The Gamengrund is a prominent, 300 to 400 meter wide glacial channel that cuts through the Barnim's ground moraine surface. It begins south of Eberswalde and runs to Hirschfelde. Due to its very strong form, it is an important geotope for Brandenburg and has been designated as a landscape protection area. The Gamengrund emerged from a tunnel valley in which meltwater from the overlying ice sheet made its way under the ice. With the collapse of the ice sheet, blocks of dead ice collected in the channel and created depressions in which today's lakes were formed. (Wikipedia) de.wikipedia.org/wiki/Gamengrund