Klonk

Klonk is a Czech national nature monument within the landscape park Český kras which lies in the northern part of the village of Suchomasty, approximately 12 kilometres from Beroun. It is globally recognized as a geologically important location due to the presence of the Global Boundary Stratotype Section and Point marking the boundary between Silurian and Devonian periods. The boundary was set based on the first appearance of the graptolite Monograptus uniformis in the bed number 20. The stratotype was ratified on the 8th of February 1972 by the International Union of Geological Sciences in Montreal as the first formally accepted GSSP. ()