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Ian Bailey - One of the best experts on this subject based on the ideXlab platform.
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southern greenland glaciation and western boundary undercurrent evolution recorded on eirik drift during the late pliocene intensification of northern hemisphere glaciation
Quaternary Science Reviews, 2019Co-Authors: Keziah Blakemizen, James E T Channell, Robert G Hatfield, J S Stoner, Anders E Carlson, Chuang Xuan, Maureen Walczak, Kira T Lawrence, Ian BaileyAbstract:Abstract We present new sedimentological and environmental magnetic records spanning ∼3.2–2.2 Ma, during the intensification of Northern Hemisphere glaciation, from North Atlantic Integrated Ocean Drilling Program Site U1307 on Eirik Drift. Our new datasets and their high-fidelity age control demonstrate that while inland glaciers – and potentially also at times restricted iceberg-calving margins – have likely existed on southern Greenland since at least ∼3.2 Ma, persistent and extensive iceberg-calving glacial margins were only established in this region at 2.72 Ma, ∼300 kyr later than in northeastern and eastern Greenland. Despite a dramatic increase in Greenland-sourced Ice-Rafted Debris deposition on Eirik Drift at this time, contemporaneous changes in the bulk magnetic properties of Site U1307 sediments, and a reduction in sediment accumulation rates, suggest a decrease in the delivery of Greenland-sourced glaciofluvial silt to our study site. We attribute these changes to a shift in depositional regime from bottom-current-dominated to glacial-IRD-dominated between ∼2.9 and 2.7 Ma, in response to a change in the depth of the flow path of the Western Boundary Undercurrent relative to our study site.
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an alternative suggestion for the pliocene onset of major northern hemisphere glaciation based on the geochemical provenance of north atlantic ocean ice rafted Debris
Quaternary Science Reviews, 2013Co-Authors: Ian Bailey, Paul A. Wilson, Gavin L. Foster, Clive N. Trueman, Georgia M Hole, Craig Storey, Maureen E RaymoAbstract:Abstract The onset of abundant Ice-Rafted Debris (IRD) deposition in the Nordic Seas and subpolar North Atlantic Ocean 2.72 millions of years ago (Ma) is thought to record the Pliocene onset of major northern hemisphere glaciation (NHG) due to a synchronous advance of North American Laurentide, Scandinavian and Greenland ice-sheets to their marine calving margins during marine isotope stage (MIS) G6. Numerous marine and terrestrial records from the Nordic Seas region indicate that extensive ice sheets on Greenland and Scandinavia increased IRD inputs to these seas from 2.72 Ma. The timing of ice-sheet expansion on North America as tracked by IRD deposition in the subpolar North Atlantic Ocean, however, is less clear because both Europe and North America are potential sources for icebergs in this region. Moreover, cosmogenic-dating of terrestrial tills on North America indicate that the Laurentide Ice Sheet did not extend to ∼39°N until 2.4 ± 0.14 Ma, at least 180 ka after the onset of major IRD deposition at 2.72 Ma. To address this problem, we present the first detailed analysis of the geochemical provenance of individual sand-sized IRD deposited in the subpolar North Atlantic Ocean between MIS G6 and 100 (∼2.72–2.52 Ma). IRD provenance is assessed using laser ablation lead (Pb) isotope analyses of single Ice-Rafted (>150 μm) feldspar grains. To track when an ice-rafting setting consistent with major NHG first occurred in the North Atlantic Ocean during the Pliocene intensification of NHG (iNHG), we investigate when the Pb-isotope composition (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb) of feldspars deposited at DSDP Site 611 first resembles that determined for IRD deposited at this site during MIS 100 (2.52 Ma), the oldest glacial for which there exists convincing evidence for widespread glaciation of North America. Whilst Quaternary-magnitude IRD fluxes exist at Site 611 during glacials from 2.72 Ma, we find that the provenance of this IRD is not constant. Instead, we find that the Pb-isotope composition of IRD at our study site is not consistent with major NHG until MIS G2 (2.64 Ma). We hypothesise that IRD deposition in the North Atlantic Ocean prior to MIS G2 was dominated by iceberg calving from Greenland and Scandinavia. We further suggest that the grounding line of continental ice on Northeast America may not have extended onto the continental shelf and calved significant numbers of icebergs to the North Atlantic Ocean during glacials until 2.64 Ma.
