Geisel valley

The Geisel valley is a region in Saxony-Anhalt, Germany, west of Merseburg in the Saalekreis district, named for the River Geisel, a roughly 25-kilometer tributary of the Saale that rises near Mücheln. Lignite was mined there from 1698 until 1994, expanding through the Industrial Revolution into twelve smaller pits that grew into one of the largest connected mining districts in Germany and drew major chemical plants, including a BASF ammonia works and the first synthetic rubber factory in the world. After mining ended, the excavated pits were flooded to form the Geiseltalsee, which by 2011 stood at 98 meters above sea level and by 2015 covered about 18.9 square kilometers, becoming one of the largest lakes in Germany, and the reclaimed valley now supports a growing viticulture industry on its sandy soil.