Question

Which is formed by glacial erosion? A) eskers C) moraines B) arêtes D) warmer climate

Short answer

C) arêtes are formed by glacial erosion.

Step-by-step solution

Understanding Glacial Erosion

Glacial erosion occurs as glaciers move, reshaping the landscape primarily through processes such as plucking and abrasion. It's important to know which landforms are the direct result of these erosional processes.

Identifying Glacial Landforms

Eskers are long, winding ridges of sand and gravel formed by retreating glacial meltwater, not primarily through erosion. Moraines are accumulations of debris deposited by glaciers. Arêtes are sharp ridges formed by glacial erosion. Warmer climate is not a landform and is unrelated to physical structures formed by erosion.

Selecting the Correct Answer

Based on the understanding of how glacial landforms develop, arêtes are specifically formed by glacial erosion. Eskers and moraines result from deposition, not primarily erosion. Option D is not relevant to landform creation.

Key concepts

Glacial Landforms

Glacial landforms are fascinating features shaped by the powerful movement of glaciers over time. As glaciers advance and retreat, they leave behind distinct marks on the landscape through both erosional and depositional processes. These features provide important insights into the history and dynamics of glacial areas.

• Erosional landforms are created as glaciers erode underlying rock and soil. These include formations like cirques, fjords, and arêtes.
• Depositional landforms result from the materials a glacier leaves behind as it melts. This includes structures like eskers and moraines.

Understanding glacial landforms helps scientists reconstruct past climate conditions and predict future changes.

Arêtes

Arêtes are striking, narrow ridges that form when two glaciers erode parallel valleys on a mountain. This erosional process leaves a sharp divide or "knife-edge" ridge between the two glacial valleys. Arêtes are a clear hallmark of glacial erosion and are often found in mountainous regions affected by glaciation.

• Formation Process: As glaciers erode two adjacent sides of a mountain, the rock between them is plucked and abraded, sharpening the ridge.
• Popular Examples: Some well-known arêtes include the Knife Edge on Mount Katahdin in the United States and the Striding Edge in the UK.

Arêtes serve as a visual reminder of the powerful and sculpting forces of glaciers on the landscape.

Eskers

Eskers are sinuous, elongated ridges composed mainly of sands and gravels. Unlike arêtes, eskers are formed from material deposited by glacial meltwater, not by erosion.

• Formation Process: As glaciers melt, meltwater flows beneath them, carrying sediment. This sediment is deposited in tunnels within and beneath the ice, eventually forming an esker when the glacier retreats.
• Characteristics: Eskers can stretch for miles, winding across the landscape, and give clues about the direction and extent of old glacial flows.

Eskers are important in understanding glacial dynamics and have been used historically as roads due to their relatively stable and elevated surfaces.

Moraines

Moraines are accumulations of debris, such as rocks and soil, collected and deposited by glaciers as they move. Unlike arêtes, which are an erosional landform, moraines are the result of glacial deposition.

• Types of Moraines: Moraines can be classified based on their position in relation to the glacier. These include terminal moraines (deposited at the farthest advance of a glacier), lateral moraines (along the sides of glaciers), and ground moraines (spread across the landscape as a glacier retreats).
• Significance: Moraines are important for understanding the extent and movement of glaciers over time. They provide evidence of past glacial activity and help in reconstructing paleoclimates.

Studying moraines allows scientists to unravel the history and impact of glaciers on the terrain.