Eskers in a complete, wet-based glacial system in the Phlegra Montes region, Mars

- The first identification of martian eskers directly linked to their parent glacier.
- The eskers are at the degraded terminus of a graben-confined glacier.
- The eskers are evidence of glacial melting and a wet-based regime.
- Melting was due to enhanced geothermal heat flux, not climate warming.
- These are new insights into glacial behaviour and meltwater production on Mars.

Although glacial landsystems produced under warm/wet based conditions are very common on Earth, even here, observations of subglacial landforms such as eskers emerging from extant glaciers are rare. This paper describes a system of sinuous ridges emerging from the in situ but now degraded piedmont terminus of a Late Amazonian-aged (∼150 Ma) glacier-like form in the southern Phlegra Montes region of Mars. We believe this to be the first identification of martian eskers that can be directly linked to their parent glacier. Together with their contextual landform assemblage, the eskers are indicative of significant glacial meltwater production and subglacial routing. However, although the eskers are evidence of a wet-based regime, the confinement of the glacial system to a well-defined, regionally significant graben, and the absence of eskers elsewhere in the region, is interpreted as evidence of sub-glacial melting as a response to locally enhanced geothermal heat flux rather than climate-induced warming. These observations offer important new insights to the forcing of glacial dynamic and melting behaviour on Mars by factors other than climate.