What is one of the two major flow mechanism in a glacier

Question

What is one of the two major flow mechanism in a glacier

Answer 1

Internal Deformation

Ice deforms under its own weight due to gravity and the movements of tiny ice crystals. Thicker and warmer ice deforms more rapidly although the overall movement is very slow, only around tens of meters a year. There are two main processes of internal deformation; creep, which forms fold structures, and faulting, which occurs when ice cannot creep fast enough and forms superficial tensional fractures.

Basal Sliding

Enhanced Basal Creep - Stress concentrations around the upstream side of an obstacle result in locally high strain rates which causes ice to accelerate around the obstacle. The basal ice continually modifies its shape to allow a continued sliding. This process works best when the obstacle is over 1m in size.

Regelation - The process allows glacier ice to slide over rough beds by melting and refreezing on the downglacier side. It occurs as the most resistance to glacier movement is provided by the upstream side of obstacles. This results in locally high pressures and the consequent encouragement of ice melting immediately upglacier of the obstacle. The resulting meltwater migrates to the lower pressure area downstream where it refreezes. This process is most effective when objects are less than 1m in size.

You also have subglacial deformation

Sediment has a lower yield strength than rock and ice and so it is deformable. As the sediment deforms, it moves the ice sheet with it.