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  • 1.
    Berntsson, Annika
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kylander, Malin E.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    De Vleeschouwer, François
    CNRS, EcoLab, Castanet Tolosan, France.
    Bertrand, Sebastien
    Ghent University.
    Late Holocene high precipitation events recorded in lake sediments and catchment geomorphology, Lake Vuoksjávrátje, NW SwedenManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, we highlight the importance of combining multi-proxy analysis of lake sediments with associated catchment geomorphology to better understand the late Holocene palaeoenvironmental evolution in a high latitude Alpine lake in N Sweden. Previous studies have suggested that such lakes may be highly sensitive to variations in catchment erosion and variations in precipitation, and that this sensitivity may influence ecologically-based reconstructions of past temperature changes. Here we have analysed lake sediments covering the last 5100 years from Lake Vuoksjávrátje in NW Sweden to identify different erosional regimes in the lake catchment and to identify sediment sources and lake sedimentary processes, which ultimately affect the palaeoecological record. Methods that were used include XRF core scanning, grain size analysis and geomorphological mapping, supported by previously published chironomid, total organic carbon and carbon/nitrogen data. From the integrated results we identify time intervals when increased amounts/intensity of precipitation altered sedimentation and lake catchment erosional processes. The most prominent event in our record occurred between 3090 and 2750 cal. a BP and is interpreted to be the result of excessive precipitation in relation to the 2.8 ka event. By combining the multi-proxy analysis of a lake sediment core with a detailed catchment characterisation it is possible to reach a better understanding of the processes active within the lake catchment, the factors governing the erosional regimes and the way these are recorded in lake sediments. For future palaeoclimatological research based on lake sediments we recommend increasing the integration of catchment geomorphology, sedimentology and palaeoecology.

  • 2.
    Berntsson, Annika
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Kylander, Malin E.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    De Vleeschouwer, Francois
    Bertrand, Sebastien
    Late Holocene high precipitation events recorded in lake sediments and catchment geomorphology, Lake Vuoksjavratje, NW Sweden2015In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 44, no 4, p. 676-692Article in journal (Refereed)
    Abstract [en]

    In this paper, we show the potential of combining multi-proxy analysis of lake sediments with catchment geomorphology to better understand palaeoenvironmental changes. Previous studies have suggested that alpine lakes in N Sweden may be highly sensitive to variations in catchment erosion and precipitation, and that this sensitivity may influence ecologically based reconstructions of past temperature changes. We analysed lake sediments covering the last 5100 years from the alpine Lake Vuoksjavratje in NW Sweden in order to identify different erosional regimes in the lake catchment, sediment sources and lake sedimentary processes, which ultimately affect the palaeoecological record. The measured proxies include elemental geochemistry from XRF core scanning, grain size, sediment accumulation rates, fraction of terrestrial organic carbon and geomorphological mapping, supported by previously published chironomid and total organic carbon data. From the integrated results we identified time intervals when increased intensity of precipitation altered sedimentation and lake catchment erosional processes. The most prominent event occurred c. 2900 cal. a BP and is interpreted to be the result of excessive precipitation, possibly related to the climatic shift towards cooler and wetter conditions referred to as the 2.8 ka event.

  • 3.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University, USA.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University, USA.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Petrakov, Dmitry A.
    Ivanov, Mikhail N.
    Alexander, Orkhonselenge
    Rudoy, Alexei N.
    Walther, Michael
    Glacial geomorphology of the Altai and Western Sayan Mountains, Central Asia2016In: Journal of Maps, ISSN 1744-5647, E-ISSN 1744-5647, Vol. 12, no 1, p. 123-136Article in journal (Refereed)
    Abstract [en]

    In this article, we present a map of the glacial geomorphology of the Altai andWestern Sayan Mountains, covering an area of almost 600,000 km2. Although numerous studies provide evidence for restricted Pleistocene glaciations in this area, others have hypothesized the past existence of an extensive ice sheet. To provide a framework for accurate glacial reconstructions of the Altai and Western Sayan Mountains, we present a map at a scale of 1:1,000,000 based on a mapping from 30 m resolution ASTER DEM and 15 m/30 mresolution Landsat ETM+ satellite imagery. Four landform classes have been mapped: marginal moraines, glacial lineations, hummocky terrain, and glacial valleys. Our mapping reveals an abundance of glacial erosional and depositional landforms. The distribution of these glacial landforms indicates that the Altai and Western Sayan Mountains have experienced predominantly alpine-style glaciations, with some small ice caps centred on the higher mountain peaks. Large marginal moraine complexes mark glacial advances in intermontane basins. By tracing the outer limits of present-day glaciers, glacial valleys, and moraines, we estimate that the past glacier coverage have totalled to 65,000 km2 (10.9% of the mapped area), whereas present-day glacier coverage totals only 1300 km2 (0.2% of the mapped area). This demonstrates the usefulness of remote sensing techniques for mapping the glacial geomorphology in remote mountain areas and for quantifying the past glacier dimensions. The glacial geomorphological map presented here will be used for further detailed reconstructions of the paleoglaciology and paleoclimate of the region.

  • 4.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Murray, Andrew
    Thomsen, Kristina J.
    Buylaert, Jan-Pieter
    Sohbati, Reza
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alexanderson, Helena
    Timing of the deglaciation in Southern Patagonia: testing the applicability of k feldspar irsl2012In: Quaternary Geochronology, ISSN 1871-1014, E-ISSN 1878-0350, Vol. 10, p. 264-272Article in journal (Refereed)
    Abstract [en]

    The timing of the ice margin retreat of the Late Glacial Patagonian Ice Sheet (PIS) in southern Patagonia has been the object of discussion for many years. In order to resolve questions about the complex response of the PIS to past climate change, any geological interpretation and data modelling need evaluation against an absolute chronology. The aim of this project is to investigate the applicability of OSL dating to sediments from southern Patagonia; in particular, we examine the dating potential of K-feldspar IRSL signals. Samples were collected from landforms interpreted as being deposited during deglaciation of the PIS, with an expected age range of 17 and 22 ka, and from recently deposited sediment. We measure small aliquots and single grain distributions using an IR50 SAR protocol with IRSL stimulation at 50 degrees C following a preheat at 250 degrees C (held for 60 s). Uncertainties are assigned to our individual dose estimates based on the over-dispersion (OD) observed in laboratory gamma dose recovery experiments (22% for small aliquots and 18% for single grains). Then the possible effects of incomplete bleaching and differential fading are examined. For our natural samples we observe environmental ODs between 30 and 130% and mean residual doses between similar to 30 and 80 Gy. Minimum age models are used to identify the part of the dose population that is most likely to have been well-bleached and results from these models are compared. The models give ages that are consistent with each other; this may imply that they successfully identified the fully-bleached grains in the distributions, although there are some discrepancies between our small aliquot and single grain data. We observe large fading rates (on average 7.9 +/- 0.6%/decade for large aliquots) but nevertheless a comparison of our fading corrected ages with the expected age range shows that 2 out of 3 ages are consistent with geological interpretation and an established radiocarbon and cosmogenic nuclide chronology. We conclude that these investigations suggest that fading corrections can be based on laboratory average small aliquot/single grain fading rates. The third age is supported by an alternative geological interpretation, and the two ages consistent with the existing chronology imply that in the Strait of the Magellan the hills of the Brunswick peninsula (>70 m.a.s.l) were deglaciated at around 22 ka.

