The main problem in defining hill involves knowing where it ends and mountain begins. Both are natural elevations of the Earth’s surface. Sometimes an upper bound for a hill is set at a thousand feet, but you can take a “hill trek” in the Himalayas at fifteen times that height. If there are no craggy peaks in the area, then hills are the rounded prominences that form the skyline; if there are mountains, then hills, however high, are what stand in front of them. For some, the hill has a softer edge. In Ceremony, Leslie Marmon Silko writes: “Years of rain and wind had weathered away the adobe plaster, exposing the symmetry of the brown adobes which were beginning to lose their square shape, taking on the softer contours of the mesas and hills.” In eastern Washington’s Palouse country, hills too steep to plow and that stand like forested islands in a sea of wheat are called eyebrow hills.

Bill McKibben