Oldest Dryas

Short description: Abrupt climatic cooling event during the last glacial retreat

Dryas octopetala is the indicator species for the period

The Oldest Dryas[lower-alpha 1] is a biostratigraphic subdivision layer corresponding to a relatively abrupt climatic cooling event, or stadial, which occurred during the last glacial retreat.[1][2] The time period to which the layer corresponds is poorly defined and varies between regions,[1] but it is generally dated as starting at 18.5–17 thousand years (ka) before present (BP) and ending 15–14 ka BP.[3][4][5][6][7] As with the Younger and Older Dryas events, the stratigraphic layer is marked by abundance of the pollen and other remains of Dryas octopetala, an indicator species that colonizes arctic-alpine regions. The termination of the Oldest Dryas is marked by an abrupt oxygen isotope excursion, which has been observed at many sites in the Alps that correspond to this interval of time.[8]

In the Alps, the Oldest Dryas corresponds to the Gschnitz stadial of the Würm glaciation. The term was originally defined specifically for terrestrial records in the region of Scandinavia, but has come to be used both for ice core stratigraphy in areas across the world, and to refer to the time period itself and its associated temporary reversal of the glacial retreat.[1]

In the Iberian Peninsula, the glaciers of the Pyrenees, Sierra Nevada, Central Range, and Northwestern Mountains, which had almost entirely disappeared by 17,500 BP, began to advance once again. Between 16,800 and 16,500 BP, these glaciers abruptly advanced into montane valleys and deposited moraines near the moraines formed during the Last Glacial Maximum. These glaciers then began to oscillate between advance and retreat until a final glacial advance at 15,500 BP. A thousand years later, following a general glacial retreat, these alpine glaciers were relegated to cirques.[9]

The edge of the ice in Greenland

## Contents

* 1 Flora
* 2 Fauna
* 3 See also
* 4 Notes
* 5 References
* 6 Further reading
* 7 External links

## Flora

During the Oldest Dryas, Europe was treeless and similar to the Arctic tundra, but much drier and grassier than the modern tundra. It contained shrubs and herbaceous plants such as the following:

* Poaceae, grasses
* Artemisia
* Betula nana, dwarf birch
* Salix retusa, dwarf willow
* Dryas octopetala

* Grassland (Inner Mongolia)

* Artemisia vulgaris

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Betula nana

* Dryas octopetala

## Fauna

Species were mainly Arctic but during the Glacial Maximum, the warmer weather species had withdrawn into refugia and began to repopulate Europe in the Oldest Dryas.

The brown bear, Ursus arctos, was among the first to arrive in the north. Genetic studies indicate North European brown bears came from a refugium in the Carpathians of Moldavia. Other refugia were in Italy, Spain and Greece.

The bears would not have returned north except in pursuit of food. The tundra must already have been well populated. It is likely that the species hunted by humans at Lake Neuchâtel in Switzerland by the end of the period were present during it. Here are other animals present:

Aves

* Gavia arctica, black-throated diver
* Podiceps nigricollis, black-necked grebe
* Cygnus cygnus, whooper swan
* Aquila chrysaetos, golden eagle

* Gavia arctica

* Podiceps nigricollis

* Cygnus cygnus

* Aquila chrysaetos

The above birds are primarily maritime. They must have fed in the copious glacial waters of the north that were just beginning to be released.

Fish

* Lota lota, burbot
* Thymallus thymallus, grayling
* Rutilus rutilus, roach
* Salmo trutta, trout
* Salvelinus alpinus, char

* Glacial stream

* Lota lota

* Salmo trutta

* Salvelinus

The smaller mammals of the food chain inhabited the herbaceous blanket of the tundra:

Cricetidae

* Discrotonyx torquatus, collared lemming
* Microtus oeconomus, root vole
* Microtus arvalis, common vole
* Chionmys nivalis, snowy vole

Leporidae

* Lepus timidus, Arctic hare

Sciuridae

* Marmota marmota, marmot

* Microtus oeconomus

* Microtus arvalis

* Lepus timidus

* Marmota marmota

In addition to bears and birds were other predators of the following small animals:

Carnivora

* Felis lynx, lynx
* Alopex lagopus, Arctic fox
* Canis lupus, wolf

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Lynx (or Felis) lynx

* Alopex lagopus

* Canis lupus

* Icelandic horse, perhaps like Equus ferus

Humans were interested in the large mammals, which included:

* Rangifer tarandus, reindeer
* Equus ferus, wild horse
* Capra ibex, ibex

At some point, the larger mammals arrived: hyena, woolly rhinoceros, cave bear and mammoth.

* Rangifer tarandus

* Capra ibex

* Woolly rhinoceros

* Mammoth

## See also

* Older Dryas
* Younger Dryas

## Notes

1. ↑ A widely-employed nomenclature for climatic change during the last glacial termination is the sequence Oldest Dryas (stadial), Bølling oscillation, Older Dryas (relatively cool), Allerød oscillation, and Younger Dryas (stadial).

