The Yorkshire Dales was designated a National Park back in the 1950s, largely due to its fascinating geological history. The Dales as they are today were primarily formed by glaciation and the natural weathering of the carboniferous limestone that characterises much of the area.
The limestone itself is a sedimentary rock and it was formed during the Carboniferous Period around 340 million years ago. The Yorkshire Dales at that time were to be found somewhere near the Equator under a warm, tropical ocean or giant river delta. The waters were full of creatures and corals and as they died their calcium-rich shells and skeletons settled on the ocean floor. This then built up and compacted over millions of years, eventually creating limestone from the sediments and the vast pressure of the ocean water. The shells, skeletons and the mineral calcite gives the rock its white or light grey colour, but this can vary depending on the other sediments that were mixed in with it such as sand.
Carboniferous limestone is a soft rock and if you scratch it with a sharp object it will mark quite easily and produce powdered rock. It’s also soluble to rainwater over a very long period of time and eventually, the many joints and fissures in the rock get eroded away. This erosion along with abrasion from sand and pebbles and spray from waterfalls produces many spectacular “karstic” limestone surface features such as pavements and underground features such as vast cave networks.