Travertines in Pamukkale

When we were in Pamukkale we saw a huge hillside spotted with pools of water, with water running down the whole thing. The most remarkable thing was that the whole hillside was made out of a brilliantly white kind of limestone called travertine. Travertine is formed by calcium carbonate deposition from mineral springs. The process begins when hot mineral springs with high levels of both calcium carbonate and carbon dioxide come out of the ground and come into contact with the air. Because of the bubbliness of the water, and the lower concentration of CO₂ in the atmosphere, the water degasses the carbon dioxide. The degassing of the carbon dioxide lowers the pH of the water. The lower pH causes the calcium carbonate to dissolve less well and therefore precipitate as solid calcium carbonate.

It was really fun because you had to walk barefoot up the hill and the water ran evenly down the entire slope. The texture of the travertine was really nice and it was amazingly grippy, even though it was wet. The water was warm and it felt delicious.