What does an esker primarily consist of?

An esker is primarily composed of sand and gravel. Eskers are long, winding ridges formed by sediment that has been deposited by meltwater from glaciers, often in subglacial or proglacial environments. As glaciers retreat, the meltwater flows beneath or alongside the ice, carrying sediments that are subsequently deposited when the water velocity decreases.

The sedimentary composition of eskers typically includes well-sorted and stratified layers of coarse materials like sand and gravel, which are characteristic of the environments in which these features form. As a result, sand and gravel are the key components that make up an esker, distinguishing them from formations that feature finer materials or other rock types.