias

The White lias is a rare, fine-grained form of

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...

from the late

period, occurring only in certain parts of

Somerset ( en, All The People of Somerset) , locator_map = , coordinates = , region = South West England , established_date = Ancient , established_by = , preceded_by = , origin = , lord_lieutenant_office =Lord Lieutenant of Somerset , lor ...

and infrequently in

Warwickshire Warwickshire (; abbreviated Warks) is a county in the West Midlands region of England. The county town is Warwick, and the largest town is Nuneaton. The county is famous for being the birthplace of William Shakespeare at Stratford-upon-Avon an ...

. It gets the name ‘lias’ from the quarrymen's dialect for ‘layers’, referring to its natural state when quarried. White lias is part of the Langport Member of the Lilstock Formation, a multi-layered bed of stone formed from

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

and limestone. At its base is a bone-bed yielding ancient marine, reptilian and

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttle ...

fossils. White lias varies in colour from white-cream to pale grey and is traditionally used for building and flooring. Evidence of its use can be seen in manor houses, churches and cathedrals all over the UK. It is most prevalent in the Somerset towns of

Midsomer Norton Midsomer Norton is a town near the Mendip Hills in Bath and North East Somerset, England, south-west of Bath, north-east of Wells, north-west of Frome, west of Trowbridge and south-east of Bristol. It has a population of around 13,00 ...

Radstock Radstock is a town and civil parish on the northern slope of the Mendip Hills in Somerset, England, about south-west of Bath and north-west of Frome. It is within the area of the unitary authority of Bath and North East Somerset. The Rads ...

Langport Langport is a small town and civil parish in Somerset, England, west of Somerton in the South Somerset district. The parish, which covers only part of the town, has a population of 1,081. Langport is contiguous with Huish Episcopi, a separate ...

and

Wincanton Wincanton ( or ) is a small town and electoral ward in South Somerset, southwest England. The town lies off the A303 road, a main route between London and South West England, and has some light industry. The town and electoral ward has a popul ...

. Bowdens quarry in Langport is the only supplier of white lias, and of the more commonly found

blue lias The Blue Lias is a geological formation in southern, eastern and western England and parts of South Wales, part of the Lias Group. The Blue Lias consists of a sequence of limestone and shale layers, laid down in latest Triassic and early Jurassi ...

and grey varieties.

White Lias

See also

References

Further reading