The Lüneburg Kalkberg is the cap rock of a salt dome in the western part of the German town of Lüneburg. The Kalkberg was a gypsum mine during the middle ages, but is today a Naturschutzgebiet and a common meeting place for city residents.
The Kalkberg is made up largely of gypsum and comes from sediments that were deposited there around 250 million years ago by the Zechstein Sea. More recently , smaller disturbances have allowed the less dense Zechstein salts to flow together and force their way upwards into the younger, overlying rocks. Today these salts are near the earth's surface. Through this process, the more geologically-recent layers of rock around the rising mass of salt were deformed, shattered, and lifted; the initially horizontally-lying layers of salt were tilted and folded as they were rose upwards. Near the surface, the resulting salt dome was leached by groundwater, so that only the less readily-soluble elements remained behind, such as carbonates and sulphates. These are the compounds that make up the Kalkberg today, and can also be seen to protrude through the surface around Lüneburg.
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