In the central part of the Dinaric mountain range, occupying an area of nearly 30,000 ha, is the oldest national park the Croatia – National Park Plitvice Lakes. Water from the Crna rijeka river, Bijela Rijeka river and Rječica river with their tributaries irrigates the series of 16 lakes separated by natural barriers that form cascades or waterfalls. This series of lakes stretches along 7.2 km with an altitude difference of 153 meters from the highest Proščansko lake to the river Korana.
Travertine barriers arise when in the area of the streams where the water is sprinkled, this sprinkling enhances precipitation of calcium carbonate crystals from the water supersaturated with calcium carbonate. This process is shown by the chemical formula:
Ca (HCO3)2 + sprinkling → CO2 + H2O + CaCO3 ↓ (travertine)
The moss that grows on the travertine barriers helps the formation of new layers of travertine that leads to an increase in the height of the barrier, which ultimately leads to the formation of waterfalls. This process is extremely long and it is estimated that the current travertine barriers are between 6,000 and 7,000 years old.
More about Plitvice Lakes National Park can be found on their website: