The Fennoscandian Ice Sheet during the Younger Dryas Stadial

Mangerud, Jan; Hughes, Anna L.C.; Johnson, Mark D.; Lunkka, Juha Pekka

doi:10.1016/b978-0-323-91899-2.00060-7

Cited by 5 publications

(5 citation statements)

References 67 publications

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“…Beyond Scotland, the pattern of Allerød advance and stadial retreat described by our record is also evident in neighboring Scandinavia, where Lateglacial deposits have been mapped extensively (see Mangerud et al., 2022). Moraine chronologies from both southern and Arctic Norway, constructed using comparable methods to those employed in this study, indicate culmination of Lateglacial advance prior to (Wittmeier et al., 2020) and at the YD transition (Andersen et al., 1995), with net recession during the stadial.…”

Section: Discussionsupporting

confidence: 72%

Lateglacial Shifts in Seasonality Reconcile Conflicting North Atlantic Temperature Signals

et al. 2023

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The Younger Dryas (YD: 12.9-11.7 ka) is a canonical example of abrupt climate change and has evolved in interpretation from a cold snap of possibly global extent to a primarily Northern Hemisphere event centered on the North Atlantic and linked to meltwater-forced disturbance of Atlantic meridional overturning circulation (AMOC) (Broecker et al., 2010;McManus et al., 2004). Northern Hemisphere palaeoclimate data confirm the YD was accompanied by atmospheric circulation shifts (Mayewski et al., 1994), permafrost expansion (Isarin, 1997), and disruption of the Asian monsoon (Cheng et al., 2020;Liu et al., 2008), while ice cores document the rapidity of these shifts (<10 years; Alley, 2000;Steffensen et al., 2008). Nonetheless, a satisfactory trigger for the YD is elusive, partly because our understanding of the event's manifestation continues to evolve (Cheng et al., 2020). For instance, emerging data suggest an out-of-phase relationship between glacier records and traditional interpretations of Lateglacial climate proxies in Europe and the circum North Atlantic (Foreman et al., 2022;Wittmeier et al., 2020). Noting the apparent disparity between the 16°C cooling inferred from Greenland δ 18 O and the muted advances of local glaciers, Denton et al. (2005) hypothesized that YD cooling was greater in winter than summer, reflecting the impact of expanded winter sea ice on ocean-atmosphere heat transfer. Recent glacial studies have explored this model further, suggesting that North Atlantic YD summers did not cool or may even have been anomalously warm (

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Section: Discussionsupporting

confidence: 72%

Lateglacial Shifts in Seasonality Reconcile Conflicting North Atlantic Temperature Signals

et al. 2023

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“…2020; Mangerud 2023; Mangerud et al . 2023). Based on our evidence from exposure‐age dating, a Younger Dryas age is clearly possible for the moraine ridges on Galdhøpiggen and Glittertinden, but further independent evidence would be necessary to distinguish between late Younger Dryas and Early Holocene possibilities.…”

Section: Discussionmentioning

confidence: 99%

“…Backwasting has been mapped and dated in multiple ways, as shown in the reviews of Nesje (2009) and Mangerud et al . (2011, 2023), and the data compilations and modelling of Cuzzone et al . (2016), Hughes et al .…”

Section: Figmentioning

confidence: 99%

“…2017; Mangerud et al . 2023), and because large tracts of these areas lay above the contemporaneous equilibrium‐line altitude (ELA).…”

Section: Figmentioning

confidence: 99%

“…At the maximum of the last (Weichselian) glaciation, the highest areas of Jotunheimen were located close to the main ice divide and ice accumulation area of the Scandinavian Ice Sheet (Vorren & Mangerud 2008; Mangerud et al . 2023). Our first objective was to establish the age of the moraines using two complementary exposure‐age dating techniques: 10 Be and Schmidt hammer exposure‐age dating (SHD).…”

Section: Figmentioning

confidence: 99%

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Deglaciation of the highest mountains in Scandinavia at the Younger Dryas–Holocene transition: evidence from surface exposure‐age dating of ice‐marginal moraines

