New satellite image showing with great clarity the morainic ridge remnants in the vicinity of Hjörnemoraene (Corner Moraine) in Kjove Land. It is clear from this evidence that a diffluent lobe of ice flowed down from the interior of the Pythagoras Massif. This was probably contemporaneous with ice from the main Nordvestfjord Glacier spilling eastwards across Syd Kap Bay and possibly terminating at a floating ice edge near Nordostbugt.
A fascinating new paper has been published:
https://www.sciencedirect.com/science/article/pii/S0277379125003518?via%3Dihub
https://doi.org/10.1016/j.quascirev.2025.109531
Relative summer temperature changes from glacial fluctuations in the Scoresby Sund region, Central East Greenland, during late-glacial time (2025)
Meredith A. Kelly, Thomas V. Lowell, Brenda L. Hall, Laura B. Levy, Colby A. Smith, Katherine Salamido, Roseanne Schwartz and Jennifer A. Howley
Quaternary Science Reviews
Volume 367, 1 November 2025, 109531
Abstract
Understanding climate conditions in the mid-to-high-latitude North Atlantic region during late-glacial time can provide valuable information to test hypotheses concerning the mechanisms of climate change that ended the last glacial period. Glaciers (particularly mountain glaciers) are sensitive recorders of summer temperature change because of its influence on the ablation season, snowline elevation and, hence, glacier length. Here, we develop a record of glacial fluctuations in the Scoresby Sund region in Central East Greenland and use these data to infer the timing and pattern of summer temperature changes in the mid-to-high-latitude North Atlantic region. We present 64 new 10Be ages of glacial landforms and remap and recalculate an additional 65 10Be ages from prior work in the region. Even with boulders with inherited nuclides in some of the datasets, a two-step pattern of glacial fluctuations is apparent, with an outer moraine dating to ∼14.0–12.8 ka, an inner moraine dating to ∼11.7–11.3 ka, and ice retreat in the time between moraine deposition. A comparison of these data with 10Be chronologies of mountain glacier fluctuations in Northeast Greenland, Svalbard, Norway and Scotland, shows a consistent pattern throughout the mid-to-high-latitude North Atlantic region of summer cooling and warming during late-glacial time.
Relative summer temperature changes from glacial fluctuations in the Scoresby Sund region, Central East Greenland, during late-glacial time (2025)
Meredith A. Kelly, Thomas V. Lowell, Brenda L. Hall, Laura B. Levy, Colby A. Smith, Katherine Salamido, Roseanne Schwartz and Jennifer A. Howley
Quaternary Science Reviews
Volume 367, 1 November 2025, 109531
Abstract
Understanding climate conditions in the mid-to-high-latitude North Atlantic region during late-glacial time can provide valuable information to test hypotheses concerning the mechanisms of climate change that ended the last glacial period. Glaciers (particularly mountain glaciers) are sensitive recorders of summer temperature change because of its influence on the ablation season, snowline elevation and, hence, glacier length. Here, we develop a record of glacial fluctuations in the Scoresby Sund region in Central East Greenland and use these data to infer the timing and pattern of summer temperature changes in the mid-to-high-latitude North Atlantic region. We present 64 new 10Be ages of glacial landforms and remap and recalculate an additional 65 10Be ages from prior work in the region. Even with boulders with inherited nuclides in some of the datasets, a two-step pattern of glacial fluctuations is apparent, with an outer moraine dating to ∼14.0–12.8 ka, an inner moraine dating to ∼11.7–11.3 ka, and ice retreat in the time between moraine deposition. A comparison of these data with 10Be chronologies of mountain glacier fluctuations in Northeast Greenland, Svalbard, Norway and Scotland, shows a consistent pattern throughout the mid-to-high-latitude North Atlantic region of summer cooling and warming during late-glacial time.
In both Holger Danskes Briller and Kjove Land, prominent lateral moraines demarcate a relatively young landscape (proximal to the moraines) from this older, more weathered landscape (distal to the moraines). Lateral moraines occur on both walls of Holger Danskes Briller and mark the margins of a glacier that filled the valley and flowed into Nordostbugt (Fig. 3, Fig. 6). On the right-lateral (south) valley wall, these moraines are contiguous with moraines in Kjoveland that mark the left-lateral margin of an ice-sheet outlet that filled Nordvestfjord. All these moraines are relatively high relief and have high surface boulder concentrations. Based on the geomorphology and elevations of the highest elevation lateral moraines in Holger Danskes Briller (both ∼300 m asl) and Kjoveland (∼260–280 m asl), we assume that they were deposited at the same time. 10Be ages of thirteen boulders on these highest elevation moraines are ∼11.8–18.9 ka. Multiple lateral moraines occur on the slopes below the highest moraines. We dated five boulders on lower elevation moraines (∼190–240 m asl) in Kjoveland. Four ages are ∼12.1–16.4 ka and one (∼30.4 ± 1.1 ka, MKG-71) is a statistical outlier. Based on their prominence and position at a weathering boundary, we consider all of these landforms to be associated with the outer moraine set. They consist entirely of lateral moraines and lack terminal features, possibly because the ice terminated offshore. The peak age of the moraines is ∼12.2 ka (n = 17) and the youngest age is ∼11.8 ± 0.4 ka (MKG-179)(Fig. 6).
