The geotope "Porphyrfächer" at the Schmieders Graben is the center of the Geological Open Air Museum in the Tharandt Forest.
The outcrop wall is formed from the rhyolite. The rock shows a fine to thick columnar segregation, which is due to shrinkage cracks during cooling. Since 1958, the quarry, which has been left open, has been designated as a natural monument.
Along an approx. 12 km long educational and hiking trail, the 12 most important geotopes are connected and their formation and the connection to the geology of Saxony are presented on panels in each case. Here you have the opportunity to get acquainted with the interesting geology of the Tharandt Forest, which covers half a billion years of geological history. Possible starting points are the parking lot "Sportplatz Mohorn-Grund" or the parking lot "Gasthaus zum Landberg Herzogswalde".
