How do solution caves form in limestone bedrock?

Solution caves form primarily through the chemical dissolution of limestone or dolomite bedrock by groundwater. This process typically involves the following stages:12

The Chemical Agent

Rainwater absorbs carbon dioxide from the atmosphere and soil, forming a weak carbonic acid ($H_{2}C{O}_3$). As this acidic water percolates through fractures, joints, and bedding planes in the bedrock, it reacts with the calcium carbonate in the limestone, gradually dissolving the rock.134

Initiation and Evolution

• Initiation Phase: Because limestone is largely impermeable, water moves slowly through existing fractures. This phase is slow, often taking 3,000 to 10,000 years to enlarge a fracture to a width of 5 to 10 millimetres.4
• Conduit Development: Once a continuous pathway reaches this threshold, flow velocity increases, and the water becomes turbulent. This transition shifts the process from slow percolation to a pipe-like flow system, which significantly accelerates the rate of dissolution and allows for the transport of sediment.4
• System Integration: Over time, these conduits form an integrated underground drainage system, creating the large passages characteristic of solution caves.42