The document discusses several land artists from the 1960s-70s including Walter de Maria, Christo, Robert Smithson, and Merille Hommik. Some of their notable works mentioned are Walter de Maria's Lightning Field in New Mexico consisting of 400 stainless steel poles, Christo's Running Fence installation in California, and Robert Smithson's Spiral Jetty, an earthwork sculpture formed in a Utah saltwater lake. These artists helped pioneer the land art movement using the natural environment as their medium.