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Flux and provenance of Ice-Rafted Debris in the earliest Pleistocene sub-polar North Atlantic Ocean comparable to the last glacial maximum
Earth and Planetary Science Letters, 2012Co-Authors: Ian Bailey, Paul A. Wilson, Gavin L. Foster, Luigi Jovane, Craig D. Storey, Clive N. Trueman, Julia BeckerAbstract:Relatively little is known in detail about the locations of the early Pleistocene ice-sheets responsible for Ice-Rafted Debris(IRD) inputs to the sub-polar North Atlantic Ocean during intensification of northern hemisphere glaciation (iNHG). To shed new light on this problem,we present the first combined in-depth analysis of IRD flux and geochemical provenance of individual sand-sized IRD deposited in the sub-polar North Atlantic Ocean during the earliest large amplitude Pleistocene glacial, marine isotope stage (MIS)100( 2.52 Ma),arguably the key glacial during iNHG. IRD provenance is assessed using laser ablation lead (Pb) isotope analyses of single feldspar grains. We find that the Pb-isotopecomposition (206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb) of individual Ice-Rafted (4150 mm)feldspars deposited at DSDP Site 611A, ODP Site 981 and IODP Site U1308 during MIS100 records a shift from predominantly Archaean-aged circum-North Atlantic Ocean continental sources during early glacial ice-rafting events to dominantly Palaeozoic and Proterozoic-aged sources during full glacial conditions. The distribution of feldspars in Pb–Pb space for full glacial MIS100 more closely resembles that documented for feldspars deposited at the centre of the last glacial IRD belt (at IODP/DSDP Site U1308/609) during ambient (non-Heinrich-event) ice-rafting episodes of MIS 2 ( 23.8 ka) than that documented for MIS 5d ( 106 Ka). Comparison of our early Pleistocene and last glacial cycle datasets suggests that MIS100 was characterised by abundant iceberg calving from large ice-sheets on multiplecontinents in the high northern latitudes (notjustonGreenland)
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iron fertilisation and biogeochemical cycles in the sub arctic northwest pacific during the late pliocene intensification of northern hemisphere glaciation
Earth and Planetary Science Letters, 2011Co-Authors: Ian Bailey, Youbin Sun, Qingsong Liu, George E A Swann, Zhaoxia Jiang, Xiang Zhao, Andrew P RobertsAbstract:Abstract Increases in the low-field mass-specific magnetic susceptibility (χ), dropstones and the terrigenous sediment component from Ocean Drilling Program (ODP) Site 882 (~ 45°N) have been interpreted to indicate a major onset of ice-rafting to the sub-Arctic northwest Pacific Ocean during marine isotope stage (MIS) G6 (from ~ 2.75 Ma). In contrast, studies of the terrigenous content of sediments cored downwind of ODP Site 882 indicate that dust and disseminated volcanic ash deposition in the sub-Arctic Pacific increased markedly during MIS G6. To investigate the relative contribution of dust, volcanic ash and ice rafting to the Pliocene χ increase, we present new high-resolution environmental magnetic and Ice-Rafted Debris records from ODP Sites 882 and 885. Our results demonstrate that the χ increase at both sites across MIS G6 is predominantly controlled by a previously overlooked mixture of aeolian dust and volcanic ash. Our findings call into question the reliability of χ as a proxy for ice-rafting to the North Pacific. They also highlight a previously undocumented link between iron fertilisation and biogeochemical cycling in the North Pacific at a key stage during intensification of late Pliocene northern hemisphere glaciation.
