The slope of the Teckberg formed by the Yellow Rock, a Schwammriff the Jura sea of bright lime. Under the Gelber Fels, is the 31 m long and 45 m high Veronikahöhle, which is connected through columns with Verena-Beutlins-Loch. East of the Gelber Fels (Yellow Rock) three grave mounds indicate from the Hallstatt period (800-400 BC) the early settlement of the Teckberg. Under the castle Teck is the 35 m long and 9 m high fabled Sibyllenloch, on the other side the 22 m long Sibyllenhöhle. It was only in 1937 discovered during construction work and was explored in 1977. During excavations in Sibyllenloch 1898/99 over 2,000 skeletal remains of cave bear, cave lion, cave hyena and wild horse were found. So many conclusions about the glacial fauna could be drawn.