Red Crag Formation

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Red Crag Formation
Stratigraphic range:
Late Pliocene - Early Pleistocene
~3.3–2.5  Ma
O
S
D
C
P
T
J
K
Pg
N
Red crag cliff at bawdsey cliff suffolk 30-10-2013.jpg
Red Crag at Bawdsey Cliff in Suffolk
Type Geological formation
Unit of Crag Group
Sub-unitsSizewell Member
Underlies Norwich Crag Formation
Overlies Coralline Crag Formation
Thicknessup to 20 metres (70 ft), locally up to 45 m, offshore up to 70 m
Lithology
Primary Sand
Location
RegionEurope
CountryEngland

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.

Contents

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 miles) 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] including mammals such as Borson's mastodon ("Mammut" borsoni, a larger relative of the famous American mastodon), [12] the gomphothere (elephant-relative) Anancus arvernensis, monkeys including Mesopithecus (a relative of modern Asian langurs) and macaques (Macacus sp), [11] tapirs ( Tapirus arvernensis [13] ), the archaic swine Hippopotamodon and Dasychoerus, [11] three-toed hipparionine equines ( Proboscidipparion and possibly Plesiohipparion and Hipparion ), [14] the rhinoceros Stephanorhinus etruscus , the bovid Parabos , the deer Cervus perrieri, Cervus pardinensis and Procapreolus cusanus , [13] and the ailurid Parailurus anglicus (a relative of the modern red panda). [11] Other Pliocene mammals found in the Red Crag include the oldest and most primitive Eurasian mammoth species, Mammuthus rumanus . [13] 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, such as the equine Equus major, [15] the mammoth Mammuthus meridionalis, the giant deer Eucladoceros falconeri , [16] porcupines ( Hystrix sp.), Eurasian beaver, and gazelles (Gazella sp), though terrestrial vertebrate fossils from the rest of the Red Crag are considerably rarer than those from the nodule bed. [12]

See also

References

  1. 1 2 Davies, Neil S.; Shillito, Anthony P.; McMahon, William J. (November 2019). "Where does the time go? Assessing the chronostratigraphic fidelity of sedimentary geological outcrops in the Pliocene–Pleistocene Red Crag Formation, eastern England". Journal of the Geological Society. 176 (6): 1154–1168. Bibcode:2019JGSoc.176.1154D. doi:10.1144/jgs2019-056.
  2. 1 2 Lee, Woods & Moorlock (2015), pp. 110–111.
  3. Dixon, R. G. (1979). "Sedimentary facies in Red Crag (Lower Pleistocene, East Anglia)". Proceedings of the Geologists' Association. 90 (3): 117–132. Bibcode:1979PrGA...90..117D. doi:10.1016/s0016-7878(79)80014-0.
  4. Dixon, R. G. (1977). Studies in mollusca of the Red Crag (Pleistocene, East Anglia) (PhD). University of London . Retrieved 18 April 2018 via British Library.
  5. "Designated Sites: Bawdsey Cliff" (PDF). Natural England . Retrieved 5 April 2018.
  6. UK Fossils - Walton on the Naze
  7. 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 .
  8. Lee, Woods & Moorlock (2015), pp. 92–93.
  9. 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.
  10. "Global Chronostratigraphical Correlation Table for the Last 2.7 Million Years". Subcommission on Quaternary Stratigraphy. University of Cambridge. 2011. Retrieved 5 August 2016.
  11. 1 2 3 4 5 6 Pickford, Martin; Gommery, Dominique; Ingicco, Thomas (2023-11-07). "Macaque molar from the Red Crag Formation, Waldringfield, England". Fossil Imprint. 79 (1): 26–36. doi: 10.37520/fi.2023.003 .
  12. 1 2 3 Stuart, A. J. (May 1974). "Pleistocene History of the British Vertebrate Fauna" . Biological Reviews. 49 (2): 225–266. doi:10.1111/j.1469-185X.1974.tb01574.x.
  13. 1 2 3 4 Rivals, Florent; Lister, Adrian M. (August 2016). "Dietary flexibility and niche partitioning of large herbivores through the Pleistocene of Britain" . Quaternary Science Reviews. 146: 116–133. Bibcode:2016QSRv..146..116R. doi:10.1016/j.quascirev.2016.06.007.
  14. Cirilli, Omar; Bernor, Raymond L.; Rook, Lorenzo (March 2021). "New insights on the Early Pleistocene equids from Roca-Neyra (France, central Europe): implications for the Hipparion LAD and the Equus FAD in Europe". Journal of Paleontology. 95 (2): 406–425. Bibcode:2021JPal...95..406C. doi:10.1017/jpa.2020.99. hdl: 2158/1222918 .
  15. 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.
  16. A. Lister. (1999). The Pliocene deer of the Red Crag Nodule Bed (UK). Deinsea, 7(1), 215–222.
  17. 1 2 Chatwin, C.P. (1954). East Anglia and adjoining areas. British Regional Geology (3rd ed.). London: Her Majesty's Stationery Office.

Bibliography

51°59′58″N1°25′16″E / 51.9994°N 1.4211°E / 51.9994; 1.4211