GEOLOGY

Detailed explanation-1: -Limestone (calcium carbonate) dissolves relatively easily in slightly acidic water, which occurs widely in nature. Rainwater percolates along both horizontal and vertical cracks, dissolving the limestone and carrying it away in solution.

Detailed explanation-2: -Another characteristic of limestone is that it can be slowly dissolved by water. When groundwater or rainwater absorbs carbon dioxide, it becomes a weak acidic solution which is especially effective at dissolving limestone.

Detailed explanation-3: -A sinkhole is a hole in the ground that forms when water dissolves surface rock. Often, this surface rock is limestone, which is easily eroded, or worn away, by the movement of water.

Detailed explanation-4: -limestone (n.) late 14c., from lime (n. 1) + stone (n.). So called because it yields lime when burnt. Another name for it, mostly in American English, is limerock.

Detailed explanation-5: -Swallow hole The water passes over the limestone and erodes vertical joints to form swallow holes. Over time the swallow hole increases in size as the result of erosion (often by solution when slightly acidic water chemically weathers the limestone). Swallow holes also appear when caverns under the ground collapse.