Standing Fossil Forests, Melting Ice Shelves, and Subglacial Lakes
I. Map boundaries: 70 to 80 degrees South; 60 to 90 degrees West
II. Country: Antarctic Treaty Secretariat (British Antarctic Survey stations at Fossil Bluff on Alexander Island and Sky Blu in Palmer Land)
III. Overview
Ice shelves in the Bellingshausen Sea are melting, making map-making a moving target. The attached map shows the grounding lines on US Geological Survey maps published for the area; the geography is subject to change as the polar regions warm and coastal features are revealed. The more northerly Wilkins Ice Shelf collapsed in 2009 between Charcot Island and Latady Island and is no longer connected to Charcot Island. The Bryan Coast contains a 250-km long ice wall along the Bellingshausen Sea coast.
In southern Alexander Island, nunatuks (rocky mountaintops) stick up above the ice sheet and reveal fossil forests still standing upright. Roots can still be excavated from fossil soils. A diverse flora of fern fossils has been found that links this flora to the Gondwana floras also found in the Cretaceous in Australia, India, and South America. Gondwana broke up about 150 million years ago. West Antarctica is made up of unstable remnants (crustal blocks) of Gondwana. On this map are the Gondwana remnants of the Antarctic Peninsula, Haag Nunatuks, and Ellsworth Mountains. The Ellsworth Mountains rise to 16,000 feet in elevation at Vinson.
To the west of the Ellsworth Mountains, a plan to drill into subglacial Lake Ellsworth has been developed by the British Antarctic Survey. Microbiologists believe that these lakes could harbor unique life forms which have been isolated for millions of years. Drilling through the 3,000 meters of ice covering the lake is scheduled for the 2012-2013 summer season.
IV. Terrestrial Ecoregion
AN 1101, Marielandia Antarctic tundra. Ice-free areas contain a tundra cushion of moss and lichens, grading to bare ground at these far southern latitudes.
V. Marine Ecoregions of the World (MEOW)
Southern Ocean Realm
Scotia Sea Province
223. Antarctic Peninsula. Found between Alexander Island and Latady and Charcot Islands and under the George VI Ice Shelf to the east of Alexander Island.
Continental High Antarctic Province
227. Weddell Sea. Found on east side of Antarctic Peninsula and under Larsen Ice Shelf
228. Amundsen/Bellingshausen Sea. Found west of Spaatz, Alexander, Latady, and Charcot Islands.
VI. Points of Interest
Ablation Valley. Found on Alexander Island. Antarctic Specially Protected Area 147. The largest ice-free area in West Antarctica, with geological, glaciological, and ecological features. The site has the greatest bryophyte (moss) diversity of any site this far south in Antarctica, and contains aquatic mosses in lakes and bryophytes and lichens in seepage areas. There are four ice-free valleys. Ecoregion 1101.
Ellsworth Mountains. Found in the southern portion of map area. These mountains contain the highest point in Antarctica, Vinson Massif, and 39 glaciers. To the west is the Ellsworth Subglacial Lake, which is the subject of a research project to sample lake water and determine if life exists under the ice. The research project of the British Antarctic Survey will involve drilling through 3,000 m of overlying ice. Subglacial lakes are of interest because they are believed to harbor unique microbes and contain records of past climate change and ice sheet evolution. Ecoregion 1101.
Fossil Bluff. Found on Alexander Island. This site contains upright fossil trees in their original positions with roots in fossil soils. Tree roots can be found to one meter deep. In Cretaceous times, this was a well-drained, seasonally dry forest in the humid temperate zone. However, this location was at 75 degrees south, so there are no modern analogues to this climate. The forest was about 60 percent conifers and 40 percent tree ferns. Fossils are found all along the southeastern coast of Alexander Island, in deposits up to 950 m thick in the southeast in the Triton Formation. A British Antarctic Survey research station provides scientific access to Fossil Bluff. Ecoregion 1101.
Lake Hodgson. Found on Alexander Island at the base of a mountain. An ice covered lake, covered by ice to 4 m deep, was formerly subglacial, and has been isolated for 30,000 to 90,000 years. It has recently been investigated and no evidence of photosynthetic life was found. Ecoregion 1101.
VII. References
Antarctic Treaty Secretariat. Antarctic Protected Areas Database. http://www.ats.aq/devPH/apa/ep_protected_search.aspx?type=2&lang=e (Accessed March 7, 2010).
British Antarctic Survey. 2010. Research Stations in Antarctica. http://www.antarctica.ac.uk/living_and_working/research_stations/index.php (accessed 7/31/2010).
