"The Blythe Intaglios or Blythe Geoglyphs are a group of gigantic figures found on the ground near Blythe, California in the Colorado Desert. The intaglios are found east of the Big Maria Mountains, about 15 miles (24 km) north of downtown Blythe, just west of U.S. Highway 95 near the Colorado River. The largest human figure is 171 feet (52 m) long. The intaglios are best viewed from the air.
The geoglyphs or intaglios (anthropomorphic geoglyphs) were created by scraping away layers of darker rocks or pebbles to reveal a stratum of lighter-valued soil. While these "gravel pictographs" are found through the deserts of southeastern California, human figures are found only near the Colorado River. The figures are so immense that they were not observed by non-Indians until the 1930s. The set of geoglyphs includes several dozen figures and a labyrinth, thought to be ceremonial in nature. They are believed to date from 1000 CE but could range from 450 to 10,000 years old, and were most likely created by Mojave and Quechan Indians."