Debris-covered glaciers on Mars formed over multiple glaciations

High-resolution imaging of the surface of Mars suggests that debris-covered glacier deposits formed during multiple punctuated episodes of ice accumulation over long timescales, a study finds. Debris-covered glacial landforms called lobate debris aprons (LDA) are widespread on Mars. It has not been clear whether these LDAs formed over the past 300-800 million years during a single long deposition period, or during multiple short-lived episodes of ice accumulation. To address this question, Joseph Levy and colleagues used high-resolution imaging to map boulders along 45 LDAs on the surface of Mars. The boulders are commonly clustered into bands across all LDAs, similar to boulders on ancient debris-covered glaciers on Earth. These bands range in abundance on the LDA from 2 to 22, with a median of 6 across all sites. Surprisingly, boulder size does not vary systematically across the LDA. Taken together, these results do not provide evidence for a single, continuous deposition period, which predicts that boulders should be randomly distributed on the surface, and smaller at the toe of LDAs than at the headwall. Instead, according to the authors, the findings point to multiple cycles of ice accumulation and advance over the past 300-800 million years, extending evidence for climate change on Mars beyond the 20-million-year window suggested by numerical modeling.

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Article #20-15971: "Surface boulder banding indicates Martian debris-covered glaciers formed over multiple glaciations," by Joseph Levy et al.

MEDIA CONTACT: Joseph Levy, Colgate University, Hamilton, NY; tel: 315-825-8484; email: <jlevy@colgate.edu>