  • 5. Glasser, N. F.
    et al.
    Harrison, S.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Anderson, K.
    Cowley, A.
    Global sea-level contribution from the Patagonian Icefields since the Little Ice Age maximum2011In: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 4, no 5, p. 303-307Article in journal (Refereed)
    Abstract [en]

    The melting of mountain glaciers and ice caps is expected to contribute significantly to sea-level rise in the twenty-first century(1-)3, although the magnitude of this contribution is not fully constrained. Glaciers in the Patagonian Icefields of South America are thought to have contributed about 10% of the total sea-level rise attributable to mountain glaciers in the past 50 years(3). However, it is unclear whether recent rates of glacier recession in Patagonia are unusual relative to the past few centuries. Here we reconstruct the recession of these glaciers using remote sensing and field determinations of trimline and terminal moraine location. We estimate that the North Patagonian Icefield has lost 103 +/- 20.7 km(3) of ice since its late Holocene peak extent in AD 1870 and that the South Patagonian Icefield has lost 503 +/- 101.1 km(3) since its peak in AD 1650. This equates to a sea-level contribution of 0.0018 +/- 0.0004 mm yr(-1) since 1870 from the north and 0.0034 +/- 0.0007 mm yr(-1) since 1650 from the south. The centennial rates of sea-level contribution we derive are one order of magnitude lower than estimates of melting over the past 50 years(3), even when we account for possible thinning above the trimline. We conclude that the melt rate and sea-level contribution of the Patagonian Icefields increased markedly in the twentieth century.

  • 6. Glasser, Neil F.
    et al.
    Harrison, Stephan
    Schnabel, Christoph
    Fabel, Derek
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Younger Dryas and early Holocene age glacier advances in Patagonia2012In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 58, p. 7-17Article in journal (Refereed)
    Abstract [en]

    Reliable dating of Southern Hemisphere glacier fluctuations since the Last Glacial Maximum (LGM) is crucial to resolving debates about millennial-scale climate change. Here we present Be-10 dates for lateral, valley-mouth and cross-valley moraines formed between the contemporary South American North Patagonian Icefield (NPI) and its LGM position in four separate valleys around 47 degrees S. This is an area near the core of the precipitation-bearing southern westerly winds, where it is known that rapid shifts in climate occurred during Lateglacial times. The dates indicate that outlet glaciers advanced, or at least stabilised, to form large moraines east of an expanded NPI at 11.0 +/- 0.5/11.2 +/- 0.6, 11.5 +/- 0.6, 11.7 +/- 0.6 and 12.8 +/- 0.7 ka (Putnam southern-hemisphere production rates and Dunai scaling scheme, assumed boulder erosion rate of 2 mm/ka). Four of these ages are statistically indistinguishable and probably represent a single, regional ice advance. The dates indicate that glaciers in Patagonia were larger during these times than at any point since the LGM and provide evidence in Patagonia for glacier advances around the time of the European Younger Dryas (12.9-11.7 ka) and into the very early Holocene. Although palaeoclimatic records from this area are often contradictory, these glacier advances were probably associated with a period of cooling or regionally increased precipitation related to the changes in the position of the southern westerly winds.

  • 7. Glasser, Neil F.
    et al.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Duller, Geoffrey A. T.
    Singarayer, Joy
    Holloway, Max
    Harrison, Stephan
    Glacial lake drainage in Patagonia (13-8 kyr) and response of the adjacent Pacific Ocean2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 21064Article in journal (Refereed)
    Abstract [en]

    Large freshwater lakes formed in North America and Europe during deglaciation following the Last Glacial Maximum. Rapid drainage of these lakes into the Oceans resulted in abrupt perturbations in climate, including the Younger Dryas and 8.2 kyr cooling events. In the mid-latitudes of the Southern Hemisphere major glacial lakes also formed and drained during deglaciation but little is known about the magnitude, organization and timing of these drainage events and their effect on regional climate. We use 16 new single-grain optically stimulated luminescence (OSL) dates to define three stages of rapid glacial lake drainage in the Lago General Carrera/Lago Buenos Aires and Lago Cohrane/Pueyrredon basins of Patagonia and provide the first assessment of the effects of lake drainage on the Pacific Ocean. Lake drainage occurred between 13 and 8 kyr ago and was initially gradual eastward into the Atlantic, then subsequently reorganized westward into the Pacific as new drainage routes opened up during Patagonian Ice Sheet deglaciation. Coupled ocean-atmosphere model experiments using HadCM3 with an imposed freshwater surface hosing to simulate glacial lake drainage suggest that a negative salinity anomaly was advected south around Cape Horn, resulting in brief but significant impacts on coastal ocean vertical mixing and regional climate.

  • 8. Glasser, Neil F.
    et al.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Goodfellow, Bradley W.
    de Angelis, Hernán
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Rodnight, Helena
    Rood, Dylan H.
    Cosmogenic nuclide exposure ages for moraines in the Lago San Martin Valley, Argentina2011In: Quaternary Research, ISSN 0033-5894, E-ISSN 1096-0287, Vol. 75, no 3, p. 636-646Article in journal (Refereed)
    Abstract [en]

    At several times during the Quaternary, a major eastward-flowing outlet glacier of the former Patagonian Ice Sheet occupied the Lago San Martin Valley in Argentina (49 degrees S, 72 degrees W). We present a glacial chronology for the valley based on geomorphological mapping and cosmogenic nuclide ((10)Be) exposure ages (n = 10) of boulders on moraines and lake shorelines. There are five prominent moraine belts in the Lago San Martin Valley, associated with extensive sandar (glaciofluvial outwash plains) and former lake shorelines. Cosmogenic nuclide exposure ages for boulders on these moraines indicate that they formed at 14.3 +/- 1.7 ka, 22.4 +/- 2.3 ka, 34.4 +/- 3.4 ka to 37.6 +/- 3.4 ka (and possibly 60 +/- 3.5 ka), and 99 +/- 11 ka (1 sigma). These dated glacier advances differ from published chronologies from the Lago San Martin Valley based on (14)C age determinations from organic sediments and molluscs in meltwater channels directly in front of moraines or in kettleholes within end moraine ridges. The moraine boulder ages also point to possible pre-LGM glacial advances during the last glacial cycle and a key observation from our data is that the LGM glaciers were probably less extensive in the Lago San Martin Valley than previously thought.

