Current issue: 53(4)
The study about the formation of hummock ridges on the peatlands is based on research conducted between years 1915-1919 in Pyhäjoki area in middle Ostrobothnia area in Western Finland, in Kuusamo and Kuolajärvi in north-east Finland, and in different parts of Finnish and partly also in Norwegian Lapland.
The hummock ridges and the “rimpis” are evolutionary in close connection with each other. Hence the sliding of peat plays an important role in the formation of hammock ridges. The formation of regularly positioned hummock ridges requires sloping surface of the moor, where the water flow or the movement of the peat goes in one direction. Formation of hummock ridges is determined by climatic factors, particularly by the floods and other weather conditions in spring time.
Conclusion of the study is that the theories up to now about the formation of hummock ridges have not understood the phenomenon completely. The different morphological factors affect by themselves or together by the formation of regular groupings of the hummock ridges.The article contains an abstract (Zusammenfassung) in German.
The hummocky peatlands are fairly common in Finland. Peatlands with hummock ridges are rare in southern Finland but become more common in northern parts of the country.
In the incompletely drained flark fens the development of the hummocks can be studied particularly well because they can be found in different development phases there. The phenomenon is more common in drained peatlands than in the peatland on their natural state.
The development of the hummock ridges is close related to development of the hummocks. The hummock ridges are formed only under certain circumstances.
Height increment of the hummock ridges is restricted by the same factors that prevent the unrestricted height increment of the hummocks. The hummock ridge may sink due to its own weight in unfrozen swamp, it may be eroded by frost, wind, flowing water or ice. Dead trees, shading or other detriments may prevent the growth of secondary peat.