glacier flow

Glacier flow is the movement of ice masses under the influence of gravity. This movement is primarily driven by two processes: internal deformation and basal sliding.1

• Internal Deformation: Ice, under shear stress from its own weight and the slope of the glacier, undergoes creep or plastic deformation. The rate of this deformation is related to the shear stress, often described by the Glen flow law.2
• Basal Sliding: Glaciers at their melting point can slide over their beds. This is facilitated by factors like stress concentrations around bed obstacles and melting/refreezing processes (regelation). High subglacial water pressures can significantly increase sliding rates, especially in temperate glaciers.23

The speed of glacier flow varies, generally being faster at the surface and in the center compared to the margins and depth. Temperature plays a crucial role; cold, polar glaciers flow slower than temperate glaciers, which are at their pressure-melting point and exhibit more active sliding. Changes in a glacier's mass balance, influenced by climate, directly affect its thickness and, consequently, its flow rate, leading to advances or retreats of the glacier's terminus.314