Among the things they left behind are beautiful ruins, a gorgeously woven basket and a nearly impossible to get to granary on a cliff. David Roberts is a well-known mountaineer who made the first ascents of some of Alaska’s most challenging peaks. For his new book, The Lost World Of The Old Ones: Discoveries in The Ancient Southwest, he set off with a backpack to explore some of the remotest corners of the American Southwest. Rappelling down cliffs to reach ancient granaries, or stumbling across artifacts that have not been touched for 1,000 years, he follows the trail of long...