Glaciers significantly impact the rock cycle through erosion, transportation, and deposition.
Erosion: The Sculpting Power of Ice
Glaciers act as powerful agents of erosion, carving out valleys, and shaping mountains through several processes:
- Plucking: As glaciers move, they freeze to the bedrock, and as the ice moves, it tears away pieces of rock, transporting them within the glacier. This process creates distinctive landforms such as U-shaped valleys.
- Abrasion: Embedded rocks within the glacier act like sandpaper, grinding and smoothing the bedrock surface. This creates polished surfaces and striations (parallel scratches) on exposed rock.
Transportation: Carrying the Load
Glaciers transport vast quantities of eroded material – from fine silt to huge boulders – over long distances. This transported material is called glacial drift. The ice acts as a conveyor belt, carrying the rock fragments far from their original location.
Deposition: Leaving Their Mark
As glaciers melt, they deposit the transported material, creating various landforms:
- Moraines: These are ridges of sediment deposited at the glacier's edge or within the glacier itself. They can be terminal moraines (at the glacier's furthest extent), lateral moraines (along the sides), or medial moraines (formed where two glaciers merge).
- Outwash plains: These are flat plains formed by meltwater streams flowing from the glacier's snout, depositing fine sediment.
- Erratics: These are large boulders deposited by glaciers far from their source rock. They are often of a different rock type than the surrounding bedrock, indicating transportation by glaciers.
As glaciers melt, the deposition of rocks and sediment directly contributes to the formation of new sedimentary rocks over time. This completes the cycle, linking glacial activity to the creation of new rock formations. The reference highlights the role of glaciers in depositing rocks and sediment as the ice melts, a key part of the deposition stage in the rock cycle.
