{{Short description|Interglacial period of the Early Pleistocene}} The '''Waalian interglacial''' ({{langx|de|Waal-Warmzeit}} or ''Waal-Interglazial'') <ref>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.</ref> 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.<ref name=BGS>{{cite web|url=https://data.bgs.ac.uk/id/Geochronology/Division/BW|title=Waalian Stage|publisher=British Geological Survey|accessdate=28 November 2021}}</ref> It is variously dated by different authorities. Oxford Reference gives 1.3 to 0.9 million years ago<ref>{{cite web|url=https://www.oxfordreference.com/view/10.1093/oi/authority.20110803120307676|title=Waalian|publisher=Oxford Reference|accessdate=28 November 2021}}</ref> and the British Geological Survey 1.6 to 1.36 million years ago.<ref name=BGS/> 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.<ref>{{cite web|url=https://stratigraphy.org/ICSchart/QuaternaryChart1.jpg|title=Global chronostratigraphical correlation table for the last 2.7 million years v. 2020b|publisher=International Commission on Stratigraphy |accessdate=28 November 2021}}</ref> 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".<ref name=":0">{{Cite journal |last=Zagwijn |first=Waldo H. |date=1992-01-01 |title=The beginning of the Ice Age in Europe and its major subdivisions |url=https://dx.doi.org/10.1016/0277-3791%2892%2990015-Z |journal=Quaternary Science Reviews |language=en |volume=11 |issue=5 |pages=583–591 |doi=10.1016/0277-3791(92)90015-Z |bibcode=1992QSRv...11..583Z |issn=0277-3791|url-access=subscription }}</ref> It has been proposed that the Waalian Interglacial was composed of three phases: a temperate phase, a cool phase, and another temperate phase.<ref name=":1">{{Cite journal |date=1962-01-09 |title=Vegetational history of the Early Pleistocene of the Royal Society Borehole at Ludham, Norfolk |url=https://royalsocietypublishing.org/doi/10.1098/rspb.1962.0011 |journal=Proceedings of the Royal Society of London. Series B. Biological Sciences |language=en |volume=155 |issue=960 |pages=437–453 |doi=10.1098/rspb.1962.0011 |bibcode=1962RSPSB.155..437W |issn=0080-4649 |last1=West |first1=R. G. |s2cid=128467486 |url-access=subscription }}</ref><ref>{{Cite journal |last=Zagwijn |first=W.H |date=1957 |title=Vegetation, climate and time-correlations in the Early Pleistocene of Europe |journal=Geologie en Mijnbouw |series=New Series|volume=19 |pages=233–244}}</ref> 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).<ref name=":0" /> In addition, though earlier research indicated that the forest species assemblage of the Waalian period mirrored that of the Tiglian,<ref name=":1" /> more recent research into pollen records show that there was a marked decrease in the number of arboreal taxa from earlier Pleistocene periods.<ref name=":2">{{Cite journal |last1=Hahne |first1=Jürgen |last2=Ellwanger |first2=Dietrich |last3=Stritzke |first3=Rüdiger |date=2009-04-01 |title=Evidence for a Waalian thermomer pollen record from the research borehole Heidelberg UniNord, Upper Rhine Graben, Baden-Württemberg |url=https://egqsj.copernicus.org/articles/57/403/2009/ |journal=E&G Quaternary Science Journal |language=en |volume=57 |issue=3/4 |pages=403–410 |doi=10.3285/eg.57.3-4.7 |issn=2199-9090|hdl=11858/00-1735-0000-0001-B9E6-4 |hdl-access=free |doi-access=free }}</ref> Common arboreal taxa from the Waalian period included ''Tsuga, Eucommia, Celtis,'' and ''Pterocarya.''<ref name=":2" />
==References== {{reflist}}
{{North German glaciations}}
Category:Pleistocene Category:Interglacials