Answer:
The two primary mechanisms of glacier flow are basal sliding and internal deformation.
1. Basal sliding occurs when a glacier slides along its bed due to the presence of water or meltwater between the glacier and the underlying surface. This water acts as a lubricant, reducing friction and allowing the glacier to move more easily. Basal sliding is more significant in warm-based glaciers where the ice temperature is near the melting point. For example, in the lower parts of a valley glacier, meltwater can accumulate and create a slippery layer between the ice and the ground, facilitating sliding.
2. Internal deformation, also known as plastic flow, refers to the movement of ice within a glacier caused by the weight and pressure of the overlying ice. As the ice mass accumulates, the pressure from the upper layers causes the ice crystals to slowly deform and flow. This process is similar to the behavior of a viscous fluid, where the ice behaves plastically rather than breaking or cracking. Internal deformation is more significant in cold-based glaciers where the ice is below the melting point.
To summarize, basal sliding involves the sliding of a glacier over its bed due to the presence of meltwater, while internal deformation refers to the slow, plastic flow of ice within the glacier caused by pressure and weight. These mechanisms differ in terms of the temperature of the ice and the presence of water or meltwater.
Step-by-step explanation: