The formation of limestone caves is most commonly attributed to a process called chemical weathering, specifically karstification. This process occurs when slightly acidic water, often from rain that has absorbed carbon dioxide from the atmosphere and the ground, percolates through soil and rock.
As this acidic water seeps into the ground and comes into contact with soluble limestone (composed primarily of calcium carbonate), it reacts with the limestone, gradually dissolving it and creating underground voids. Over time, these voids can expand into caves.
Other contributing factors in cave formation can include the flow of groundwater, the presence of fractures and faults in the rock, and the continuous erosion and dissolution of limestone.