Caption text Formation of caves Credit NERC Key stages Key Stage 2 Key Stage 3 Key Stage 4 Key Stage 5 Higher Education Lifelong learning Themes Geology Curriculum subject Geography Science Find out how caves are formed by the particular geology of the Mendip Hills. Keywords swallet cave limestone percolate impermeable permeable erode erosion slocker sink hole phreatic stalactite stalagmite Foundations of Mendip (British Geological Survey) – How Caves Form