Anglian glaciation
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| Anglian glaciation | |
|---|---|
| Name | Anglian glaciation |
| Period | Middle Pleistocene |
| Lithology | till, outwash, glacial sands, gravels |
| Namedfor | East Anglia |
| Region | Britain, Ireland, North Sea |
| Coordinates | 52.5°N 0.5°E |
Anglian glaciation was a major Middle Pleistocene glacial event that profoundly reshaped the landscapes of Great Britain, Ireland, and the North Sea. It produced extensive till sheets, reworked river systems such as the River Thames and River Trent, and left a record in stratigraphic sequences studied across sites like Hoxne, Suffolk, and Anglia. Paleoclimatic reconstructions tie the event to global shifts recorded in marine cores from the North Atlantic Ocean and polar ice records from Greenland and Antarctica.
Overview
The Anglian stage corresponds to a glaciation during the Middle Pleistocene recognized in the stratigraphy of England and referenced in continental correlations with sequences in France, Belgium, and The Netherlands. Classic study sites include Norfolk, Cambridgeshire, and Hertfordshire, while offshore evidence derives from surveys in the North Sea Basin and cores from the Rockall Trough. Key researchers associated with its definition include figures from the British Geological Survey and universities such as University of Cambridge and University College London.
Chronology and extent
Dating places the Anglian event within Marine Isotope Stage 12, approximately 478,000–424,000 years ago according to correlations with stacks like the LR04 benthic stack and the Speleothem record from Carlsbad Caverns National Park. Its maximum extent drove ice across much of England to the Thames Estuary and possibly into the Isle of Man, with lobes reaching the Wash and shaping the Cromer Ridge. Mapping by the Ordnance Survey and regional stratigraphic syntheses shows ice limits comparable to those of the Devensian glaciation in certain sectors but more extensive in others, implicating ice sourced from the Fennoscandian Ice Sheet and local British ice centers.
Causes and paleoclimate
Climatic forcing of the Anglian glaciation is attributed to orbital parameters described by Milutin Milanković and the Milankovitch cycles, particularly low obliquity and eccentricity modulating summer insolation for the Northern Hemisphere. Feedbacks involving atmospheric carbon dioxide drawn down into the cryosphere and ocean circulation shifts in the Atlantic Meridional Overturning Circulation likely amplified cooling, as inferred from proxies in cores from the North Atlantic Drift and the Rockall Plateau. Pollen records from sites like Hoxne and isotopic signatures in foraminifera point to dramatic biome shifts from temperate woodland to tundra-steppe conditions across Britain.
Glacial deposits and geomorphology
Anglian deposits include widespread tills, erratics, glaciofluvial outwash, and raised beaches, documented at localities such as Cromer, Clacton-on-Sea, and the Thames Valley. Landforms attributed to Anglian ice comprise terminal moraines, drumlins, and flattened surfaces mapped in Lincolnshire and Norfolk. Sedimentological analyses by teams from University of Oxford and University of Leeds reveal stratigraphic sequences where Anglian tills overlie older Hoxnian interglacial deposits and are in turn capped by interstadial loess and fluvial units, a pattern also observed in sections studied by the Natural History Museum, London.
Biotic and sea-level impacts
Flora and fauna experienced range shifts and regional extirpations during the Anglian, documented via pollen assemblages, beetle remains, and vertebrate fossils recovered at sites such as Weybourne, West Runton, and Hoxne. Mammalian faunas including taxa comparable to forms known from Boxgrove and Swanscombe records show turnover consistent with cold-stage extinctions and recolonizations. Global eustatic sea-level fall associated with ice volume is reconstructed from oxygen isotope stages and raised shoreline records at Dogger Bank and East Anglia; concomitant exposure of the Doggerland land bridge altered migration routes between Britain and continental Europe.
Correlation with other glaciations
The Anglian is correlated with the Mindel glaciation in the classical Alpine sequence and with glacial events recorded in the Scandinavian region and the Shetland and Orkney shelves. Stratigraphic correlation utilizes marine isotope stratigraphy, tephrochronology where available, and lithostratigraphic comparisons with sequences in Belgium, Northern France, and the Netherlands. Continental correlations draw upon work by researchers affiliated with institutions such as the Geological Survey of Denmark and Greenland and the Institut de Physique du Globe de Paris.
Research history and dating methods
Investigation of the Anglian began with 19th-century field mapping by geologists from the Geological Society of London and advanced through 20th-century syntheses by scholars at Cambridge University and the British Museum (Natural History). Modern dating integrates marine isotope stratigraphy, optically stimulated luminescence dating of glaciofluvial sands, uranium-series dating of carbonate deposits, and paleomagnetic analyses from continental and marine cores collected by research vessels like the RRS James Cook and platforms coordinated through the International Ocean Discovery Program. Ongoing work employs cosmogenic nuclide exposure dating by teams at University of Stirling and geochemical fingerprinting to refine ice-sheet models developed in collaboration with the Plymouth Marine Laboratory and computational groups at University of Edinburgh.