Meeting point: Diebsteich S-Bahn station

The geological underground of Bahrenfeld and the adjacent districts has, in the truest sense of the word, a dynamic history. Salt domes have formed from thick layers of rock salt created in the Permian period over 250 million years ago. Some have risen to the Earth's surface. The examples from Bad Segeberg or Lüneburg, mistakenly called chalk mountains, are clearly visible. The Othmarschen-Langenfelde salt dome behaves somewhat more inconspicuously. During its ascent, it has cut through, bent, and tilted the geological layers deposited above the salt. As a result of this process, interesting raw materials for the construction industry, such as clay and gypsum, are found in the area of the salt dome today.Furthermore, glaciers that migrated from Scandinavia in several ice ages over the last good 2 million years have traversed the Hamburg area, partly reshaping the near-surface layers and finally leaving behind the rock debris, large amounts of sand and gravel, brought from Scandinavia.The aforementioned raw materials were mined extensively around the turn of the 19th to the 20th century and are now incorporated into the old buildings of Altona, Eimsbüttel, and Ottensen.On the other hand, subsidence occurs in the area of the salt dome due to the leaching of gypsum layers, leaving its mark on the surface and in buildings.During this excursion, we will learn about the still visible traces of raw material extraction and subsidence.End point: Bahrenfeld S-Bahn stationDistance: 12 kmParticipation in the cycling tour is at your own risk.