Cold-seep fossil macrofaunal assemblages from Vestnesa Ridge, eastern Fram Strait, during the past 45 000 years

  • Elsebeth Thomsen The Arctic University Museum of Norway, UiT—The Arctic University of Norway, Tromsø, Norway
  • Tine Lander Rasmussen Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT—The Arctic University of Norway, Tromsø, Norway
  • Kamila Sztybor Akvaplan-niva AS, Fram Centre, Tromsø, Norway
  • Nils-Martin Hanken Department of Geosciences, UiT—The Arctic University of Norway, Tromsø, Norway; Department of Geosciences, University of Oslo, Oslo, Norway
  • Ole Secher Tendal Natural History Museum of Denmark, Zoological Museum, Copenhagen Ø, Denmark
  • Alfred Uchman Jagiellonian University, Institute of Geological Sciences, Kraków, Poland
Keywords: Methane release, macrofossils, trace fossils, foraminifera, mid-late Weichselian glacial to Holocene, Svalbard margin


Four cores from Vestnesa Ridge on the western Svalbard margin from water depth of 1200 m have been studied. The Vestnesa Ridge is known for the presence of numerous pockmarks and active methane gas seepage is often observed in the form of acoustic gas flares. Three of the cores were collected from a pockmark with active seepage of methane and one core was taken just outside the seepage area for comparison. The cores show a range of influence from methane from no seepage (control core), moderate seepage, strong seepage to very strong seepage. All cores have been analyzed for the distribution of macrofossils, trace fossils, planktic foraminifera, stable isotopes, geochemistry and sedimentology. The main purpose of the study is to improve knowledge about the fossil macrofauna and past methane emissions in the area. The results show a major difference between the fauna recovered from cores taken inside a pockmark with chemosymbiotic bivalves and in some cases with a rich macrofauna  and from the core recovered outside the pockmark that contained no macrofauna. The faunal relationships with the sedimentary environments confirm a close connection between the macrofauna and the presence/absence of cold-seepage, particularly seen in the occurrence of chemosymbiotic bivalves Archivesica arctica, Isorropodon nyeggaensis, potentially chemosymbiotic Rhacothyas kolgae and polychaetes. A barren zone in the core that was taken from the deepest part of the pockmark may indicate that a blow-out took place in the late glacial and the deglaciation into the early Holocene at c. 21,000–9000 years.


Download data is not yet available.


Aagard K., Foldvik A. & Hillman S.R. 1987. The West Spitsbergen Current: disposition and water mass transformation. Journal of Geophysical Research—Oceans 92, 3778–3784,

Ambrose W.G., Panieri G., Schneider A., Plaza-Faverola A., Carroll M.L., Åström E.K.L., Locke W.L. & Carroll J. 2015. Bivalve shell horizons in seafloor pockmarks of the last glacial–interglacial transition: a thousand years of methane emissions in the Arctic Ocean. Geochemistry, Geophysics, Geosystems 16, 4108–4129,

Åström E.K.L., Carroll M.L., Ambrose W.G. Jr. & Carroll J. 2016. Arctic cold seep in marine methane hydrate environments: impacts on shelf microbenthic community structure offshore Svalbard. Marine Ecology Progress Series 552, 1–18,

Åström E.K.L., Carroll M.L., Ambrose W.G. Jr., Sen A., Silyakova A. & Carroll J. 2018. Methane cold seeps as biological oases in the High-Arctic deep sea. Limnology and Oceanography 63, S209–S231,

Åström E.K.L., Oliver P.G. & Carroll M.L. 2017. A new genus and two new species of Thyasiridae associated with methane seeps off Svalbard, Arctic Ocean. Marine Biology Research 13, 402–416,

Barry J.P., Kochevar R.E. & Baxter C.H. 1997. The influence of pore-water chemistry and physiology on the distribution of vesicomyid clams of cold seeps in Monterey Bay: implications for patterns of chemosynthetic community organization. Limnology and Oceanography 42, 318–328,

Barthel D. & Tendal O.S. 1993. The sponge association of the abyssal Norwegian–Greenland Sea: species composition, substrate relationships and distribution. Sarsia 782, 83–96,

Bergmann M., Dannheim J., Bauerfeind E. & Klages M. 2009. Trophic relationships along a bathymetric gradient at the deep-sea observatory Hausgarten. Deep-Sea Research Part I 56, 408–424,

