Waalian interglacial

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The Waalian interglacial (German : Waal-Warmzeit or Waal-Interglazial) [1] or Waalian Stage was an interglacial period of the Early Pleistocene in north-west Europe. It was preceded by the Eburonian Stage and succeeded by the Menapian Stage. It coincides with part of the much longer Beestonian stage in Britain. [2] It is variously dated by different authorities. Oxford Reference gives 1.3 to 0.9 million years ago [3] and the British Geological Survey 1.6 to 1.36 million years ago. [2] However, the 2020 chart of the international authority on stratigraphic dating, the International Commission on Stratigraphy shows it as c. 1.6 to 1.4 million years ago. [4] It is distinct from other Pleistocene periods in its complexity, vegetational composition, and vegetational succession.

Its name is derived from a major branch of the Rhine delta, the Waal.

Distinguishing features

Unlike later interglacial periods, the Waalian Interglacial had at least one period of permafrost conditions, making it a "complex stage". [5] It has been proposed that the Waalian Interglacial was composed of three phases: a temperate phase, a cool phase, and another temperate phase. [6] [7] The Waalian Interglacial is also distinct from later interglacial periods in that the migration of tree species during this period did not follow a clear pattern of succession (i.e., most of the species that were present at the end of the Waalian were there at the beginning). [5] In addition, though earlier research indicated that the forest species assemblage of the Waalian period mirrored that of the Tiglian, [6] more recent research into pollen records show that there was a marked decrease in the number of arboreal taxa from earlier Pleistocene periods. [8] Common arboreal taxa from the Waalian period included Tsuga, Eucommia, Celtis, and Pterocarya. [8]

References

  1. ↑ Zagwijn, W.H., 1960. Aspects of the Pliocene and Early Pleistocene vegetation in the Netherlands. Mededelingen Geologische Stichting, Serie C-III-l, 5: 178 pp.
  2. 1 2 "Waalian Stage". British Geological Survey. Retrieved 28 November 2021.
  3. ↑ "Waalian". Oxford Reference. Retrieved 28 November 2021.
  4. ↑ "Global chronostratigraphical correlation table for the last 2.7 million years v. 2020b". International Commission on Stratigraphy. Retrieved 28 November 2021.
  5. 1 2 Zagwijn, Waldo H. (1992-01-01). "The beginning of the Ice Age in Europe and its major subdivisions". Quaternary Science Reviews. 11 (5): 583–591. Bibcode:1992QSRv...11..583Z. doi:10.1016/0277-3791(92)90015-Z. ISSN   0277-3791.
  6. 1 2 West, R. G. (1962-01-09). "Vegetational history of the Early Pleistocene of the Royal Society Borehole at Ludham, Norfolk". Proceedings of the Royal Society of London. Series B. Biological Sciences. 155 (960): 437–453. Bibcode:1962RSPSB.155..437W. doi:10.1098/rspb.1962.0011. ISSN   0080-4649. S2CID   128467486.
  7. ↑ Zagwijn, W.H (1957). "Vegetation, climate and time-correlations in the Early Pleistocene of Europe". Geologie en Mijnbouw. New Series. 19: 233–244.
  8. 1 2 Hahne, Jürgen; Ellwanger, Dietrich; Stritzke, Rüdiger (2009-04-01). "Evidence for a Waalian thermomer pollen record from the research borehole Heidelberg UniNord, Upper Rhine Graben, Baden-Württemberg". E&G Quaternary Science Journal. 57 (3/4): 403–410. doi: 10.3285/eg.57.3-4.7 . hdl: 11858/00-1735-0000-0001-B9E6-4 . ISSN   2199-9090.
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