Pamukkale's terraces are made of travertine, a sedimentary rock deposited by water from the hot springs.
In this area, there are 17 hot water springs in which the temperature ranges from 35 °C (95 °F) to 100 °C (212 °F).[citation needed] The water that emerges from the spring is transported 320 metres (1,050 ft)[citation needed] to the head of the travertine terraces and deposits calcium carbonate on a section 60 to 70 metres (200 to 230 ft) long covering an expanse of 24 metres (79 ft) to 30 metres (98 ft). When the water, supersaturated with calcium carbonate, reaches the surface, carbon dioxide de-gasses from it, and calcium carbonate is deposited. The depositing continues until the carbon dioxide in the water balances the carbon dioxide in the air.[citation needed] Calcium carbonate is deposited by the water as a soft jelly,[citation needed] but this eventually hardens into travertine.