The Red Crag Formation is a geological formation in England, deposited from the latest Pliocene to the earliest Pleistocene (Gelasian). 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. 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. The most common fossils are bivalves and gastropods that were often worn by the abrasive environment. The most extensive exposure is found at Bawdsey Cliff, which is designated a Site of Special Scientific Interest (SSSI); here a width of around of Crag is exposed. At the coastline by Walton-on-the-Naze, remains of megalodon were found.UK Fossils - Walton on the Naze
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. 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, 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. This has led to the UK stratigraphic stage name Waltonian, which is usually correlated with the final Pliocene Reuverian Stage in the Netherlands. 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. 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. While some of these animals are as old as the Eocene (such as Hyracotherium and Coryphodon, originating from the London Clay), 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. 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. During the Late Pliocene, the region is thought to have had a temperate climate. 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. 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.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
Paleobiota
Mammals
Proboscidea Genus/speciesLocalityNotesImage"Mammut" borsoniNodule BedA member of the family Mammutidae, closely related to the American mastodon (Mammut americanum). One of the largest land mammals ever, originates from Pliocene depositsAnancus arvernensisNodule Bed and higher stratigraphic layersA "tetralophodont gomphothere", related to elephants, dating to the Pliocene-Early PleistoceneMammuthus rumanusThe oldest mammoth species known outside of Africa, dating to the PlioceneMammuthus meridionalisA. Lister. (1999). The Pliocene deer of the Red Crag Nodule Bed (UK). Deinsea, 7(1), 215–222.A large mammoth dating to the Early Pleistocene
Ungulates Genus/speciesLocalityNotesImageProboscidipparion sp.Nodule BedKnown 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.Plesiohipparion rocinantisNodule BedA three toed equine belonging to the extinct tribe Hipparionini. Suggested to be late Pliocene in ageEquus majorA large equine of Early Pleistocene ageStephanorhinus etruscusA rhinoceros belonging to the extinct genus Stephanorhinus, dating to the Late Pliocene-Early PleistoceneTapirus arvernensisNodule BedAn extinct tapir belonging to the genus Tapirus, dating to the PlioceneDasychoerus arvernensisNodule BedAn extinct swine (Suidae) dating to the Late Pliocene (MN zone 16), related to living African giant forest hogs.Hippopotamodon sp.Nodule BedA 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).Parabos sp.A bovineCervus perrieriNodule BedA large deer dating to the Pliocene, also known as Praeelaphus perrieriMetacervocerus pardinensisNodule BedA medium sized deer dating to the Pliocene, also referred to as Cervus pardinensisProcapreolus cusanusNodule BedA small deer dating to the PlioceneEucladoceros falconeriRed Crag properA deer of Early Pleistocene ageGazella sp.A gazelle of Early Pleistocene ageLeptobos etruscusNodule BedA bovine of Pliocene age closely related to living bison.
Primates Genus/speciesLocalityNotesImageMesopithecus sp.Nodule BedKnown 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.Macaca sp.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.
Rodents Genus/speciesLocalityNotesImageHystrix sp.An Old World porcupine, of Early Pleistocene ageCastor fiberCommonly known as the Eurasian beaver, species extant, remains are of Early Pleistocene ageTrogontherium minus Nodule BedA member of the beaver family (Castoridae) belonging to the extinct genus Trogontherium, of Pliocene-Early Pleistocene age
Carnivorans Genus/speciesLocalityNotesImageParailurus anglicusA member of the family Ailuridae, closely related to the living red panda, of Pliocene agePuma pardoidesA medium sized cat related to the living cougar/mountain lion (Puma concolor)Pliocrocuta perrieriA large bone cracking hyena, of Pliocene-Early Pleistocene ageUrsidae indet.A large bearOntocetus emmonsiAn 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
Cetaceans Genus/speciesLocalityNotesImage"Balaenodon physaloides"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.Belemnoziphius compressusA beaked whale.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.Balaenopteridae indet.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 Balaena gibbosa Owen, 1844, but these are now considered nomina dubia due to their fragmentary natureDelphinidae indet.Fitzgerald EMG. 2005. Pliocene marine mammals from the Whalers Bluff Formation of Portland, Victoria, Australia Memoirs of Museum Victoria 62(1):67-89Indeterminate remains of oceanic dolphins
Fish Genus/speciesLocalityNotesImageOtodus megalodonKnown from a tooth. A giant macropredatory shark, the largest shark ever Micromesistius poutassouKnown from an otolith. Commonly known as blue whiting, species extant
Invertebrates Over 240 mollusc species have been described from the Red Crag, making the table below only a small fraction of the total number of invertebrates. Genus/speciesLocalityNotesImageGlycymeris glycymerisCommonly known as a "dog cockle", belongs to the bittersweet clam family Glycymerididae, species extantTapes A saltwater clamSpisulaA surf clamMacomaA saltwater clam, includes extinct speciesMya arenariaCommonly known as the soft-shell clam, species extantMytilus edulisCommonly known as the blue mussel, species extantVaricorbula gibbaA bivalve commonly known as a basket shell, species extantVenerupis A bivalve commonly known as carpet shellsNeptunea contrariaA true whelk, species extant though with a much more southerly modern rangeNucella lapillusHarrison, Martin David (1984) A computer aided palaeoecological study of selected Red Crag (Lower Pleistocene) gastropods. Doctoral thesis, Polytechnic of North London.Commonly known as the dog whelk, species extantCerastoderma eduleKnown as the common cockle, species extantAnomiaA saltwater clam, BuccinumA true whelkCapulusA cap snailCalyptraea chinensisA superficially limpet-like gastropod, commonly known as the Chinese hat snail, species extantEmarginula crassaA species of keyhole limpet, still extantVenus casinaA saltwater clam, species extantAporrhais pespelecaniA gastropod, species extantTurritella communisA sea snail, species extantEuspira catenaA sea snail, commonly known as the large necklace shell, species extantColus gracilisA sea snail, species extantEnsisA razor clamTerebratulaA terebratulid brachiopod
See also
Cromer Forest Bed fossiliferous Pleistocene deposit in Norfolk, England
References
Bibliography