In the early 1970s, a group of artists rebelled against the market-driven forces in New York. They moved out West and began to use the earth as their canvas. In time, their works became known as earth art or land art. The Lightning Field by Walter De Maria is one of the best examples. On a high plain in the mountains of New Mexico, he placed 400 stainless steel poles in a rectangular array that measures one mile by one kilometer.