Bergmann M., Langwald N., Ontrup J., Soltwedel T., Scheve I., Klages M. & Nattkemper T.W. 2011. Megafaunal assemblages from two shelf stations west of Svalbard. Marine Biology Research 7, 525–539,

Bergmann M., Soltwedel T. & Klages M. 2011. The interannual variability of megafaunal assemblages in the Arctic deep sea: preliminary results of the Hausgarten observatory (79oN). Deep-Sea Research Part I 58, 711–723,

Boetius A., Ravenschlag K., Schubert C.J., Rickert D., Widdel F., Gieseke A., Amann R., Jorgensen B.B., Witte U. & Pfannkuche O. 2000. A marine microbial consortium apparently mediating anaerobic oxidation of methane. Nature 407, 623–626,

Bond G., Broecker W., Johnsen S., McManus J., Labeyrie L., Jouzel J. & Bonani G. 1993. Correlations between climate records from the North Atlantic sediments and Greenland ice. Nature 365, 143–147,

Borowski W.S., Paull C.K. & Ussler W. 1996. Marine pore-water sulphate profiles indicate in situ methane flux from underlying gas hydrate. Geology 24, 655–658,<0655:MPWSPI>2.3.CO;2.

Bromley R.G. 1993. Predation habits of octopus past and present and a new ichnospecies Oichnus ovalis. Bulletin of the Geological Society of Denmark 40, 167–173.

Brooks J.M., Kennicutt M.C., Fisher C.R., Macko S.A., Cole K. Childress J.J., Bidigare R.R. & Vetter R.D. 1987. Deep-sea hydrocarbon seep communities: evidence for energy and nutritional carbon sources. Science 238, 1138–1142,

Bünz S., Polyanov S., Vadakkepuliyambatta S., Consolaro C. & Mienert J. 2012. Active gas venting through hydrate-bearing sediments on the Vestnes Ridge, offshore W-Svalbard. Marine Geology 332–334, 189–197,

Consolaro C., Rasmussen T.L., Panieri G., Mienert J., Buenz S. & Sztybor K. 2015. Carbon isotope (δ13C) excursions suggest times of major methane release during the last 14 ka in Fram Strait, the deep-water gateway to the Arctic. Climate of the Past 11, 669–685,

Cook M.S., Keigwin L.D., Birgel D. & Hinrichs K.-U. 2011. Repeated pulses of vertical methane flux recorded in glacial sediments from the southeast Bering Sea. Paleoceanography 26, PA2210,

Decker C., Morineaux M., van Gaever S., Caprais J.-C., Lichtschlag A., Gauthier O., Andersen A.C. & Olu K. 2012. Habitat heterogeneity influences cold-seep macrofaunal communities within and among seeps along the Norwegian margin. Part 1: macrofaunal community structure. Marine Ecology 33, 205–230,

Decker C. & Olu K. 2012. Habitat heterogeneity influences cold-seep macrofaunal communities within and among seeps along the Norwegian margin. Part 2: contribution of chemosynthesis and nutritional patterns. Marine Ecology 33, 231–245,

Decker C., Zorn N., Le Bruchec J., Caprais J.-C., Potier N., Leize-Wagner E., Lallier F.H., Olu K. & Andersen A.C. 2017. Can the haemoglobin characteristics of vesicomyid clam species influence their distribution in deep-sea sulfide-rich sediments? A case study in the Angola Basin. Deep-Sea Research Part II 142, 219–232,

Decker C., Zorn N., Potier N., Leize-Wagner E., Lallier F.H. & Olu K. 2014. Globin’s structure and function in vesicomyid bivalves from the Gulf of Guinea cold seeps as an adaptation to life in reduced sediments. Physiological and Biochemical Zoology 87, 855–869,

Dokken T. & Hald M. 1996. Rapid climatic shifts during isotope stages 2–4 in the polar North Atlantic. Geology 24, 599–602,<0599:RCSDIS>2.3.CO;2.

