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Difficulty: MediumLandform Development by Wind Action and Glaciation

During glacial retreat, meltwater channels flowing beneath or within a decaying ice sheet deposit stratified layers of sand and gravel. Which of the following features is produced as a long, winding ridge along the course of these subglacial streams?

  1. An eskerAnswer
  2. B
    A drumlin
  3. C
    An oxbow lake
  4. D
    A roche moutonnée

Answer

An esker is the sinuous ridge of stratified sand and gravel formed by subglacial meltwater streams.
An esker is a distinctive glaciofluvial feature formed when sediment-laden meltwater flows through tunnels beneath or within stagnant, melting ice sheets. As the surrounding ice melts away, the sorted layers of sand and gravel deposited in the tunnel bed are left behind as a continuous, winding ridge across the landscape.

Step-by-Step Solution

1
Identify the agent and depositional process described in the scenario.
The feature is created by fluvioglacial deposition (meltwater streams transporting and sorting sediment inside or beneath stagnant glacial ice).
Meltwater running under ice carries sorted sand and gravel, distinguishing fluvioglacial deposits from unsorted glacial till deposited directly by ice.
2
Match the specific morphology (long, winding ridge) with the corresponding glaciofluvial landform.
An esker matches the description of an elongated, sinuous ridge marking the path of a former subglacial stream channel.
Other glacial features differ in structure and origin; drumlins are streamlined hills of unsorted till, while roche moutonnées are sculpted bedrock knobs.

Key Concept

Fluvioglacial Depositional Landforms (Eskers)
Estimated Time:1m 0s
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Topics

Landform Development by Wind Action and Glaciation

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