Rheological models of active rock glaciers: Evaluation, critique and a possible test

Rheological properties of ice and ice/rock‐fragment mixtures relating to rock glaciers are examined. The basic criteria for flow (neglecting sliding components) are discussed with reference to published work. Even if the internal composition of a rock glacier is very variable, ranging from pure ice to an ice/rock mixture, then similar surface velocities are likely to be measured and accounted for by at least two rheological models. Under some circumstances, even when there is ice in excess of the rock debris voids ratio, flow of the frozen material may not be possible. Uncertainty in the ice/debris composition in rock glaciers allows a wide variety of temperature, density, shear strength and creep properties to account for measured velocities. Ice lenses (segregation ice) must interconnect within a surrounding mass of stronger material for substantial deformation to occur. It is suggested that a glacier ice origin can account for the measured surface flow velocities of rock glaciers as long as the ice body is thin, generally