Cave formation starts with a simple chemical reaction between water and carbon dioxide in the atmosphere, creating carbonic acid. This weak acid forms when rainwater combines with CO2, then ...

Caves don’t appear suddenly, and they aren’t carved by violence. They form quietly, over immense stretches of time. This video explains how water, rock, and patience shape massive underground systems.

Mammoth Cave, the world's longest known cave system, stretches 426 miles under Kentucky. The cave's limestone began forming 330 million years ago when the region was submerged under an ocean. Visitors ...