  • 9. Glasser, Neil
    et al.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harrison, Stephan
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    The glacial geomorphology and Pleistocene history of South America between 38 degrees S and 56 degrees S2008In: QUATERNARY SCIENCE REVIEWS, ISSN 0277-3791, Vol. 27, no 3-4, p. 365-390Article in journal (Refereed)
    Abstract [sv]

    This paper presents new mapping of the glacial geomorphology of southern South America between latitudes 38 degrees S and 56 degrees S, approximately the area covered by the former Patagonian Ice Sheets. Glacial geomorphological features, including glacial lineations, moraines, meltwater channels, trimlines, sandur and cirques, were mapped from remotely sensed images (Landsat 7 ETM +, pan-sharpened Landsat 7 and ASTER). The landform record indicates that the Patagonian Ice Sheets consisted of 66 main outlet glaciers, together with numerous local cirque glaciers and independent ice domes in the surrounding mountains. In the northern part of the mapped area, in the Chilean Lake District (38-42 degrees S), large piedmont glaciers developed on the western side of the Andes and the maximum positions of these outlet glaciers are, in general, marked by arcuate terminal moraines. To the east of the Andes between 38 degrees S and 42 degrees S, outlet glaciers were more restricted in extent and formed "alpine-style" valley glaciers. Along the eastern flank of the Andes south of similar to 45 degrees S a series of large fast-flowing outlet glaciers drained the ice sheet. The location of these outlet glaciers was topographically controlled and there was limited scope for interactions between individual lobes. West of the Andes at this latitude, there is geomorphological evidence for an independent ice cap close to sea level on the Taitao Peninsula. The age of this ice cap is unclear but it may represent evidence of glacier growth during the Antarctic Cold Reversal and/or Younger Dryas Chronozone. Maximum glacier positions are difficult to determine along much of the western side of the Andes south of 42 degrees S because of the limited land there, and it is assumed that most of these glaciers had marine termini. In the south-east of the mapped area, in the Fuegan Andes (Cordillera Darwin), the landform record provides evidence of ice-sheet initiation. By adding published dates for glacier advances from the literature we present maps of pre-Last Glacial Maximum (LGM) glacier extent, LGM extent and the positions of other large mapped moraines younger than LGM in age. A number of large moraines occur within the known LGM limits. The age of these moraines is unknown but, since many of them lie well outside the established maximum Neoglacial positions, the possibility that they reflect a return to glacial climates during the Younger Dryas Chronozone or Antarctic Cold Reversal cannot be discounted.

  • 10.
    Goodfellow, Bradley
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Deciphering a non-glacial/glacial landscape mosaic in the northern Swedish mountains2008In: Geomorphology, Vol. 93, no 3-4, p. 213-232Article in journal (Refereed)
    Abstract [en]

    Relict surfaces contain information on past surface processes and long-term landscape evolution. A detailed investigation of relict non-glacial surfaces in a formerly glaciated mountain landscape of northern Sweden was completed, based on interpretation of colour infrared aerial photographs, analysis in a GIS, and fieldwork. Working backwards from landscape to process, surfaces were classified according to large- and small-scale morphologies that result from the operation of non-glacial processes, the degree of weathering, regolith characteristics, and the style of glacial modification. Surfaces were also compared in the GIS according to elevation, slope angle, and bedrock lithology. The study revealed five types of relict non-glacial surfaces but also two types of extensively weathered glacial surfaces that were transitional to relict non-glacial surfaces, illustrating spatially variable processes and rates of non-glacial and glacial landscape evolution. Rather than being static preglacial remnants, relict non-glacial surfaces are dynamic features that have continued to evolve during the Quaternary. The classification provides hypotheses for landscape evolution that can be field tested through, for example, terrestrial cosmogenic nuclide studies and geochemical analyses of fine matrix materials. The classification may be applicable to relict non-glacial surfaces in other formerly glaciated landscapes

  • 11.
    Goodfellow, Bradley
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fabel, Derek
    Fredin, Ola
    Derron, M.-H.
    Relict non-glacial surfaces in formerly glaciated landscapes: dynamic landform systems?2007In: Quaternary International, 2007Conference paper (Refereed)
    Abstract [en]

    Relict non-glacial surfaces occur within many formerly glaciated landscapes

    and contain important information on past surface processes and long-term landscape evolution. While cosmogenic dating has confirmed

    the antiquity of relict non-glacial surfaces, the processes that contribute to their evolution and, consequently, the time scales over which they develop remain poorly understood. Of particular importance

    is the possibility that relict non-glacial surfaces may provide geomorphic markers for the reconstruction of preglacial landscapes, which would allow subsequent glacial erosion to be quantified. Furthermore,

    relict non-glacial surfaces may also hold information on preglacial

    and interglacial environmental conditions. An investigation of relict non-glacial surfaces was undertaken through remote sensing, mapping and analysis of surfaces in a GIS, and regolith studies involving

    cosmogenic dating-, grain size-, X-ray diffraction-, and X-ray fluorescence

    analyses. On the basis of these on-going studies, we show that depending on spatial variables such as bedrock lithology, slope, regolith thickness, and the abundance of fine matrix and water some surfaces are denuding very slowly, while others display more rapid denudation. High spatial variability in denudation rates results in changing surface morphologies over time. Rather than being static preglacial

    remnants, relict non-glacial surfaces are dynamic features that have evolved during the Quaternary. While reconstructions of preglacial

    landscapes and subsequent quantifications of glacial erosion from relict non-glacial surfaces remain valid, the Quaternary evolution of these surfaces should also be considered.

  • 12.
    Goodfellow, Bradley
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fabel, Derek
    Fredin, Ola
    Derron, M.-H.
    Relict non-glacial surfaces in formerly glaciated landscapes: dynamic landform systems?2007In: Geophysical Research Abstracts, 2007Conference paper (Refereed)
    Abstract [en]

    Relict non-glacial surfaces occur within many formerly glaciated landscapes and contain

    important information on past surface processes and long-term landscape evolution

    (Goodfellow, 2007). While cosmogenic dating has confirmed the antiquity of

    relict non-glacial surfaces, the processes that contribute to their evolution and, consequently,

    the time scales over which they develop remain poorly understood. Of particular

    importance is the possibility that relict non-glacial surfaces may provide geomorphic

    markers for the reconstruction of preglacial landscapes, which would allow

    subsequent glacial erosion to be quantified. Furthermore, relict non-glacial surfaces

    may also hold information on preglacial and interglacial environmental conditions.

    An investigation of relict non-glacial surfaces was undertaken through remote sensing,

    mapping and analysis of surfaces in a GIS, and regolith studies involving cosmogenic

    dating-, grain size-, X-ray diffraction-, and X-ray fluorescence analyses. On

    the basis of these on-going studies, we show that depending on spatial variables such

    as bedrock lithology, slope, regolith thickness, and the abundance of fine matrix and

    water some surfaces are denuding very slowly, while others display more rapid denudation.

    High spatial variability in denudation rates results in changing surface morphologies

    over time. Rather than being static preglacial remnants, relict non-glacial

    surfaces are dynamic features that have evolved during the Quaternary. While reconstructions

    of preglacial landscapes and subsequent quantifications of glacial erosion

    from relict non-glacial surfaces remain valid, the Quaternary evolution of these surfaces

    should also be considered.

