Herrenhausfelsen (Panská skála), Czech Republic
These remarkable basalt columns are part of a volcanic tertiary volcanic complex in northern Czech Republic. The columns were quarried for building stones. The deserted quarry is now filled by a small lake, fed entirely by rainwater, which beautifully reflects the highly regular rock structures. As seen form various angles, the columnar basaltic rock outcrop looks remarkably artificial.
Fluctuating lake level
|How the columns form: When basaltic lava cools and solidifies, its volume decreases slightly and causes fracturing. The fractures develop parallel to the temperature gradient (in this example more or less from top to bottom). Individual columns tend to have a hexagonal (six-sided) cross section. Weathering takes place preferentially along the fractures, so that whole sections of columns may break off. Quarrying, and later use of the rocks for building construction, was also facilitated by the columnar structure of the basalt.
Photos Jürg Alean, July 2006