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north atlantic paleoceanography the last five million years
Eos Transactions American Geophysical Union, 2006Co-Authors: Ruediger Stein, Toshiya Kanamatsu, Carlos A Alvarezzarikian, Sean M Higgins, J E T Channell, Essam Aboud, Masao Ohno, Gary D Acton, Kazumi Akimoto, Ian BaileyAbstract:In the North Atlantic, cold, relatively salty water sinks in the icy Labrador and Greenland seas, forming North Atlantic Deep Water (NADW).This circulates through the global ocean, driving ocean overturning and global heat transport and, thus, impacting global climate. As one of the most climatically sensitive regions on Earth, the North Atlantic has experienced abrupt changes to its oceanatmosphere-cryosphere system, triggered by fluctuations in meltwater delivery to source areas of NADW formation. For about the past 100 thousand years, these abrupt jumps in climate state have manifested as ‘Dansgaard/Oeschger’ (D/O) oscillations (millennial-scale warm-cold oscillations) and 'Heinrich' events in ice and marine sediment cores, respectively [e.g., Dansgaard et al., 1993; Bond and Lotti, 1995]. These Heinrich events are characterized as huge input of Ice-Rafted Debris (IRD) and meltwater pulses, documenting episodes of sudden instability and collapse of the current Greenland ice sheets and the Laurentide ice sheet, the latter of which covered northern North America several times during the Pleistocene Epoch.
Andrew P Roberts - One of the best experts on this subject based on the ideXlab platform.
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iron fertilisation and biogeochemical cycles in the sub arctic northwest pacific during the late pliocene intensification of northern hemisphere glaciation
Earth and Planetary Science Letters, 2011Co-Authors: Ian Bailey, Youbin Sun, Qingsong Liu, George E A Swann, Zhaoxia Jiang, Xiang Zhao, Andrew P RobertsAbstract:Abstract Increases in the low-field mass-specific magnetic susceptibility (χ), dropstones and the terrigenous sediment component from Ocean Drilling Program (ODP) Site 882 (~ 45°N) have been interpreted to indicate a major onset of ice-rafting to the sub-Arctic northwest Pacific Ocean during marine isotope stage (MIS) G6 (from ~ 2.75 Ma). In contrast, studies of the terrigenous content of sediments cored downwind of ODP Site 882 indicate that dust and disseminated volcanic ash deposition in the sub-Arctic Pacific increased markedly during MIS G6. To investigate the relative contribution of dust, volcanic ash and ice rafting to the Pliocene χ increase, we present new high-resolution environmental magnetic and Ice-Rafted Debris records from ODP Sites 882 and 885. Our results demonstrate that the χ increase at both sites across MIS G6 is predominantly controlled by a previously overlooked mixture of aeolian dust and volcanic ash. Our findings call into question the reliability of χ as a proxy for ice-rafting to the North Pacific. They also highlight a previously undocumented link between iron fertilisation and biogeochemical cycling in the North Pacific at a key stage during intensification of late Pliocene northern hemisphere glaciation.
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continental ice in greenland during the eocene and oligocene
Nature, 2007Co-Authors: Paul A. Wilson, James S Eldrett, Ian C Harding, Emily Butler, Andrew P RobertsAbstract:The Eocene and Oligocene epochs (approximately 55 to 23 million years ago) comprise a critical phase in Earth history. An array of geological records supported by climate modelling indicates a profound shift in global climate during this interval, from a state that was largely free of polar ice caps to one in which ice sheets on Antarctica approached their modern size. However, the early glaciation history of the Northern Hemisphere is a subject of controversy. Here we report stratigraphically extensive Ice-Rafted Debris, including macroscopic dropstones, in late Eocene to early Oligocene sediments from the Norwegian-Greenland Sea that were deposited between about 38 and 30 million years ago. Our data indicate sediment rafting by glacial ice, rather than sea ice, and point to East Greenland as the likely source. Records of this type from one site alone cannot be used to determine the extent of ice involved. However, our data suggest the existence of (at least) isolated glaciers on Greenland about 20 million years earlier than previously documented, at a time when temperatures and atmospheric carbon dioxide concentrations were substantially higher.
Grant R Bigg - One of the best experts on this subject based on the ideXlab platform.
