Groundwater naturally contains carbon dioxide (CO2), which allows it to dissolve limestone and form caverns. Here's how it works:

1. CO2 absorption: As rainwater falls through the atmosphere, it absorbs carbon dioxide.

2. Formation of carbonic acid: The dissolved CO2 in water reacts with water molecules to form carbonic acid (H2CO3).

3. Acidic water: Carbonic acid is a weak acid.

4. Limestone dissolution: When this acidic water comes into contact with limestone (calcium carbonate, CaCO3), the acid reacts with the calcium carbonate, dissolving it. The reaction produces calcium bicarbonate (Ca(HCO3)2), which is soluble in water.

The reaction:

```

CaCO3 (limestone) + H2CO3 (carbonic acid) -> Ca(HCO3)2 (calcium bicarbonate)

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Result: The limestone is gradually dissolved, creating cavities and eventually, caves and caverns.

Factors that influence dissolution:

* Amount of CO2: The more CO2 in the water, the more acidic it becomes, and the faster the limestone dissolves.

* Flow rate: Faster-moving water can dissolve more limestone.

* Temperature: Colder water can hold more CO2, making it more acidic.

* Presence of other minerals: The presence of other minerals in the water can affect the rate of dissolution.

This process of limestone dissolution by acidic groundwater is known as karst formation, which is responsible for the creation of many spectacular cave systems around the world.