Which term describes a long, winding ridge formed by glacial meltwater flowing beneath or within a glacier?

• A. Esker
• B. Moraine
• C. Drumlin
• D. Outwash plain

Answer: (A)

This question tests knowledge of glacial landforms created by meltwater channels. An esker is a long, winding ridge of sand and gravel that forms from a meltwater stream flowing through a tunnel or conduit within or beneath a glacier. As the water moves, it sorts and deposits sediment along the channel floor. When the ice retreats, the sediment-filled tunnel remains as a sinuous ridge that marks the former flow path.

Moraine is a ridge of till deposited at the glacier’s edge, not shaped by subglacial channels. Drumlin is an elongated hill formed by ice flow, often smooth and streamlined, but not the result of a meltwater tunnel. An outwash plain is formed by meltwater streams depositing layered sands and gravels beyond the glacier terminus, typically more spread out and planar rather than a single winding ridge.