Mystery of new California crop circle
California residents have been left puzzled by a mysterious crop circle which appeared at a farm over the weekend.
The pattern, in Salinas Valley, near Monterey, was reported by two friends in a YouTube post.
They claimed to have seen two bursts of light before dawn on Sunday.
No-one has claimed responsibility.
Update 7 January 2014: The technology firm Nvidia later said it had created the crop circle as a stunt.