This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Skomer Formation | |
|---|---|
| Name | Skomer Formation |
| Period | Silurian |
| Type | Geological formation |
| Region | Pembrokeshire |
| Country | Wales |
| Namedfor | Skomer |
Skomer Formation The Skomer Formation is a Silurian stratigraphic unit exposed on the island of Skomer and adjacent parts of Pembrokeshire, Wales, notable for its well-preserved marine fossils and distinctive sedimentary facies. It has been the focus of regional studies by field geologists from institutions such as the British Geological Survey, the Natural History Museum, London, and the University of Cardiff, and features in palaeontological inventories maintained by the Geological Society of London and the Natural Resources Wales.
The Skomer Formation crops out across Skomer Island and nearby coastlines in Pembrokeshire Coast National Park, presenting a sequence of siliciclastic strata that records Silurian marine conditions contemporaneous with units in the Wales-Llanberis Basin and the Irish Sea Basin. It has been mapped and described in regional syntheses by authors affiliated with the Palaeontological Association, the Cambridge University Geological Department, and the University of Oxford, and figures in conservation plans for Skomer National Nature Reserve and the RSPB reserves on the adjacent mainland.
The formation lies within a tectonostratigraphic framework influenced by the Caledonian orogeny, related to terranes such as the Avalonia microcontinent and juxtaposed against the Laurentia margin during the Silurian. Stratigraphically it overlies older Cambrian–Ordovician sequences correlated with the Fishguard Volcanic Group and is overlain by younger Silurian and Devonian successions correlated with the Old Red Sandstone facies. Regional correlation has been made with sections at Trefin and St David's Peninsula and integrated into the British regional chronostratigraphy in reports by the Institute of Geological Sciences and the Royal Society.
The Skomer Formation consists chiefly of dark grey to black mudstones, siltstones and fine sandstones, punctuated by bioturbated horizons and occasional calcareous concretions studied by petrographers at the University of Manchester and the University of Liverpool. Sedimentological features include hummocky cross-stratification, parallel lamination and storm-related event beds comparable to those described from the Silurian of Gotland and the Cook Fjord Formation analogue studies. Grain-size analyses undertaken by teams from the British Antarctic Survey and the Plymouth University applied sequence stratigraphic concepts developed by researchers at the University of California, Santa Cruz and the ETH Zurich.
Fossil assemblages are dominated by benthic marine invertebrates including brachiopods, trilobites, cystoids and graptolites, with faunal affinities noted to classic localities such as Llandovery and Ludlow type sections. Important genera recorded include representatives studied in monographs from the Natural History Museum, London and the Smithsonian Institution, and microfossil work has been coordinated with the Palaeontographical Society and the Royal Society of Edinburgh. Vertebrate remains are rare but comparable finds have prompted comparisons with material from the Mawddach Group and collections curated by the National Museum Cardiff.
Biostratigraphic dating based on graptolite zones and brachiopod assemblages places the Skomer Formation within the Llandovery to Wenlock epochs of the Silurian, with correlations drawn to zonations developed by the International Commission on Stratigraphy and regional schemes advanced by the Geological Society of London. Correlative strata have been identified in the Pembroke Coast and linked to Baltican and Laurentian successions through faunal ties recognized in publications from the Danish Geological Survey and the Geological Survey of Ireland.
Sedimentological and paleontological evidence indicates deposition in a shallow epicontinental shelf to storm-influenced outer shelf setting under a generally warm Silurian greenhouse climate, consistent with paleogeographic reconstructions published by the Palaeomap Project and the University of Edinburgh. Oxygenation fluctuations and episodic anoxia inferred from black mudstone intervals have been interpreted in the context of Silurian events discussed at meetings of the International Palaeontological Association and in journals associated with the Geological Society of America.
Although not a major economic target for hydrocarbons or mineral extraction, the Skomer Formation is important for scientific research, educational fieldwork, and nature conservation, forming part of protected landscapes managed by the Pembrokeshire Coast National Park Authority and the Joint Nature Conservation Committee. Its fossil sites contribute to geoconservation registers maintained by the Geological Conservation Review and underpin public outreach coordinated with the National Trust and local museums including the St David's Museum.
Category:Geologic formations of the United Kingdom Category:Silurian Wales Category:Pembrokeshire