A crop circle or crop formation is a pattern created by flattening a crop, usually a cereal. A commentary in The Guardian noted that "[i]t is still open to dispute whether some are caused by natural phenomena or all created by human hand," but crop circles, as Taner Edis, professor of physics at Truman State University puts it, "all fall within the range of the sort of thing done in hoaxes." Although obscure natural causes or alien origins of crop circles are suggested by fringe theorists, there is no scientific evidence for such explanations, and human causes are consistent for all crop circles.
The number of crop circles has substantially increased from the 1970s to current times. There has been almost no serious scientific study of them. Circles in the United Kingdom are not spread randomly across the landscape but appear near roads, areas of medium to dense population, and cultural heritage monuments, such as Stonehenge or Avebury, and always in areas of easy access. In 1991, two hoaxers, Bower and Chorley, made disputed claims to have created many circles throughout England after one of their circles was publicly certified by a notable circle investigator, as impossible to be made by human hand.
Formations are usually created overnight, although some are reported to have appeared during the day. In contrast to crop circles or crop formations, archeological 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.
- 1 History
- 2 How they are made
- 3 Alternate explanations
- 4 Folklore
- 5 See also
- 6 Notes
- 7 References
- 8 Further reading
- 9 External links
The concept of "crop circles" began with the original late-1970s hoaxes by Doug Bower and Dave Chorley (see Bower and Chorley, below). They said that they were inspired by the Tully "saucer nest" case in Australia, where a farmer found a flattened circle of swamp reeds after observing a UFO.
Early reports of circular formations
A 1678 news pamphlet The Mowing-Devil: or, Strange News Out of Hartfordshire is claimed by some cereologists to be the first depiction of a crop circle. Crop circle researcher Jim Schnabel does not consider it to be a historical precedent because it describes the stalks as being cut rather than bent. (see folklore section)
In 1686, British naturalist Robert Plot reported on rings or arcs of mushrooms (see fairy rings) in The Natural History of Stafford-Shire and proposed air flows from the sky as a cause. In 1991 meteorologist Terence Meaden linked this report with modern crop circles, a claim that has been compared with those made by Erich von Däniken.[n 1]
In 1932, archaeologist E C Curwen, observed four dark rings in a field at Stoughton Down near Chichester, he could examine only one: "a circle in which the barley was 'lodged' or beaten down, while the interior are was very slightly mounded up."
In 1963 amateur astronomer Sir Patrick Moore described a crater in a potato field in Wiltshire, probably caused by an unknown meteoric body. In nearby wheat fields, there were several circular and elliptical areas where the wheat had been flattened. There was evidence of "spiral flattening". He thought they could be caused by air currents from the impact, since they led towards the crater. Astronomer Hugh Ernest Butler observed similar craters and said they were likely caused by lighting strikes.
In the 1960s, in Tully, Queensland, Australia, and in Canada, there were many reports of UFO sightings and circular formations in swamp reeds and sugar cane fields. For example, on 8 August 1967, three circles were found in a field in Duhamel, Alberta, Canada, and the Department of National Defence sent two investigators, who concluded that it was artificially made but couldn't make definite conclusions on who made them or how. The most famous case is the 1966 Tully "saucer nest", when a farmer said he witnessed a saucer-shaped craft rise 30 or 40 feet (12 m) up from a swamp and then fly away. When he went to investigate the location where he thought the saucer had landed, he found a nearly circular area 32 feet long by 25 feet wide where the grass was flattened in clockwise curves to water level within the circle, and the reeds had been uprooted from the mud. The local police officer, the Royal Australian Air Force, and the University of Queensland concluded that it was most probably caused by natural causes, like a down draught, a willy-willy (dust devil), or a waterspout. In 1973, G.J. Odgers, Director of Public Relations, Department of Defence (Air Office), wrote to a journalist that the "saucer" was probably debris lifted by the causing willy-willy. Hoaxers Bower and Chorley said they were inspired by this case to start making the modern crop circles that appear today.
