An esker indicates that there were tunnels with flowing meltwater in the glacier. The esker itself is the material left inside the tunnel when the tunnel stopped being active. Photograph by B. Washburn, courtesy of Eugene Domack, Hamilton College. Many glacial landscapes are characterized by the presence of esker ridges snaking across the terrain. The remnants of eskers can be seen across North America where glaciers were once active.
Eskers are good indicators of past glaciations.
Where glacial geologists find eskers, they know that ice once was present. Photograph courtesy of Eugene Domack, Hamilton College. Remember that there is little meltwater in the cold glacial setting of Antarctica. Well-developed meltwater drainage tunnel systems do not have the opportunity to form, so eskers are not seen on the Antarctic continent to mark the locations of the tunnels.