3D MORPHOMETRIES OF ESKERS ON MARS, AND COMPARISONS TO ESKERS IN FINLAND

International audienceIntroduction: We present new, high-resolution measurements of the 3D morphometries of eskers associated with debris-covered glaciers in the Phlegra Mon-tes [1] and NW Tempe Terra [2] regions of Mars' northern mid-latitudes. We compare them with the ancient south polar 'Dorsa Argentea' eskers on Mars [3], and first large database (n > 20,000) of 3D morphome-tries of terrestrial eskers, from SW Finland [4]. Eskers are ridges of glaciofluvial sediment deposited by meltwater flowing through tunnels within or beneath glaciers. They are vital tools for reconstructing the dynamics, extent, and environmental drivers of wet-based glaciation on Earth and Mars. For example, reconstructions of Mars' climate conditions at the Noa-chian-Hesperian transition [e.g., 5] have relied heavily upon insights from the Dorsa Argentea eskers [e.g., 3], which record basal melting of a large south polar ice sheet ~3.5 Ga. Morphometric studies of candidate eskers on Mars are vital both for testing hypotheses of their origins as eskers [e.g., 3], and for informing insights into the magnitude and dynamics of meltwater flows that formed them [e.g., 5-6]. Previously, such work has been limited by a lack of large-scale surveys of the 3D morphometries of eskers on Earth, to which the martian landforms can be compared. A new database comprising >20 000 measurements of 3D esker morphometries from SW Finland provides new opportunities for such-comparisons, which we exploit in this study [4]. Methods: We used 1-2 m/pixel digital elevation models generated from High Resolution Imaging Science Experiment (HiRISE) images to measure esker heights (H) and widths (W) from cross-sectional tran-sects spaced at 10 and 20 m intervals along the Phlegra Montes and NW Tempe Terra eskers, respectively (fol-lowing [3]). We calculated average slopes across cross-sectional transects (θ) as: tan −1 (H/0.5W). We classified transects into sharp-, multi-, and round-crested morphologies according to the scheme of [6]. The NW Tempe Terra esker comprises two 'stacked' esker ridges (see [7], this conference) which we treat separately in the present study. Storrar and Jones [4] obtained similar H, W, and θ measurements at 10 m intervals along ~70 km of Qua-ternary-aged eskers in SW Finland, using 2 m/pixel elevation data from airborne LiDAR