## References

1. ↑ 1.0 1.1 1.2 Rasmussen, Sune O.; Bigler, Matthias; Blockley, Simon P.; Blunier, Thomas; Buchardt, Susanne L.; Clausen, Henrik B.; Cvijanovic, Ivana; Dahl-Jensen, Dorthe et al. (December 2014). "A stratigraphic framework for abrupt climatic changes during the Last Glacial period based on three synchronized Greenland ice-core records: refining and extending the INTIMATE event stratigraphy". Quaternary Science Reviews (Amsterdam: Elsevier) 106: 14–28. doi:10.1016/j.quascirev.2014.09.007. Bibcode: 2014QSRv..106...14R.
2. ↑ Hoek, Wim (2009). "Bølling-Allerød Interstadial". in Gornitz, Vivien. Encyclopedia of Paleoclimatology and Ancient Environments. Dordrecht: Springer. ISBN 978-1-4020-4551-6. https://www.springer.com/gp/book/9781402045516. Retrieved 15 January 2021.
3. ↑ Carlson, Anders E.; Winsor, Kelsey (26 August 2012). "Northern Hemisphere ice-sheet responses to past climate warming". Nature Geoscience (London: Nature Portfolio) 5 (9): 607–613. doi:10.1038/NGEO1528. Bibcode: 2012NatGe...5..607C. http://geoscience.wisc.edu/geoscience/wp-content/uploads/2011/05/carlson_nat_geo_2012_deglac.pdf. Retrieved 5 July 2019.
4. ↑ Clark, P. U.; Shakun, J. D.; Baker, P. A.; Bartlein, P. J.; Brewer, S.; Brook, E.; Carlson, A. E.; Cheng, H. et al. (13 February 2012). "Global climate evolution during the last deglaciation". Proceedings of the National Academy of Sciences (Washington: National Academy of Sciences) 109 (19): E1134–E1142. doi:10.1073/pnas.1116619109. PMID 22331892. PMC 3358890. https://authors.library.caltech.edu/31815/1/Clark2012p18363P_Natl_Acad_Sci_Usa.pdf. Retrieved 5 December 2019.
5. ↑ Roberts, Neil (2014). The Holocene: an environmental history (3rd ed.). Oxford: John Wiley & sons, Ltd. p. 98. ISBN 978-1-4051-5521-2.
6. ↑ Shakun, Jeremy D.; Carlson, Anders E. (July 2010). "A global perspective on Last Glacial Maximum to Holocene climate change". Quaternary Science Reviews (Amsterdam: Elsevier) 29 (15–16): 1801–1816. doi:10.1016/j.quascirev.2010.03.016. Bibcode: 2010QSRv...29.1801S. http://geoscience.wisc.edu/geoscience/wp-content/uploads/2010/07/Shakun_Carlson_QSR_2010.pdf. Retrieved 5 July 2019.
7. ↑ Zheng, Yanhong; Pancost, Richard D.; Liu, Xiaodong; Wang, Zhangzhang; Naafs, B.D.A.; Xie, Xiaoxun; Liu, Zhao; Yu, Xuefeng et al. (2 October 2017). "Atmospheric connections with the North Atlantic enhanced the deglacial warming in northeast China". Geology (Boulder: Geological Society of America) 45 (11): 1031–1034. doi:10.1130/G39401.1. Bibcode: 2017Geo....45.1031Z.
8. ↑ Eicher, U.; Siegenthaler, U.; Wegmüller, S. (20 January 2017). "Pollen and Oxygen Isotope Analyses on Late- and Post-Glacial Sediments of the Tourbière de Chirens (Dauphiné, France)". Quaternary Research 15 (2): 160–170. doi:10.1016/0033-5894(81)90102-2. https://www.cambridge.org/core/journals/quaternary-research/article/abs/pollen-and-oxygen-isotope-analyses-on-late-and-postglacial-sediments-of-the-tourbiere-de-chirens-dauphine-france/96A073BA264D5F8B9C884D8086C6CE0E. Retrieved 14 April 2023.
9. ↑ Palacios, David; De Andrés, Nuria; Gómez-Ortiz, Antonio; García-Ruiz, José M. (18 January 2016). "Evidence of glacial activity during the Oldest Dryas in the mountains of Spain". Geological Society, London, Special Publications 433: 87–110. doi:10.1144/sp433.10. https://www.lyellcollection.org/doi/abs/10.1144/sp433.10. Retrieved 15 April 2023.