Since the 1960s, there had been a surge of UFOlogists in Wiltshire, and there were rumours of "saucer nests" appearing in the area, but they were never photographed. There are other pre-1970s reports of circular formations, especially in Australia and Canada, but they were always simple circles, which could have been caused by whirlwinds. In Fortean Times David Wood reported that in 1940 he had already made crop circles near Gloucestershire using ropes. In 1997, the Oxford English Dictionary recorded the earliest usage of the term "crop circles" in a 1988 issue of Journal of Meteorology, referring to a BBC film. The coining of the term "crop circle" is attributed to Colin Andrews in the late 1970s or early 1980s.
The majority of reports of crop circles have appeared in and spread since the late 1970s as many circles began appearing throughout the English countryside. This phenomenon became widely known in the late 1980s, after the media started to report crop circles in Hampshire and Wiltshire. After Bower's and Chorley's 1991 statement that they were responsible for many of them, circles started appearing all over the world. To date, approximately 10,000 crop circles have been reported internationally, from locations such as the former Soviet Union, the UK, Japan, the U.S., and Canada. Sceptics note a correlation between crop circles, recent media coverage, and the absence of fencing and/or anti-trespassing legislation.
Although farmers have expressed concern at the damage caused to their crops, local response to the appearance of crop circles can be enthusiastic, with locals taking advantage of the increase of tourism and visits from scientists, crop circle researchers, and individuals seeking spiritual experiences. The market for crop-circle interest has consequently generated bus or helicopter tours of circle sites, walking tours, T-shirts, and book sales.
Since 2000, crop formations have increased in size and complexity of form, some featuring as many as 2000 different shapes, and some incorporating complex mathematical and scientific characteristics.
A researcher found that crop circles in the UK are not spread randomly across the landscape. They tend to appear near roads, areas of medium to dense population, and cultural heritage monuments, such as Stonehenge or Avebury. They always appear in areas that are easy to access. This suggests strongly that circles are more likely to be caused by intentional human action than by paranormal activity. Another strong indication is that inhabitants of the zone with the most circles have a historical tendency for making big formations, including stone circles such as Stonehenge, burial mounds such as Silbury Hill, long barrows such as West Kennet Long Barrow, and White horses in chalk hills.
A video sequence used in connection with the opening of the Olympic Games in London in 2012 shows two crop circle areas shaped as the Olympic Rings. Another Olympic crop circle area was visible for those landing at Heathrow Airport, London, UK before and during the Olympic Games.
Bower and Chorley
In 1991, self-professed pranksters Doug Bower and Dave Chorley made headlines claiming it was they who started the phenomenon in 1978 with the use of simple tools consisting of a plank of wood, rope, and a baseball cap fitted with a loop of wire to help them walk in a straight line. To prove their case they made a circle in front of journalists; a "cereologist" (advocate of paranormal explanations of crop circles), Pat Delgado, examined the circle and declared it authentic before it was revealed that it was a hoax. Inspired by Australian crop circle accounts from 1966, Bower and Chorley claimed to be responsible for all circles made prior to 1987, and for more than 200 crop circles in 1978–1991 (with 1000 other circles not being made by them). After their announcement, the two men demonstrated making a crop circle. According to Professor Richard Taylor, "the pictographs they created inspired a second wave of crop artists. Far from fizzling out, crop circles have evolved into an international phenomenon, with hundreds of sophisticated pictographs now appearing annually around the globe."
Smithsonian Magazine wrote:
- Since Bower and Chorley’s circles appeared, the geometric designs have escalated in scale and complexity, as each year teams of anonymous circle-makers lay honey traps for New Age tourists 
Art and business
Since the early 1990s, the UK arts collective named Circlemakers founded by artists Rod Dickinson and John Lundberg (and subsequently including artists Wil Russell and Rob Irving) have been creating crop circles in the UK and around the world both as part of their art practice and for commercial clients.
