A New England term for esker, or a long narrow ridge of remnant glacial debris, is horseback. As in whaleback or hogbackcommon names for ridges in the Northeast—and, in Kansas, swayback, the word contains the obvious visual: a horse’s back is not straight but has a declivity, a sway, between shoulder and haunch, as an esker so strikingly does from end to end.

Susan Brind Morrow