Which feature best describes an Esker?

Which feature best describes an Esker?

• A. A wind-sculpted sand dune in deserts.
• B. Steep sided winding ridge of till
• C. A submerged limestone cave.
• D. A glacial lake formed in a valley.

Answer: (B)

Eskers are long, winding ridges formed by sediment deposited by meltwater flowing through channels within or beneath a glacier. The key idea is that these features record the path of subglacial or englacial rivers, leaving a sinuous ridge of material as the ice retreats. That makes the description of a steep-sided, winding ridge of glacial sediment the best match, since it captures both the shape (long and twisty) and the glacial origin of the feature. Desert wind dunes are shaped by wind, not ice. A submerged limestone cave is a karst feature formed by dissolving rock, not deposited sediment in a glacier. A glacial lake formed in a valley is a body of water, not a raised ridge of sediment. Eskers stand out as the glacial sediment ridge left behind by ancient meltwater pathways.

Eskers are long, winding ridges formed by sediment deposited by meltwater flowing through channels within or beneath a glacier. The key idea is that these features record the path of subglacial or englacial rivers, leaving a sinuous ridge of material as the ice retreats. That makes the description of a steep-sided, winding ridge of glacial sediment the best match, since it captures both the shape (long and twisty) and the glacial origin of the feature.

Desert wind dunes are shaped by wind, not ice. A submerged limestone cave is a karst feature formed by dissolving rock, not deposited sediment in a glacier. A glacial lake formed in a valley is a body of water, not a raised ridge of sediment. Eskers stand out as the glacial sediment ridge left behind by ancient meltwater pathways.