Caves of the Mendip Hills Caves of the Mendip Hills The caves of the Mendip Hills are formed by the particular geology of the Mendip Hills: large areas of limestone worn away by water makes it a national centre for caving. The hills conceal the largest underground river system in Britain. The hills consist of anticlines of Carboniferous Limestone lying over Devonian Old Red Sandstone, with the sandstone exposed on the summits. When a surface stream running off the sandstone reaches the limestone it sinks below ground through a "swallet", (also known locally as a "slocker"), continuing on its way down towards sea level by
Caves of Meghalaya partially explored, for a total length of caves explored. With an explored length of , Krem Liat Prah in Jaintia Hills is the longest cave in Meghalaya, as well as India, and is listed among the longest caves in the world. Krem Liat Prah contains a huge passage called the "Aircraft Hangar." Since the MAA was established in 1994, the explored caves account for only about 5% of the total underground passages in the state of Meghalaya. Limestone mining for the cement industry is a major threat to the Caves of Meghalaya, causing a major collapse of the Krem Mawmluh