At the foot of the Gottlob in the Schmalkalder Strasse is a 25 m high old quarry face. This is where sandstone slabs, so-called "Thuringian Forest Slabs", were extracted between 1885 and 1940, to be used for constructing foundations, dry walls or pavements. The abandoned quarry was designated a geological natural monument in 1968.

The quarry also exposes a 2 m thick horizon of mainly black finely laminated mudstones (Schwarzschiefer) about 10-6 m above the floor of the quarry. This is the lithified bed of a lake, which is extraordinarily rich in fossils. Life in an Early Permian Lake can be reconstructed using the fossil archive in the lake deposits. The Plattenbruch Quarry at the Gottlob is also type locality for the Tetrapod track fossil Ichnotherium cottae.

The well documented fossil record of the Plattenbruch Quarry resulted from research of engaged local collectors, among them:

  • ALWIN LANGENHAHN (1850-1916)
  • ALFRED EISFELD (1883-1965)
  • FRITZ KONTHER (1895-1968)
  • ALFRED ARNHARDT (1888-1973) and
  • BERNHARD JACOBI (1907-1987).

A diorama of "Gottlob Lake" can be seen in the exhibition at the GeoInformationcentre at the Marienglashöhle Friedrichroda.