The giant pattern - thought to represent a traditional Mayan head-dress - appeared next to the tallest prehistoric man-made mound in Europe last week.

Members of the crop circle community believe the mystic symbol is a signal of the end of the 5,126-year Mayan 'Long Count' calendar on December 21, 2012.

Karen Alexander, a crop circle enthusiast, said: "This is one of the most interesting crop circles I have ever seen. It is definitely a Mayan symbol and we are sure it is linked to the Mayan calendar, which ends in 2012.

"It appears to be a warning about the world coming to an end when the calendar does. For the ancient Maya, reaching the end of a cycle was a momentous event, so we are taking this crop circle very seriously as an indicator of a possibly huge event in 2012."

Last month a 400-foot crop circle depicting a phoenix rising from the flames appeared in a barley field in Yatesbury near Devizes, Wiltshire.

Crop circle theorists believe the patterns are created by UFOs during nocturnal visits, or caused by natural phenomena such as unusual forms of lightning striking the earth.

[link to www.telegraph.co.uk]