On the night of 11–12 July 1992 a crop-circle making competition, for a prize of £3,000 (partly funded by the Arthur Koestler Foundation), was held in Berkshire. The winning entry was produced by three Westland Helicopters engineers, using rope, PVC pipe, a plank, string, a telescopic device and two stepladders. According to Rupert Sheldrake the competition was organised by him and John Michell and "co-sponsored by The Guardian and The Cerealogist". The prize money came from PM, a German magazine. Sheldrake wrote that "The experiment was conclusive. Humans could indeed make all the features of state-of-the-art crop formations at that time. Eleven of the twelve teams made more or less impressive formations that followed the set design
In 2002, Discovery Channel commissioned five aeronautics and astronautics graduate students from MIT to create crop circles of their own, aiming to duplicate some of the features claimed to distinguish "real" crop circles from the known fakes such as those created by Bower and Chorley. The creation of the circle was recorded and used in the Discovery Channel documentary Crop Circles: Mysteries in the Fields.
In 2009 The Guardian reported that crop circle activity had been waning around Wiltshire, one of the reasons being that makers preferred making promotional circles for companies that pay well for their efforts.
In 1992, Hungarian youths Gábor Takács and Róbert Dallos, both then 17, were the first people to face legal action after creating a crop circle. Takács and Dallos, of the St. Stephen Agricultural Technicum, a high school in Hungary specializing in agriculture, created a 36-metre (118 ft) diameter crop circle in a wheat field near Székesfehérvár, 43 miles (69 km) southwest of Budapest, on June 8, 1992. On September 3, the pair appeared on Hungarian TV and exposed the circle as a hoax, showing photos of the field before and after the circle was made. As a result, Aranykalász Co., the owners of the land, sued the youngsters for 630,000 Ft (~$3,000 USD) in damages. The presiding judge ruled that the students were only responsible for the damage caused in the circle itself, amounting to about 6,000 Ft (~$30 USD), and that 99% of the damage to the crops was caused by the thousands of visitors who flocked to Székesfehérvár following the media's promotion of the circle. The fine was eventually paid by the TV show, as were the students' legal fees.
In 2000, Matthew Williams became the first man in the UK to be arrested for causing criminal damage after making a crop circle near Devizes. In November 2000, he was fined £100 and £40 in costs. As of 2008[update], no one else has been successfully prosecuted in the UK for criminal damage caused by creating crop circles.[n 3]
How they are made
The scientific consensus on crop circles is that they are constructed by human beings as hoaxes. The most widely known method for a person or group to construct a crop formation is to tie one end of a rope to an anchor point and the other end to a board which is used to crush the plants. Sceptics of the paranormal point out that all characteristics of crop circles are fully compatible with them being made by hoaxers.
Bower and Chorley confessed in 1991 to making the first crop circles in South England. When some people refused to believe them, they deliberately added straight lines and squares to show that they could not have natural causes. In a copycat effect, increasingly complex circles started appearing in many countries around the world, including fractal figures. Physicists have suggested that the most complex formations might be made with the help of GPS and lasers. In 2009, a circle formation was made over the course of three consecutive nights and was apparently left unfinished, with some half-made circles.
The main criticism of alleged non-human creation of crop circles is that while evidence of these origins, besides eyewitness testimonies, is essentially absent, some are definitely known to be the work of human pranksters, and others can be adequately explained as such. There have been cases in which researchers declared crop circles to be "the real thing", only to be confronted with the people who created the circle and documented the fraud, like Bower and Chorley and tabloid Today hoaxing Pat Delgado, the Wessex Sceptics and Channel 4's Equinox hoaxing Terence Meaden, or a friend of a Canadian farmer hoaxing a field researcher of the Canadian Crop Circle Research Network. In his 1997 book The Demon-Haunted World: Science as a Candle in the Dark, Carl Sagan concludes that crop circles were created by Bower and Chorley and their copycats, and speculates that UFOlogists willingly ignore the evidence for hoaxing so they can keep believing in an extraterrestrial origin of the circles. Many others have demonstrated how complex crop circles can be created. Scientific American published an article by Matt Ridley, who started making crop circles in northern England in 1991. He wrote about how easy it is to develop techniques using simple tools that can easily fool later observers. He reported on "expert" sources such as The Wall Street Journal, who had been easily fooled and mused about why people want to believe supernatural explanations for phenomena that are not yet explained. Methods of creating a crop circle are now well documented on the Internet.