Duplessy J.C., Shackleton N.J., Fairbanks R.G., Labeyrie L., Oppo D. & Kallel N. 1988. Deepwater source variations during the last climatic cycle and their impact on the global deepwater circulation. Paleoceanography 3, 343–360,

Eiken O. & Hinz K. 1993. Contourites in the Fram Strait. Sedimentary Geology 82, 15–32,

Ezat M., Rasmussen T.L. & Groeneveld J. 2014. Persistent intermediate water warming during cold stadials in the southeastern Nordic seas during the past 65 k.y. Geology 42, 663–666,

Fisher R.E., Sriskantharajah S., Lowry D., Lanoisellé M., Fowler C.M.R., James R.H., Hermansen O., Lund Myhre C., Stohl A., Greinert J., Nisbet-Jones P.B.R., Mienert J. & Nisbet E.G. 2011. Arctic methane sources: isotopic evidence for atmospheric input. Geophysical Research Letters 38, L21803,

Fontanier C., Koho K.A., Goñi-Urizza M.S., Deflandre B., Galaup S., Ivanovsky A., Gayet N., Dennielou B., Crémare A., Bichon S., Gassie C., Anschutz P., Duran R. & Reichart G.J. 2014. Benthic foraminifera from the deep-water Niger delta (Gulf of Guinea): assessing present-day and past activity of hydrate pockmarks. Deep-Sea Research Part I 94, 87–106,

Hansen J., Ezat M.M., Åström E.K.L. & Rasmussen T.L. 2019. New Late Pleistocene species of Acharax from Arctic methane seeps off Svalbard. Journal of Systematic Palaeontology, early access,

Hansen J., Hoff U., Sztybor K. & Rasmussen T.L. 2017. Taxonomy and palaeoecology of two Late Pleistocene species of vesicomyid bivalves from cold methane seeps at Svalbard (79°N). Journal of Molluscan Studies 3, 270–279,

Heyl T.P., Gilhooly W.P., Chambers R.M., Gilchrist G.W., Macko S.A., Ruppel C.D. & Van Dover C.L. 2007. Characteristics of vesicomyid clams and their environment at the Blake Ridge cold seep, South Carolina, USA. Marine Ecology Progress Series 339, 169–184,

Hill T.M., Paull C.K. & Crister R.B. 2012. Glacial and deglacial seafloor methane emissions from pockmarks on the northern flank of the Storegga Slide complex. Geo-Marine Letters 32, 73–84,

Hong W.-L., Sauer S., Pameri G., Ambrose W.G. Jr., James R.H., Plaza-Faverola A. & Schneider A. 2016. Removal of methane through hydrological, microbial, and geochemical processes in the shallow sediments of pockmarks along eastern Vestnesa Ridge (Svalbard). Limnology and Oceanography 61, 324–343,

Hopkins J.S. 1991. The GIN Sea—A synthesis of its physical oceanography and literature review 1972–1985. Earth Science Reviews 30, 175–318,

Hovland M. 2008. Deep-water coral reefs. Unique biodiversity hot-spots. Chichester, UK: Springer.

Hovland M. & Thomsen E. 1989. Hydrocarbon based communities in the North Sea? Sarsia 74, 29–42,

Howe J.A., Shimmield T.M. & Harland R. 2008. Late Quaternary contourites and glaciomarine sedimentation in the Fram Strait. Sedimentology 55, 179–200,

Hustoft S., Bünz S., Mienert J. & Chand S. 2009. Gas hydrate reservoir and active methane-venting province in sediments on <20 Ma young oceanic crust in the Fram Strait, offshore NW-Svalbard. Earth and Planetary Science Letters 284, 12–24,

Hustoft S., Dugan B. & Mienert J. 2009. Effects of rapid sedimentation on developing the Nyegga pockmark field: constraints from hydrological modeling and 3-D seismic data, offshore mid-Norway. Geochemistry, Geophysics, Geosystems 10, Q06012,

Jessen S.P., Rasmussen T.L., Nielsen T. & Solheim A. 2010. A new Late Weichselian and Holocene marine chronology for the western Svalbard slope 30,000-0 cal. years BP. Quaternary Science Reviews 29, 1301–1312,

Klitgaard A.B. & Tendal O.S. 2004. Distribution and species composition of mass occurrences of large-sized sponges in the northeast Atlantic. Progress in Oceanography 61, 57–98,

