Landscape evolution under the southern Laurentide Ice Sheet

Shawn Naylor; Andrew D. Wickert; Douglas A. Edmonds; Brian J. Yanites

doi:10.1126/sciadv.abj2938

Landscape evolution under the southern Laurentide Ice Sheet

Shawn Naylor, Andrew D. Wickert, Douglas A. Edmonds, Brian J. Yanites

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Abstract

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.

Original language	English (US)
Article number	eabj2938
Journal	Science Advances
Volume	7
Issue number	48
DOIs	https://doi.org/10.1126/sciadv.abj2938
State	Published - Nov 2021
Externally published	Yes

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© 2021 American Association for the Advancement of Science. All rights reserved.

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Landscape evolution under the southern Laurentide Ice Sheet

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