Land art, variously known as Earth art, environmental art, and Earthworks, is an art movement that emerged in the 1960s and 1970s, largely associated with Great Britain and the United States but that also includes examples from many other countries. As a trend, "land art" expanded the boundaries of traditional art making in the materials used and the siting of the works. The materials used are often the materials of the Earth, including the soil, rocks, vegetation, and water found on-site, and the sites are often distant from population centers. Though sometimes fairly inaccessible, photo documentation is commonly brought back to the urban art gallery.