Engineering Geological Map of Lower Saxony 1: 50000 – Saltstock elevations (WMS service)

Description

Subrosion is the underground leaching and transport of mostly easily soluble rocks. Subrodable are chemical sediments, such as the easily soluble chlorides rock salt and potassium salt, sulphate rocks such as gypsum and anhydrite (sulfate carbonate) and also the heavy soluble carbonate rocks e.g. limestone (carbonate carbonate). Most damage in Lower Saxony is due to the leaching of sulphate rocks. In the case of subrosion, a distinction must be made between regular and irregular leaching. A regular leaching takes place on the surface of the subrodable rock and leads to wide-ranging, usually low drops of the terrain. Irregular leaching focuses on a small-scale, narrowly-limited area and can lead to the formation of caves, cloaks or coagulation. It progresses in solid rocks, especially along clefts or joints in the rock. Therefore, loosened mountain areas in tectonic fault zones are also usually areas of intense subrosion. If the boundary load capacity of the mountain above a cavity is exceeded, this cavity can collapse and break through to the earth’s surface (earthfall). The layer strength of the soluble rock and thus the possible size of a cavity are decisive for the size of the burglary on the terrain surface. About 50 percent of the earthfalls in Lower Saxony have a diameter of up to two meters and at about 40 percent the diameter is between two and five meters. Although these diameters seem quite small, the effects on buildings can be very large. In the map ISH50, on the basis of the Geotectonic Atlas of Northwest Germany, 1:100.000 Saltstock highlands were identified, in which salt rocks above -200 m NN – in a few exceptions above -300 m NN – occur and are surrounded by groundwater-containing layers. Here soil falls can be caused by leaching in the area of the salt level and by leaching in the area of the plaster hat. The information shown in the map does not replace ground investigation in accordance with DIN EN 1997-2 (DIN 4020).

Resources

Name Format Description Link
0 https://nibis.lbeg.de/net3/public/ogc.ashx?NodeId=196&Service=WMS&Request=GetCapabilities&

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