Hoaxers have been caught in the process of making new circles, for example, in 2004 in the Netherlands. (See more cases in the "legal implications" section)
Advocates of non-human causes discount on-site evidence of human involvement as attempts to discredit the phenomena. Some even argue a conspiracy theory, with governments planting evidence of hoaxing to muddle the origins of the circles. When popular science writer Matt Ridley wrote negative articles in newspapers, he was accused of spreading "government disinformation" and of working for the UK military intelligence service MI5. Ridley responded by noting that many cereologists make good livings from selling books and providing high-priced personal tours through crop fields, and he claimed that they have vested interests in rejecting what is by far the most likely explanation for the circles.
It has been suggested that crop circles may be the result of extraordinary meteorological phenomena ranging from freak tornadoes to ball lightning, but there is no evidence of any crop circle being created by any of these causes.
In 1880, an amateur scientist, John Rand Capron, wrote a letter to the editor of journal Nature about some circles in crops and blamed them on a recent storm, saying their shape was "suggestive of some cyclonic wind action".[n 2]
In 1980, Terence Meaden, a meteorologist and physicist, proposed that the circles were caused by whirlwinds whose course was affected by southern England hills. As circles became more complex, Terence had to create increasingly complex theories, blaming electromagneto-hydrodynamic "plasma vortexes". The meteorological theory became popular, and it was even referenced in 1991 by physicist Stephen Hawking who said that, "Corn circles are either hoaxes or formed by vortex movement of air". The weather theory suffered a serious blow in 1991, but Hawking's point about hoaxes was supported when Bower and Chorley stated that they had been responsible for making all those circles.[n 5] By the end of 1991 Meaden conceded that those circles that had complex designs were made by hoaxers.
Since becoming the focus of widespread media attention in the 1980s, crop circles have become the subject of speculation by various paranormal, ufological, and anomalistic investigators ranging from proposals that they were created by bizarre meteorological phenomena to messages from extraterrestrial beings. Many crop circles have been found near ancient sites such as Stonehenge, a prehistoric monument located in the English county of Wiltshire. They have also been found near mounds of earth and stones raised over a grave or graves, also known as tumuli barrows, or barrows and chalk horses, or trenches dug and filled with rubble made from brighter material than the natural bedrock, often chalk. There has also been speculation that crop circles have a relation to ley lines. Many New Age groups incorporate crop circles into their belief systems.
Some paranormal advocates think that crop circles are caused by ball lighting and that the patterns are so complex that they have to be controlled by some entity. Some proposed entities are: Gaia asking to stop global warming and human pollution, God, supernatural beings (for example Indian devas), the collective minds of humanity through a proposed "quantum field", or extraterrestrial beings.
Responding to local beliefs that "extraterrestrial beings" in UFOs were responsible for crop circles appearing, the Indonesian National Institute of Aeronautics and Space (LAPAN) described crop circles as "man-made". Thomas Djamaluddin, research professor of astronomy and astrophysics at LAPAN stated, "We have come to agree that this 'thing' cannot be scientifically proven." Among others, paranormal enthusiasts, ufologists, and anomalistic investigators have offered hypothetical explanations that have been criticized as pseudoscientific by sceptical groups and scientists, including the Committee for Skeptical Inquiry. No credible evidence of extraterrestrial origin has been presented.
In 2009, the attorney general for the island state of Tasmania stated that Australian wallabies had been found creating crop circles in fields of opium poppies, which are grown legally for medicinal use, after consuming some of the opiate-laden poppies and running in circles.
Changes to crops
A small number of scientists (physicist Eltjo Haselhoff, the late biophysicist William Levengood) have found differences between the crops inside the circles and outside them, even though there is a consensus among scientists that the circles are man-made.
Levengood published papers in journal Physiologia Plantarum in 1994 and 1999. In his 1994 paper he found that certain deformities in the grain inside the circles were correlated to the position of the grain inside the circle. In 1996 sceptic Joe Nickell objected that correlation is not causation, raised several objections to the Levengood's methods and assumptions, and said "Until his work is independently replicated by qualified scientists doing 'double-blind' studies and otherwise following stringent scientific protocols, there seems no need to take seriously the many dubious claims that Levengood makes, including his similar ones involving plants at alleged 'cattle mutilation' sites." (in reference to cattle mutilation).
A study by Eltjo Haselhoff reported that the pulvini of wheat in 95% of the crop circles investigated were elongated in a pattern falling off with distance from the centre and that seeds from the bent-over plants grew much more slowly under controlled conditions. Furthermore, traces of crop circle patterns are sometimes found in the crop the following year, "suggesting long-term damage to the crop field consistent with Levengood's observations of stunted seed growth." These current investigations seem to imply that at least in some crop circles, there is more at work than the effects of mechanical crushing of plants.
In 2000, Colin Andrews, who had researched crop circles for 17 years, stated that while he believed 80% were man-made, he thought the remaining circles, with less elaborate designs, could be explained by a three-degree shift in the Earth's magnetic field, that creates a current that "electrocutes" the crops, causing them to flatten and form the circle.
Researchers of crop circles have linked modern crop circles to old folkloric tales to support the claim that they are not artificially produced. Circle crops are culture-dependent: they appear mostly in developed and secularized Western countries where people are receptive to New Age beliefs, including Japan, but they don't appear at all in other zones, such as Muslim countries.
A 17th-century English woodcut called the Mowing-Devil depicts the devil with a scythe mowing (cutting) a circular design in a field of oats. The pamphlet containing the image states that the farmer, disgusted at the wage his mower was demanding for his work, insisted that he would rather have "the devil himself" perform the task. Crop circle researcher Jim Schnabel does not consider this to be a historical precedent for crop circles because the stalks were cut down, not bent. The circular form indicated to the farmer that it had been caused by the devil.
In the 1948 German story Die zwölf Schwäne (The Twelve Swans), a farmer every morning found a circular ring of flattened grain on his field. After several attempts, his son saw twelve princesses disguised as swans, who took off their disguises and danced in the field. Crop rings produced by fungi may have inspired such tales since folklore holds these rings are created by dancing wolves or fairies.
- Center pivot irrigation
- Gerald Hawkins
- Land art
- List of hoaxes
- List of topics characterized as pseudoscience
- Nazca Lines
- Rice paddy art
- Viking ring fortress
- Keving Greene wrote,
The difficulties that exist in communicating the results of archaeology have undoubtedly contributed to the flourishing of writers, such as Erich von Däniken, who take a particular delight in deriding the inability of 'experts' to find explanations that seize the imagination of the public. (...) Few archaeologists have sold as many paperbacks as von Däniken; more recently, a meteorologist who linked crop circles to prehistoric ring-ditches or round barrows generated a reaction that no orthodox student of these monuments has ever achieved (Meaden 1991) [in reference to T. Meaden (1991). The Goddess of the Stones: The Language of the Megaliths. London: Souvenir Press.]
- John Rand Capron wrote,
The storms about this part of Surrey have been lately local and violent, and the effects produced in some instances curious. Visiting a neighbour's farm on Wednesday evening (21st), we found a field of standing wheat considerably knocked about, not as an entirety, but in patches forming, as viewed from a distance, circular spots (...) they all presented much the same character, viz, a few standing stalks as a centre, some postrate stalks with their heads arranged pretty evenly in a direction forming a circle round the centre, and outside there a circular wall of stalks which had not suffered. (...) I could not trace locally any circumstances accounting for the peculiar forms of the patches in the field, nor indicating whether it was wind or rain, or both combined, which had caused them, beyond the general evidence everywhere of heavy rainfall. They were suggestive to me of some cyclonic wind action, and may perhaps have been noticed elsewhere by some of your readers.
- In a newspaper article Lewis Cohen wrote, "Williams is probably best known as the only person in the UK to be successfully prosecuted for making crop circles. He has since made a name for himself creating crop circles for TV companies and commercial firms..."
