We have observed sliding at a cold (-17 ¿C) ice-rock interface beneath Meserve Glacier, Antarctica, and the segregation of ice into clean lenses amidst the dirty basal layers of this glacier. We interpret these as manifestations of thin water films at ice-rock interfaces. We use Shreve's theory for sub-freezing sliding to estimate the nominal film thickness to be at least tens of nanometers. Such water films should exist around rocks in most polar ices, and likely have high solute concentrations due to solute rejection during regelation and due to exchange with veins and grain boundaries where impurities reside. ¿ 1999 American Geophysical Union