Požáry National Nature Monument

A world stratotype of the Požáry Formation (Strata) which is also the boundary between the Kopanina and Požáry Formations is exposed in the Požáry quarry. Požáry NNM lies in the parish of Řeporyje, on the south-western outskirts of the city of Prague. The protected area was declared in 1982 on an area of 2.71ha at elevations of 310-340 metres above sea level.
 
Požáry NNM can boast a stratigraphy of world-wide importance. In 1979 the International Sub-commission for Silurian Stratigraphy was given the task of collecting evidence for the declaration of the fourth international chronographical division of the Silurian period and its international stratotype. The Přídolí layers of the Požáry Formation were officially recognized as the uppermost level of the Silurian period by the International Silurian Subcommission in 1979, with the Požáry Formation at the Požáry 1 quarry accepted as its stratotype.
 
The Požáry Formation was originally called the Přídolí Formation, but was renamed to avoid confusion, as another level and formation has the same name.
 
Rust-brown tuffite shales with lenses and concretions of grey limestones of the Kopanina Formation are exposed in the cutting before the tunnel into the Požáry quarry. These rocks contain an abundance of brachiopods and trilobites, especially the dominant trilobite Cromus beaumonti. This is followed by a 130cm-thick bench which is rich in fossils, especially trilobites. This bench is overlain by brachiopod limestone and above this we can find crinoid limestone, which belongs to the Ananaspis fecunda trilobite horizon in the Kopanina Formation. The upper positions in the Kopanina Formation are built of thinly-layered, dark-grey limestone with bodies of calcareous shales which belong to the Prinopeltis archiaci trilobite horizon. This layer is overlain by a 100cm thick bench of grey-black, fine-grained laminated limestone. This bench forms the highest position of the Kopanina Formation (Ludlow Level) and above this is the base of the Požáry Formation (Přídolí Level). The base of the Přídolí Level is defined by the first occurrence of the graptolite Monograptus parultimu. The majority of the Požáry Formation is characterized by its fine-grained limestones with subsidiary bodies of calcareous shales. However, several thick beds of grainy limestones with abundant cephalopods also occur here. The Požáry Formation and the entire Silurian formation end with the last occurrence of the trilobite Tetinia minuta. Above this we can find rose-coloured, grainy crinoid Devonian limestone. The highest sequence of strata is not of stratigraphic significance as they are disturbed by tectonic movements, unlike the older contiguous strata.