The forested mountains of northeastern Utah can be as green and inviting as any in the world, but just over the ridge, you can find an alien landscape as well: rolling hills of red dirt and rock, much like the vistas visible from the Spirit rover on Mars. The similarity isn’t just coincidental. Like at least part of the Red Planet, Utah’s red hills were once covered with water. In fact, as you drive through Logan Canyon, the fossilized traces of marine worms from 400 million years ago are visible literally on the side of the road. Today, that bounty of water is gone, leaving Martian-style dirt and stone that is reddened by iron oxide.