- The website Crop Circle Research.com described one formation stating, "It looks reminiscent of a fake dummy constructed by 'Balok' in a Star Trek episode called 'Corbomite Manourvre' [sic] (series 1)' or the logo of local soccer club Feyenoord".
- In a Physics World article Richard Taylor wrote, "Today, with the benefit of hindsight, such explanations sound rather contrived. At the height of the debate, though, no less a physicist than Stephen Hawking was prepared to accept some version of Meaden's theory. When a spate of circles appeared in the countryside near his Cambridge home in 1991, Hawking told a local newspaper that "crop circles are either hoaxes or formed by vortex movement of air"
- "Every crop circle in England in 2009 - with co-ordinates". The Guardian. September 15, 2009. Retrieved August 8, 2015.
- Edis, T. Science and Nonbelief. Prometheus Books. 2008, p. 138. ISBN 1-59102-561-3 "Skeptics begin by pointing out that many paranormal claims are the result of fraud or hoaxes. Crop circles — elaborate patterns that appear on fields overnight — appear to be of this sort. Many crop circle makers have come forth or have been exposed. We know a great deal about their various techniques. So we do not need to find the perpetrator of every crop circle to figure out that probably they all are human made. Many true believers remain who continue to think there is something paranormal — perhaps alien — about crop circles. But the circles we know all fall within the range of the sort of thing done in hoaxes. Nothing stands out as extraordinary."
- Parker, Martin. "Human science as conspiracy theory". The Sociological Review (Wiley Online Library) 48 (S2): 191––207 year=2000.
- Hines. T. Pseudoscience and the Paranormal. Prometheus Books, 2003. pp. 295-296. ISBN 1-57392-979-4
- Soto, J. Crop Cirles. In Michael Shermer (Ed). The Skeptic Encyclopedia of Pseudoscience. ABC-CLIO. pp. 67-70. ISBN 1-57607-653-9
- Radford, B. "Crop Circles Explained". LiveScience.
- Jeremy Northcote. "Spatial distribution of England's crop circles" (PDF). Geography Online (online journal, without ISSN). Southern Illinois University.
- William E. Schmidt (10 September 1991). "2 'Jovial Con Men' Demystify Those Crop Circles in Britain". New York Times.
- Richard Taylor (August 2011). "Coming soon to a field near you" (PDF). Feature: Crop circles. Physics World.
- Margry & Roodenburg 2007, pp. 140-2.
- Peter Jan Margry; Herman Roodenburg (2007). Reframing Dutch Culture: Between Otherness and Authenticity. Progress in European Ethnology (illustrated ed.). Ashgate Publishing. pp. 150–1. ISBN 9780754647058.
- Laurie Eddie (4 November 2004). "The Skeptics SA Guide to: Crop circles". Skepticssa.org.au. Skeptics SA. Retrieved 2012-01-01.
- Carl Sagan (1997). The Demon-Haunted World. Headline Publishing Group. pp. 72–6. ISBN 0747251568.
- Hillary Mayell (2 August 2002). "Crop circles: Artwork or alien signs". National Geographic. p. 2. Retrieved 28 October 2010.
- Rob Irving; Peter Brookesmith (December 15, 2009). "Crop Circles: The Art of the Hoax". Smithsonian.com.
- John Aubrey. The Natural History of Stafford-Shire. at Project Gutenberg
- "The Natural History of Staffordshire by Robert Plott; Sciotericum Telescopicum or a new Contrivance of adapting a Telescope to a Horizontall Diall, for observing the moment of time by day or night by Will Molineux". Accounts of Books. Philosophical Transactions (1683–1775). 16 (1686-1692): 207–16. JSTOR 101866.
- Kevin Greene (1995). Archaeology: An Introduction: The History, Principles and Methods of Modern Archaeology (PDF) (3, fully revised ed.). Routledge. ISBN 0203447204.
