Three figures from the paper showing a map of bedrock channels on the seafloor, an image of a remotely-operated vehicle, and an image of potholes.
(a) Massive bedrock channels on the seafloor around Antarctica, some with smaller channels cut into their floors, plus data from a remotely-operated vehicle (b) including potholes (c) and stepped sidewalls, point towards multiple phases of channel incision related to cycles of subglacial lake filling and drainage (frame in (c) is about 1 m wide). Credit: Hogan et al. [2022], Figure 3(a) and Figure 4(b,c)
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Earth Surface

Evolution of a subglacial water system formed at the interface between ice and underlying bedrock has a strong impact on the behavior of the Antarctic Ice Sheet. By analyzing novel observations collected during recent research cruises by echosounders, remotely operated vehicles and sediment coring in Marguerite Trough (Antarctic Peninsula), Hogan et al. [2022] describe the complex morphology of the subglacial channel network. 

The channels were formed by intermittent subglacial floods and outbursts from subglacial lakes under an ice stream. This occurred as the Antarctic Ice Sheet was decaying and retreating from the maximum extent it had grown to at the peak of the Last Glacial Maximum. The observed subglacial forms include potholes and small, branching channels on the floors of the main bedrock channels. From morphological analyses the authors infer that these forms were eroded by highly intense turbulent water flow. Using a hydrological model, the authors also find that such water flow was associated with intermittent outbursts and floods from subglacial lakes that happened every few tens to hundreds of years.

These results shed light on the dynamics of the subglacial water system that operated under the Antarctic Ice Sheet tens of thousands of years ago.

Citation: Hogan, K. A., Arnold, N. S., Larter, R. D., Kirkham, J. D., Noormets, R., Ó Cofaigh, C., et al. (2022). Subglacial water flow over an Antarctic palaeo-ice stream bed. Journal of Geophysical Research: Earth Surface, 127, e2021JF006442.

—Olga Sergienko, Editor, Journal of Geophysical Research: Earth Surface

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