A crop circle is a sizable pattern created by the flattening of a crop such as wheat, barley, rye, maize, or rapeseed. Crop circles are also referred to as crop formations, because they are not always circular in shape. The first crop circles reports started appearing in the 1970s in South England, and spread to other countries after the 1991 confession of two hoaxers who claimed authorship. The documented cases have substantially increased from the 1970s to current times. Twenty-six countries reported approximately ten thousand crop circles in the last third of the 20th century. Ninety percent of those were located in southern England.