up to 20 metres (70 ft), locally up to 45 m, offshore up to 70 m
Region
Europe
Country
England
The Red Crag Formation is a geological formation in England, deposited from the latest Pliocene to the earliest Pleistocene (Gelasian).[1] It outcrops in south-eastern Suffolk and north-eastern Essex. The name derives from its iron-stained reddish colour and crag which is an East Anglian word for shells. It is part of the Crag Group, a series of notably marine strata which belong to a period when Britain was connected to continental Europe by the Weald–Artois Anticline, and the area in which the Crag Group was deposited was a tidally dominated marine bay.[2] This bay would have been subjected to enlargement and contraction brought about by transgressions and regressions driven by the 40,000-year Milankovitch cycles.
The sediment in the outcrops mainly consists of coarse-grained and shelly sands that were deposited in sand waves (megaripples) that migrated parallel to the shore in a south-westward direction.[3] The most common fossils are bivalves and gastropods[4] that were often worn by the abrasive environment.[2] The most extensive exposure is found at Bawdsey Cliff, which is designated a Site of Special Scientific Interest (SSSI);[5] here a width of around 2 kilometres (1.2 mi) of Crag is exposed. At the coastline by Walton-on-the-Naze, remains of megalodon were found.[6]
The Red Crag Formation at depth in eastern Suffolk clearly has one member, the Sizewell Member, a coarse shelly sand with thin beds of clay and silt.[7] It was interpreted as having been deposited in large scale sand waves where the sea bed was deeper. The overlying Thorpeness Member, was provisionally assigned to the Red Crag based on its lithology but there is more evidence to suggest that it is part of the Norwich Crag Formation.
It has been proposed that the Red Crag started in the late Pliocene and to have possibly extended up into the early Pleistocene, but there is disagreement on more precise dating. According to the British Geological Survey,[8] the Red Crag sits within a segment of time from about 3.3 to 2.5 mya. It is considered that the Red Crag at Walton-on-the–Naze is the oldest and that it was deposited in only a few decades at some time between 2.9 and 2.6 mya.[9] This has led to the UK stratigraphic stage name Waltonian, which is usually correlated with the final Pliocene Reuverian Stage in the Netherlands.[10] While the precise age of the formation is uncertain, it is generally suggested that deposition of the formation as a whole spanned around 600–800,000 years.[1] There are difficulties in reconciling how the Red Crag equates with international chronological stages. In particular, the start and end dates are poorly defined due to the general paucity of age-diagnostic stratigraphic indicators and the fragmentary nature of the geology. It can also be difficult to separate the Red Crag from the overlying Norwich Crag Formation.
The base of the formation contains a nodule-rich bed (termed the "Nodule Bed", or "Coprolite Bed") with fossils including terrestrial vertebrates (as well as marine fossils such as those of whales and shark teeth), some of which were reworked from deposits considerably older than the Red Crag Formation itself and often display abrasion and polish indicating reworking.[11] While some of these animals are as old as the Eocene (such as Hyracotherium and Coryphodon, originating from the London Clay),[12] most originate from the Pliocene and late Miocene, at least as early as MN 11–12, around 9-7 million years ago in the case of some species.[11] The presence of monkeys and other thermophilic species implies that during the late Miocene-early Pliocene, the region was probably considerably warmer than today, and had a subtropical climate.[11] During the Late Pliocene, the region is thought to have had a temperate climate.[13] The Red Crag also contains Early Pleistocene fossils of animals similar in age to the formation itself, though terrestrial vertebrate fossils from the rest of the Red Crag are considerably rarer than those from the nodule bed.[12] The phosphatic nodules and bones in the bed were historically during the mid-late 19th century ground up on industrial scales to use as fertilizer.[14]
A member of the family Mammutidae, closely related to the American mastodon (Mammut americanum). One of the largest land mammals ever, originates from Pliocene deposits
Known from teeth. A three toed equine belonging to the extinct tribe Hipparionini. Suggested to be Pliocene in age. Previously referred to as "Hipparion" crassum. Although previously hipparionine teeth remains from the Red Crag have been attributed to other genera, including Plesiohipparion and Hipparion sensu lato, a 2021 paper suggested that all hipparionine remains from the Red Crag may represent Proboscidipparion.[16]
A swine (Suidae) either representing the species H. erymanthius or H. major, likely originate from the Late Miocene (MN zone 11-12, around 9-7 million years ago).