Krylova E.M., Gebruk A.V., Portnova D.A., Todt C. & Haflidason H. 2001. New species of the genus Isorropodon (Bivalvia: Vesicomyidae: Pliocardiinae) from cold methane seeps at Nyegga (Norwegian Sea, Vøring Plateau, Storegga Slide). Journal of the Marine Biological Association of the United Kingdom 91, 1135–1144,

Krylova E.M. & von Cosel R. 2011. A new genus of large Vesicomyidae (Mollusca, Bivalvia, Vesicomyidae, Pliocardiinae) from the Congo margin, with the first record of the subfamily Pliocardiinae in the Bay of Biscay (northeastern Atlantic). Zoosystema 33, 83–99,

Laier T., Rasmussen T.L., Sztybor K. & Nielsen T. 2017. Gas migration through a 150 m hydrate stability zone off Svalbard results in local shallow ‘secondary’ hydrate formation. Poster presented at the 9th International Conference on Gas Hydrates, 25–30 June, Denver, CO.

Lartaud F., de Rafelis M., Oliver G., Krylova E., Dymnet J., Ildefonse B., Thibaus R., Gente P., Hoisé E., Meistertzheim A.-L., Fouquet Y. Gaill F. & le Bris N. 2010. Fossil clams from a serpentinite-hosted sedimented vent field near the active smoker complex Rainbow, MAR, 36 13´N: insight into the biography of vent fauna. Geochemistry, Geophysics, Geosystems 11, Q0AE01,

Levin L. 2005. Ecology of cold seep sediments: interactions of fauna with flow, chemistry and microbes. In R.N. Gibson et al. (eds.): Oceanography and marine biology. An annual review. Vol. 43. Pp. 1–46. Boca Raton, FL: Taylor & Francis.

Levin L.A., Ziebis W., Mendoza G.F., Growney V.A., Tryons M.D., Brown K.M., Mahn C., Gieske J.M. & Rathburn A.E. 2003. Spatial heterogeneity of macrofauna at northern California methane seeps: influence of sulfide concentration and fluid flow. Marine Ecology Progress Series 265, 123–130,

Lisiecki L.E. & Raymo M.E. 2005. A Pliocene–Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20, PA1003,

MacDonald I.R., Boland G.S., Baker J.S., Brooks J.M., Kennicutt M.C. & Bidigare R.R. 1989. Gulf of Mexico hydrocarbon seep communities. Marine Biology 101, 235–247,

Marcon Y., Sahling H., Allais A.-G., Borhmann G. & Olu K. 2014. Distribution and temporal variation of mega-fauna at the Regab pockmark (northern Congo Fan), based on a comparison of videomosaics and geographic information systems analyses. Marine Ecology 35, 77–95,

Menot L., Galeron J., Olu K., Caprais J.C., Crassous P., Khripounoff, A. & Sibuet M. 2010. Spatial heterogeneity of macro-infaunal communities in and near a giant pockmark area in the deep Gulf of Guinea. Marine Ecology 31, 78–93,

Myrvang K. 2016. Correlation between changes in paleoceanography, paleoclimate and methane seepage on Vestnesa Ridge, eastern Fram Strait. Master’s thesis, Dept. of Geology, UiT—The Arctic University of Norway, Tromsø, Norway.

Niemann H., Losekann T., de Beer D., Elvert M., Nadalig T., Knittel K., Amann R., Sauter E.J., Klages M., Foucher J.P. & Boetius A. 2006. Novel microbial communities of the Håkon Mosby mud volcano and their role as a methane sink. Nature 443, 854–858,

Oliver P.G. & Killeen J.J. 2002. The Thyasiridae (Mollusca: Bivalvia) of the British continental shelf and North Sea oilfields. An identification manual. BIOMÔR 3. Cardiff: National Museums and Galleries of Wales.

