The Cromerian Stage or Cromerian Complex, also called the Cromerian (), is a stage in the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

glacial history of north-western Europe, mostly occurring more than half a million years ago. It is named after the

East Anglia East Anglia is an area of the East of England, often defined as including the counties of Norfolk, Suffolk and Cambridgeshire, with parts of Essex sometimes also included. The name derives from the Anglo-Saxon kingdom of the East Angles, ...

n town of

Cromer Cromer ( ) is a coastal town and civil parish on the north coast of the North Norfolk district of the county of Norfolk, England. It is north of Norwich, northwest of North Walsham and east of Sheringham on the North Sea coastline. The local ...

Great Britain Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...

where interglacial deposits that accumulated during part of this stage were first discovered. The

stratotype In geology, a stratotype or type section is the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, whereas the ...

for this

interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...

is the Cromer Forest Bed situated at the bottom of the coastal cliff near West Runton. The Cromerian stage preceded the Anglian and Elsterian glacials and show an absence of glacial deposits in western Europe, which led to the historical terms Cromerian interglacial and the Cromerian warm period (). It is now known that the Cromerian consisted of multiple glacial and interglacial periods.Böse et al. (2012), Quaternary Glaciations of Northern Europe, Quaternary Science Reviews 44, 1-25.
/ref>

Chronology

The core of the Cromerian is the first half of the

Middle Pleistocene The Chibanian, more widely known as the Middle Pleistocene (its previous informal name), is an Age (geology), age in the international geologic timescale or a Stage (stratigraphy), stage in chronostratigraphy, being a division of the Pleistocen ...

stage (Ionian) approximately 800-500 ka ago, just before the Anglian glaciation. In terms of

Marine isotope stage Marine isotope stages (MIS), marine oxygen-isotope stages, or oxygen isotope stages (OIS), are alternating warm and cool periods in the Earth's paleoclimate, deduced from Oxygen isotope ratio cycle, oxygen isotope data derived from deep sea core ...

s (MIS) this corresponds to MIS 19 to MIS 13. Some authors instead put the start at MIS 22, corresponding to a start 900 ka ago, which includes the last 100 ka of the Calabrian stage, after the Beestonian Stage.Lee et al. (2011), The Glacial History of the British Isles during the early and Middle Pleistocene: Implications for the long-term development of the British Ice Sheet, Quaternary Glaciations-Extent and Chronology, pages 59-74, Elsevier.
/ref> Some sources today correlate the Elster glaciation to MIS 10 instead of MIS 12, while keeping the Cromerian running up to the start of the Elsterian. The result is an end to the Cromerian stage in continental Europe at the end of MIS 11 (400 ka ago), and that the continental Cromerian continues beyond its end in Britain and Ireland and runs in parallel to the Anglian and Hoxnian Stages (MIS 12-11). In the Alpine region the corresponding stage is called

Günz The Günz is a river in Bavaria, Germany. It is formed near Lauben by the confluence of its two source rivers: the Östliche Günz (eastern Günz) and the Westliche Günz (western Günz). It is approx. long (including its western source river ...

. The Cromerian had been equated to the Aftonian in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. However, the Aftonian, along with the Yarmouthian (Yarmouth), Kansan, and Nebraskan, have been abandoned by North American Quaternary geologists and merged into the Pre-Illinoian.Hallberg, G.R., 1986, ''Pre-Wisconsin glacial stratigraphy of the Central Plains region in Iowa, Nebraska, Kansas, and Missouri'', Quaternary Science Reviews. vol. 5, pp. 11-15.Richmond, G.M. and D.S. Fullerton, 1986, ''Summation of Quaternary glaciations in the United States of America'', Quaternary Science Reviews. vol. 5, pp. 183-196. At this time, the Cromerian is correlated with the period of time, which includes the Pre-Illinoian C, Pre-Illinoian D, and Pre-Illinoian E glaciations of North America.Walker, M., 2005, ''Quaternary Dating Methods'', John Wiley & Son, Chichester, United Kingdom. Proposals for structuring the Cromerian complex have become quite confusing. Great potential for a full breakdown has been provided by the extensive, continental series at Gorleben.

Glacial cycles

Based on a lack of glacial evidence in Western Europe for the

(Ionian) before the Anglian glaciation, the Cromerian was originally thought to be a period without major glaciations. However, there is evidence for ice-rafting of material across the North Sea from this period. Investigations in the 1950s of oxygene isotopes in deep sea core samples revealed five glacial cycles during MIS 22 - MIS 13. The

Mid-Pleistocene Transition The Mid-Pleistocene Transition (MPT), also known as the Mid-Pleistocene Revolution (MPR), is a fundamental change in the behaviour of glacial cycles during the Quaternary glaciations. The transition lasted around 550,000 years, from 1.25 million ...

to the 100,000 year glacial cycle became established during the Cromerian. Four of the glaciations (MIS 22, MIS 20, MIS 18, MIS 14) were moderate, probably involving low-land glaciation in Scandinavia, but not spreading to England and northern Germany. One of the glaciations, Marine Isotope Stage 16 (MIS 16), is globally as strong as the most recent glaciations, MIS 6 (main

Saale The Saale (), also known as the Saxon Saale ( ) and Thuringian Saale (), is a river in Germany and a left-bank tributary of the Elbe. It is not to be confused with the smaller Fränkische Saale, Franconian Saale, a right-bank tributary of the M ...

) and MIS 2 ( Weichsel/Devensian). There is plenty of evidence in Russia for a major glaciation during this stage, which is called the Don Glaciation and believed to correspond to MIS 16. It is not clear why western Europe seems so unaffected by this major glacial.

Fossils

In 1990 the West Runton Mammoth skeleton was found, the best example of the species

Mammuthus trogontherii ''Mammuthus trogontherii'', sometimes called the steppe mammoth, is an extinct species of mammoth that ranged over most of northern Eurasia during the Early Pleistocene, Early and Middle Pleistocene, approximately 1.7 million to 200,000 years ag ...

to be unearthed so far. A significant

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

site, with animal remains dating about 600,000 years ago, is the Mosbach Sands in Germany, named after an abandoned village near

Wiesbaden Wiesbaden (; ) is the capital of the German state of Hesse, and the second-largest Hessian city after Frankfurt am Main. With around 283,000 inhabitants, it is List of cities in Germany by population, Germany's 24th-largest city. Wiesbaden form ...

, Germany.Ernst Probst: ''Deutschland in der Urzeit''. Munich: Bertelsmann, 1986
German National Library catalogue
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References

Sources

www.Stratigraphy.org

{{North German glaciations Quaternary geochronology Ice ages Pleistocene Interglacials

Chronology

Glacial cycles

Fossils

See also

References

Sources