1. Erosion:
* Abrasion: As the glacier moves, embedded rocks and debris within the ice act like sandpaper, scraping and grinding the underlying bedrock. This creates smooth, polished surfaces and striations (scratches) in the rock.
* Plucking: Melting water at the base of the glacier freezes and expands, breaking off pieces of bedrock and incorporating them into the glacier. This process creates jagged, irregular features.
* U-shaped valleys: Glaciers carve out valleys with a characteristic U-shape, in contrast to the V-shaped valleys formed by rivers. The steep sides and flat bottoms of U-shaped valleys are a hallmark of glacial erosion.
2. Deposition:
* Moraines: As glaciers melt, they deposit sediment in various forms known as moraines:
* Terminal moraines: Mark the farthest extent of the glacier.
* Lateral moraines: Form along the sides of the glacier.
* Medial moraines: Form when two glaciers merge.
* Outwash plains: Meltwater from glaciers carries sediment downstream, depositing it as outwash plains, often with distinctive braided stream patterns.
* Drumlins: Elongated, tear-drop shaped hills formed by glacial deposition. They are oriented in the direction of glacial flow.
* Eskers: Long, winding ridges of sand and gravel deposited by meltwater streams flowing within or beneath a glacier.
3. Landform Creation:
* Fjords: Deep, narrow inlets formed by glacial erosion of valleys that have been flooded by seawater.
* Cirques: Bowl-shaped depressions carved out by glaciers at the head of a valley.
* Aretes: Sharp, jagged ridges formed by glacial erosion of two adjacent cirques.
* Peaks: Pointed mountain summits formed by glacial erosion of multiple cirques.
4. Isostatic Rebound:
* Continental glaciers exert immense pressure on the Earth's crust, causing it to sink. When glaciers melt, the land gradually rises back up, a process called isostatic rebound. This can have significant effects on coastal areas, potentially leading to land emergence and changes in coastline.
5. Climate Change:
* Continental glaciers play a major role in regulating Earth's climate. Their reflective surface helps keep the planet cool, and their presence affects atmospheric circulation patterns.
Overall Impact:
The combined effects of erosion, deposition, and isostatic rebound significantly shape the Earth's topography. Continental glaciers leave behind a distinctive landscape characterized by U-shaped valleys, moraines, drumlins, and other glacial landforms. They also influence global climate and sea level.
