The limestone pavement above Malham Cove has been deeply eroded by acid rain, leaving clints (lumps of limestone) and grykes (the gaps in between). Grykes provide habitat for many rare and unusual plants, such as hart's tongue ferns and enchanter's nightshade. Malham Cove is a 250 foot high ancient outcrop of curved limestone cliffs in Yorkshire Dales, UK was once the location of a spectacular waterfall, though today there is only a small stream flowing from the base. The area is rich in wildlife and managed as a National Nature Reserve.