Huge crack in the earth appears in Wyoming (video)

A crack that's six times as long as a football pitch has mysteriously appeared in the Bighorn Mountains in Wyoming, USA.

A guide first stumbled upon the crack while hunting in the mountain area in early October.

Just a few weeks later, the crack has grown to about 50 yards wide.

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No one saw the crack emerge, but experts have some ideas about what might have happened.

The Wyoming Geological Survey has said the crack appears to be from groundwater creating weaknesses in the unstable hillside.

On its Facebook page the organisation said: "The WSGS is aware of the apparent active landslide in the southern end of the Big Horn Mountains, Wyo. "The Crack," as it has been called, looks to be a relatively large yet slow-moving event.

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"Based on anecdotal evidence from postings on Facebook and other social media sites, it appears that this event may be due to groundwater creating weakness in an unstable hillside. WSGS geologists have not visited the site so we do not have any first-hand information about this event."

SNS Outfitter and Guides, who first found the crack, had an engineer take a look at the unusual landform.

They reported back on their Facebook page, saying: "Apparently a wet spring lubricated across a cap rock. Then, a small spring on either side caused the bottom to slide. He estimated 15 to 20 million yards of movement."

Thanks to the crevice's remote location, experts say there is no immediate danger to members of the public.