A soft hollow rock built of calcite that settles around algae, moss and "travertine" bacteria, usualy found in cold, fast waters.
It is formed faster in warmer weather, slower in cold weather. It is gentle and can be easily destroyed if water runs out or the water is polluted. It's very important for the flora and fauna of the water. Tufa is responsible for the beautiful waterfalls, cascades and caves on the river Una. Tufa can be found in Jajce "Plivsko" Lake and National Park "Una" in Bosnia and Herzegovina, "Plitvice Lakes" National Park in Croatia, Pyramid Lake in Nevada, Mono Lake in California. Pamukkale in Turkey is a great tourist attraction where barriers have been created by tufa and formed lakes.