- John Rand Capron (1880). "Storm Effects" (PDF). Nature 22 (561): 290. Bibcode:1880Natur..22..290C. doi:10.1038/022290d0. Retrieved from "Nature archive for the decade 1880–1889". nature.com. Nature. Retrieved 23 August 2011. Republished in "A case of genuine crop circles dating from July 1880 – as published in Nature in the year 1880". Journal of Meteorology 25: 20–1. January 2000.
- Sussex Notes and Queries, 1937 Eliot Cecil Curwen p.139-140
- Moore P. ‘That Wiltshire Crater’ Letter to the editor New Scientist 8th August 1963
In the adjoining wheatfields were other features, taking the form of circular or elliptical areas in which the wheat had been flattened. I saw these myself; they had not been much visited, and were certainly peculiar One, very well-defined, was an oval 15 yards long by 41 broad. There was evidence of "spiral flattening", and in one case there was a circular area in the centre in which the wheat had not been flattened. In no case was there any evidence of an actual depression in the ground.
(...) [The crater] could have been caused by natural subsidence, but it did not give that impression, and in any case there are the areas of flattened wheat to be taken into account; it would be remarkable coincidence if these areas were not associated with the crater. Since the areas of flattened wheat "led" to the crater, it looks very much as though they, and the crater, were caused by something which came from the sky. In this case, the wheat would have been flattened by violent air-currents produced by the falling body.
- Hugh Ernest Butler 'That Wiltshire Crater', New Scientist issue 352, 15 August 1963 Letters to the editor
- "Canada's Unidentified Flying Objects: The Search for the Unknown: Duhamel, Alberta: August 1967". 14 December 2007 . At Library and Archives Canada. (Original in French).
- Jim Gilchrist (September 7, 2002). "The flattened crops society". The Scotsman. (registration required)
- Eddie 2004 citing: D. Wood (2000). "Pioneer pranksters?". Fortean Times 131 (52).
- Oxford English Dictionary, "Crop: Draft additions 1997", in Jrnl. Meteorol. 13 290.
- Brian Regal (2009). Pseudoscience: A Critical Encyclopedia. Greenwood Press. p. 47. ISBN 9780313355073.
- "Crop circle picture gallery shows more complex forms". The Telegraph. 5 June 2009. Retrieved 23 October 2013.
- "Disease brings poor crop of circles". BBC News. 2001-08-17. Retrieved 2007-02-08.
- Benjamin Radford (8 June 2010). "'Beautiful Math Equation' Found in Crop Circle". LiveScience. Retrieved 2012-01-01.
- Marc West (2008-06-30). "Pi appears in crop circle". plus.maths.org. Retrieved 2012-01-01.
- "Crop circle season arrives with a mathematical message". This Britain. The Independent. 2010-05-26. Retrieved 2012-01-01.
- Clarke, John (July 9, 2012). "Mystery Crop Circles Revealed As Olympic Publicity Stunt". Forbes. Retrieved July 29, 2015.
- Graham Brough (1991). "Men who conned the world". Today (defunct) (UK).
- "Two British artists admit playing `circles' hoax for the past 13 years". Houston Chronicle (Star ed.). Houston Chronicle News Services. 10 September 1991. p. A2.
- Hola Ridley (15 July 2002). "Crop circle confession". Scientific American. Retrieved 2007-08-16.
- Henry Hemming (2009). In Search of the English Eccentric. John Murray. ISBN 0719522129.
- Andrea Pelleschi (2012). Crop Circles. Essential Library/ABDO. p. 73.
- David Jenkins (25 August 2010). "Crop circle conundrum". The Daily Telegraph. Retrieved 10 August 2012.
- Rupert Sheldrake. "The Crop Circle Making Competition" (PDF). Rupert Sheldrake. Retrieved 10 August 2012.
- Crop Circles: Mysteries in the Fields. Discovery Channel. 2002-10-10.
- John Vidal (5 June 2009). "The bizarre revival of crop circles – and advice on how to make your own". The Guardian.
- Cahal Milmo (November 4, 2000). "Police unravel mystery of the crop circle". The Independent (London).
- "Man fined £100 for making crop circle". thisiswiltshire.co.uk (Weybridge). 7 November 2000.
