Rogen Moraine

Rogen moraine, also called ribbed moraine, is a type of moraine formed beneath glacial ice that appears on the landscape as a series of large, wavy, roughly parallel ridges. It is named after Lake Rogen in Sweden, where the landform was first identified, and similar moraines are also found more broadly in Fennoscandia, Scotland, Ireland and Canada. Its exact formation is not settled: proposed explanations include megaripples cut into the base of the ice during subglacial flooding, the reshaping of pre-existing ridges such as drumlins when the direction of ice flow shifted, and the shearing, stacking or folding of sediment beneath compressing ice. Because Rogen moraines vary in character from place to place, more than one of these processes may be responsible for different examples.