A Rogen moraine (also called ribbed moraine) is a subglacially (''i.e.'' under a

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at La ...

) formed type of moraine landform,Hättestrand, C. & Kleman, J., 1999. Ribbed moraine formation. ''Quaternary Science Reviews, 18'':43-61 that mainly occurs in Fennoscandia,

Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...

,Finlayson, A. G. & Bradwell, T., 2008. Morphological characteristics, formation and glaciological significance of Rogen moraine in northern Scotland. ''Geomorphology, 101'':607-617

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

Dunlop, P. & Clark, C. D., 2006. The morphological characteristics of ribbed moraine. ''Quaternary Science Reviews, 25'':1668-1691 and

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

.Marich, A., Batterson, M. & Bell, T., 2005. The morphology and sedimentological analyses of Rogen moraines, central Avalon Peninsula, Newfoundland. ''Current Research, Newfoundland and Labrador Department of Natural Resources, Geological Survey, Report, 05-1'':1-14 It is one of the three main types of

hummocky moraine In geology, a hummock is a small Hillock, knoll or mound above ground.Bates, Robert L. and Julia A. Jackson, ed. (1984). “hummock.” Dictionary of Geological Terms, 3rd Ed. New York: Anchor Books. p. 241. They are typically less than in he ...

s. They cover large areas that have been covered by ice, and occur mostly in what is believed to have been the central areas of the ice sheets. Rogen moraines are named after Lake RogenMöller, P., 2006. Rogen moraine: an example of glacial re-shaping of pre-existing landforms. ''Quaternary Science Reviews, 25'':362-389 in

Härjedalen Härjedalen (; no, Herjådalen or ) is a historical province (''landskap'') in the centre of Sweden. It borders the Norwegian county of Trøndelag as well as the provinces of Dalarna, Hälsingland, Medelpad, and Jämtland. The province origi ...

, Sweden, the landform's type locality.

Rogen Nature Reserve Rogen Nature Reserve ( sv, Rogens naturreservat) is a nature reserve in Jämtland County in Sweden. It is part of the EU-wide Natura 2000-network. The nature reserve is centred on Lake Rogen and is part of a wider network of nature protection ar ...

serves to protect the unusual area. The landform occurs in groups that are often closely and regularly spaced. They consist of glacial drift, with

till image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...

being the most common constituent. The individual moraines are large, wavy ridges orientated transverse to ice flow.

Drumlin A drumlin, from the Irish word ''droimnín'' ("littlest ridge"), first recorded in 1833, in the classical sense is an elongated hill in the shape of an inverted spoon or half-buried egg formed by glacial ice acting on underlying unconsolidated ...

s are often found in close proximity of Rogen moraines, and are often interpreted to be formed at the same time as the Rogen moraines. Although Rogen moraines can span a large range of sizes, the most common distribution seems to be 10–30 metres high, 150–300 metres wide and 300–1,200 metres long. The exact mechanics of Rogen moraine formation are not known, but since the 1970s, several theories on the formation have been proposed: * Megaripples eroded in the basal ice fill during subglacial outburst floods.Fisher, T. G. & Shaw, J., 1992. A depositional model for Rogen moraine, with examples from the Avalon Peninsula, Newfoundland. ''Canadian Journal of Earth Sciences, 29'':669-686 * Already existing landforms, such as drumlins and

flutes The flute is a family of classical music instrument in the woodwind group. Like all woodwinds, flutes are aerophones, meaning they make sound by vibrating a column of air. However, unlike woodwind instruments with reeds, a flute is a reedless ...

Boulton, G. S., 1987. A theory of drumlin formation by subglacial deformation. ''In'': Menzies, J. & Rose, J. (Eds.), ''Drumlin Symposium'', Balkema, Rotterdam, The Netherlands, pp. 25-80 or marginal moraines are reshaped due to a ≈90° change in the direction of the ice flow. * Debris-rich basal ice or pre-existing

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...

s are sheared and stacked, or folded during compressive ice flow.Lindén, M., Möller, P. & Adrielsson, L., 2008. Ribbed moraine formed by subglacial folding, thrust stacking and lee-side cavity infill. ''Boreas, 37'':102-131 * Shearing of sediment under a glacier causes growth of waves with spacing characteristic of Rogen moraine (300 m to 1000 m). * Sediment sheets become fractured and extended during a transition of the overlying glacier from being cold based ice to warm based. However, it has been suggested that, due to the diversity of morphological characteristics displayed by Rogen moraine, different processes might be able to create the landform. This means that all of the processes mentioned above might be correct. The different theories that proposed a formation near or at the glacial margin have largely been abandoned. Some of these theories proposed that Rogen moraines had an origin as a series of end moraines, that they formed in association with calving ice termini in glacial lakes, or that Rogen moraines formed in

dead-ice Dead ice is ice which, though part of a glacier or ice sheet, is no longer moving. When this melts it does so in situ, leaving behind a hummocky terrain known as dead-ice moraine which is produced by the deposition of glacio-fluvial sediments and ...

, where supraglacial material fell down into crevasses in the ice.

References

External links

Scientific paper about ribbed moraines (Marich et al., 2005)
{{DEFAULTSORT:Rogen Moraine Glacial deposits of Sweden Moraines

See also

References

External links