Baku, July 1, AZERTAC These beautiful travertine terraces in northern Iran are an incredible natural phenomenon that developed over thousands of years. Travertine is a type of limestone formed from the calcium deposit in flowing water, and in this case it's two hot springs with different mineral properties. The unusual reddish colour of the terraces is caused by the high content of iron oxide in one of the springs. Badab-e Surt has been inscribed as the second saltwater spring in the world after Pamukkale spring in Turkey. It includes a variety of springs with very different flavors, smells, and water volumes.Badab is a Persian compound of Bad which means gas and ab which means water, translating to ‘gassed water’, referring to the springs’ waters being carbonated mineral waters. Surt is an old name for the Orost village located near the site and a Persian word meaning intensity.