How the Earth Changed History: Beneath the Crust Dr. Stewart travels into the Earth's crust to understand Mother Nature's forces. We begin almost a thousand feet below the surface in a geological wonder: the Naica crystal cave in Mexico. It's an environment so hostile that anyone entering the cave would die in less than 30 minutes. Then we jet over to Israel's Negev Desert, where we'll uncover man's earliest source of copper, which changed our relationship with the planet forever. Credits Videos 3:03Finding Faultlines in the DesertNo VideoNo Video Photos Episode "Beneath the Crust"