Read this: The landscapes of Thuringia are quite diverse. The far north is occupied by the Harz mountains, followed by the Goldene Aue, a fertile floodplain around Nordhausen with the Helme as most important river. The north-west includes the Eichsfeld, a hilly and sometimes forested region, where the Leine river emanates. The central and northern part of Thuringia is defined by the 3000 km² wide Thuringian Basin, a very fertile and flat area around the Unstrut river and completely surrounded by the following hill chains (clockwise from the north-west): Dün, Hainleite, Windleite, Kyffhäuser, Hohe Schrecke, Schmücke, Finne, Ettersberg, Steigerwald, Thuringian Forest, Hörselberge and Hainich. Within the Basin the smaller hill chains Fahner Höhe and Heilinger Höhen. South of the Thuringian Basin is the Land's largest mountain range, marked by the Thuringian Forest in the north-west, the Thuringian Highland in the middle and the Franconian Forest in the south-east. Most of this range is forested and the Großer Beerberg (983 m) is Thuringia's highest mountain. To the south-west, the Forest is followed up by Werra river valley, dividing it from the Rhön Mountains in the west and the Grabfeld plain in the south. Eastern Thuringia, commonly described as the area east of Saale and Loquitz valley, is marked by a hilly landscape, rising slowly from the flat north to the mountainous south. The Saale in the west and the Weiße Elster in the east are the two big rivers running from south to north and forming densely settled valleys in this area. Between them lies the flat and forested Holzland in the north, the flat and fertile Orlasenke in the middle and the Vogtland, a hilly but in most parts non-forested region in the south. The far eastern region (east of Weiße Elster) is the Osterland or Altenburger Land along Pleiße river, a flat, fertile and densely settled agricultural area.

What is Thuringia's oldest mountain?
What is the answer? (If it cannot be answered, return "unanswerable")
unanswerable