Lom Mušlovka, Limestone quarry in Reporyje, Czech Republic

Lom Mušlovka is a limestone quarry in the Dalejské Valley in Reporyje, Prague, abandoned after 1918. Its walls expose a continuous sequence of Upper Silurian limestone layers, numbered 0 to 39, belonging to the Kopanina Formation, with the youngest beds at the top of the southeastern wall assigned to the lower Přídolí Formation. The quarry is part of the Dalejský profil national natural monument, declared in 1982.

The quarry was abandoned after 1918, when limestone extraction ceased. In 1984 the International Geological Congress in Moscow designated the nearby Požáry quarries as the international stratotype for the Ludlow–Přídolí boundary (419 million years ago). The Mušlovka section exposes the same boundary and serves as a reference profile for the Požáry standard. In 1982 the site became part of the Dalejský profil national natural monument.

The quarry is now a place where geologists and students study the ancient seafloor that once covered this region. Visitors can observe how the walls reveal different periods of Earth's history and understand why this site matters for scientific research.

The quarry sits about 1.5 kilometers from Reporyje and can be reached by public transportation from Prague. Visitors should wear sturdy shoes and watch for uneven ground, since the walls are steep and the terrain is rough in places.

The quarry walls expose a fold from the Variscan orogeny that began about 370 million years ago, when pressure on the microcontinent Perunika tilted the originally horizontal limestone beds. The section also serves as a reference profile for the Požáry standard of the Ludlow–Přídolí boundary.