How do travertine terraces form?
Travertine is rock formed as calcium-carbonate-rich water deposits minerals at the surface. Repeated flow over steps and pools can build a terraced appearance.
From dissolved calcium to solid rock
After groundwater takes up calcium and bicarbonate, conditions of pressure, temperature and gas exchange change at the surface. Loss of carbon dioxide promotes calcium carbonate precipitation. Small growing rims can hold water in terrace pools. Microorganisms may influence some deposits' textures. Travertine does not always come from springs of the same temperature.
Protecting a delicate balance
Changed spring flow or chemistry may slow active deposition. Walking on surfaces, diverting water or contamination can damage fragile structures. Mineral composition and texture must be checked before classifying every pale rock as travertine. Travertine records renewed mineral precipitation, unlike dissolution opening a cave; both processes may occur in one water system.