How are caves formed?

• A. Caves are formed through dissolution of soluble rocks, such as limestone, by acidic water.
• B. Caves are created by volcanic activity during eruptions.
• C. Caves are formed when rocks melt and flow.
• D. Caves develop from the deposition of minerals in voids.

Answer: (A)

Caves form mainly through dissolution of soluble rocks by acidic water. When rainwater seeps underground, it picks up carbon dioxide from the air and soil, creating a weak carbonic acid. This acid dissolves limestone (calcium carbonate) and similar rocks, slowly widening the natural cracks and joints. Over long times, these voids grow into larger tunnels and rooms, producing a cave system. Water that drips through the cave deposits minerals as calcite, forming stalactites and stalagmites. Lava tubes from volcanic activity can also create empty passages, but the most common caves develop from chemical dissolution rather than rock melting. Mineral deposition happens after the cave exists, shaping features rather than creating the hollow itself.