Landscape evolution under the southern Laurentide Ice Sheet

Subglacial landscapes, revealed in regions of recent ice-sheet retreat, provide a window into ice-sheet dynamics and interactions with evolving subglacial topography. Here, we document landscape evolution beneath the southern Laurentide Ice Sheet of North America since the end of the Pliocene, 2.6 m...

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Bibliographic Details
Published in:Science Advances
Main Authors: Naylor, Shawn, Wickert, Andrew D., Edmonds, Douglas A., Yanites, Brian J.
Format: Text
Language:English
Published: American Association for the Advancement of Science 2021
Subjects:
Earth
Environmental
Ecological
and Space Sciences
Ice Sheet
Online Access:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8612676/
http://www.ncbi.nlm.nih.gov/pubmed/34818050
https://doi.org/10.1126/sciadv.abj2938
Description
Summary:Subglacial landscapes, revealed in regions of recent ice-sheet retreat, provide a window into ice-sheet dynamics and interactions with evolving subglacial topography. Here, we document landscape evolution beneath the southern Laurentide Ice Sheet of North America since the end of the Pliocene, 2.6 million years (Ma) ago, by reconstructing the isostatically adjusted preglacial surface and modern bedrock topography at 250 m horizontal resolution. We use flow routing to reconstruct drainage networks and river longitudinal profiles, revealing the pattern and extent of their glacially forced reorganization. The overall mean Quaternary (2.6 Ma ago to present) erosion rate is 27 m/Ma, rising within ice-streaming corridors to 35 m/Ma (and locally reaching 400 m/Ma) and falling to 22 m/Ma in non–ice-streaming regions. Our results suggest that subglacial erosion was sufficient to lower the southern Laurentide Ice Sheet into warmer environments, thereby enhancing ablation and reducing ice-sheet extent over time.

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