    Goodfellow B.W., 2007. Relict non-glacial surfaces in formerly glaciated landscapes.

    Earth-Science Reviews, 80(1-2): 47-73.

  • 13.
    Goodfellow, Bradley W.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Stanford University, USA.
    Skelton, Alasdair
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Martel, Stephen J.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Controls of tor formation, Cairngorm Mountains, Scotland2014In: Journal Of Geophysical Research: Earth Surface, ISSN 2169-9003, Vol. 119, no 2, p. 225-246Article in journal (Refereed)
    Abstract [en]

    Tors occur in many granitic landscapes and provide opportunities to better understand differential weathering. We assess tor formation in the Cairngorm Mountains, Scotland, by examining correlation of tor location and size with grain size and the spacing of steeply dipping joints. We infer a control on these relationships and explore its potential broader significance for differential weathering and tor formation. We also assess the relationship between the formation of subhorizontal joints in many tors and local topographic shape by evaluating principle surface curvatures from a digital elevation model of the Cairngorms. We then explore the implications of these joints for tor formation. We conclude that the Cairngorm tors have formed in kernels of relatively coarse grained granite. Tor volumes increase with grain size and the spacing of steeply dipping joints. We infer that the steeply dipping joints largely formed during pluton cooling and are more widely spaced in tor kernels because of slower cooling rates. Preferential tor formation in coarser granite with a wider joint spacing that is more easily grusified indicates that joint spacing is a dominant control on differential weathering. Sheet jointing is well developed in tors located on relatively high convex surfaces. This jointing formed after the gross topography of the Cairngorms was established and before tor emergence. The presence of closely spaced (tens of centimeters), subhorizontal sheeting joints in tors indicates that these tors, and similarly sheeted tors elsewhere, formed either after subaerial exposure of bedrock or have progressively emerged from a regolith only a few meters thick. Key Points <list list-type=bulleted id=jgrf20195-list-0001> <list-item id=jgrf20195-li-0001>Tors form in kernels of coarse-grained granite among finer-grained granite <list-item id=jgrf20195-li-0002>Wide joint spacing in tors attributable to a slow cooling rate of the granite <list-item id=jgrf20195-li-0003>Sheet jointing discounts tor formation within a thick regolith

  • 14.
    Gribenski, Natacha
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Leibniz Institute for Applied Geophysics, Germany.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Preusser, Frank
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography. Purdue University, USA.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Trauerstein, Mareike
    Blomdin, Robin
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Heyman, Jakob
    Caffee, Marc W.
    Lifton, Nathaniel A.
    Zhang, Wei
    Re-evaluation of MIS 3 glaciation using cosmogenic radionuclide and single grain luminescence ages, Kanas Valley, Chinese Altai2018In: Journal of Quaternary Science, ISSN 0267-8179, E-ISSN 1099-1417, Vol. 33, no 1, p. 55-67Article in journal (Refereed)
    Abstract [en]

    Previous investigations observed a period of major glacial advances in Central Asia during marine oxygen isotope stage (MIS) 3 (57-29 ka), out of phase with global ice volume records. We have re-examined the Kanas moraine complex in the Altai Mountains of Central Asia, where an MIS 3 glaciation had been previously inferred. New and consistent cosmogenic exposure and single-grain luminescence ages indicate that the Kanas complex was formed during MIS 2 (29-12 ka), which brings its timing in line with the global ice volume record. We also identified a lateral moraine from a more extensive ice extent that dates to late MIS 5/MIS 4. To place our results in a wider contextual framework, we review the chronologies of another 26 proposed major MIS 3 glacial advances in Central Asia. For most of these sites, we find that the chronological data do not provide an unequivocal case for MIS 3 glaciation.

  • 15.
    Gribenski, Natacha
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Lukas, Sven
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography. Purdue University, USA.
    Blomdin, Robin
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Ivanov, Mikhail N.
    Heyman, Jakob
    Petrakov, Dmitry A.
    Rudoy, Alexei
    Clifton, Tom
    Lifton, Nathaniel A.
    Caffee, Marc W.
    Reply to comment received from J. Herget et al. regarding "Complex patterns of glacier advances during the late glacial in the Chagan Uzun Valley, Russian Altai" by Gribenski et al. (2016), Quaternary Science Reviews 149, 288-3052017In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 168, p. 219-221Article in journal (Refereed)
  • 16. Harrison, Stephan
    et al.
    Glasser, Neil
    Winchester, Vanessa
    Haresign, Eleanor
    Warren, Charles
    Duller, Geoff
    Bailey, Richard
    Ivy-Ochs, Susan
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kubik, Peter
    Glaciar Leon, Chilean Patagonia: late-Holocene chronology and geomorphology2008In: Holocene, ISSN 0959-6836, Vol. 18, no 4, p. 643-652Article in journal (Refereed)
    Abstract [sv]

    Glaciar Leon is a temperate, grounded outlet of the eastern North Patagonian Icefield (NPI). It terminates at an active calving margin in Lago Leones, a 10 km long proglacial lake. We take a multidisciplinary approach to its description and use ASTER imagery and clast sedimentology to describe the geomorphology of the glacier and its associated moraines. We date periods of glacier retreat over the last 2500 years using a combination of lichenometric, dendrochronological, cosmogenic and optically stimulated luminescence techniques and show that the glacier receded from a large terminal moraine complex some 2500 years ago and underwent further significant recession from nineteenth-century moraine limits. The moraine dates indicate varying retreat rates, in conjunction with significant downwasting. The bathymetry of Lago Leones is characterized by distinct ridges interpreted as moraine ridges that dissect the lake into several basins, with water depths reaching 360 m. The fluctuations of Glaciar Leon appear to have been controlled by the interplay between climatic forcing and calving dynamics.

  • 17.
    Jansson, Krister
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alm, Göran
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Dahlgren, T.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    GIS modelling of the MIS 2-8 onshore glacial erosional pattern in northern Scandinavia2007In: Quaternary International, 2007Conference paper (Refereed)
    Abstract [en]

    A 50-m cell size digital elevation dataset over northern Scandinavia has been analysed for patterns of glacial erosion using filtering techniques of the Erdas Imagine 8.6

    spatial modeller software. A maximum value filtering technique using variable neighbourhoods has been applied such that existing highpoints in the landscape have been

    used as erosional base levels for the reconstruction of past landscape relief. We assume that the highest surfaces have experienced no down-wearing (or, alternatively, an

    even down-wearing could be specified) and also that the size of the valleys rather than the direction of the valleys relative to former ice flow directions determines how

    much material has been removed by ice sheet erosion. Over multiple runs the reconstructed paleo-relief becomes increasingly dominated by the highest summits in the

    landscape and the valley pattern is smoothed by in-filling from the sides. The model was run until eroded bedrock volumes equalled bedrock equivalents of erosion

    products deposited during MIS 2, 6, 8, 10, 12, 18 and for the full glacial period offshore of northern Norway. The pattern of glacial erosion, which is mainly correlated to

    slope angles and relative relief, is characterized by: (1) An abrupt start of glacial erosion below preserved summit areas; (2) Enhanced erosion in narrow valleys; (3)

    Restricted erosion of smooth areas, independently of elevation; (4) Erosion of small scale irregularities, and; (5) Restricted erosion on isolated hills in low-relief terrain.