Cantrill, David J. and Nathalie S. Nagalingum. 2005. Ferns from the Cretaceous of Alexander Island, Antarctica: Implications for Cretaceous Phytogeography of the Southern Hemisphere. Review of Palaeobotany and Palynology 137:83-103. http://www.huh.harvard.edu/research/mathews-lab/nsn/2005CantrillNagalingum.pdf (accessed July 24, 2010).
British Antarctic Survey. 2010. Press Release: Drilling into the unknown—the first exploration of a sub-glacial Antarctic lake is a major step closer. Issued 04 June 2010. http://www.antarctica.ac.uk/press/press_releases/press_release.php?id=1212 (accessed July 24, 2010).
Ferrigno, Jane G., Alison J. Cook, Amy M Mathie, Richard S. Williams, Jr., Charles Swithinbank, Kevin M. Foley, Adrian J. Fox, Janet W. Thomson, and Jorn Sievers. 2009. Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947-2009. Geologic Investigations Series Map I-2600-C. U.S. Geological Survey, Washington, DC. http://pubs.usgs.gov/imap/i-2600-c/ (accessed March 30, 2010).
Ferrigno, Jane G., Kevin M. Foley, Charles Swithinbank, Richard S. Williams, Jr. and Lina M. Dailide. 2005. Coastal-Change and Glaciological Map of the Ronne Ice Shelf Area, Antarctica: 1974-2002. Geologic Investigations Series map I-2600-D. U.S. Geological Survey, Washington, DC. http://pubs.usgs.gov/imap/2600/D/ (accessed July 24, 2010).
Fitzgerald, Paul G. and Edmund Stump. 1991. Early Cretaceous Uplift in the Ellsworth Mountains of West Antarctica. Science 254:92-94.
Hodgson, Dominic A., Stephen J. Roberts, Michael J. Bentley, James A. Smith, Joanne S. Johnson, Elie Verleyen, Wim Vyverman, Andy J. Hodgson, Melanie J. Leng, Andreas Cziferszky, Adrian J. Fox and David C. W. Sanderson. 2009. Exploring Former Subglacial Hodgson Lake, Antarctica Paper I: Site Description, Geomorphology and Limnology. Quaternary Science Reviews 28:2295-2309.
Holland, P.R., A. Jenkins, and D.M. Holland. 2010. Ice and Ocean Processes in the Bellingshausen Sea, Antarctica. Journal of Geophysical Research 115:CO5020, doi:10:1029/2008jc005219. http://efdl.cims.nyu.edu/publications/refereed/jgr_bellingshausen_10.pdf (accessed July 24, 2010).
Howe, J. and J.E. Francis. 2005. Metamorphosed palaeosols associated with Cretaceous fossil forests, Alexander Island, Antarctica. Journal of the Geological Society, London 162:951-957. http://www.see.leeds.ac.uk/ebi/publications/Howe_2005.pdf (accessed July 24, 2010).
Nagalingum, Natalie S. and David J. Cantrill. 2006. Early Cretaceous Gleicheniaceae and Matoniaceae (Gleicheniales) from Alexander Island, Antarctica. Review of Palaeobotany and Palynology 138:73-93. http://www.huh.harvard.edu/research/mathews-lab/nsn/2006NagalingumCantrill.pdf (accessed July 24, 2010).
Olson, David M., et al., 2001. Terrestrial Ecoregions of the World: A New Map of Life on Earth. BioScience 51:933-938. Ecoregion map at http://www.nationalgeographic.com/wildworld/terrestrial.html
Scientific Committee on Antarctic Research. 2003. Management Plan for ASPA No. 147, Ablation Valley and Ganymede Heights, Alexander Island. Scientific Committee on Antarctic Research Bulletin No. 151. www.scar.org/publications/bulletins/151/aspa147.html (accessed July 24, 2010).
Spalding, Mark D. and 14 others. 2007. Marine Ecoregions of the World: A Bioregionalization of Coastal and Shelf Areas. BioScience 57:573-583.
Swithinbank, Charles, Richard S. Williams, Jr., Jane G. Ferrigno, Kevin M. Foley, Christine E. Rosanova, and Lina M. Dailide. 2004. Coastal-Change and Glaciological Map of the Eights Coast Area, Antarctica: 1972-2001. Geologic Invesigations Series Map I-2600-E. U.S. Geological Survey, Washington, D.C. http://pubs.usgs.gov/imap/2600/E/ (accessed July 24, 2010).
