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05/12/2012 1 A Geological History of Britain WEEK 9 Cretaceous: not just chalk http://commons.wikimedia.org/ Woodcock & Strachan (2012) HOW MUCH OF IT IS CRETACEOUS?
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A Geological History of Britain
WEEK 9
Cretaceous: not just chalk
http://commons.wikimedia.org/
Woodcock & Strachan (2012)
HOW MUCH OF IT
ISCRETACEOUS?
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Early Cretaceous:The non-cretaceous
South
Speeton ClaySandringham Fm
Hunstanton Fm
Purbeck & WealdenWessex & WightGault & Greensand
North
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Rifting and lifting
Tectonics of Early Cretaceous Europe
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BGS Geoscenic
'Purbeckian'
Stair Hole, Lulworth Cove
Purbeck Group
Tithonian-Berriasian (Jurassic-Cretaceous)
J-C boundary poorly definedFew marine fossils
Very shallow basin:Arid to semi-arid lagoons, lakes, salt flatsLots of non-marine fossils
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Purbeck leaf bed
Purbeck Mammal Bed
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Weald
Wealden Dome
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Wealden GroupUp to 800m thick
Sandstones, siltstones, claystones, palaeosols
Braided rivers, lagoons, floodplains, soils
Wonders of the Weald
Baryonyx claw – 35 cm
Iguanodon teeth
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GreensandLower and Upper
Green marine sands
Gault Clay
Lower Greensand
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Vectis
Woody Wight
Fossil pine trunk, Hanover Pt, Isle of Wight
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Dinosaur Isle
Palaeontological Association field guide – Martill et al. (2001)
Further north...Separate marine
basin + shelf
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Sandringham Sands
Ferruginous marine sandstones
Speeton Clay
Grey clays + phosphate bed, Filey Bay
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The Straits of Bedfordshire
The Albian of Albion
MWH
Late Albian = beginning of true CretaceousChalk seas begin to flood Britain
Woodcock & Strachan (2012)
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The Albian of Albion
MWH
Atlantic opening = sea floor spreading= basaltic magma = carbon dioxide= GLOBAL WARMING + SEA LEVEL RISE
Woodcock & Strachan (2012)
Red Chalk first
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Late Cretaceous:The Flood
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Coccolithophores
Wikimedia Commons
Chalky creatures
Woodcock & Strachan (2012)
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Southern Chalk
Chalk-marl couplets show
climate cyclicity
Humidity = mud = marl
Northern Chalk
GCR Image Bank
Bempton Cliffs
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Chalk across the board
Late Campanian
Woodcock & Strachan (2012)
Northern Irish Chalk
White Cliffs, Portrush, Co. Antrim
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Mysterious Morvern
Loch Aline sandstone,Upper Cretaceous
BGS GeoScenic
Mull
GCR Image Bank
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The End (of the Mesozoic)
Next week
'Modern' Britain: The last 65 million years
Q. What links the Eocene with the Metropolitan Line?
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Geo-nealogy
WHERE
WERE
Links
Geology of the Wessex Coast – Ian M. West:http://www.southampton.ac.uk/~imw/
British Upper Cretaceous Stratigraphy:http://www.thegcr.org.uk/ImageBank.cfm?v=23&Style=All
Baryonyx:http://en.wikipedia.org/wiki/Baryonyx
Isle of Wight – Dinosaur Isle:http://www.dinosaurisle.com/newhomepage.aspx
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