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  • 1
    Online Resource
    Online Resource
    Svalbard glaciers re‐advanced during the Pleistocene–Holocene transition
    Wiley ; 2018
    In:  Boreas Vol. 47, No. 4 ( 2018-10), p. 1022-1032
    Details
    In: Boreas, Wiley, Vol. 47, No. 4 ( 2018-10), p. 1022-1032
    Abstract: Despite warming regional conditions and our general understanding of the deglaciation, a variety of data suggest glaciers re‐advanced on Svalbard during the Lateglacial–early Holocene ( LGEH ). We present the first well‐dated end moraine formed during the LGEH in De Geerbukta, NE Spitsbergen. This landform was deposited by an outlet glacier re‐advancing into a fjord extending 4.4 km beyond the late Holocene ( LH ) maximum. Comparing the timing of the De Geerbukta glacier re‐advance to a synthesis of existing data including four palaeoclimate records and 15 other proposed glacier advances from Svalbard does not suggest any clear synchronicity in glacial and climatic events. Furthermore, we introduce six additional locations where glacier moraines have been wave‐washed or cut by postglacial raised marine shorelines, suggesting the landforms were deposited before or during high relative sea‐level stands, thus exhibiting a similar LGEH age. Contrary to current understanding, our new evidence suggests that the LGEH glaciers were more dynamic, exhibited re‐advances and extended well beyond the extensively studied LH glacial expansion. Given the widespread occurrence of the LGEH glacier deposits on Svalbard, we suggest that the culmination of the Neoglacial advances during the Little Ice Age does not mark the maximum extent of most Svalbard glaciers since deglaciation; it is just the most studied and most visible in the geological record.
    Type of Medium: Online Resource
    ISSN: 0300-9483 , 1502-3885
    URL: Issue
    URL: Article
    DOI: 10.1111/bor.2018.47.issue-4
    DOI: 10.1111/bor.12326
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 2028632-6
    detail.hit.zdb_id: 185110-X
    SSG: 14
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  • 2
    Online Resource
    Online Resource
    Progressive formation of modern drumlins at Múlajökull, Iceland: stratigraphical and morphological evidence
    Wiley ; 2016
    In:  Boreas Vol. 45, No. 4 ( 2016-10), p. 567-583
    Details
    In: Boreas, Wiley, Vol. 45, No. 4 ( 2016-10), p. 567-583
    Abstract: The drumlin field at Múlajökull, Iceland, is considered to be an active field in that partly and fully ice‐covered drumlins are being shaped by the current glacier regime. We test the hypothesis that the drumlins form by a combination of erosion and deposition during successive surge cycles. We mapped and measured 143 drumlins and studied their stratigraphy in four exposures. All exposures reveal several till units where the youngest till commonly truncates older tills on the drumlin flanks and proximal slope. Drumlins inside a 1992 moraine are relatively long and narrow whereas drumlins outside the moraine are wider and shorter. A conceptual model suggests that radial crevasses create spatial heterogeneity in normal stress on the bed so that deposition is favoured beneath crevasses and erosion in adjacent areas. Consequently, the crevasse pattern of the glacier controls the location of proto‐drumlins. A feedback mechanism leads to continued crevassing and increased sedimentation at the location of the proto‐drumlins. The drumlin relief and elongation ratio increases as the glacier erodes the sides and drapes a new till over the landform through successive surges. Our observations of this only known active drumlin field may have implications for the formation and morphological evolution of Pleistocene drumlin fields with similar composition, and our model may be tested on modern drumlins that may become exposed upon future ice retreat.
    Type of Medium: Online Resource
    ISSN: 0300-9483 , 1502-3885
    URL: Issue
    URL: Article
    DOI: 10.1111/bor.2016.45.issue-4
    DOI: 10.1111/bor.12195
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 2028632-6
    detail.hit.zdb_id: 185110-X
    SSG: 14
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  • 3
    Online Resource
    Online Resource
    Glacio‐isostatic age modelling and Late Weichselian deglaciation of the Lögurinn basin, East Iceland
    Wiley ; 2019
    In:  Boreas Vol. 48, No. 3 ( 2019-07), p. 563-580
    Details
    In: Boreas, Wiley, Vol. 48, No. 3 ( 2019-07), p. 563-580
    Abstract: Knowledge of the glaciation of central East Iceland between 15 and 9 cal. ka BP is important for the understanding of the extent, retreat and dynamics of the Icelandic Ice Sheet. Crucially, it is not known if the key area of Fljótsdalur‐Úthérað carried a fast‐flowing ice stream during the Last Glacial Maximum; the timing and mode of deglaciation is unclear; and the history and ages of successive lake‐phases in the Lögurinn basin are uncertain. We use the distribution of glacial and fluvioglacial deposits and gradients of former lake shorelines to reconstruct the glaciation and deglaciation history, and to constrain glacio‐isostatic age modelling. We conclude that during the Last Glacial Maximum, Fljótsdalur‐Úthérað was covered by a fast‐flowing ice stream, and that the Lögurinn basin was deglaciated between 14.7 and 13.2 cal. ka BP at the earliest. The Fljótsdalur outlet glacier re‐advanced and reached a temporary maximum extent on two separate occasions, during the Younger Dryas and the Preboreal. In the Younger Dryas, about 12.1 cal. ka BP , the outlet glacier reached the Tjarnarland terminal zone, and filled the Lögurinn basin. During deglaciation, a proglacial lake formed in the Lögurinn basin. Through time, gradients of ice‐lake shorelines increased as a result of continuous but non‐uniform glacio‐isostatic uplift as the Fljótsdalur outlet glacier retreated across the Valþjófsstaður terminal zone. Changes in shoreline gradients are defined as a function of time, expressed with an exponential equation that is used to model ages of individual shorelines. A glaciolacustrine phase of Lake Lögurinn existed between 12.1 and 9.1 cal. ka BP ; as the ice retreated from the basin catchment, a wholly lacustrine phase of Lake Lögurinn commenced and lasted until about 4.2 cal. ka BP when neoglacial ice expansion started the current glaciolacustrine phase of the lake.
