Viviparus diluvianus
Het Needien:
Introduction
Definition and age
Relation with units used formerly and elsewhere
On Viviparus diluvianus
On the age of Neede
More information
Literature


Inleiding
The 'Needien' is a stratigraphical unit from the Quaternary subdivision of Van der Vlerk & Florschütz (1950). The name is outdated and not in use anymore. The unit formed part of the Dutch Quaternary subdivision and was preceeded by the Taxandrien and succeeded by the Drenthien (now Saalian).

Definition and age
The ice-pushed (by the Saalian glaciers) Middle Pleistocene fluvial deposits with Viviparus diluvianus as formerly exposed in clay pits in the 'Needse Berg' in the Eastern Netherlands are considered as the stratotype of the unit. The 'Needien' was correlated with the Holsteinian (J.D. de Jong, 1957). However, serious doubts exist about the justification of this correlation. A higher age can't be excluded (see below). Besides moluscs, also macro plant remains, pollen and vertebrate remains are known from this site. An incomplete pollen diagram has been published by Van der Vlerk & Florschütz (1953). Only a selection of tree species are included in this diagram. These data provide an interglacial but otherwise indifferent signal: no age can be deduced.
According to Van Kolfschoten (1990) the vertebrates point to an interglacial immediately preceding the Belvédère Interglacial.

Relation with units used formerly and elsewhere
Still older names for this unit are 'Horizon van Neede' and 'Horizon van Viviparus diluvianus' (Tesch, 1929). With this 'horizon' Tesch included all deposits with Viviparus diluvianus present between the Saalian and the 'Taxandrian'.

On Viviparus diluvianus
This extinct species is known from Middle Pleistocene deposits of many sites in Poland, Germany, the Netherlands and other countries. Many authors consider this as an 'index fossil' for the 'Holsteinian'. This has been one of the reasons for correlating the Needien with the Holsteinian. However, the taxonomy of this species is still unclear. Almost certainly Viviparus viviparus en Viviparus acerosus (and other species) have been misidentified as Viviparus diluvianus. The stratigraphic and geographic occurrence of Viviparus diluvianus should be reconsidered and a taxonimic revision may appear to be necessary. Besides, the Dutch specimens identified as Viviparus diluvianus (including those of Neede) may than appear to be misidentied as well.
Apparently, therefore, Viviparus diluvianus can't be used as an index fossil for the Holsteinian. This leaves apart the question of the status of the Holsteinian, but that is quite another problem.

On the age of Neede
The fluvial deposits from the 'Needse Berg' may be older than the stage that is currently considered to represent the Holsteinian. If this is correct than this should have a considerable impact on the present Netherlands (and consequently also European) Quaternary subdivision.

More information
A small molluscan assemblage from the Neede clay (Dutch language)
Aminostratigraphy of the Netherlands. Correlations & Implications

Literature
Jong, J.D. de, 1957. On the correlation of Needian in the Netherlands and Holstein deposits in Western Germany. Geologie en Mijnbouw, 19(7): 286-287.
Kolfschoten, T. van, 1990. The evolution of the mammal fauna in the Netherlands and the middle Rhine Area (Western Germany) during the late middle Pleistocene. Mededelingen Rijks Geologische Dienst, 43(3): 1-69.
Pannekoek, A.J. (ed.), 1956. Geologische geschiedenis van Nederland. Staatsdrukkerij- en Uitgeversbedrijf, 's-Gravenhage, 154 pp.
Tesch, P., 1929. Lijst der land- en zoetwatermolluscen aangetroffen in de Kwartaire lagen in Nederland. Mededelingen Rijks Geologische Dienst, A(3): V + 32 pp.
Vlerk, I.M. van der & Florschütz, F., 1950. Nederland in het IJstijdvak. De geschiedenis van flora, fauna en klimaat, toen aap en mammoet ons land bewoonden. -- Utrecht, Uitg. De Haan N.V., 289 pp.
Vlerk, I.M. van der & Florschütz, F., 1953. The palaeontological base of the subdivision of the Pleistocene in the Netherlands. Verhandelingen Koninklijke Nederlandse Akademie van Wetenschappen, Afdeling Natuurkunde, 1e Reeks, XX(2): 1-58.
Zagwijn, W.H., Van Staalduinen, C.J. (eds), 1975. Toelichtingen bij Geologische overzichtskaarten van Nederland. Rijks Geologische Dienst, Haarlem: 134 pp.