Final answer:
Glaciers move by basal sliding, which is faster, and internal deformation known as creep. Basal sliding occurs when meltwater beneath the glacier acts as a lubricant, allowing the ice to slide over the bedrock.
Step-by-step explanation:
Glaciers flow across bedrock by basal sliding and they also flow by internal deformation called creep. Of these two processes, basal sliding is faster. Basal sliding refers to the process where the glacier slides over the bedrock due to the presence of meltwater at its base, which acts as a lubricant. Creep, on the other hand, is the internal deformation of the ice itself, and it occurs as the weight and mass of the glacier causes it to deform and flow slowly. Glaciers can also erode the landscape, creating features like U-shaped valleys and fjords. This erosive action is strongest at the edges of ice sheets where the movement is more pronounced.