Eye opener

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In­cred­i­ble im­ages from around the world.

This is Lake Cas­trovalva, lo­cated in­side the Lechuguilla Cave in New Mex­ico. When Lechuguilla was fully opened up for ex­plo­ration in 1986, a rare va­ri­ety of speleothems – min­eral for­ma­tions – was dis­cov­ered, in­clud­ing the rim­stone dams pic­tured. “They are formed at the air/ wa­ter in­ter­face,” says mi­cro­bi­ol­o­gist Dr Hazel Bar­ton, who stud­ied these caves. “When wa­ter splooshes over the edge, it changes the par­tial pres­sure of the dis­solved CO2 in the wa­ter, caus­ing it to off-gas. This causes the pH to change, which makes the cal­cium car­bon­ate pre­cip­i­tate out so it adds it­self to the edges. Based on where they are and how thick they are, I ex­pect they took at least 500,000 years to form. Lake Cas­trovalva is a pretty spe­cial place. I’ve maybe only seen one or two other places where they form to this ex­tent.”

The caves are home to sev­eral species of pre­vi­ously un­known micro­organ­ism, in­clud­ing some that may have medic­i­nal prop­er­ties – and one that, de­spite be­ing four mil­lion years old, is re­sis­tant to mod­ern an­tibi­otics.

PHOTO: ROBBIE SHONE/NA­TIONAL GEO­GRAPHIC IM­AGES

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