Buildwas Formation
{{Use dmy dates|date=September 2019}}
{{Infobox rockunit
| name = Buildwas Formation
formerly Wenlock Shale
| image =
| caption =
| type = Formation
| age = Sheinwoodian
{{fossil range|433.4|430.5}}
| period = Sheinwoodian
| prilithology = Mudstone
| otherlithology = Limestone
| namedfor = Buildwas
| namedby = Butler
| year_ts = 1937
| region = Shropshire
| country = England
| coordinates = {{coord|52.6|N|2.5|W|display=inline,title}}
| paleocoordinates = {{coord|27.8|S|13.0|W|display=inline}}
| unitof =
| subunits =
| underlies = Barr Limestone Formation
| overlies = Rubery Formation
| thickness = {{convert|22|to|40|m|ft|abbr=on}}
| extent = Walsall to Wenlock Edge
| area =
| map = {{Location map+ | England#Shropshire
| relief = 1
| width = 250
| float = center
| places =
{{Location map~ | England#Shropshire
| lat_deg = 52.6
| lon_deg = -2.5
| mark = SpringGreen pog.svg
| marksize = 8
}}
}}
| map_caption =
| location_ts = Left bank of Hughley Brook
| coordinates_ts = {{coord|52|38|32|N|002|32|05|W|display=inline}}
| thickness_ts =
}}
The Buildwas Formation (Bw, BUI), formerly called Wenlock Shale and Buildwas Beds, is a geologic formation in Shropshire, England. It preserves fossils dating back to the Silurian period. The formation is the defining formation of the Sheinwoodian age of the Wenlock epoch, the Middle Silurian.
Description
The Buildwas Formation comprises olive-green and grey calcareous mudstones and nodular to lenticular calcareous mudstones and argillaceous limestones with shell fragments present throughout. The basal part of the formation consists of grey-green rubbly mudstones, containing comminuted shell debris and overlies the mottled green, grey and purple mudstones of the Rubery Formation with a {{convert|1|m|ft}} thick transition in colour and upward decrease in number of hard siltstone beds. The top of the Buildwas Formation shows a gradational increase in thickness of beds and a number of limestone beds, where it grades into the overlying Barr Limestone Formation.
The thickness of the formation ranges from {{convert|22|to|40|m|ft}}, with the thinnest outcrops occurring near Walsall thickening towards Wenlock Edge. The type section of the formation was defined by Barrett in 1989 along the left (north) bank of Hughley Brook, {{convert|200|m|ft}} southeast of Leasows Farm and {{convert|500|m|ft}} northeast of Hughley Church.[https://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=BUI Buildwas Formation - BGS Lexicon of Named Rock Units] - British Geological Survey The formation has provided fossils of Eodictyonella capewellii.[https://paleobiodb.org/classic/displayCollResults?collection_no=165224 Buildwas] at Fossilworks.org
See also
References
{{reflist|2}}
Further reading
- Bassett, M G, 1989. The Wenlock Series in the Wenlock area. 51-73 in "A global standard for the Silurian System". Holland, C H and Bassett, M G, (editors). National Museum of Wales, Gelogical series No.9, Cardiff.
- A. D. Wright. 1981. The External Surface of Dictyonella and of other Pitted Brachiopods. Palaeontology 24(3):443-481
- Basset, M G, 1974. Review of the stratigraphy of the Wenlock Series of the Welsh Borderlands and South Wales. Palaeontology, 17, 745-777.
- Cocks, L R M, Holland, C H, Rickards, R B and Strachan, I, 1971. A correlation of Silurian rocks in the British Isles. Geological Society of London, Special Report No.1.
- Butler, A J, 1937. On Silurian and Cambrian rocks encountered in a deep boring at Walsall, South Staffordshire, Geological Magazine, 74, 241-257.
Category:Fossiliferous stratigraphic units in Wales
Category:Geologic formations of England
Category:Silurian System of Europe
Category:Mudstone formations of the United Kingdom
Category:Silurian southern paleotropical deposits