Submarine glacial landforms and rates of ice-stream collapse
J.A. Dowdeswell et al., Scott Polar Research Institute, University of Cambridge, Cambridge CB2 1ER, UK. Pages 819-822.
The rate of deglacial ice-sheet retreat across polar continental shelves, and possible ice-stream collapse and sea-level rise, has been much debated. High-resolution imagery of seafloor morphology is available for many polar shelves and fjords. Dowdeswell et al. infer the rapidity of ice retreat from diagnostic assemblages of submarine landforms, produced at ice-stream sedimentary beds. These landforms, exposed by ice retreat across high-latitude shelves, demonstrate that deglaciation occurs in three main ways: (1) rapidly, by flotation and breakup; (2) episodically, by stillstands and/or grounding events punctuating rapid retreat; (3) or by slower retreat of grounded ice. Submarine landform assemblages imply, through the presence of grounding-zone wedges overprinting mega-scale glacial lineations on many polar shelves, that ice-stream retreat is more often episodic than catastrophic. These observations provide a robust test of the ability of numerical models to predict the varied response of ice-sheet basins to environmental changes.
GSA Today Science Article
Turbulent lifestyle: Microbial mats on Earth's sandy beachestoday and 3 billion years ago
Nora Noffke, Old Dominion University, Department of Ocean, Earth & Atmospheric Sciences, Norfolk, Virginia
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Geological Society of America