The Cloppenburg Geest (german: Cloppenburger Geest) is a

geest Geest is a type of landform, slightly raised above the surrounding countryside, that occurs on the plains of Northern Germany, the Northern Netherlands and Denmark. It is a landscape of sandy and gravelly soils formed as a glacial outwash plai ...

region near the town of

Cloppenburg Cloppenburg (; nds, Cloppenborg; stq, Kloppenbuurich) is a town in Lower Saxony, Germany, capital of Cloppenburg District and part of Oldenburg Münsterland. It lies 38 km south-south-west of Oldenburg in the Weser-Ems region between Brem ...

North Germany Northern Germany (german: link=no, Norddeutschland) is a linguistic, geographic, socio-cultural and historic region in the northern part of Germany which includes the coastal states of Schleswig-Holstein, Mecklenburg-Vorpommern and Lower Saxony an ...

and the centre of the

Saalian glaciation The Saale glaciation or Saale Glaciation, sometimes referred to as the Saalian glaciation, Saale cold period (german: Saale-Kaltzeit), Saale complex (''Saale-Komplex'') or Saale glacial stage (''Saale-Glazial'', colloquially also the ''Saale-Eiszei ...

Upper Pleistocene The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within ...

terrain of the Ems-Hunte Geest region. The

meltwater Meltwater is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing. Meltwater can be ...

sands (''Schmelzwassersande'') of the advancing

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 Las ...

covered the old terrain with outwash sands (''Vorschüttsande''). Woldstedt (1955: 159) spoke about underlying sands that, in the "Cloppenburg-Bassum Geest", belonged to the

Elster glaciation The Elster glaciation (german: Elster-Kaltzeit, ''Elster-Glazial'' or ''Elster-Zeit'') or, less commonly, the Elsterian glaciation, in the older and popular scientific literature also called the Elster Ice Age (''Elster-Eiszeit''), is the oldest k ...

. A covering of

boulder clay Boulder clay is an unsorted agglomeration of clastic sediment that is unstratified and structureless and contains gravel of various sizes, shapes, and compositions distributed at random in a fine-grained matrix. The fine-grained matrix consists ...

was deposited over the outwash sands during the Saale glaciation, or more precisely the Drenthe stage. A series of meltwater valleys characterises the surface of the Cloppenburg Geest, something that was vital to the emergence of the river network. "Numerous parallel, flat channels cross the terrain and so create a landscape of parallel ridges" writes Woldstedt (1955: 158). There are two opposing theories for the formation of the rivers. Hausfeld (1983; 1984) put their emergence down to large cracks in the Drenthe ice sheet, through which meltwaters flowed as the glacier thawed, cutting through the ground moraines and down into the outwash sands. Woldstedt (1956) spoke of channels (''Rinnen'') in another connexion. The advancing ice followed the depth contours, conserving and deepening them. When the ice sheet retreated,

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 a ...

(''Toteis'') remained deep in these channels; it was their thawing that then enabled the rivers to flow down their old valleys. During the

marine regression A marine regression is a geological process occurring when areas of submerged seafloor are exposed above the sea level. The opposite event, marine transgression, occurs when flooding from the sea covers previously-exposed land. Evidence of marine ...

of the

Weichselian glaciation The Weichselian glaciation was the last glacial period and its associated glaciation in northern parts of Europe. In the Alpine region it corresponds to the Würm glaciation. It was characterized by a large ice sheet (the Fenno-Scandian ice sheet) ...

that ended about 12,000 years ago, in which the

northwest German plain The North German Plain or Northern Lowland (german: Norddeutsches Tiefland) is one of the major geographical regions of Germany. It is the German part of the North European Plain. The region is bounded by the coasts of the North Sea and the Balti ...

was not covered by ice, the rivers of the Cloppenburg Geest cut deeply into the valley sands. At that time the windborne and

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...

sands were formed especially as the area around the perimeter dried out. The climate of the post-glacial period was moister and warmer. The rise in

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...

, the base level for river

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

, probably led to a rise in the

water table The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. T ...

in the geest depression (Roeschmann, 1971: 189). In the valleys vast

fen A fen is a type of peat-accumulating wetland fed by mineral-rich ground or surface water. It is one of the main types of wetlands along with marshes, swamps, and bogs. Bogs and fens, both peat-forming ecosystems, are also known as mires. T ...

peats formed, whilst on the valley edges and the larger basins

raised bog Raised bogs, also called ombrotrophic bogs, are acidic, wet habitats that are poor in mineral salts and are home to flora and fauna that can cope with such extreme conditions. Raised bogs, unlike fens, are exclusively fed by precipitation ( ombro ...

s were formed (Hausfeld, 1983: 245).

References

* R. Hausfeld: Die Entwicklung der Hümmlingsbäche und ihre heutige Pflanzenwelt. Jahrbuch des Emsländischen Heimatbundes, Bd. 29, 1983, S.244-266. * R. Hausfeld: Die Vegetation nordwest-niedersächsischer Bachtäler in Abhängigkeit von landwirtschaftlicher Nutzung und wasserbaulichen Eingriffen. In: Fließgewässer und ihr Einzugsgebiet. Hrsg.: Biologische Schutzgemeinschaft Hunte Weser-Ems. Wardenburg: BSH-Vlg. 1984, S.137-170. (= Informationen zu Naturschutz und Landschaftspflege in Nordwestdeutschland, Bd.4). * R. Hausfeld: Das Markatal, eines der letzten naturnahen erhaltenen Bachtäler Nordwestdeutschlands. Jahrbuch für das Oldenbuger Münsterland, 1984, S.184-207. * G. Roeschmann: Die Böden der nordwestdeutschen Geestlandschaft. Mitteilungen der Deutschen Bodenkundlichen Gesellschaft, Bd. 13, H.1, 1971, S.155-231. * P. Woldstedt: Die Geschichte des Flußnetzes in Norddeutschland und angrenzende Gebiete. Eiszeitalter und Gegenwart, Bd. 7, 1956, S.5-12. * P. Woldstedt: Nordwestdeutschland und angrenzende Gebiete im Eiszeitalter. Stuttgart 1955. (= Geogr. Handbücher).

Sources

* Heinz-Josef Lücking: Ökologische Bewertung des Soestetals zwischen Cloppenburg und Stedingsmühlen (LK Cloppenburg, Nordwest-Deutschland) aus der Sicht des Naturschutzes unter besonderer Berücksichtigung der Vegetation, Gewässergüte und des ökomorphologischen Gewässerzustandes. BSH/NVN naturspecialREPORT 1995, Heft 21. Diplomarbeit im Fach Geographie an der Justus-Liebig-Universität, Gießen, 1992. {{coord, 52.8333, N, 8.16667, E, source:kolossus-dewiki, display=title Geography of Oldenburg Regions of Lower Saxony Geest Cloppenburg (district)