Lilstock Formation

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Lilstock Formation
Stratigraphic range: Rhaetian
~205–202  Ma
O
S
D
C
P
T
J
K
Pg
N
Type Formation
Unit of Penarth Group
Sub-unitsCotham Member, Langport Member
Underlies Blue Lias Formation, Scunthorpe Mudstone Redcar Mudstone Formation
Overlies Westbury Formation
Thickness1–10 m (3.3–32.8 ft)
Lithology
Primary Shale, siltstone, limestone, mudstone
Location
Coordinates 51°12′N3°18′W / 51.2°N 3.3°W / 51.2; -3.3 Coordinates: 51°12′N3°18′W / 51.2°N 3.3°W / 51.2; -3.3
Approximate paleocoordinates 35°30′N0°30′E / 35.5°N 0.5°E / 35.5; 0.5
Region England
CountryFlag of the United Kingdom.svg  United Kingdom
Type section
Named for Lilstock
United Kingdom relief location map.jpg
Pink ff0080 pog.svg
Lilstock Formation (the United Kingdom)
England relief location map.jpg
Pink ff0080 pog.svg
Lilstock Formation (England)

The Lilstock Formation is a geologic formation in England. It preserves bivalve, insect and other invertebrate fossils, as well as fossil fish of Agkistracanthus mitgelensis and the basal theropod dinosaur Newtonsaurus cambrensis dating back to the Rhaetian of the Triassic period. [1] [2]

Contents

White Lias

The White lias is a rare, fine-grained form of limestone from the late Triassic period, occurring only in certain parts of Somerset and infrequently in Warwickshire. [3] 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, [4] a multi-layered bed of stone formed from shale and limestone. At its base is a bone-bed yielding ancient marine, reptilian and ammonite fossils. [3]

White lias varies in colour from white-cream to pale grey and is traditionally used for building and flooring. [3] 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, Radstock, Langport and Wincanton. [3] Bowdens quarry in Langport is the only supplier of white lias, and of the more commonly found blue lias and grey varieties.

See also

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Beacon Limestone Formation Geological formation in England

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References

  1. Lilstock Formation at Fossilworks.org
  2. Galton PM. Bones of large dinosaurs (Prosauropoda and Stegosauria) from the Rhaetic Bone Bed (Upper Triassic) of Aust Cliff, southwest England. Revue de Paléobiologie, Genève. 2005; 24:51–74.
  3. 1 2 3 4 "Lias Stone Suppliers | Somerset Lias Quarry | Lovell Stone Group".
  4. Swift, Andrew (1995). "A review of the nature and outcrop of the 'White Lias' facies of the Langport Member (Penarth Group: Upper Triassic) in Britain". Proceedings of the Geologists' Association. 106 (4): 247–258. doi:10.1016/S0016-7878(08)80236-2.

Further reading