The Economic Times

In 1932, a pilot spotted giant human and animal figures carved into California's desert; the largest stretches 171 feet from head to toe

Giant desert drawings near Blythe, California, have been dated using rock varnish. These ancient figures are now estimated to be at least one thousand years old. Scientists used a technique called cation-ratio dating to analyze rock surfaces. This method revealed the figures are of similar age and quite ancient. The Blythe Intaglios remain North America's best-known example of ground art.