In contrast, on the Holger Danskes Briller valley floor, an ice-contact delta is spectacularly preserved, with a steep and boulder-covered ice-contact slope and kettles and meltwater channels on its surface (Fig. 3E). The upper delta surface is at ∼101 m asl. 10Be ages of seven boulders on the delta are ∼11.6–15.3 ka with a peak age of ∼11.7 ka (n = 7) and youngest age of ∼11.6 ± 0.3 ka (MKG-172)(Fig. 6). Given the substantial distance between inferred minimum terminal ice positions of the outer moraines and this ice-contact delta, as well as the fact that the delta grades to 101 m asl, well-below the 135 m asl sea level associated with at least one outer moraine in Gurreholm Dal, we conclude that the delta is associated with the inner moraine set.
----------------
The paper contains some fascinatingf material, particularly withy respect to the cosmogenic dating of assorted morainic features. This is a wonderful image of the HDB ice-contact delta, associated with a sea level at 101m:
Because of its association with a sea level at 101m, the authors suggest that the HDB feature is one of the "inner moraines", linked in age (c 11,000 yrs BP) and origin to some of the moraines associated with the glaciers in the Schuchert Valley.
However, in trying to understand the complexities of the morainic topography of the area around Hjörnemoraene, I think the authors have missed the point that there was (1) a diffluent ice lobe coming from the Pythagoras Bjerg plateau, with a loop of moraines around 270m asl; (2) a series of lateral moraines at a lower level, around 200 - 190 m asl, associated with the Nordvestfjord outlet glacier; and (3) an intervening "proglacial" strip of land characterised by older morainic deposits and some washed surfaces. This can be picked up rather clearly on Figure 6 of the article:
Sampling point 83, labelled as "distal to moraines" should have been labelled "proximal to moraines" because it is inside the diffluent glacier morainic loop. This makes sense, because the date (13,600 yrs BP) is younger than some of those obtained from boulders on the moraines themselves.
The highest ridge of lateral moraine associated with the Nordvestfjord Glacier at c 200m, near Hjörnemoraene. Additional annotations by me -- on the authors' Fig 3.
My annotations on another of the authors' photos, in Fig 3 of the article. This is a close-up of the same ridge featured in the photo above.
All in all, a somewhat messy situation, with the morainic features of Kjove Land interpreted in three different ways. In 1965 David Sugden and I interpreted the features as associated with two glacier retreat stages or readvances, coinciding with sea-level stillstands at 134m and 101m.
We has no sophisticated dating techniques available to us in 1962, but we used shell faunas in the Gurreholmsdal raised delta staircase in our interpretations, and our estimates of the nature of the morainic and delta features and their ages were not far wide of the mark.
In some of the early papers on the Milne Land Stage it was assumed that the Kjove Land and Pythagoras Bjerg moraines were associated with an extended Schuchert Glacier, flowing down the Schuchertv Valley and then pushing into Hall Bredning and westwards across Syd Kap Bay. That idea does not seem to be supported by any of the more recent papers. The third interpretation, involving a lobe of diffluent ice pushing south-eastwards from the plateau of Pythagoras Bjerg, is one I am increasingly attracted by, as seen in assorted posts on this blog.
I think the landforms of the plateau suggest a long history of diffluent ice flow, maybe during several distinct glaciations. But the most recent ice flow, associated with the creation of two sets of prominent morainic ridges above Hjörnemoraene, appears to have been associated with the Late Glacial readvance that occurred around 13,000 years ago.
The new work -- associated with an extensive cosmogenic dating programme -- confirms that the late-glacial readvance phases here were not very closely synchronised with the old Zone I (cold) >> Zone II / Allerodn (warmer) >> Zone III (cold) sequence. Everything here in East Greenland seems to have been slightly out of step, for reasons still to be properly elucidated.
The "Younger Dryas Question" has still not been satisfactorily answered.......
================
PS. Some more old photos found in the slide collection:
View from one of the morainic ridges towards Syd Kap Bay
1962 photo of the highest morainic ridge -- virtually the same view as that in one of the photos published above.
B/W view of the highest shoreline against the morainic ridge.
No comments:
Post a Comment