The Geisel valley () is a valley in Saxony-Anhalt, Germany, situated west of Merseburg, Saalekreis district. It is named after the River Geisel which rises in Mücheln and is a tributary of the Saale, just under long. Its main settlements are Braunsbedra and Mücheln, which in the future will merge into the 'collective municipality' of Geiseltal. The Geisel valley was quarried for coal from 1698 until the mines were closed in 1994; The mining of brown coal is first attested for 1698 near the Zöbigker grove but is most likely to be older. Initially, only twelve smaller pits emerged at the beginning of the Industrial Revolution in the late 19th century, which spread to large areas; ultimately, the Braunsbedra-Geiseltal mines became one of the largest connected mining regions in Germany. Coal/Lignite mining At the beginning of the twentieth century, the region was characterized by mostly independent pits (Elisabeth 1906, Großkayna 1907, Beuna 1907, Cecilie 1907, Rheinland 1908, Leonhardt 1910, Pfännershall 1911). In the course of the further processing of coal, nine briquetting plants were built. The immense coal deposits in the Geisel Valley and its favorable transport conditions also led to the development of several chemical plants settled. BASF constructed construction of the ammonia plant Merseburg of BASF (the later Leuna plants) with its subsidiary Buna-Werke, the world's first synthetic rubber producer (founded in April 1936), as well as the mineral oil plant built by Wintershall AG from 1936, is significant in this context Lützkendorf, a plant for fuel and lubrication oil production. After the Second World War, there was a further intensification of the dismantling. The Mächeln opencast mine, founded in 1949 by merging several existing abbeys (including Pauline, Elisabeth, Emma, and Elise II), charred mainly the western Geisel Valley, while the opencast mining Großkayna, founded 1949 (from the Grube Rheinland) and Kayna-Süd. Founded in 1948, in the excavation operation encountered large open-pit open-cast mining in Großkayna to a depth of in the open-cast mining area Mücheln up to (natural upper edge at about above sea level). In the 1990s, the embankments of the Mücheln opencast mine were moved; around 26 million cubic meters of earth mass were flattened and support the embankment. The completion of these measures began on June 30, 2003 with the flooding of the remaining hole to the Geiseltalsee, which on April 26, 2011, has a water level at above sea level. As of 2015,