The Jonastal valley is a cut in the terrain within the Ohrdrufer Platte, which stretches from Crawinkel to Arnstadt in central Thuringia. It is crossed by the Wilde Weiße river, which has eroded deep into the shell limestone in places, creating steep precipices. The approx. 10 km long valley is deeply incised, has mostly very steep walls, is mostly very narrow and very winding. In many places, the valley is so narrow that there is just enough room for a narrow district road, apart from the River Weiße.

Many rare orchids and other plants that prefer limestone soils, such as the cowslip, grow in this valley. As there is hardly any space for agricultural land in the valley, the vegetation is very natural.

On the plateau to the west of the valley is the former Ohrdruf military training area, which is now classified as a military training area, where nature has been able to develop freely for decades and where wolves have now settled.

The valley is also known for a secret construction project in this area during the National Socialist era.

The Jonastal separates the Gossel plateau to the right of the Wilde Weiße from the western Ohrdrufer Platte.