Matthews,

Linge,

Nesje

et al. 2023

Boreas

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Surface exposure–age dating was applied to rock surfaces associated with ice‐marginal moraines at elevations of ~1520–1780 m a.s.l. on the slopes of Galdhøpiggen and Glittertinden, the two highest mountains in Scandinavia located in the Jotunheimen mountains of central southern Norway. This is important for understanding the pattern and timing of wastage of the Scandinavian Ice Sheet at the Younger Dryas–Holocene transition. Cosmogenic exposure dating (here 10Be dating) of boulders from the moraine ridges yielded overall mean ages (corrected for glacio‐isostatic uplift, surface erosion and snow shielding) of ~11.6 ka from Galdhøpiggen and ~11.2 ka from Glittertinden. Similar 10Be ages were also obtained from additionally collected proximal and distal erratic boulders and bedrock samples. These enabled age calibration of Schmidt‐hammer R‐values and independent Schmidt‐hammer exposure‐age dating (SHD) of the moraine ridges, which yielded comparable mean SHD ages of ~10.8 and ~10.6 ka from the Galdhøpiggen and Glittertinden sites, respectively. Taking account of the age resolution and other limitations of both dating techniques, the results suggest that the two sets of moraines have approximately the same age but that neither technique can distinguish unambiguously between moraine formation in the late Younger Dryas or Early Holocene. Together with features of moraine‐ridge morphology and estimates of equilibrium‐line altitude depression of ~360–575 m (corrected for land uplift), the results imply moraine formation during short‐lived re‐advances of active glaciers, at least the lower reaches of which were warm‐based. It is concluded that the local glaciers remained active and advanced during deglaciation either very late in the Younger Dryas or very early in the Holocene, possibly in response to the Preboreal Oscillation at ~11.4 ka. The study supports the concept of a thin Younger Dryas ice sheet and places time constraints on the timing of final deglaciation in southern Norway.

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Schmidt-hammer exposure-age dating of talus slopes in upper Jostedalen, southern Norway: Interpreting the age and development of diachronous surfaces

Matthews,

Mourne

2024

The Holocene

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Schmidt-hammer exposure-age dating (SHD) was used to evaluate the surface age, dynamics and evolution of eight talus (scree) slopes located between ~520 and ~1010 m a.s.l. in the upper Jostedalen area of southern Norway. Statistically significant differences in mean R-values were found between talus slopes but there was no consistent difference in R-values between three mid- to lower-slope positions, two operators, or first and second impacts from the same boulders. A new regional age-calibration equation yielded SHD ages ranging from 8425 ± 700 years to 2620 ± 740 years. SHD ages from talus slopes and other landforms with diachronous surfaces (such as alluvial fans, snow-avalanche fans, pronival ramparts and rock glaciers) represent the average exposure age of the surface boulders and provide insights into landform evolution. Here, our SHD ages are interpreted in terms of Early Holocene paraglacial rock-slope instability, Mid-Holocene permafrost degradation, low but possibly variable rates of rockfall activity in the Late-Holocene, and spatial variations affected by local site differences. Survival of rock particles with relatively old exposure ages towards the distal margins of the talus slopes is attributed to their slow development with low levels of modern activity. SHD ages from diachronous surfaces may considerably underestimate landform age (defined as the onset of landform formation). Greater application can be anticipated, however, in the inference of landform dynamics from the R-value distributions of diachronous surfaces and in the use of SHD age as an indicator of the extent of modern activity.

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The Fennoscandian Ice Sheet during the Younger Dryas Stadial

Cited by 5 publications

References 67 publications

Lateglacial Shifts in Seasonality Reconcile Conflicting North Atlantic Temperature Signals

Lateglacial Shifts in Seasonality Reconcile Conflicting North Atlantic Temperature Signals

Deglaciation of the highest mountains in Scandinavia at the Younger Dryas–Holocene transition: evidence from surface exposure‐age dating of ice‐marginal moraines

Schmidt-hammer exposure-age dating of talus slopes in upper Jostedalen, southern Norway: Interpreting the age and development of diachronous surfaces

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