How does acidic groundwater contribute to cavern formation?

Acidic groundwater contributes to cavern formation primarily through the process of chemical weathering, where the acidic solution effectively dissolves soluble materials like limestone or gypsum present in the rock. When rainwater absorbs carbon dioxide from the atmosphere or soil, it can form a weak carbonic acid. This acidic water seeps into the ground and enters cracks and fissures in the rock.

As the acidic groundwater moves through these weaknesses in the rock, it reacts chemically with the calcium carbonate in limestone, dissolving it over time. This process gradually enlarges the openings, leading to the creation of underground cavities or caverns. The continual flow of acidic water enhances this dissolution process, eventually resulting in significant underground formations. This mechanism is fundamental in karst topography, where cavern systems and sinkholes are prevalent.

Other options do not accurately describe the role of acidic groundwater in cavern formation. For example, freezing and expanding water can cause physical fracturing but does not contribute to the chemical dissolution necessary for cavern development. Similarly, preventing water from entering rocks would inhibit dissolution and cavern formation, while making rocks more solid is contrary to the transformative effects of acidic groundwater.