Cleopatra's Antique Pool
A thermal pool where you swim among ancient marble columns toppled into the water by an earthquake; the water stays warm year-round.
How Do the Travertines Form?
Pamukkale's white terraces are not a rock formation but the residue of a chemical process still underway — water rising from underground deposits the lime it carries here.
The Part Underground
The story does not begin at the surface but hundreds of metres below it. Rainwater seeps into the limestone layers and warms up at depth. Under pressure, this water holds a high amount of dissolved carbon dioxide, and water rich in carbon dioxide dissolves limestone.
The water making its way upward thus reaches the surface loaded with as much calcium carbonate as it can carry. Nearly seventeen main springs do this at Pamukkale, and the temperature at which they reach the surface ranges between 35 and 56 degrees.
What Happens When the Pressure Drops
The moment the water reaches the surface, the pressure on it is released. The carbon dioxide inside it escapes into the air as gas — the same process as the bubbles in an opened bottle of sparkling water, only much slower.
Once the carbon dioxide is gone, the water's capacity to hold dissolved lime drops. It is forced to release what it can no longer carry, and the calcium carbonate begins to precipitate in the form of calcite crystals. What is deposited is soft at first; over time it hardens into travertine.
This is why the travertine surface is shaped not by the fracturing of rock but by the path the water takes as it flows. Wherever the water flows, it deposits lime there; if the flow path changes, a new terrace begins forming there while the old terrace dries out and discolours.
The Terraces Forming Steps
Precipitation speeds up where the flow slows down. Water pooling behind a small obstacle stays longer, deposits more lime, and raises the obstacle; the raised obstacle then holds even more water. This self-reinforcing cycle divides the slope into stacked pools instead of a single flat sheet.
The jagged, lace-like ridges at the pool edges have the same cause: the water overflows there the most, and deposits the most lime there. Looked at closely, the surface is not smooth — it is made up of tiny steps.
The Reason for the Whiteness, and Its Limit
Pure calcium carbonate is white; that is why the colour of the terraces is an unpainted white. But the whiteness is preserved only while the surface stays wet and precipitation continues. Sections where the water has withdrawn gradually turn grey with dust, algae and footprints.
This is why the water flow across the site is now channelled and controlled, and why walking barefoot is required: a terrace is not a monument but a surface under ongoing maintenance. The red deposits at Karahayıt are the same process — there, the iron content of the water changes the colour.