TY  - JOUR
A1  - Egholm, David L.
A1  - Jansen, John D.
A1  - Braedstrup, Christian F.
A1  - Pedersen, Vivi K.
A1  - Andersen, Jane Lund
A1  - Ugelvig, Sofie V.
A1  - Larsen, Nicolaj K.
A1  - Knudsen, Mads F.
T1  - Formation of plateau landscapes on glaciated continental margins
JF  - Nature geoscience
N2  - Low-relief plateaus separated by deeply incised fjords are hallmarks of glaciated, passive continental margins. Spectacular examples fringe the once ice-covered North Atlantic coasts of Greenland, Norway and Canada, but low-relief plateau landscapes also underlie present-day ice sheets in Antarctica and Greenland. Dissected plateaus have long been viewed as the outcome of selective linear erosion by ice sheets that focus incision in glacial troughs, leaving the intervening landscapes essentially unaffected. According to this hypothesis, the plateaus are remnants of preglacial low-relief topography. However, here we use computational experiments to show that, like fjords, plateaus are emergent properties of long-term ice-sheet erosion. Ice sheets can either increase or decrease subglacial relief depending on the wavelength of the underlying topography, and plateau topography arises dynamically from evolving feedbacks between topography, ice dynamics and erosion over million-year timescales. This new mechanistic explanation for plateau formation opens the possibility of plateaus contributing significantly to accelerated sediment flux at the onset of the late Cenozoic glaciations, before becoming stable later in the Quaternary.
Y1  - 2017
U6  - https://doi.org/10.1038/NGEO2980
SN  - 1752-0894
SN  - 1752-0908
VL  - 10
SP  - 592
EP  - +
PB  - Nature Publ. Group
CY  - New York
ER  - 
TY  - JOUR
A1  - Strunk, Astrid
A1  - Knudsen, Mads Faurschou
A1  - Egholm, David L.
A1  - Jansen, John D.
A1  - Levy, Laura B.
A1  - Jacobsen, Bo H.
A1  - Larsen, Nicolaj K.
T1  - One million years of glaciation and denudation history in west Greenland
JF  - Nature Communications
N2  - The influence of major Quaternary climatic changes on growth and decay of the Greenland Ice Sheet, and associated erosional impact on the landscapes, is virtually unknown beyond the last deglaciation. Here we quantify exposure and denudation histories in west Greenland by applying a novel Markov-Chain Monte Carlo modelling approach to all available paired cosmogenic Be-10-Al-26 bedrock data from Greenland. We find that long-term denudation rates in west Greenland range from >50 m Myr(-1) in low-lying areas to similar to 2 m Myr(-1) at high elevations, hereby quantifying systematic variations in denudation rate among different glacial landforms caused by variations in ice thickness across the landscape. We furthermore show that the present day ice-free areas only were ice covered ca. 45% of the past 1 million years, and even less at high-elevation sites, implying that the Greenland Ice Sheet for much of the time was of similar size or even smaller than today.
Y1  - 2017
U6  - https://doi.org/10.1038/ncomms14199
SN  - 2041-1723
VL  - 8
PB  - Nature Publishing Group UK
CY  - London
ER  -