Red Crag Formation

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The Red Crag Formation is a series of marine deposits at the base of the Pleistocene in Suffolk and Essex. This material rests on an erosion surface of Cretaceous to Palaeogene rocks. It is a shore deposit, medium to coarse-grained and locally shelly.[1]

The most extensive exposure of Red Crag is found at Bawdsey Cliff, the site of which is designated a Site of Special Scientific Interest.[2] Around 2 kilometres (1.2 mi) of Crag from the Gelasian are exposed.[2] Red Crag deposits have been dated from Piacenzian age at Walton-on-the-Naze to Preludhamian age at Sizewell on the basis of microfossils.[3]

Crag is a local word for a shelly sand. The Red Crag is generally stained red by ferruginous compounds.


  1. ^ Sumbler, M.G. (1996). London and the Thames Valley. British Regional Geology (4th ed.). British Geological Survey. ISBN 0-11-884522-5. 
  2. ^ a b Bawdsey Cliff, SSSI citation, Natural England. Retrieved 2013-01-25.
  3. ^ Brenchley, Patrick J.; Rawson, Peter F., eds. (2006). The Geology of England and Wales (2nd ed.). The Geological Society. pp. 433–434. ISBN 1-86239-200-5.