Olu K., Decker C., Pastor L., Caprais J.-C., Khripounoff A., Morineaux M., Ain Baziz M., Menot L. & Rabobouille C. 2017. Cold-seep-like macrofaunal communities in organic- and sulphide-rich sediments of the Congo deep-sea fan. Deep-Sea Research Part II 142, 180–196,

Olu K., Lance S., Sibuet M., Henry P., Fiala Medioni A. & Dinet A. 1997. Cold seep communities as indicators of fluid expulsion patterns through mud volcanoes seaward of the Barbados accretionary prism. Deep-Sea Research Part I 44, 811–841,

Paull C.K., Hecker B., Commeau R., Freeman-Lynde R.P., Neumann C., Corso W.P., Golubic S., Hook J.E., Sikes E. & Curray J. 1984. Biological communities at the Florida Escarpment resemble hydrothermal vent taxa. Science 226, 965–967,

Petersen C.J., Bünz S., Hustoft J., Mienert J & Klaeschen D. 2010. High-resolution P-Cable 3D seismic imaging of gas chimney structures in gas hydrated sediments of an Arctic sediment drift. Marine and Petroleum Geology 27, 1981–1994,

Piepenburg D., Chernova N.V., Dorrien C., Gutt J., Neyelov A.V., Rachor E., Saldanha L. & Schmid M.K. 1996. Megabenthic communities in the waters around Svalbard. Polar Biology 16, 431–446,

Pimenov N.V., Savvichev A.S., Rusanov I.I., Lein A.Y. & Ivanov M.V. 2000. Microbiological processes of the carbon and sulfur cycles at cold methane seeps of the North Atlantic. Microbiology 69, 709–720,

Plaza-Faverola A., Bünz S. Johnson J.E., Chand S., Knies J., Mienert J. & Franek P. 2015. Role of tectonic stress in seepage evolution along the gas hydrate-charged Vestnesa Ridge, Fram Strait. Geophysical Research Letters 42, 733–742, .

Plaza-Faverola A. & Keiding M. 2019. Correlation between tectonic stress regimes and methane seepage on the western Svalbard margin. Solid Earth 10, 79–94,

Ponder W.F. 1984. A review of the genera of the Rissoidae (Mollusca: Mesogastropoda: Rissoacea). Records of the Australian Museum Supplement 4. Sydney: Australian Museum.

Pop Ristova P., Wenzhöfer F., Ramette A., Zabel M., Fischer D., Kasten S. & Boetius A. 2012. Bacterial diversity and biogeochemistry of different chemosynthetic habitats of the REGAB cold seep (West African margin, 3160 m water depth). Biogeosciences 9, 5031–5048,

Rasmussen T.L., Thomsen E. & Nielsen T. 2014. Water mass exchange between the Nordic seas and the Arctic Ocean on millennial time scale during MIS 4–MIS 2. Geochemistry, Geophysics, Geosystems 15, 530–544,

Reimer P.J., Bard E., Beck J.W., Baillie M.G.L., Blackwell P.G., Bronk Ramsey C., Buck C.E., Cheng H., Edwards R.L., Friedrich M., Grootes P.M., Guilderson T.P., Haflidason H., Hajdas I., Hatte M., Reimer R.W., Richards D.A., Scott E.M., Southon J.R., Staff R.A., Turney C.S.M. & van der Plicht J. 2013. IntCal13 and Marine13 radiocarbon age calibration curves, 0–50,000 years cal BP. Radiocarbon 55, 1869–1887,

Sahling H., Galkin S.V., Salyuk A., Greinert J., Foerstel H., Piepenburg D. & Suess E. 2003. Depth-related structure and ecological significance of cold-seep communities—a case study from the Sea of Okhotsk. Deep-Sea Research Part I 50, 1391–1409,

Sahling H., Rickert D., Lee D., Linke R.W. & Suess E. 2002. Macrofaunal community structure and sulfide flux at hydrate deposits from the Cascadia convergent margin, NE Pacific. Marine Ecology Progress Series 231, 121–138,

Schauer U., Fahrbach E., Osterhus S. & Rohardt G. 2004. Arctic warming through the Fram Strait: oceanic heat transport from 3 years of measurements. Journal of Geophysical Research—Oceans 109, C06026,

Schneider A., Crémiere A., Panieri C., Lepland A. & Knies J. 2017. Diagenetic alteration of benthic foraminifera from a methane seep site on Vestnesa Ridge (NW Svalbard). Deep-Sea Research Part I 123, 22–34,

Sen A., Åström E.K.L., Hong W.-L., Portnov A., Waage M., Serov P., Carroll M. & Carroll J. 2018. Geophysical and geochemical controls on the megafaunal community of a High Arctic cold seep. Biogeosciences 15, 4533–4559,

Sen A., Himmler T., Hong W.-L., Chitkara C., Lee R.W., Ferré B., Lepland A. & Knies J. 2019. Atypical biological features of a new cold seep site on the Lofoten–Vesterålen continental margin (northern Norway). Scientific Reports 9, article no. 1762,

Shackleton N.J. 1974. Attainment of isotopic equilibrium between ocean water and the benthonic foraminifera genus Uvigerina: isotopic changes in the ocean during the last glacial. Colloques Internationaux du C.N.R.S. 219, 203–209.

