Geoglyph
A geoglyph is a large design or motif – generally longer than 4 metres (13 ft) – 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.