# Haig Fras
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{{Short description|Rocky outcrop near Cornwall, England}}
{{Use dmy dates|date=August 2021}}
thumb|450px|Map of granite outcrops onshore and offshore southwest England
'''Haig Fras''' is a 45 km long submarine [granitic](/source/Granite) rocky outcrop in the southern part of the [Celtic Sea](/source/Celtic_Sea), lying about 95 km northwest of the [Isles of Scilly](/source/Isles_of_Scilly). It covers an area of {{convert|356.5|km2|sqmi}}.[{{cite book|last=Smith|first=A.J. |author2=Stride A.H. |author3=Whittard W.F.|year=1965|title=Submarine geology and geophysics|editor1=Whittard W.F. |editor2=Bradshaw R.|chapter=The geology of the Western Approaches of the English Channel IV. A recently discovered Variscan granite west-north-west of the Scilly Isles|series=Proceedings Colston Research Society|volume=17|pages=287–301|publisher=Butterworths|chapter-url=http://chemport.cas.org/cgi-bin/sdcgi?APP=ftslink&action=reflink&origin=npg&version=1.0&coi=1:CAS:528:DyaF28Xms1CqsA%3D%3D&pissn=0028-0836&pyear=1966&md5=821b515b97b39907e7dd97d83ecd5bfb|issn=0069-6277}}][{{cite book|last=Edwards|first=J.W.F.|title=Variscan Tectonics of the North Atlantic Region |chapter-url=http://sp.lyellcollection.org/cgi/content/abstract/14/1/119|accessdate=10 January 2011|series=Special Publications|volume=14|year=1984|publisher=Geological Society|location=London|chapter=Interpretations of seismic and gravity surveys over the eastern part of the Cornubian platform}}] It is dated at 277 [Ma](/source/Year), [Early Permian](/source/Early_Permian) in age,[{{cite journal|last=Jones|first=D.G. |author2=Miller J.M. |author3=Roberts P.D.|year=1988|title=A seabed radiometric survey of Haig Fras, S. Celtic Sea, U.K.|journal=Proceedings of the Geologists' Association|volume=99|issue=3|pages=193–203|doi=10.1016/S0016-7878(88)80035-X}}]
The granite is thought to be cut by a [swarm](/source/Dike_swarm) of [basic](/source/Mafic) [dykes](/source/dike_(geology)) inferred from magnetic and [seismic reflection data](/source/Reflection_seismology). This swarm is interpreted to be 56 km long and 2.5 km across and at least six separate intrusive bodies have been identified. The proposed intrusions are though most likely to be of [Mesozoic](/source/Mesozoic) age.[{{cite journal|last=Edwards|first=J.W.F.|author2=Briant, M.|author3=Arthur, M.J.|year=1991|title=Proposed Mesozoic dykes in the Celtic Sea|journal=Proceedings of the Ussher Society|volume=7|pages=344–349|url=http://www.ussher.org.uk/journal/90s/1991/documents/Edwards_et_al_1991.pdf|accessdate=10 January 2011}}{{Dead link|date=July 2025 |bot=InternetArchiveBot |fix-attempted=yes }}]
==Fauna==
thumb|Devonshire cup corals are found at the top of the reef.
The bedrock reef at Haig Fras supports a range of fauna. Jewel anemones (''[Corynactis viridis](/source/Corynactis)'') and Devonshire cup corals (''[Caryophyllia smithii](/source/Caryophylliidae)'') are found at the top of the outcrop. Encrusting sponges, [crinoid](/source/crinoid)s and Ross coral ''[Pentapora fascialis](/source/Bitectiporidae)'' are found near base of the outcrop. Mobile fauna observed include [urchins](/source/Sea_urchin) such as ''[Echinus esculentus](/source/Echinus_esculentus)'', [brittle star](/source/brittle_star)s and the [squat lobster](/source/squat_lobster) ''[Munida](/source/Munida)''.[{{cite web|url=http://www.jncc.gov.uk/PDF/HaigFras_SelectionAssessment_4.0.pdf|title=Offshore Special Area of Conservation: Haig Fras SAC Selection Assessment|year=2008|pages=14|last=Joint Nature Conservation Committee|accessdate=10 January 2011|archive-date=13 October 2010|archive-url=https://web.archive.org/web/20101013150722/http://www.jncc.gov.uk/PDF/HaigFras_SelectionAssessment_4.0.pdf|url-status=dead}}]
==Special area of conservation==
The area of the proposed SAC is {{convert|481|km2|sqmi}}, which includes a margin of {{convert|330|m|ft}} around the mapped bedrock area, derived from the maximum water depth of {{convert|110|m|ft}} and an assumed length to depth ratio of a [fishing warp](/source/Fishing_trawler) (the cable used to tow the fishing gear) of 3:1.[{{cite web | url=https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/182373/vt-case-study5.pdf | title=Case Study 5 – The Benefits of Designation of Marine Conservation Sites | publisher=Department for Environment, Food and Rural Affairs | date=2010 | accessdate=14 September 2014}}] The area was first proposed in 2004 and was included in the first tranche of candidate SACs submitted to the [European Commission](/source/European_Commission) in August 2008.[{{cite web|url=http://www.jncc.gov.uk/page-1488#t36|title=Latest changes to the UK SAC list|last=JNCC|year=2010|accessdate=12 January 2011}}] It was selected on the basis of being an ''Annex I'' habitat, 1170 (reefs), in the terms of the [EU](/source/European_Union) [Habitats Directive](/source/Habitats_Directive).