Soltwedel T., Jaeckisch N., Ritter N., Hasemann C., Bergmann M. & Klages M. 2009. Bathymetric patterns of megafaunal assemblages from the Arctic deep-sea observatory Hausgarten. Deep-Sea Research Part I 56, 1856–1872,

Stuiver M. & Reimer P.J. 1993. Extended 14C database and revised CALIB radiocarbon calibration program. Radiocarbon 35, 215–230.

Sztybor K. & Rasmussen T.L. 2017a. Diagenetic disturbances of marine sedimentary records from methane-influenced environments in the Fram Strait as indications of variation in seep intensity during the last 35 000 years. Boreas 46, 212–228,

Sztybor K. & Rasmussen T.L. 2017b. Late glacial and deglacial palaeoceanographic changes at Vestnesa Ridge, Fram Strait: methane seep versus non-seep environments. Palaeogeography, Palaeoclimatology, Palaeoecology 476, 77–89,

Sztybor K., Rasmussen T.L., Mienert J., Bünz S. & Consolaro C. 2013. Climate reconstruction from a methane influenced environment. Abstract PP31A-1854. Poster presented at the AGU Fall Meeting. 9–13 December, San Francisco, CA.

Teichert B.M.A., Eisenhauer A., Bohrmann G., Haase-Schramm A., Bock B. & Linke P. 2003. U/Th systematics and ages of authigenic carbonates from Hydrate Ridge, Cascadia margIn: recorders of fluid flow variations. Geochimica et Cosmochimica Acta 67, 3845–3857,

Thomsen E. 1987. Environmental evaluation of pockmark areas near Gullfaks, Heimdal and Forties in the North Sea. Intern Skrift Serie 52. Oslo: Institute of Geology, University of Oslo.

Thomsen E. & Vorren T.O. 1986. Macrofaunal palaeoecology and stratigraphy in Late Quaternary shelf sediments off northern Norway. Palaeogeography, Palaeoclimatology, Palaeoecology 56, 103–150,

Treude T., Boetius A., Knittel K., Wallmann K. & Jørgensen B.B. 2003. Anaerobic oxidation of methane above gas hydrates at Hydrate Ridge, NE Pacific Ocean. Marine Ecology Progress Series 264, 1–14,

Vinogradov G.M. 1999. Deep-sea near-bottom swarms of pelagic amphipods Themisto: observations from submersibles. Sarsia 84, 465–467,

Vogt P.R., Crane K., Sundvor E., Max M.D. & Pfirman S.L. 1994. Methane-generated (?) pockmarks on young, thickly sedimented oceanic crust in the Arctic: Vestnesa Ridge, Fram Strait. Geology 22, 255–258,<0255:MGPOYT>2.3.CO;2.

Walczowski W., Piechura, J., Osinski, R. & Wieczorek, P. 2005. The West Spitsbergen Current volume and heat transport from synoptic observations in summer. Deep Sea Research Part 1. Oceanographic Research Papers 52, 1374–1391,

Wallmann K., Riedel M., Hong W.L., Patton H., Hubbard A., Pape T., Hsu C.W., Schmidt C., Johnson J.E., Torres M.E., Andreassen K., Berndt C. & Bohrmann G. 2018. Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming. Nature Communications 9, article no. 83,

Wollenburg J.E., Kuhnt W. & Mackensen A. 2001. Changes in Arctic Ocean paleoproductivity and hydrography during the last 145 kyr: the benthic foraminiferal record. Paleoceanography 16, 65–77,
How to Cite
Thomsen E., Lander Rasmussen T., Sztybor K., Hanken N.-M., Secher Tendal O., & Uchman A. (2019). Cold-seep fossil macrofaunal assemblages from Vestnesa Ridge, eastern Fram Strait, during the past 45 000 years. Polar Research, 38.
Research Articles