Luobi Cave Luobi Cave Luobi Cave () is a karst cave under the west face of Yin Ridge (印岭) located north east of Lizhigou Town (荔枝沟镇), from Sanya City, Hainan Province, People's Republic of China. The entrance to the cave is approximately high and wide. Inside the apex reaches a height of with a floor area of about Two large stalactites hang down from the roof like large pens, hence the cave's name. A number of inscriptions carved into the walls of the cave are believed to date to the Yuan Dynasty (1271–1368). One of these refers to the precise date of
Calcium cycle layers of shell which over time cement to form limestone. This is the origin of both marine and terrestrial limestone, formed over long periods of time . The concentration of marine calcium depends on the depth of the ocean, as its solubility is altered with pressure. In deep ocean, roughly 1% more calcium is present when compared to surface concentrations. This is due to the solubility of calcium at higher pressure, thus associating higher concentration with increasing depth. The higher pressure stops calcium carbonate precipitation, whilst simultaneously enabling the dissolution of calcium carbonate sediment such as shells. As a result,