The number of reports of crop circles has substantially increased since the 1970s. There has been scant scientific study of them. Circles in the United Kingdom are not distributed randomly across the landscape but appear near roads, areas of medium to dense population, and cultural heritage monuments, such as Stonehenge or Avebury. In 1991, two hoaxers, Doug Bower and Dave Chorley, took credit for having created many circles throughout England after one of their circles was described by an investigator as impossible for human beings to make.

Formations are usually created overnight, although some are reported to have appeared during the day In contrast to crop circles or crop formations, archaeological remains can cause cropmarks in the fields in the shapes of circles and squares, but they do not appear overnight, and they are always in the same places every year. Nearly half of all crop circles found in the UK in 2003 were located within a 15 kilometres (9.3 mi) radius of the Avebury stone circles.