The driving mechanisms of glacier fast flow and the cyclical instability inherent in ice streams and surging glaciers are not fully understood. Current theories suggest fast flow is driven by glacier sliding and basal deformation facilitated by water at the ice–bed interface and/or the presence of weak till. However, the wettability of sediments and the physics driving these sediment–water interactions have yet to be fully explored. Here, we review recent work on superhydrophobicity, hydrophobic soils and lubricated surfaces, and bring together aspects of materials science, biophysics and geoscience, to propose three modes by which a subglacial environment could become super slippery. Those modes are via (i) hydrophobic chemistry, (ii) microbial biofilms or (iii) the incorporation of oil. We then hypothesise how ice flow on super slippery sediments would result in enhanced sliding and deformation by introducing or increasing a lubricated interface and/or creating zones of sediment weakness and instability. We propose that future research should further explore this potential paradigm to soft bed deformation and sliding.

We present a theoretical study of the statics and dynamics of a partially wetting liquid droplet, of equilibrium contact angle $\unicode[STIX]{x1D703}_{e}$ , confined in a solid wedge geometry of opening angle $\unicode[STIX]{x1D6FD}$ . We focus on a mostly non-wetting regime, given by the condition $\unicode[STIX]{x1D703}_{e}-\unicode[STIX]{x1D6FD}>90^{\circ }$ , where the droplet forms a liquid barrel – a closed shape of positive mean curvature. Using a quasi-equilibrium assumption for the shape of the liquid–gas interface, we compute the changes to the surface energy and pressure distribution of the liquid upon a translation along the symmetry plane of the wedge. Our model is in good agreement with numerical calculations of the surface energy minimisation of static droplets deformed by gravity. Beyond the statics, we put forward a Lagrangian description of the droplet dynamics. We focus on the overdamped limit, where the driving capillary force is balanced by the frictional forces arising from the bulk hydrodynamics, the corner flow near the contact lines and the contact-line friction. Our results provide a theoretical framework to describe the motion of partially wetting liquids in confinement, and can be used to gain further understanding on the relative importance of dissipative processes that span from microscopic to macroscopic length scales.