Question
How do glaciers erode? Describe three erosional and two depositional features of a glacier. with suitable diagrams.
Answer
Glaciers erode the landscape in several ways. The three main types of glacial erosion are abrasion, plucking, and freeze-thaw weathering.
Glaciers are capable of eroding and shaping the landscape through a range of processes. Here are three erosional and two depositional features of a glacier:
Erosional features:
- Cirques: Cirques are steep amphitheater-like depressions that form at the head of a glacier. They are formed through plucking and abrasion, as the glacier erodes the rock and scoops out the bedrock. Over time, the cirque may enlarge and deepen, forming a bowl-shaped valley known as a glacial trough.
- Striations: Striations are parallel grooves or scratches on rocks that are caused by the abrasive action of glacial ice. As the glacier moves, it grinds rocks beneath it and carries the debris along, leaving behind parallel scratches or grooves.
- Roche moutonnée: A roche moutonnée is a rock outcropping that has been sculpted by the movement of a glacier. One side of the rock may be smoothed and rounded, while the other side is jagged and angular.
Depositional features:
- Moraines: Moraines are accumulations of rock and sediment that are carried by the glacier and deposited along its edges or at its terminus. There are different types of moraines, including lateral, medial, and terminal moraines, which all form at different points in the glacier’s journey.
- Eskers: Eskers are long, winding ridges of gravel and sand that are deposited by meltwater streams flowing through a glacier. When the glacier melts, the sediment carried by the streams is deposited in a sinuous ridge, sometimes reaching tens of meters high.
