Academic literature on the topic 'Oldest Dryas'

The Tröllaskagi peninsula is located in north central Iceland, between meridians 19º30’W and 18º10’W , limited by Skagafjödur fiord to the west and the Eyjafjödur fiord to the east, jutting out into the North Atlantic to latitude 66º12’N and linked to the central Icelandic highlands to the south. The peninsula is a Tertiary basalt plateau topped by flat summits with altitudes of 1000-1500 m, intensely dissected by the drainage network. The aim of this present study is to synthesize the recent advances in our understanding of the landscape and its dynamics in the Tröllaskagi peninsula and find the origin of its significant difference from the rest of Iceland. Results of the most recent research suggest the situation of Tröllaskagi as ice-free, delimited by the two great glacial outlets flowing down from the Icelandic Ice Sheet through the Skagafjödur and Eyjafjödur fiords, from at least the Oldest Dryas to the end of the Early Preboreal. Inland in Tröllaskagi, the glaciers formed in the north-facing cirques without losing their alpine characteristics during the Late Pleistocene and Holocene. The advances of these glaciers during the Oldest, Older and Youngest Dryas and the Early Preboreal were only a few hundred metres greater than the most important advance in the second half of the Holocene, during the Little Ice Age. Only a few of these glaciers remained debris-free and are sensitive to the minor climate oscillations. The rest, due to the important geomorphological activity on their walls, developed into debris-covered and rock glaciers and lost this significant dynamism.

Abstract. Evidence for abrupt changes in western Mediterranean climate between 20 and 6 cal ka BP is examined in marine core MD95-2043 (Alborán Sea), using pollen data for temperate Mediterranean forest development and pollen-based climate reconstructions using the modern analogue technique (MAT) for annual precipitation (Pann) and mean temperatures of the coldest and warmest months (MTCO and MTWA). Major climatic shifts with parallel temperature and precipitation changes occurred at the onsets of Heinrich Event 1 (equivalent to the Oldest Dryas), the Bölling-Allerød (BA), and the Younger Dryas (YD). Multi-centennial-scale oscillations in forest development related to regional precipitation (Pann) variability occurred throughout the BA, YD, and early Holocene, with drier atmospheric conditions in phase with Lateglacial events of high-latitude cooling including GI-1d (Older Dryas), GI-1b (Intra-Allerød Cold Period) and GS-1 (YD), and during Holocene events associated with high-latitude cooling, meltwater pulses and N. Atlantic ice-rafting (events at 11.4, 10.1, 9.3, 8.2 and 7.4 cal ka BP). The forest record also indicates multi-centennial variability within the YD interval and multiple Preboreal climate oscillations. A possible climatic mechanism for the recurrence of dry intervals and an opposed regional precipitation pattern with respect to western-central Europe relates to the dynamics of the jet stream and the prevalence of atmospheric blocking highs. Comparison of radiocarbon and ice-core ages for well-defined climatic transitions in the forest record suggests possible enhancement of marine reservoir ages in the Alborán Sea by ~200 years (surface water age ~600 years) during the Lateglacial.

IA subfossil reindeer track is found in lake shore sediments in a drill core through the Late Glacial and Holocene lacustrine succession from the Lille Slotseng kettle-hole basin, located in the southeastern part of Jylland. The track is dated to 11,795 ± 80 14C yr BP or 13,635 cal. yr BP. This is the first vertebrate track recognized from a soft sediment drill core. Hitherto, convincing vertebrate trace fossils have only been described from boreholes through lithified Triassic sediments. During a previous excavation at the site, skeletal remains of at least ten reindeer were recovered from the Bølling succession and a vertebra was dated to approximately 14,100 cal. yr BP. The Lille Slotseng basin is semicircular with a maximum diameter of 23 m and the overall transgressive–regressive succession covers the time period from 16,000 to around 8,000 cal. yr BP. The oldest basin-fill sediments are melt-water deposits. They are overlain by a succession belonging to the Bølling Interstadial (GI 1-e), older Dryas (GI 1-d), Allerød, (GI 1-c, 1-b, 1-a), and Younger Dryas (GS 1), which terminates the Late Glacial succession. Then follows Preboreal algal gyttja and nearshore woody peat from the Boreal and Early Atlantic times, filling the basin.

AbstractA 7.6-m core recovered from Lough Inchiquin, western Ireland provides evidence for rapid and long-term climate change from the Late Glacial period to the Mid-Holocene. We determined percentage of carbonate, total organic matter, mineralogy, and δ18Ocalcite values to provide the first high-resolution record of climate variability for this period in Ireland. Following deglaciation, rapid climate amelioration preceded large increases in GISP2 δ18Oice values by ∼2300 yr. The Oldest Dryas (15,100 to 14,500 cal yr B.P.) Late Glacial event is documented in this record as a decrease in δ18Ocalcite values. Brief warming at ∼12,700 cal yr B.P. was followed by characteristic Younger Dryas cold and dry climate conditions. A rapid increase in δ18Ocalcite values at ∼10,500 cal yr B.P. marked the onset of Boreal warming in western Ireland. The 8200 cal yr B.P. event is represented by a brief cooling in our record. Prior to general warming, a larger and previously undescribed climate anomaly between 7300 and 6700 cal yr B.P. is characterized by low δ18Ocalcite values with high-frequency variability.