  • 18.
    Jansson, Krister
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glasser, Neil
    Modification of peripheral mountain ranges by former ice sheets:The Brecon Beacons, Southern UK2008In: GeomorphologyArticle in journal (Refereed)
    Abstract [en]

    The Brecon Beacons in southern Wales is a large upland area (900 km2) close to the periphery of the former British–Irish Ice

    Sheet. The geomorphology of the Brecon Beacons highlands and surrounding areas was mapped using satellite imagery and a

    digital elevation model (DEM). A fragmentary pattern of glacial lineations is inferred to represent ice build-up in the mountains. A

    more coherent set of glacial lineations formed by southward ice flow across the area from the Welsh Ice Cap represents recession

    from the Last Glacial Maximum (LGM). During this phase the Brecon Beacons acted as an obstacle, deflecting the ice around

    higher terrain. Most of the higher terrain in the Brecon Beacons therefore appears to have escaped significant glacial erosion during both phases of ice-flow due to cold-based ice or low basal ice velocities beneath a local ice cap. Landforms previously interpreted as cirques in fact have v-shaped profiles and lack evidence of major over-deepening. They are interpreted to have been formed primarily by processes other than glacial erosion. The overall impact of glaciation in the Brecon Beacons appears to be limited primarily to the time when the area was over-run by the Welsh Ice Cap and the influence of local glaciation has been minimal. This study has two main implications for landscape evolution in mountain ranges that lie at the periphery of former ice sheets. First, due to the presence of cold-based ice or low basal ice velocities beneath a local ice cap it may be possible to find fragmentary traces of pre-LGM ice flow. Second, the pattern of glacial lineations in and around the Brecon Beacons indicates that peripheral mountain ranges may have deflected ice flow at the LGM, resulting in low basal ice flow velocities and possible frozen-bed conditions over higher terrain which consequently resulted in ineffective glacial erosion within the mountains themselves.

  • 19.
    Jansson, Krister
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glasser, Neil
    Paleaeoglaciological events in the Brecon Beacons area2007In: The Quaternary of the Brecon Beacons, Quaternary Research Association , 2007, p. 23-35Chapter in book (Refereed)
  • 20.
    Jansson, Krister N.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Dahlgren, K. I. Torbjörn
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alm, Göran
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glasser, Neil F.
    Goodfellow, Brad W.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glacial erosion and the evolution of relief in northern Scandinavia over the last 2.7 Myr2008In: Geophysical Research Abstracts, Vol. 10, EGU2008-A-07548, 2008Conference paper (Refereed)
  • 21.
    Jansson, Krister
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alm, Göran
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Dahlgren, K. I. T.
    Glasser, N. F.
    Goodfellow, B. W.
    Using a GIS filtering approach to replicate patterns of glacial erosion2011In: Earth Surface Processes and Landforms, ISSN 0197-9337, E-ISSN 1096-9837, Vol. 36, no 3, p. 408-418Article in journal (Refereed)
    Abstract [en]

    In order to extend our knowledge of glacial relief production in mountainous areas new methods are required for landscape reconstructions on a temporal resolution of a glacial cycle and a spatial resolution that includes the most important terrain components. A generic data set and a 50 m resolution digital elevation model over a study area in northern Sweden and Norway (the present day landscape data set) were employed to portray spatial patterns of erosion by reconstructing the landscape over successive cycles of glacial erosion. A maximum-value geographic information system (GIS) filtering technique using variable neighbourhoods was applied such that existing highpoints in the landscape were used as erosional anchor points for the reconstruction of past landscape topography. An inherent assumption, therefore, is that the highest surfaces have experienced insignificant down-wearing over the Quaternary. Over multiple reconstruction cycles, proceeding backwards in time, the highest summits increase in area, valleys become shallower, and the valley pattern becomes increasingly simplified as large valleys become in-filled from the sides. The sum of these changes reduces relief. The pattern of glacial erosion, which is to 60% correlated to slope angle and to 70% correlated to relative relief, is characterized by (i) an abrupt erosional boundary below preserved summit areas, (ii) enhanced erosion in narrow valleys, (iii) restricted erosion of smooth areas, independently of elevation, (iv) eradication of small-scale irregularities, (v) restricted erosion on isolated hills in low-relief terrain, and (vi) a valley widening independent of valley directions. The method outlined in this paper shows how basic GIS filtering techniques can mimic some of the observed patterns of glacial erosion and thereby help deduce the key controls on the processes that govern large-scale landscape evolution beneath ice sheets.

  • 22.
    Kaislahti Tillman, Päivi
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Berntsson, Annika
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Risberg, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Helmens, Karin
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Diatom stratigraphy of the MIS 3 deposits at Sokli, Northern Finland2007In: Nordic Diatomists´ Meeting, 2007Conference paper (Other academic)
  • 23.
    Kleman, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    de Angelis, Hernán
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alm, Göran
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glasser, Neil
    Aberystwyth University.
    North American Ice Sheet build-up during the last glacial cycle, 115-21 kyr2010In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 29, no 17-18, p. 2036-2051Article in journal (Refereed)
    Abstract [en]

    The last glacial maximum (LGM) outline and subsequent retreat pattern (21e7 kyr) of North Americanice sheets are reasonably well established. However, the evolution of the ice sheets during their build-upphase towards the LGM between 115 and 21 kyr has remained elusive, making it difficult to verifynumerical ice sheet models for this important time interval. In this paper we outline the pre-LGM icesheet evolution of the Laurentide and Cordilleran ice sheets by using glacial geological and geomorphologicalrecords to make a first-order reconstruction of ice sheet extent and flow pattern. We mappedthe entire area covered by the Laurentide and Cordilleran ice sheets in Landsat MSS images andapproximately 40% of this area in higher resolution Landsat ETMþ images. Mapping in aerial photographsadded further detail primarily in Quebec-Labrador, the Cordilleran region, and on Baffin Island.Our analysis includes the recognition of approximately 500 relative-age relationships from crosscuttinglineations. Together with previously published striae and till fabric data, these are used as the basis forrelative-age assignments of regional flow patterns. For the reconstruction of the most probable ice sheetevolution sequence we employ a stepwise inversion scheme with a clearly defined strategy for delineatingcoherent landforms swarms (reflecting flow direction and configuration), and linking these topreviously published constraints on relative and absolute chronology. Our results reveal that icedispersalcentres in Keewatin and Quebec were dynamically independent for most of pre-LGM time andthat a massive Quebec dispersal centre, rivalling the LGM in extent, existed at times when the SW sectorof the ice sheet had not yet developed. The oldest flow system in eastern Quebec-Labrador (Atlanticswarm had an ice divide closer to the Labrador coast than later configurations). A northern Keewatin-Central Arctic Ice Sheet existed prior to the LGM, but is poorly chronologically constrained. There is alsoevidence for older and more easterly Cordilleran Ice Sheet divide locations than those that prevailedduring the Late Wisconsinan. In terms of ice sheet build-up dynamics, it appears that “residual” ice capsafter warming phases may have played an important role. In particular, the location and size of remnantice masses at the end of major interstadials, i.e. OIS 5c and 5a, must have been critical for subsequentbuild-up patterns, because such remnant “uplands” may have fostered much more rapid ice sheetgrowth than what would have occurred on a fully deglaciated terrain. The ice-sheet configuration duringstadials would also be governed largely by the additional topography that such “residual” ice constitutesbecause of inherent mass balance-topography feedbacks.

