Géoglyphe

A geoglyph is a large design or motif (generally longer than 4 metres) produced on the ground by durable elements of the landscape, such as stones, stone fragments, gravel, or earth. A positive geoglyph is formed by the arrangement and alignment of materials on the ground in a manner akin to petroforms, while a negative geoglyph is formed by removing part of the natural ground surface to create differently coloured or textured ground in a manner akin to petroglyphs. Geoglyphs are generally a type of land art, and sometimes rock art. A hill figure is created on a slope, so that it can be seen from a distance. Perhaps the most famous geoglyphs are the Nazca lines in Peru. The cultural significance of these geoglyphs for their creators remains unclear, despite many hypotheses. The "Works of the Old Men" in Arabia, "stone-built structures that are far more numerous than (the) Nazca Lines, far more extensive in the area that they cover, and far older," have been described as geoglyphs by Amelia Sparavigna, a physics professor at Politecnico di Torino in Italy. The use of this term to describe these features is probably inaccurate, as recent research has shown that most were not constructed primarily as art, but were rather built to serve a range of purposes including burial sites and funerary customs, aiding in the trapping of migratory animals, and as cleared areas for camps, houses and animal enclosures. Since the 1970s, numerous geoglyphs have been discovered on deforested land in the Amazon rainforest, Brazil, leading to claims about Pre-Columbian civilizations. Ondemar Dias is accredited with first discovering the geoglyphs in 1977 and Alceu Ranzi with furthering their discovery after flying over Acre. Other areas with geoglyphs include Megaliths in the Urals, South Australia (Marree Man, which is not ancient, but rather a modern work of art, with mysterious origins), Western Australia and parts of the Great Basin Desert in the southwestern United States.