GCR block - Oxfordian (OXF)

Oxfordian

Block Description

UK map showing distribution of GCR sites of GCR block OXF
Distribution of GCR sites of GCR block Oxfordian

The GCR sites selected for this GCR Block represent the British geological record of Earth history from about 157 to 155 million years ago (Ma). This interval is the first part of the Late Jurassic Epoch, which spans from 157 to 140 Ma and is followed by the Kimmeridgian Age (see KIM). Rocks that formed during the Late Jurassic Epoch (part of the Jurassic Period) constitute the Upper Jurassic Series (part of the Jurassic System).

Outcrop pattern

On maps showing the solid geology of England, Upper Jurassic rocks crop out in an almost continuous strip from the Dorset coast to the North Yorkshire coast. In Scotland, Upper Jurassic rocks crop out in scattered patches in the islands to the north-west as well as in northern Scotland. The Corallian facies is well-known because it forms the hilly ground between Dorset and Oxford, and also in North Yorkshire

Palaeoenvironment and palaeogeography

Towards the end of the Mid Jurassic Epoch there was a significant marine transgression across much of Britain, drowning the varied shallow marine, fluvial, deltaic, saltmarsh and coastal lagoonal environments that had gone before. Thus, by the beginning of the Oxfordian Age, a shallow shelf sea was established over much of Britain. Sea levels rose throughout the Oxfordian Age and mudrock deposition was widespread, although limestones and sandstones of the ‘Corallian’ facies (near-shore or shallow water deposits) had developed by the end of early Oxfordian times.

GCR site selection

For the purposes of site evaluation and selection, the GCR sites can be grouped into five themes or ‘networks’, reflecting depositional setting largely controlled by deep-seated structural features. The networks are:

• Dorset to Oxford (Wessex Basin, and western margins of the ‘London Platform’)

• East Midlands (East Midlands Shelf)

• North Yorkshire (Cleveland Basin)

• Scotland (Moray Firth and Hebrides basins)

Although the relatively common invertebrate fossils do not have a separate selection category in the GCR in their own right, the scientific importance of many stratigraphy sites lies in their fossil content. Therefore, some of the GCR sites are selected specifically for their fossil fauna, which facilitates stratal correlation and enables the interpretation of the environments in which the animals lived. Moreover, some sites have international significance because they have yielded fossils that are the ‘type’ material for a taxonomic group.

Palaeontology, fauna and flora

The traditional means of subdividing the Jurassic System is by means of ammonites, abundant and diverse nektonic cephalopod molluscs that, because of their rapid evolution, prove to be almost ideal ‘zone fossils’, enabling the correlation and division of the rocks into relative ages by way of a distinct fossil ‘signature’.

Invertebrate faunas included abundant bivalve molluscs, such as oysters, smooth terebratulid and ribbed rhynchonellid brachiopods, gastropods (snails), asteroids (starfish), echinoids (sea urchins) and crinoids (sea lilies). Corals became a significant part of the fauna where there was carbonate sedimentation, along with sponges, bryozoa, echinoids and gastropds. Microscopic organisms included foraminifera, ostracods and phytoplankton (dinoflagellates and coccolithophorid algae).

Lobster- and shrimp-like crustaceans often produced burrows within sediments, preserved as trace fossils.

Belemnites, relatives of the ammonites, were abundant and along with fish were probably the main food of the aquatic reptiles, which were the largest vertebrate animals in the sea. These included plesiosaurs, pliosaurs and marine crocodiless. The fish included both holostean and teleostean bony fishes, and sharks and rays.

On land, dinosaurs had already become established in Mid Jurassic times but in Britain the Upper Jurassic record is fully marine.

In contrast to the manner in which most invertebrate fossils are represented in the GCR, fossils of vertebrates, arthropods (except trilobites) and terrestrial plants do have their own dedicated selection categories, owing to the relative rarity of the fossil material. See APD; JUR-CRE-RP; MES-MAM; MES-PALBOT; MZ-TR-FI-A; PALENT


Volume Introduction

Oxfordian


Site List

Your selection found 31 GCR sites. Sites are sorted alphabetically by country, local authority and then by site name -
CodeNameCountryLocal AuthorityGrid RefGCR Site Account
2100Dimmock's Cote Quarry (Upware)EnglandCambridgeshire CCTL543725Not available
2825Upware South PitEnglandCambridgeshire CCTL539709Site Account
1719Warboys Clay PitEnglandCambridgeshire CCTL309817Site Account
432Lynch CoveEnglandDorset CCSY649781Site Account
910OsmingtonEnglandDorset CCSY697816Site Account
828SandsfootEnglandDorset CCSY684797Site Account
2022South FerribyEnglandNorth and North East LincolnshireSE993204Site Account
898Betton FarmEnglandNorth Yorkshire CCTA002856Site Account
2122Cornelian BayEnglandNorth Yorkshire CCTA064855Site Account
1014Filey BriggEnglandNorth Yorkshire CCTA126816Site Account
897Hackness HeadEnglandNorth Yorkshire CCSE965904Site Account
928NewbridgeEnglandNorth Yorkshire CCSE800863Site Account
896NunningtonEnglandNorth Yorkshire CCSE646785Site Account
926Shaw`s GateEnglandNorth Yorkshire CCSE524824Site Account
927SnapeEnglandNorth Yorkshire CCSE509787Site Account
1984Spikers HillEnglandNorth Yorkshire CCSE979863Site Account
2121Wath QuarryEnglandNorth Yorkshire CCSE675750Site Account
831Cross Roads QuarryEnglandOxfordshireSP550064Site Account
1982CumnorEnglandOxfordshireSP462032Site Account
900Dry Sandford PitEnglandOxfordshireSU467996Site Account
1208Lamb & FlagEnglandOxfordshireSU380974Site Account
903LittlemoreEnglandOxfordshireSP532028Site Account
904LyehillEnglandOxfordshireSP592068Site Account
899Magdalen PitEnglandOxfordshireSP552071Site Account
830Shellingford CrossroadsEnglandOxfordshireSU326942Site Account
829Seend CleeveEnglandWiltshire CCST933609Site Account
920Steeple AshtonEnglandWiltshire CCST916559Site Account
1983WestburyEnglandWiltshire CCST853508Site Account
2007BroraScotlandCaithness and Sutherland and Ross and CromartyNC908040Site Account
2796North Elgol CoastScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNG518154Site Account
827StaffinScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNG468717Site Account
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