  • 24.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Evaluation of data sources for mapping glacial meltwater features2012In: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 33, no 8, p. 2355-2377Article in journal (Refereed)
    Abstract [en]

    The meltwater system of disintegrating ice sheets provides an important source of information for the reconstruction of ice-retreat patterns during deglaciation. Recent method development in glacial geomorphology, using satellite imagery and digital elevation models (DEMs) for glacial landform mapping, has predominantly been focused on the identification of lineation and other large-scale accumulation features. Landforms created by meltwater have often been neglected in these efforts. Meltwater features such as channels, deltas and fossil shorelines were traditionally mapped using stereo interpretation of aerial photographs. However, during the transition into the digital era, driven by a wish to cover large areas more economically, meltwater features were lost in most mapping surveys. We have evaluated different sets of satellite images and DEMs for their suitability to map glacial meltwater features (lateral meltwater channels, eskers, deltas, ice-dammed lake drainage channels and fossil shorelines) in comparison with the traditional mapping from aerial photographs. Several sets of satellite images and DEMs were employed to map the landform record of three reference areas, located in northwestern Scotland, northeastern Finland and western Sweden. The employed satellite imagery consisted of Landsat 7 Enhanced Thematic Mapper Plus (ETM+), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Satellite Pour l’Observation de la Terre (SPOT) 5 and Indian Remote Sensing (IRS)1C, and the DEMs used were from NEXTMap Britain, Panorama, National elevation data set of Sweden and National Land Survey of Finland. ASTER images yielded better results than the panchromatic band of Landsat 7 ETM+ in all three regions, despite the same spatial resolution of the data. In agreement with previous studies, this study shows that DEMs display accumulation features such as eskers suitably well. Satellite images are shown to be insufficiently detailed for the interpretation of smaller features such as meltwater channels. Hence, satellite imagery and DEMs of intermediate resolution contain meltwater system information only at a general level that allows for the identification of landforms of medium to large sizes. It is therefore pertinent that data with an appropriate spatial and spectral resolution are accessed to fulfil the need of a particular mapping effort. Stereointerpretation of aerial photographs continues to be an advisable method for local meltwater system reconstructions; alternatively, it can be replaced by mapping fromhigh-resolution DEMs such as NEXTMap Britain. For regional to sub-continental reconstructions, the use of ASTER satellite imagery is recommended, because it provides both spectral and spatial resolutions suitable for the identification of meltwater features on a medium to large scale.

  • 25.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glacial geomorphology and glacial lakes of central Transbaikalia, Siberia, Russia2011In: Journal of Maps, ISSN 1744-5647, p. 18-30Article in journal (Refereed)
    Abstract [en]

    A glacial geomorphological map is presented covering the poorly investigated mountainous region ofcentral Transbaikalia, Russia. Interpretation of geomorphology is achieved using remotely sensed data (SRTM digital elevation model, Landsat 7 ETM+ satellite imagery and Google Maps). Glacially modified terrain is mapped together with moraines, glacial lineations and meltwater channels, in order to provide an estimate of the area affected by glaciation. The glacial landform record varies across the mapped region implying that the character of glaciation was not uniform in the area. Several moraine generations occur in the main valleys and at some places glaciers blocked the drainage routes, which resulted in the formation of glacial lakes. The largest, Glacial Lake Vitim, was dammed by a glacier lobe blocking the Vitim valley in the Kodar Range. A distinct fossil shoreline of Glacial Lake Vitim occurs along a substantial part of the former shore at a level of 840 m a.s.l. A col through which the lake drained to the River Nercha occurs at an elevation consistent with the shoreline level of 840 m a.s.l. The existence of another glacial lake in the Chara basin is inferred from mapped delta surfaces and a probable blockage of the Chara River by advancing valley glaciers. The rich and diverse geomorphology and the sedimentary record of glacial lakes represent a potential for more detailed studies of the glacial and climate history of this remote region.

  • 26.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Towards method development in mapping meltwater features from remotely sensed and digital elevation data2008In: 28th Nordic Geological Winter Meeting: Abstract Volume, 2008Conference paper (Other academic)
    Abstract [en]

    The use of satellite data has revolutionized glacial geomorphological mapping. However, the focus has often been on mapping features such as glacial lineations and ribbed moraines, leaving the meltwater system largely unexplored. Hence, we are currently in the need to perform a methods development necessary for a full transformation from air-photo based approaches in meltwater landform mapping to a fully integrated use of satellite imagery and DTM’s in a GIS environment. We will target the method development objective by exploration of a range of diverse data with different spatial and spectral resolutions. The meltwater system is known to play a vital role in paleoglaciology in reconstructing ice marginal retreat patterns in areas previously covered by cold-based ice for basically three reasons: (1) During cold-based deglaciation, meltwater features are the only landforms formed and used for reconstructions of ice marginal retreat. (2) Meltwater features play a fundamental role in the separation of young imprints from older ice-flow events preserved in the landform record. (3) The spatial and temporal distribution of meltwater is known to have had a profound role on its environment and it is therefore important topic of study. Methods developed as part of this project will be used to perform paleoglaciological reconstructions of the deglacial environment in Glen Roy, Scotland and in northern Sweden. These areas are chosen because of their stunning landforms examples and the, at least on the local scale, particularly well-known glacial history.

  • 27.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glacial meltwater landforms of central British Columbia2011In: Journal of Maps, ISSN 1744-5647, p. 486-506Article in journal (Refereed)
    Abstract [en]

    The Cordilleran Ice Sheet (CIS), which grew and melted repeatedly across the mountain ranges of westernmost Canada during the late Cenozoic, has imprinted its legacy in the form of glacial landforms, such as meltwater landforms. However, despite their abundance, a coherent effort to map meltwater landforms has been lacking. Here, we present a first regional geomorphological map of glacial meltwater landforms of central British Columbia. Series of well-developed meltwater channels occur at higher elevations on the Interior Plateau, in marginal ranges east of the Coast Mountains, in the Skeena and Omineca mountains, and, in much lower abundances, in the Rocky Mountains. Single-ridged eskers, that in direction are consistent with the regional ice flow direction from glacial lineations, occur in elevated areas of the Interior Plateau. Multiple-ridged larger eskers and esker complexes are, on the other hand, confined to the main topographic lows. The geographical distribution of meltwater landforms is a new reliable dataset for use in palaeoglaciological reconstructions and inference of late glacial ice sheet dynamics in central British Columbia.