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Exploring the extent to which fluctuations in Ice-Rafted Debris reflect mass changes in the source ice sheet: a model–observation comparison using the last British–Irish Ice Sheet
'Wiley', 2021Co-Authors: Dj Wilton, Grant R Bigg, Jd Scourse, Jc Ely, Cd ClarkAbstract:This is the final version. Available from Wiley via the DOI in this record. Modelling data are available on request from the authors. IRD data are available as a mix of data in public repositories that issue datasets with DOIs and some on request from the authors.The British and Irish Ice Sheet (BIIS) was highly dynamic during the Late Quaternary, with considerable regional differences in the timing and extent of its change. This was reflected in equally variable offshore Ice-Rafted Debris (IRD) records. Here we reconcile these two records using the FRUGAL intermediate complexity iceberg–climate model, with varying BIIS catchment-level iceberg fluxes, to simulate change in IRD origin and magnitude along the western European margin at 1000-year time steps during the height of the last BIIS glaciation (31–6 ka bp). This modelled IRD variability is compared with existing IRD records from the deep ocean at five cores along this margin. There is general agreement of the temporal and spatial IRD variability between observations and model through this period. The Porcupine Bank off northwestern Ireland was confirmed by the modelling as a major dividing line between sites possessing exclusively northern or southern source regions for offshore IRD. During Heinrich events 1 and 2, the cores show evidence of a proportion of North American IRD, more particularly to the south of the British Isles. Modelling supports this southern bias for likely Heinrich impact, but also suggests North American IRD will only reach the British margin in unusual circumstances.Natural Environment Research CouncilNatural Environment Research CouncilUniversity of ExeterUniversity of Sheffiel
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last glacial ice rafted Debris off southwestern europe the role of the british irish ice sheet
Journal of Quaternary Science, 2010Co-Authors: Grant R Bigg, Richard C Levine, Chris D Clark, Sarah L Greenwood, Haflidi Haflidason, Anna L C Hughes, Atle Nygard, Hans Petter SejrupAbstract:Ice-Rafted Debris (IRD) seeded into the ocean from Northern Hemisphere ice sheets is found in ocean cores along the southwestern European margin through the last glacial period. It is known that the origin of this IRD, especially off Iberia, can vary between North America and western Europe during short-lived episodes of greatly enhanced iceberg flux, known as Heinrich events, although in most Heinrich events the IRD has a North American source. During the longer times of much lower IRD fluxes between Heinrich events, use of an intermediate complexity climate model, coupled to an iceberg dynamic and thermodynamic model, shows that background levels of IRD most likely originate from western Europe, particularly the British Irish Ice Sheet. Combining modelling with palaeoceanographic evidence supports reconstructions of a short-lived, but substantial, Celtic and Irish Sea Ice Stream around 23 ka.
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a last glacial ice sheet on the pacific russian coast and catastrophic change arising from coupled ice volcanic interaction
Earth and Planetary Science Letters, 2008Co-Authors: Grant R Bigg, Chris D Clark, Anna L C HughesAbstract:Abstract Controversy exists over the extent of glaciation in Eastern Asia at the Last Glacial Maximum: complete ice sheet cover vs. restricted mountain icefields (an area discrepancy equivalent to 3.7 Greenland Ice Sheets). Current arguments favour the latter. However, significant last glacial Ice-Rafted Debris (IRD) exists in NW Pacific ocean cores, which must have been sourced from a major ice sheet somewhere bordering the North Pacific. The origin of this IRD is addressed through a combination of marine core analysis, iceberg trajectory modelling and remote sensing of glacial geomorphology. We find compelling evidence for two stages of glaciation centred on the Kamchatka area of maritime southeast Russia during the last glacial, with ice extent intermediate in size between previous maximum and minimum reconstructions. Furthermore, a significant increase in iceberg flux precedes, and accompanies, a substantial marine core ash deposit at around 40 ka BP. We speculate that rapid decay of the first stage of the ice sheet may have triggered substantial volcanic activity.
Anna L C Hughes - One of the best experts on this subject based on the ideXlab platform.