Known from a single tooth. A monkey belonging to the subfamily Colobinae, related to living African colobus monkeys and Asian langurs. Possibly of Late Miocene-Early Pliocene age.
An indeterminate macaque known from a tooth, possibly of Early Pliocene age. Has affinities with the Barbary macaque (Macaca sylvanus), which has a fossil record in Europe spanning the Pliocene and into the Pleistocene.
An extinct genus of pinniped in the family Odobenidae, related to the living walrus. Known from tusks. Previously referred to as Odobenus huxleyi and Trichecodon huxleyi
A problematic toothed whale taxon known from abraded teeth, suggested to be part of Physeteroidea, the group that includes the sperm whale and its close relatives.
Several species of rorqual whales have been described based on partial tympanic bullae, including Balaenoptera definata (Owen, 1844) Balaenoptera emarginata (Owen, 1844) and Balaenoptera or Balaenagibbosa Owen, 1844, but these are now considered nomina dubia due to their fragmentary nature
^Zalasiewicz, J. A.; Mathers, S. J.; Hughes, M. J.; Gibbard, P. L.; Peglar, S. M.; Harland, R.; Nicholson, R. A.; Boulton, G. S.; Cambridge, P.; Wealthall, G. P. (19 December 1988). "Stratigraphy and palaeoenvironments of the Red Crag and Norwich Crag formations between Aldeburgh and Sizewell, Suffolk, England". Philosophical Transactions of the Royal Society B. 322 (1210): 221–272. Bibcode:1988RSPTB.322..221Z. doi:10.1098/rstb.1988.0125
^Head, M. J. (1998). "Pollen and dinoflagellates from the Red Crag at Walton on the Naze, Essex". Geological Magazine. 135: 803–817. doi:10.1017/S0016756898001745
^Hunt, A.P. ∙ Lucas, S.G. ∙ Lichtig, A.J. A helical coprolite from the Red Crag Formation (Plio-Pleistocene) of England N. M. Mus. Nat. Hist. Sci. Bull. 2015; 67:59-247
^A. Lister. (1999). The Pliocene deer of the Red Crag Nodule Bed (UK). Deinsea, 7(1), 215–222.
^Cirilli, Omar; Machado, Helena; Arroyo-Cabrales, Joaquin; Barrón-Ortiz, Christina I.; Davis, Edward; Jass, Christopher N.; Jukar, Advait M.; Landry, Zoe; Marín-Leyva, Alejandro H.; Pandolfi, Luca; Pushkina, Diana; Rook, Lorenzo; Saarinen, Juha; Scott, Eric; Semprebon, Gina (2022-08-24). "Evolution of the Family Equidae, Subfamily Equinae, in North, Central and South America, Eurasia and Africa during the Plio-Pleistocene". Biology. 11 (9): 1258. doi:10.3390/biology11091258. PMC 9495906. PMID 36138737
^Lambert O. 2005. — System atics and phylogeny of the fossil beaked whales Ziphirostrum du Bus, 1868 and Choneziphius Duvernoy, 1851 (Mammalia, Cetacea, Odontoceti), from the Neogene of Antwerp (North of Belgium). Geodiversitas 27 (3) : 443-497.
^Boessenecker, Robert W.; Ehret, Dana J.; Long, Douglas J.; Churchill, Morgan; Martin, Evan; Boessenecker, Sarah J. (2019-02-13). "The Early Pliocene extinction of the mega-toothed shark Otodus megalodon: a view from the eastern North Pacific". PeerJ. 7. doi:10.7717/peerj.6088. ISSN 2167-8359. PMC 6377595. PMID 30783558