Limestone pavement and tree. Limestone is a sedimentary rock formed from calcium minerals such as calcium carbonate. This landscape shows the clints and grykes that are a characteristic feature of limestone scenery. The grykes are the deep fissures, caused by the erosion of joints in the limestone, which criss-cross the pavement. The clints are the separated blocks of rock that remain. Grykes are often inhabited by shade-loving plants. Photographed in September, near Malham in the Yorkshire Dales National Park, UK.