The Allerød-Younger Dryas Transition: vegetation and geomorphological responses to rapid climate change in the Netherlands and surroundings
Wim Z. Hoek 1 & Johanna A.A. Bos 2
1
Department of Physical Geography, Faculty of Geosciences, Utrecht University, The Netherlands
2
ADC ArcheoProjecten, Nijverheidsweg-Noord 114, 3812 PN Amersfoort, The Netherlands
Faculty of Geosciences Department of Physical Geography Global Change Geomorphology
NGRIP oxygen isotopes and events
NGRIP ice ye ar s b 2 k
0 20 40 60 80 100
Usselo
LOI %
1c 2a 3a
2b 3b
pollen
1b Zone
Kostverloren Veen pollen
LOI %
1c 2a 3a
2b 3b 4 5 Zone
1 (above): The INTIMATE isotope events as recorded in the Greenland Ice cores seems to be reflected in the lithology and Lateglacial and Early Holocene
vegetation development on a calibrated 14C-timescale. pollen diagrams from Usselo (van Geel et al, 1989) and De Borchert (van Geel et al, 1981). Smaller scale events within GI-1 and the Early Holocene might also be reflected in the vegetation. The Allerød-Younger Dryas Transition (biozone 2b-3a) is marked by a sharp drop in the pollen of pine (Pinus) and is followed by an increase of sand.
summed probabilities
10,930 BP
References
• Bohncke, S.J.P., Vandenberghe, J.F., Coope, R., Reiling, R., 1987. Geomorphology and palaeoecology of the Markvalley (southern Netherlands): palaeoecology, palaeohydrology and climate during the Weichselian Lateglacial. Boreas 16: 69-85.
• Bohncke, S.J.P., Vandenberghe, J.F., Huijzer, A.S., 1993. Periglacial palaeoenvironment during the Lateglacial in the Maas valley.
Geologie en Mijnbouw 72: 193-210.
• Bos, J.A.A., Bohncke, S.J.P. & Janssen, C.R., 2006. Lake level fluctuations and small-scale vegetation patterns during the Lateglacial in The Netherlands. Journal of Paleolimnology 35: 211–238.
• Bos, J.A.A., De Smedt, Ph., Demiddele, H., Hoek, W.Z., Langohr, R., Marcelino, V., Van Asch, N., Van Damme, D., Van der Meeren, T., Verniers, J., Boeckx, P., Boudin, M., Court-Picon, M., Finke, P., Gelorini, V., Gobert, S., Heiri, O., Martens, K., Mostaert, F.,
Serbruyns, L., Van Strydonck, M., Crombé, Ph., 2017. Multiple oscillations during the Lateglacial as recorded in a multi-proxy, high- resolution record of the Moervaart palaeolake (NW Belgium). Quaternary Science Reviews 162, 26-41.
• Davies, S. M., Hoek, W. Z., Bohncke, S. J. P., Lowe, J. J., Pyne O’Donnell, S. & Turney, C. S. M., 2005. Detection of Lateglacial distal tephra layers in the Netherlands. Boreas 34, 123-135.
• Hoek, W.Z., Bohncke, S.J.P., 2001. Oxygen-isotope wiggle matching as a tool for synchronising ice-core and terrestrial records over Termination 1. Quaternary Science Reviews 20, 1251-1264.
• Hoek W.Z., Bohncke S.J.P., Ganssen G.M. and Meijer T., 1999. Lateglacial environmental changes recorded in calcareous gyttja deposits at Gulickshof, southern Netherlands. Boreas 28: 416–432.
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• Van Geel, B., Coope, G.R. & van der Hammen, T., 1989. Palaeoecology and stratigraphy of the Lateglacial type section at Usselo (the Netherlands). Review of Palaeobotany and Palynology 60: 25-130.
• Vanmontfort, B., Van Gils, M., Paulissen, E., Bastiaens, J., De Bie, M., Meirsman, E., 2010. Human occupation of the Late and Early Post-Glacial environments in the Liereman Landscape (Campine, Belgium). Journal of Archaeology in the Low Countries 2-2, 31-51.
3 (below): The Allerød-Younger Dryas Transition 14C-dated in several pollen diagrams (numbers refer to locations on the map). Summed probabilty of the dates centre around 10,930 BP, which markes the transition from zone 2b-3a in The Netherlands.
2 (above): Selection of pollen diagrams, in which the Allerød-Younger Dryas Transition (2b-3a) is recorded. Red dots represent the 14C-dated boundaries. Green dots represent Kostverloren Veen and Usselo (fig. 4&5). The yellow dots represent calcareous gyttja locations where the Allerød- Younger Dryas Transition is represented by a sudden a stop in CaCO3 precipitation supported by a drop in measured oxygen isotopes, which is linked directly to the abrupt temperature change.
A: Moervaart (Bos et al., 2017), B: Weerterbos & C: Gulickshof (Hoek & Bohncke, 2001), D Empe (Hoek, unpublished).
5 (below): Pollen diagram Usselo (location F)
shows a clear decrease in Pinus pollen associated with a relative increase in non arboreal pollen
(NAP), which is characteristic for the transition of pollenzone 2b to 3a. The response in the lithology is also lagging this decrease in pollen (indicated in blue). Alternatively, the pollen zone boundary can be placed at the point where Betula becomes more important, this is however, not the moment of
change but in this case some 50-100 years later.
4 (left): Pollen diagram Kostverloren Veen (location E) shows a decrease in Pinus pollen associated with a slight increase in non arboreal pollen (NAP), which is characteristic for the
transition of pollenzone 2b to 3a. The response in the lithology as represented in the Loss on
Ignition (organic content) is lagging this decrease in pollen, with some 8 cm in the core (indicated in blue). The decrease in pollen production is
supposed to be the result of a decrease in
temperature. The reduction in vegetation cover follows later, represented by a delayed increased influx of aeolian sand. This is a common feature, because most of the geomorphological processes are controlled by vegetation density changes.
During the transition to the Holocene (indicated in red), the increase in tree pollen is directly linked to aan increase in organic production, without a distinct delay.
1 2
3
4
5/7 8
9 10
6/12 11
13 A
B
C D
E
F