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last glacial ice rafted Debris off southwestern europe the role of the british irish ice sheet
Journal of Quaternary Science, 2010Co-Authors: Grant R Bigg, Richard C Levine, Chris D Clark, Sarah L Greenwood, Haflidi Haflidason, Anna L C Hughes, Atle Nygard, Hans Petter SejrupAbstract:Ice-Rafted Debris (IRD) seeded into the ocean from Northern Hemisphere ice sheets is found in ocean cores along the southwestern European margin through the last glacial period. It is known that the origin of this IRD, especially off Iberia, can vary between North America and western Europe during short-lived episodes of greatly enhanced iceberg flux, known as Heinrich events, although in most Heinrich events the IRD has a North American source. During the longer times of much lower IRD fluxes between Heinrich events, use of an intermediate complexity climate model, coupled to an iceberg dynamic and thermodynamic model, shows that background levels of IRD most likely originate from western Europe, particularly the British Irish Ice Sheet. Combining modelling with palaeoceanographic evidence supports reconstructions of a short-lived, but substantial, Celtic and Irish Sea Ice Stream around 23 ka.
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a last glacial ice sheet on the pacific russian coast and catastrophic change arising from coupled ice volcanic interaction
Earth and Planetary Science Letters, 2008Co-Authors: Grant R Bigg, Chris D Clark, Anna L C HughesAbstract:Abstract Controversy exists over the extent of glaciation in Eastern Asia at the Last Glacial Maximum: complete ice sheet cover vs. restricted mountain icefields (an area discrepancy equivalent to 3.7 Greenland Ice Sheets). Current arguments favour the latter. However, significant last glacial Ice-Rafted Debris (IRD) exists in NW Pacific ocean cores, which must have been sourced from a major ice sheet somewhere bordering the North Pacific. The origin of this IRD is addressed through a combination of marine core analysis, iceberg trajectory modelling and remote sensing of glacial geomorphology. We find compelling evidence for two stages of glaciation centred on the Kamchatka area of maritime southeast Russia during the last glacial, with ice extent intermediate in size between previous maximum and minimum reconstructions. Furthermore, a significant increase in iceberg flux precedes, and accompanies, a substantial marine core ash deposit at around 40 ka BP. We speculate that rapid decay of the first stage of the ice sheet may have triggered substantial volcanic activity.
Paul A. Wilson - One of the best experts on this subject based on the ideXlab platform.
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an alternative suggestion for the pliocene onset of major northern hemisphere glaciation based on the geochemical provenance of north atlantic ocean ice rafted Debris
Quaternary Science Reviews, 2013Co-Authors: Ian Bailey, Paul A. Wilson, Gavin L. Foster, Clive N. Trueman, Georgia M Hole, Craig Storey, Maureen E RaymoAbstract:Abstract The onset of abundant Ice-Rafted Debris (IRD) deposition in the Nordic Seas and subpolar North Atlantic Ocean 2.72 millions of years ago (Ma) is thought to record the Pliocene onset of major northern hemisphere glaciation (NHG) due to a synchronous advance of North American Laurentide, Scandinavian and Greenland ice-sheets to their marine calving margins during marine isotope stage (MIS) G6. Numerous marine and terrestrial records from the Nordic Seas region indicate that extensive ice sheets on Greenland and Scandinavia increased IRD inputs to these seas from 2.72 Ma. The timing of ice-sheet expansion on North America as tracked by IRD deposition in the subpolar North Atlantic Ocean, however, is less clear because both Europe and North America are potential sources for icebergs in this region. Moreover, cosmogenic-dating of terrestrial tills on North America indicate that the Laurentide Ice Sheet did not extend to ∼39°N until 2.4 ± 0.14 Ma, at least 180 ka after the onset of major IRD deposition at 2.72 Ma. To address this problem, we present the first detailed analysis of the geochemical provenance of individual sand-sized IRD deposited in the subpolar North Atlantic Ocean between MIS G6 and 100 (∼2.72–2.52 Ma). IRD provenance is assessed using laser ablation lead (Pb) isotope analyses of single Ice-Rafted (>150 μm) feldspar grains. To track when an ice-rafting setting consistent with major NHG first occurred in the North Atlantic Ocean during the Pliocene intensification of NHG (iNHG), we investigate when the Pb-isotope composition (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb) of feldspars deposited at DSDP Site 611 first resembles that determined for IRD deposited at this site during MIS 100 (2.52 Ma), the oldest glacial for which there exists convincing evidence for widespread glaciation of North America. Whilst Quaternary-magnitude IRD fluxes exist at Site 611 during glacials from 2.72 Ma, we find that the provenance of this IRD is not constant. Instead, we find that the Pb-isotope composition of IRD at our study site is not consistent with major NHG until MIS G2 (2.64 Ma). We hypothesise that IRD deposition in the North Atlantic Ocean prior to MIS G2 was dominated by iceberg calving from Greenland and Scandinavia. We further suggest that the grounding line of continental ice on Northeast America may not have extended onto the continental shelf and calved significant numbers of icebergs to the North Atlantic Ocean during glacials until 2.64 Ma.
