TEXT: Slide 60 of 73: DENIZLI, TURKEY - JANUARY 6: A drone photo shows ancient city of Hierapolis and hot spring travertine pools and terraces at the UNESCO World Heritage Site of Pamukkale in Denizli, Turkey on January 6, 2017. Warm water at a temperature of 33-36 containing calcium hydro carbonate springing from 320 meters depth appears on the surface and water falls into terraces and forms the travertines.