    Type of Medium: Online Resource
    ISSN: 0300-9483 , 1502-3885
    URL: Issue
    URL: Article
    DOI: 10.1111/bor.2019.48.issue-3
    DOI: 10.1111/bor.12366
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2028632-6
    detail.hit.zdb_id: 185110-X
    SSG: 14
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  • 4
    Online Resource
    Online Resource
    Holocene tephrostratigraphy in Vestfirðir, NW Iceland
    Wiley ; 2018
    In:  Journal of Quaternary Science Vol. 33, No. 7 ( 2018-10), p. 827-839
    Details
    In: Journal of Quaternary Science, Wiley, Vol. 33, No. 7 ( 2018-10), p. 827-839
    Abstract: We present a tephra stratigraphical and tephrochronological record from eight lakes in Vestfirðir, NW Iceland. About 50 tephra units have been identified, representing nearly 30 eruptive events originating from five volcanic systems: Hekla, Katla, Snæfellsjökull, Grímsvötn and Veiðivötn‐Bárðarbunga. Most of the tephra layers originate from Grímsvötn, although there is a prominent presence of andesitic to basaltic tephra layers from Hekla in the record. We propose that the previously described Brattihjalli tephra is actually the 6060‐year‐old Hekla Ö tephra marker layer, recording a more north‐westerly dispersal than before and providing new correlation possibilities across Iceland. Thus, the Hekla Ö tephra covers as large an area in Iceland as the Hekla 5, Hekla 4, Hekla 3 and Hekla 1104 tephra layers, emphasizing its importance as a chronological marker. The tephra markers Hekla 1693, V877/Settlement layer, Sn‐1, Hekla 3 and Hekla 4 have been found and, additionally, our study identifies four potential tephra markers, the Katla D1 ∼2750 cal a BP , Katla D2 ∼3700 cal a BP , Reykjarfjörður tephra ∼8800 cal a BP and Dagverðardalur tephra ∼9300–9500 cal a BP . Our data reveal several new tephra layers in Vestfirðir, including chronological markers important for dating and correlation.
    Type of Medium: Online Resource
    ISSN: 0267-8179 , 1099-1417
    URL: Issue
    URL: Article
    DOI: 10.1002/jqs.v33.7
    DOI: 10.1002/jqs.3063
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 2031875-3
    SSG: 13
    SSG: 14
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  • 5
    Online Resource
    Online Resource
    Dynamic Holocene glacial history of St. Jonsfjorden, Svalbard
    Wiley ; 2017
    In:  Boreas Vol. 46, No. 3 ( 2017-07), p. 585-603
    Details
    In: Boreas, Wiley, Vol. 46, No. 3 ( 2017-07), p. 585-603
    Abstract: Evidence of a dynamic Holocene glacial history is preserved in the terrestrial and marine archives of St. Jonsfjorden, a small fjord‐system on the west coast of Spitsbergen, Svalbard. High‐resolution, remotely sensed imagery from marine and terrestrial environments was used to construct geomorphological maps that highlight an intricate glacial history of the entire fjord‐system. The geomorphology and stratigraphy indicate an early Holocene local glacier advance constrained to the Lateglacial–early Holocene transition. Identification and 14 C dating of the thermophilous bivalve mollusc Modiolus modiolus to 10.0±0.12 cal. ka BP suggest a rapid northward migration of the species shortly after deglaciation. Further evidence enhances the understanding of the onset and subsequent climax of the Neoglacial‐Little Ice Age in inner St. Jonsfjorden. The present‐day terminus of Osbornebreen, the dominating glacier system in St. Jonsfjorden, is located over 8.5 km up‐fjord from its Neoglacial maximum extent. Cross‐cutting relationships suggest subsequent advances of all the smaller glaciers in the area following the break‐up of Osbornebreen. Glacial deposits, landforms and their cross‐cutting relationships observed in both terrestrial and marine settings imply a complex and highly dynamic environment through the later part of the Holocene.
    Type of Medium: Online Resource
    ISSN: 0300-9483 , 1502-3885
    URL: Issue
    URL: Article
    DOI: 10.1111/bor.2017.46.issue-3
    DOI: 10.1111/bor.12269
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 2028632-6
    detail.hit.zdb_id: 185110-X
    SSG: 14
    Location Call Number Limitation Availability
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    Online Resource
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