  • 28.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Late-glacial ice dynamics of the Cordilleran Ice Sheet in northern British Columbia and southern Yukon Territory: retreat pattern of the Liard Lobe reconstructed from the glacial landform recordManuscript (preprint) (Other academic)
    Abstract [en]

    The Liard Lobe formed a part of the northeastern sector of the Cordilleran Ice Sheet and drained ice from accumulation areas in the Selwyn, Pelly, Cassiar and Skeena mountains. This study reconstructs the ice retreat pattern of the Liard Lobe during the last deglaciation from the glacial landform record that is comprised of glacial lineations and landforms of the meltwater system such as eskers, meltwater channels, perched deltas and outwash fans. The spatial distribution of these landforms defines the successive configurations of the ice sheet during the deglaciation. The Liard Lobe retreated to the west and southwest across the Hyland Highland from its local Last Glacial Maximum position in the southeastern Mackenzie Mountains where it coalesced with the Laurentide Ice Sheet. The retreat across the Liard Lowland and a subsequent splitting of the thus far uniform ice surface into several ice lobes is evidenced by large esker complexes that stretch across the Liard Lowland cutting across the contemporary drainage network. Ice margin positions from the late stage of deglaciation are reconstructed locally at the foot of the Cassiar Mountains and farther up-valley in an eastern facing valley of the Cassiar Mountains. The presented landform record indicates that the deglaciation of the Liard Lobe was accomplished mainly by active ice retreat and that ice stagnation did not play a significant role in the deglaciation of this region.

  • 29.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Clague, John
    Simon Fraser University, Department of Earth Sciences.
    Late-glacial retreat pattern of the Cordilleran Ice Sheet in central British Columbia reconstructed from glacial meltwater landformsArticle in journal (Refereed)
    Abstract [en]

    The Cordilleran Ice Sheet (CIS) covered much of the mountainous northwestern part of North America during Pleistocene glaciations. In contrast to other ephemeral Pleistocene ice sheets, the pattern and timing of growth and decay of the CIS are poorly understood. Here, we present a reconstruction of the pattern of late-glacial ice sheet retreat in central British Columbia based on a palaeoglaciological interpretation of ice-marginal meltwater channels, eskers, and deltas mapped from satellite imagery and digital elevation models. A consistent spatial pattern of high-elevation ice-marginal meltwater channels (1600-2400 m a.s.l.) occurs across central British Columbia. They indicate the presence of ice domes over the Skeena Mountains and the central Coast Mountains early during deglaciation. Ice sourced in the Coast Mountains remained dominant over the southern and east-central parts of the Interior Plateau during late-glacial time. Our reconstruction shows a successive westward retreat of the ice margin away from the western foot of the Rocky Mountains, accompanied by the formation and rapid evolution of a glacial lake in the upper Fraser River basin. Final stages of deglaciation were characterized by the frontal retreat of ice lobes through the valleys of the Skeena and Omineca mountains and by the formation of large esker systems in the most prominent topographic lows of the Interior Plateau. We conclude that the CIS underwent a large-scale reconfiguration early during deglaciation and subsequently diminished by thinning and complex frontal retreat towards the Coast Mountains.

  • 30.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Clague, John J.
    Retreat pattern of the Cordilleran Ice Sheet in central British Columbia at the end of the last glaciation reconstructed from glacial meltwater landforms2013In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 42, no 4, p. 830-847Article in journal (Refereed)
    Abstract [en]

    The Cordilleran Ice Sheet (CIS) covered much of the mountainous northwestern part of North America at least several times during the Pleistocene. The pattern and timing of its growth and decay are, however, poorly understood. Here, we present a reconstruction of the pattern of ice-sheet retreat in central British Columbia at the end of the last glaciation based on a palaeoglaciological interpretation of ice-marginal meltwater channels, eskers and deltas mapped from satellite imagery and digital elevation models. A consistent spatial pattern of high-elevation (1600-2400m a.s.l.), ice-marginal meltwater channels is evident across central British Columbia. These landforms indicate the presence of ice domes over the Skeena Mountains and the central Coast Mountains early during deglaciation. Ice sourced in the Coast Mountains remained dominant over the southern and east-central parts of the Interior Plateau during deglaciation. Our reconstruction shows a successive westward retreat of the ice margin from the western foot of the Rocky Mountains, accompanied by the formation and rapid evolution of a glacial lake in the upper Fraser River basin. The final stage of deglaciation is characterized by the frontal retreat of ice lobes through the valleys of the Skeena and Omineca Mountains and by the formation of large esker systems in the most prominent topographic lows of the Interior Plateau. We conclude that the CIS underwent a large-scale reconfiguration early during deglaciation and was subsequently diminished by thinning and complex frontal retreat towards the Coast Mountains.

  • 31.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Lateglacial ice dynamics of the Cordilleran Ice Sheet in northern British Columbia and southern Yukon Territory: retreat pattern of the Liard Lobe reconstructed from the glacial landform record2013In: Journal of Quaternary Science, ISSN 0267-8179, E-ISSN 1099-1417, Vol. 28, no 2, p. 180-188Article in journal (Refereed)
    Abstract [en]

    The Liard Lobe formed a part of the north-eastern sector of the Cordilleran Ice Sheet and drained ice from accumulation areas in the Selwyn, Pelly, Cassiar and Skeena mountains. This study reconstructs the ice retreat pattern of the Liard Lobe during the last deglaciation from the glacial landform record that comprises glacial lineations and landforms of the meltwater system such as eskers, meltwater channels, perched deltas and outwash fans. The spatial distribution of these landforms defines the successive configurations of the ice sheet during the deglaciation. The Liard Lobe retreated to the west and south-west across the Hyland Highland from its local Last Glacial Maximum position in the south-eastern Mackenzie Mountains where it coalesced with the Laurentide Ice Sheet. Retreat across the Liard Lowland is evidenced by large esker complexes that stretch across the Liard Lowland cutting across the contemporary drainage network. Ice margin positions from the late stage of deglaciation are reconstructed locally at the foot of the Cassiar Mountains and further up-valley in an eastern-facing valley of the Cassiar Mountains. The presented landform record indicates that the deglaciation of the Liard Lobe was accomplished mainly by active ice retreat and that ice stagnation played a minor role in the deglaciation of this region.

  • 32.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansen, John
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glacial Lake Vitim, a 3000 km³ outburst flood from Siberia to the Arctic Ocean2011In: Quaternary Research, ISSN 0033-5894, E-ISSN 1096-0287, Vol. 76, no 3, p. 393-396Article in journal (Refereed)
    Abstract [en]

    A prominent lake formed when glaciers descending from the Kodar Range blocked the River Vitim in central Transbaikalia, Siberia. Glacial Lake Vitim, evidenced by palaeoshorelines and deltas, covered 23,500 km2 and held a volume of ~3000 km3. We infer that a large canyon in the area of the postulated ice dam served as a spillway during an outburst flood that drained through the rivers Vitim and Lena into the Arctic Ocean. The inferred outburst flood, of a magnitude comparable to the largest known floods on Earth, possibly explains a freshwater spike at ~13 cal ka BP inferred from Arctic Ocean sediments.

