Deep in Prague’s Dalejský údolí valley lies the Černý lom. This isn’t just any quarry. It’s a window into deep time a place where history and geology intertwine.
Originally known as Kamčatka this quarry was once a bustling hub of activity. Workers toiled extracting the light-colored high-percentage limestone perfect for making lime. This limestone formed millions of years ago in a warm shallow sea when the ancient microcontinent Perunika drifted near the equator. The quarry operated until around 1919. Its impressive size 275 meters long and 30 meters high was testament to its productivity.
Then came a change. The need for limestone ended. The quarry’s floor was filled with waste from other quarries. But this wasn’t the end of the Černý lom’s story.
In 1923 collector František Hanuš renamed it Černý lom or Black Quarry after the dark Silurian limestone. This dark rock holds a secret. It marks a globally significant boundary. The International Geological Congress in Montreal in 1972 designated a spot near Beroun as the international standard for the Silurian-Devonian boundary. A similar boundary exists right here in the Černý lom. It shows the transition between these two ancient geological periods about 418 million years ago.
The Černý lom is also famed for its fossils. Specifically remains of ancient sea lilies or Crinoidea. These creatures had long stems and crowns. Some were rooted to the seafloor others floated using unique structures called lobolites. These lobolites are incredibly rare fossils found only in a few places worldwide including here in the Czech Republic and Morocco. In fact the western part of the quarry known as the Lobolitová stráň is specifically known for its lobolite finds. These small spherical structures are the fossilized floats of the sea lilies. You can find small round stem sections of these creatures. Sometimes even complete five-armed star-like crowns are visible. Look carefully at the dark limestone. You might even find shiny fragments of brachiopods ancient shelled creatures. You might spot the trilobite Tetinia minuta that marks the upper limit of the Silurian or Warburgella rugulosa which denotes the lower Devonian.
The Černý lom is more than a quarry. It’s a geological monument. It’s a testament to the deep history of our planet. It’s a place where you can touch the past. Walk along the edge and let the vastness of this former quarry inspire you. Remember you’re standing on an ancient seabed. A place once teeming with life. This is the Černý lom a story etched in stone.