Some of the rock art and granaries are in such remote spots, the scientists aren't sure how Fremont people reached them.

The segment introduces Range Creek canyon, in the rugged and remote country near the Green River in eastern Utah. The canyon was recently sold to the state and federal governments by a rancher, who'd lived there for 50 years. The canyon held a secret that the rancher and his family had kept to themselves — the whole place is filled with the surprisingly well-preserved remains of the Fremont people, a Native American culture that flourished in the region for about a thousand years.

Our guides in the canyon are archeologists who are just beginning to survey the vast number of ancient sites that are now in their care. Of all America's ancient peoples, the Fremont are among the most enigmatic. As we see in the canyon, for some reason they built houses and storage granaries in extremely precarious and hazardous places. They were prolific creators of often mysterious rock art. And their way of life appears to have come to a sudden end around 1300 AD.