## Further reading

* Ehlers, Gibbard, Hughes (eds) (2011) Quaternary Glaciations - Extent and Chronology: A Closer Look Elsevier ISBN 9780444534477
* Bradley, Raymond S. (2013) Paleoclimatology: Reconstructing Climates of the Quaternary Academic Press ISBN 9780123869951

## External links

* the Holocene
* High-resolution studies of lake sediments
* Glaciers and Climate in Western Austria
* Late Glacial Shetland
* Chronology of Climatic Change During the Last Deglaciation
* Late Glacial Ice Advances in Maritime Canada
* The Venus of Neuchatel
* Brown Bears

* v
* t
* e

Continental glaciations

General|

* Cordilleran ice sheet
* Laurentide Ice Sheet
* Last Glacial Maximum
* Canadian Shield
* Glacial history of Minnesota
* List of prehistoric lakes
* Proglacial lake
* Lake Agassiz
* Lake Chicago
* Lake Tight
* Teays River
* Post-glacial rebound
* Timeline of glaciation

Landforms|

| Erosional|

* Fjord
* Glacial striae
* Ribbon lake
* Roche moutonnée
* Tunnel valley
* U-shaped valley

|

Depositional|

* Drumlin
* Erratic block
* Moraine
* Pulju moraine
* Rogen moraine
* Terminal moraine
* Till plain
* Veiki moraine

| Glacifluvial|

* Diluvium
* Esker
* Giant current ripples
* Kame
* Kame delta
* Kettle hole
* Outwash fan
* Sandur

|

North America|

| Canada|

* Arrowhead Provincial Park, Ontario
* Big Rock (glacial erratic), Alberta
* Cypress Hills (Canada), Saskatchewan
* Eramosa River, Ontario
* Eskers Provincial Park, British Columbia
* Foothills Erratics Train, Alberta
* Lion's Head Provincial Park, Ontario
* Origin of the Oak Ridges Moraine, Ontario
* Ovayok Territorial Park, Nunavut

|

United
States|

* Chippewa Moraine State Recreation Area, Wisconsin
* Coteau des Prairies, South Dakota
* Devil's Lake State Park, Wisconsin
* Glacial Lake Wisconsin, Wisconsin
* Glacial Lakes State Park, Minnesota
* Horicon Marsh State Wildlife Area, Wisconsin
* Ice Age Floods National Geologic Trail, Idaho, Oregon & Washington
* Ice Age National Scientific Reserve, Wisconsin
* Ice Age Trail, Wisconsin
* Interstate State Park, Minnesota & Wisconsin
* Kelleys Island, Ohio
* Kettle Moraine State Forest, Wisconsin
* Lake Bonneville, Utah
* Lake Lahontan, Nevada
* Lake Missoula, Montana
* Mill Bluff State Park, Wisconsin
* Oneida Lake, New York
* Two Creeks Buried Forest State Natural Area, Wisconsin
* Withrow Moraine and Jameson Lake Drumlin Field, Washington
* Yosemite National Park, California

Eurasia and
Antarctica|

* Antarctica
* Hardangerfjord
* Killary Harbour
* Lambert Glacier
* Monte Rosa
* Ross Ice Shelf
* Svalbard

Time periods|

* Quaternary glaciation
* Illinoian Stage
* Interglacial
* Interstadial
* Penultimate Glacial Period
* Last Glacial Period
* Last Glacial Maximum
* Mousterian Pluvial
* Holocene glacial retreat
* Oldest Dryas
* Older Dryas
* Pleistocene
* Pre-Illinoian Stage
* Quaternary glaciation
* Sangamonian Stage
* Wisconsin glaciation
* Bølling-Allerød warming
* Late Glacial Interstadial
* Huelmo–Mascardi Cold Reversal
* Younger Dryas
* African humid period
* 8.2 kiloyear event
* 4.2 kiloyear event
* Piora Oscillation
* Little Ice Age

* Category

* v
* t
* e

Ice ages

Quaternary /
Late Cenozoic|

| Quaternary|

* Antarctica
* Greenland
* Penultimate Glacial Period
* Last Glacial Period (Last Glacial Maximum)
* 1st: Würm, Wisconsin, Weichselian, Devensian/Midlandian, Pinedale/Fraser, Merida, Llanquihue
* 2nd: Riss, Illinoian, Saale, Wolstonian, Santa María
* 3rd–6th: Mindel, Pre-Illinoian, Elster, Anglian, Rio Llico
* 7th–8th: Günz, Pre-Illinoian, Elbe or Menapian, Beestonian, Caracol (2.5 to 0 Mya)

|

Pliocene
Miocene
Oligocene|

* Antarctic (34 to 2.5 Mya)

Carboniferous–Permian|

* Late Paleozoic icehouse (360 Mya to 260 Mya)

Late Ordovician glaciation|

* Andean-Saharan (460 Mya to 430 Mya)

Ediacaran|

* Gaskiers (579.88 to 579.63 Mya)
* Baykonurian (547 to 541.5 Mya)

Cryogenian|

* Sturtian (717 to 660 Mya); Marinoan (650 to 635 Mya)

Paleoproterozoic|

* Huronian (2.4 to 2.1 Gya)

Mesoarchean|

* Pongola (2.9 to 2.78 Gya)

Related topics|

* Greenhouse and icehouse Earth
* Great Oxygenation Event
* Snowball Earth
* Interglacial
* Milankovitch cycles
* Stadial

Timeline of glaciation

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