Travertines around the world: Pamukkale at sunset

Photo: muratart/Shutterstock

Travertine terraces are some of the most bizarre-looking geological formations on Earth. The rock that makes up these unique formations is a type of limestone commonly deposited by mineral springs through a process of rapid precipitation of carbonate minerals.

Travertine has been used as a building material since the time of the ancient Romans, and it was even used in the construction of St. Peter's Basilica and Square in Vatican City. However, the most stunning structures this rock has been known to produce are the travertine terraces!

The most iconic example of the travertine terrace phenomenon is found in Pamukkale (above) in Denizli Province of southwestern Turkey. Pamukkale, which means "cotton castle" in Turkish, is located near the ruins of the ancient city of Hierapolis, and it has been a popular bathing spot for thousands of years. Pamukkale and Hierapolis were jointly named a World Heritage Site in 1988, and the area remains one of the country's most beloved tourist destinations to this day.

Pamukkale shouldn't hog all the glory, however. From China to Guatemala to Iran, the Earth has quite a collection of natural travertine treasures. Continue below for more instances of this geological wonder!

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Travertines around the world: Huanglong, Sichuan, China

Photo: Manamana/Shutterstock

Huanglong, Sichuan, China

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Travertines around the world: Aerial of Semuc Champey

Photo: sfeichtner/Shutterstock

Semuc Champey, Guatemala

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Travertines around the world: Detail of Pamukkale

Photo: Sergei Starus/Shutterstock

Detail of Pamukkale, Turkey

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Travertines around the world: Mammoth Hot Springs

Photo: Philip Bird/Shutterstock

Mammoth Hot Springs, Yellowstone National Park, Wyoming

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Travertines around the world: Badab-e Surt

Photo: Lomita/Wikimedia Commons

Badab-e Surt, Mazandaran, Iran

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Travertines around the world: Aerial of Huanglong

Photo: chensiyuan/Wikimedia Commons

Aerial view of Huanglong, Sichuan, China

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Travertines around the world: Bagni San Filippo

Photo: Udo Schröter/Flickr

Bagni San Filippo, Tuscany, Italy

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Travertines around the world: Mammoth hot springs detail

Photo: Don Graham/Flickr

Detail of Mammoth Hot Springs, Yellowstone National Park, Wyoming

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Travertines around the world: Eger, Hungary

Photo: Pecold/Shutterstock

Eger, Hungary

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Travertines around the world: Plitvice National Park in Croatia

Photo: Fesus Robert/Shutterstock

Plitvice National Park, Croatia

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Travertines around the world: Sunbather at Pamukkale

Photo: rickroma78/Flickr

Sunbathers at Pamukkale, Turkey

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Catie Leary is a photo editor at Mother Nature Network. Follow her on Twitter and Google+.