  • 33. Napieralski, Jacob
    et al.
    Hubbard, Alun
    Li, Yingkui
    Harbor, Jon
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alm, Göran
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Towards a GIS assessment of numerical ice sheet model performance using geomorphological data2007In: Journal of Glaciology, Vol. 53, no 180, p. 71-83Article in journal (Refereed)
    Abstract [en]

    A major difficulty in assimilating geomorphological information with ice-sheet models is the lack of a consistent methodology to systematically compare model output and field data. As an initial step in establishing a quantitative comparison methodology, automated proximity and conformity analysis (APCA) and automated flow direction analysis (AFDA) have been developed to assess the level of correspondence between modelled ice extent and ice-marginal features such as end moraines, as well as between modelled basal flow directions and palaeo-flow direction indicators, such as glacial lineations. To illustrate the potential of such an approach, an ensemble suite of 40 numerical simulations of the Fennoscandian ice sheet were compared to end moraines of the Last Glacial Maximum and the Younger Dryas and to glacial lineations in northern Sweden using APCA and AFDA. Model experiments evaluated in this manner were ranked according to level of correspondence. Such an approach holds considerable promise for optimizing the parameter space and coherence of ice-flow models by automated, quantitative assessment of multiple ensemble experiments against a database of geological or glaciological evidence.

  • 34. Sahlin, Eva A. U.
    et al.
    Glasser, Neil F.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Hambrey, Michael J.
    Connectivity analyses of valley patterns indicate preservation of a preglacial fluvial valley system in the Dyfi basin, Wales2009In: Proceedings Geological Association, ISSN 0016-7878, Vol. 120, p. 245-255Article, review/survey (Refereed)
    Abstract [en]

    Coastal valleys in the west part of Mid-Wales, such as the Mawddach, Dysynni, Tal-y-Ilyn and Dyfi, acted as corridors for ice which drained the Welsh Ice Cap during the Devensian. Analyses of detailed digital elevation models, and interpretation of satellite images and aerial photographs, show the existence of large variations in the amount of glacial modification between these valleys. Although all the valleys are glacially over-deepened along late Caledonian fault lines, only the Dyfi basin exhibits a dendritic pattern, with V-shaped cross-profiles and valley spurs typical of valleys formed by fluvial processes. Connectivity analysis of the Dyfi basin shows that it exhibits an almost completely dendritic pattern with connectivity alpha and beta values of 0.74 and 1.01, respectively, with little glacial modification of the preglacial fluvial valley pattern in the form of glacial valley breaching. Several examples of glacial meltwater incision into a well-developed pre-existing river valley system, causing river capture across watersheds, have been identified in the Dyfi basin. The degree of preservation of the preglacial fluvial valley system within the Dyfi basin indicates limited modification by glacial processes, despite the area being subjected to glacier activity during the Late Devensian at least. It is possible that major parts of the basin were covered by cold-based or slow-moving ice, close to, or under, a migrating ice-divide, with the major ice drainage Occurring along the weaker zone of the Pennal Fault along which teh Dyfi valley is located, causing minor adjustments to the Surrounding interfluves and uplands. it is proposed here that the general river valley morphology of the Dyfi basin is of a pre-Late Devensian age. 

  • 35. Sahlin, Eva
    et al.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hambrey, Mike
    Glasser, Neil
    Evidence for cold based ice: Preservation of a preglacial fluvial valley system in the Dyfi River basin, Mid-Wales2007In: BSG abstracts, 2007Conference paper (Other academic)
    Abstract [en]

    Coastal valleys in the west part of Mid-Wales, such as the Mawddach, Dysynni, Tal-y-llyn and Dyfi, are believed to have acted as corridors for ice, which drained the Welsh Ice Cap during the Devensian. Analysis of detailed DEMs and interpretation of satellite images and aerial photographs show the existence of large variations in the amount of glacial modification between these valleys. Although all the valleys are glacially over-deepened along Silurian fault lines, only the Dyfi basin exhibits a dendritic pattern, with V-shaped cross profiles and valley spurs typical of valleys formed by fluvial processes.

    It is proposed here that the general river valley morphology of the Dyfi basin is of a pre-Late Devensian age. Several examples have been identified of glacial meltwater incision into a well-developed pre-existing river valley system, causing river capture across watersheds. The degree of preservation of the pre-glacial fluvial valley system within the Dyfi basin indicates moderate modification by glacial processes, despite the area being subjected to Late Devensian glacier activity. It is possible that major parts of the basin were covered by cold-based or slow-moving ice, with the major ice drainage occurring along the weaker zone of the fault line, causing minor adjustments to the surrounding interfluves and uplands. The findings are important for palaeoglaciological reconstructions of the Welsh Ice Cap.

  • 36.
    Shala, Shyhrete
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Helmens, Karin F.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kylander, Malin E.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Risberg, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Löwemark, Ludvig
    Palaeoenvironmental record of glacial lake evolution during the early Holocene at Sokli, NE Finland2014In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 43, no 2, p. 362-376Article in journal (Refereed)
    Abstract [en]

    The development of a glacial lake impounded along the retreating, northeastern ice margin of the Fennoscandian Ice Sheet during the last deglaciation and environmental conditions directly following the early Holocene deglaciation have been studied in NE Finland. This so-called Sokli Ice Lake has been reconstructed previously using topographic and geomorphologic evidence. In this paper a multiproxy approach is employed to study a 3-m-thick sediment succession consisting of laminated silts grading into gyttja cored in Lake Loitsana, a remnant of the Sokli Ice Lake. Variations in the sediment and siliceous microfossil records indicate distinct changes in water depth and lake size in the Loitsana basin as the Sokli Ice Lake was drained through various spillways opening up along the retreating ice front. Geochemical data (XRF core-scanning) show changes in the influence of regional catchment geochemistry (Precambrian crystalline rocks) in the glacial lake drainage area versus local catchment geochemistry (Sokli Carbonatite Massif) within the Lake Loitsana drainage area during the lake evolution. Principal component analysis on the geochemical data further suggests that grain-size is an additional factor responsible for the variability of the sediment geochemistry record. The trophic state of the lake changed drastically as a result of morphometric eutrophication once the glacial lake developed into Lake Loitsana. The AMS radiocarbon dating on tree birch seeds found in the glaciolacustrine sediment indicates that Lake Loitsana was deglaciated sometime prior to 10 700 cal. a BP showing that tree Betula was present on the deglaciated land surrounding the glacial lake. Although glacial lakes covered large areas of northern Finland during the last deglaciation, only few glaciolacustrine sediment successions have been studied in any detail. Our study shows the potential of these sediments for multiproxy analysis and contributes to the reconstruction of environmental conditions in NE Finland directly following deglaciation in the early Holocene.

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