The process of forming caves in soluble rock is very slow. It all begins with rain. As rain falls through the atmosphere, it absorbs a small amount of carbon dioxide. It gathers additional carbon dioxide as it moves through the soil.
Water mixed with carbon dioxide is weak carbonic acid solution.
As this solution of water and carbon dioxide seeps through the cracks and crevices, it dissolves the soluble rock and forms cavities and channels as it moves downward and laterally. After thousands of years of solution, underground rooms and chambers can be formed. Not all cave passages in soluble rocks form in precisely the same way. Water enters the cave system through sinkholes, losing streams, and other points on the surface. It travels underground and exits at a spring.