During the Saale glacial period (230,000 to 130,000 years ago), inland ice from Scandinavia spread across part of the Netherlands and Germany. The glaciers push huge amounts of soil in front of them. Large hills, so-called moraines, are formed. Today’s villages and towns such as Uelsen, Oldenzaal and Enschede are located on such moraines. Epe lies on ‘material’ that was carried along by a glacier and deposited at its end, a so-called terminal moraine. The soil beneath the heavy, moving ice is ground down into boulder clay. Boulder clay is almost impermeable to water and prevents water seepage: this is very important for the formation of bogs.