Every month this fall, KNAU has been taking you to places on the Colorado Plateau. They may be places you know, they may be places you've only heard of. It's a series we call Land Lines and today we're visiting Monument Valley. People come from all over the world to see this valley, one of the most evocative landscapes in the southwest. But at least one rock feature doesn't quite fit the mold of the mesas and buttes. In today's Land Lines, Rose Houk and Michael Collier explore the origins of El Capitan.