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 countries. As a trend, "land art" expanded boundaries of art by the materials used and the siting of the works. The materials used were often the materials of the Earth, including the soil, rocks, vegetation, and water found on-site, and the sites of the works were often distant from population centers. Though sometimes fairly inaccessible, photo documentation was commonly brought back to the urban art gallery.