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Flux and provenance of Ice-Rafted Debris in the earliest Pleistocene sub-polar North Atlantic Ocean comparable to the last glacial maximum
Earth and Planetary Science Letters, 2012Co-Authors: Ian Bailey, Paul A. Wilson, Gavin L. Foster, Luigi Jovane, Craig D. Storey, Clive N. Trueman, Julia BeckerAbstract:Relatively little is known in detail about the locations of the early Pleistocene ice-sheets responsible for Ice-Rafted Debris(IRD) inputs to the sub-polar North Atlantic Ocean during intensification of northern hemisphere glaciation (iNHG). To shed new light on this problem,we present the first combined in-depth analysis of IRD flux and geochemical provenance of individual sand-sized IRD deposited in the sub-polar North Atlantic Ocean during the earliest large amplitude Pleistocene glacial, marine isotope stage (MIS)100( 2.52 Ma),arguably the key glacial during iNHG. IRD provenance is assessed using laser ablation lead (Pb) isotope analyses of single feldspar grains. We find that the Pb-isotopecomposition (206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb) of individual Ice-Rafted (4150 mm)feldspars deposited at DSDP Site 611A, ODP Site 981 and IODP Site U1308 during MIS100 records a shift from predominantly Archaean-aged circum-North Atlantic Ocean continental sources during early glacial ice-rafting events to dominantly Palaeozoic and Proterozoic-aged sources during full glacial conditions. The distribution of feldspars in Pb–Pb space for full glacial MIS100 more closely resembles that documented for feldspars deposited at the centre of the last glacial IRD belt (at IODP/DSDP Site U1308/609) during ambient (non-Heinrich-event) ice-rafting episodes of MIS 2 ( 23.8 ka) than that documented for MIS 5d ( 106 Ka). Comparison of our early Pleistocene and last glacial cycle datasets suggests that MIS100 was characterised by abundant iceberg calving from large ice-sheets on multiplecontinents in the high northern latitudes (notjustonGreenland)
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continental ice in greenland during the eocene and oligocene
Nature, 2007Co-Authors: Paul A. Wilson, James S Eldrett, Ian C Harding, Emily Butler, Andrew P RobertsAbstract:The Eocene and Oligocene epochs (approximately 55 to 23 million years ago) comprise a critical phase in Earth history. An array of geological records supported by climate modelling indicates a profound shift in global climate during this interval, from a state that was largely free of polar ice caps to one in which ice sheets on Antarctica approached their modern size. However, the early glaciation history of the Northern Hemisphere is a subject of controversy. Here we report stratigraphically extensive Ice-Rafted Debris, including macroscopic dropstones, in late Eocene to early Oligocene sediments from the Norwegian-Greenland Sea that were deposited between about 38 and 30 million years ago. Our data indicate sediment rafting by glacial ice, rather than sea ice, and point to East Greenland as the likely source. Records of this type from one site alone cannot be used to determine the extent of ice involved. However, our data suggest the existence of (at least) isolated glaciers on Greenland about 20 million years earlier than previously documented, at a time when temperatures and atmospheric carbon dioxide concentrations were substantially higher.