Ribbed or Rogen Moraines
Landform assemblage of numerous, parallel, closely-spaced ridges consisting of glacial drift, usually TILL.
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The ridges are formed transverse to ice flow in a subglacial position and are usually found in the central portions of former ice sheets.
Individual ridges are typically 10-30 m high, 300-1200 m long and 150-300 m wide, have a straight to arcuate planform, concave in the down-ice direction.
Their name derives from Lake Rogen in Sweden.
Ribbed moraine is the North American, and perhaps, the preferred term.
Their formation is uncertain but is often closely linked to that of drumlins (see subglacial bedforms).