How do glaciers transport rocks and other debris through valleys?

Glaciers transport rocks and other debris by picking them up from the valley walls and floor as they move, carrying this material in, on, or under the ice.1

This debris is acquired through several processes:
* Glacial Plucking (Quarrying): The glacier removes larger pieces of rock from its bed, often by exploiting pre-existing joints or cracks in the bedrock through stress, hydraulic pressure, or the refreezing of meltwater (regelation).23
* Abrasion: As the glacier moves, the debris already embedded in its base acts like sandpaper, grinding against the bedrock and picking up additional material in the process.23
* Surface Accumulation: Debris can also enter the glacier from rockfalls occurring on steep slopes bordering the ice or by overriding unconsolidated sediments as the glacier advances.2

Once the material is incorporated, it is transported downstream until the glacier reaches lower elevations where ablation (melting) occurs. At this point, the debris is released and may be deposited as till or concentrated into landforms such as moraines.1