Luray Caverns

Figure 7.1 Cave formations are caused when rainwater and carbon dioxide mix and form a weak carbonic acid, which then dissolves the calcium carbonate of limestone beneath the earth, allowing for cave formation. The photo shows stalactites and stalagmites and other formations at Luray Caverns in Virginia.

The reaction of limestone (CaC03) with water containing carbon dioxide in relatively high concentration can form natural caves, such as Luray Caverns in Virginia (Figure 8.9). If the carbon dioxide concentration is lowered, the reverse reaction can occur ... 

Investigations of the state of carbonate equilibrium of water which is transiting the vadose zone have not been numerous. The equilibrium COj (carbon dioxide partial pressure) and state of saturation with respect to calcite was studied by Holland et al. (1964) in Indian Echo Cave, Pennsylvania, and Luray Caverns, Virginia, and by Thrailkill (1971) in Carlsbad Caverns, New Mexico. These investigations showed that seepage water entering the cave was in equilibrium with a f cO2 much higher than that of the normal atmosphere and was often supersaturated with respect to calcite. 

Luray Caverns, Virginia. Stalactites form like icicles when dissolved calcium carbonate is deposited by groundwater dripping from fhe ceiling of fhe limestone cave. 

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