Glacial ice is divided into two zones, the upper rigid or brittle zone where the ice cracks into crevasses and the lower plastic zone where under the pressure of overlying ice, the ice bends and flows...Glacial ice is divided into two zones, the upper rigid or brittle zone where the ice cracks into crevasses and the lower plastic zone where under the pressure of overlying ice, the ice bends and flows exhibiting ductile behavior. The zone of income for the glacier is called the zone of accumulation, where snow is converted into firn then ice by compression and recrystallization, and the zone of expense called the zone of ablation, where ice melts or sublimes away.