- "Secrets of crop circles". thisiswiltshire.co.uk (Weybridge). 2 May 2002.
- Lewis Cohen (25 February 2008). "Mystery surrounds emergency landing". thisiswiltshire.co.uk (Weybridge).
- "Magnetic 'solution' to crop circle puzzle". BBC News. 9 August 2000. Retrieved 30 September 2015.
- Joe Nickell (September–October 2002). "Circular Reasoning: The 'Mystery' of Crop Circles and Their 'Orbs' of Light". Skeptical Inquirer 26.5. Archived from the original on 2006-12-06.
- Joe Nickell. "Crop-circle mania: An investigative update". Skeptical Inquirer. Cited as reference 6 in Nickell 1996
- "Flattened. (crop circles hoax)". The Economist (US). 14 September 1991 – via Highbeam. (subscription required (. ))
- "Farmer embarrassed by crop circle hoax". canada.com. Canwest News Service. 2 October 2007.
- Sagan 1997.
- Roel Van der Meulen (1994). "Faking UFOs". Roel Van der Meulen.
- Margry & Roodenburg 2007, pp. 143-5.
- Former RAF engineer: MI5 'paid people to fake crop circles' to discredit UFO research - Jon Austin - Express.co.uk - Tue, Sep 22, 2015
- Matt Ridley (4 June 2011). "Houdini, crop circles and the need to believe". Wall Street Journal.
- Taylor 2011
- Simon Hoggart; Mike Hutchinson (1995). Bizarre Beliefs. London: Richard Cohen Books. p. 59. ISBN 9781573921565. Cited in Nickell 2002
- Robert Todd Carroll (19 December 2011). "crop "circle"". The Skeptic's Dictionary. Retrieved 2012-06-15.
- Eltjo Haselhoff (2001). The Deepening Complexity of Crop Circles: Scientific Research & Urban Legends. Frog Ltd. ISBN 1583940464.
- Jerome Clark; Nancy Pear (1995). Strange and Unexplained Happenings: When Nature Breaks the Rules of Science 3. Gale. ISBN 0810397803.
- Margry & Roodenburg 2007, pp. 138-9.
- Charles Godfrey-Faussett (2004). England. Footprint Travel Guides. ISBN 1903471915.
- Margry & Roodenburg 2007, p. 138.
- Joe Nickell (June 1996). "Levengood’s crop-circle plant research". Skeptical Inquirer 6.2.
- W.C. Levengood (1994). "Anatomical anomalies in crop formation plants". Physiologia Plantarum 92 (2): 356–63. doi:10.1111/j.1399-3054.1994.tb05348.x. ISSN 0031-9317.
- Ika Krismantari (6 February 2011). "Crop circles provide food for thought". The Star.
- "Stoned wallabies make crop circles". BBC News. 25 June 2009. Retrieved 31 May 2011.
- W.C. Levengood; Nancy P. Talbott (1999). "Dispersion of energies in worldwide crop formations". Physiologia Plantarum 105: 615–24. doi:10.1034/j.1399-3054.1999.105404.x.
- Margry & Roodenburg 2007, p. 152.
- Jim Schnabel (1993). Round in Circles: Physicists, Poltergeists, Pranksters, and the Secret History of the Cropwatchers. Harmondsworth: Penguin. ISBN 0140179526.
- Ralph Noyes, ed. (1990). The Crop Circle Enigma: Grounding the Phenomenon in Science, Culture and Metaphysics. Bath: Gateway Books. ISBN 0946551669.
- Michael Glickman (2009). Crop Circles: The Bones of God. Frog Books. ISBN 978158394-2284.
- Suzanne Taylor (2011), What On Earth? Inside the Crop Circle Mystery (DVD 81-minute feature), UBC, Prod #724101746123.
- Richard Taylor (2010). "The crop circle evolves". Nature 465 (7299): 693. Bibcode:2010Natur.465..693T. doi:10.1038/465693a.
- Brian Dunning (21 August 2007). "Crop Circle Jerks". Skeptoid. Episode 62.