The Phoenix  metro area is ringed with mountains, deep canyons, and broad, alluvial valleys watered by rivers than can go from shallow trickles to raging torrents in a matter of minutes. This landscape is part of the vast basin and range zone born 15 million years ago when the Earth’s crust beneath what is now the western United States was pulled apart by shifting tectonic plates. It stretched as much as 50 percent, pushing up and pulling down the land to form a regular pattern of small but steep mountains and broad, flat valleys.
Today, a ring of such mountain ranges around metro Phoenix gives the area its nickname: the Valley of the Sun. The major ranges surrounding the Valley are the White Tank Mountains to the west, the Sierra Estrella to the southwest, South Mountain to the south, the Superstitions to the southeast, the Usery Mountains to the east, the McDowell Mountains to the northeast and the Hieroglyphic Mountains to the northwest. Smaller ranges also ring the center of the city, including the Phoenix Mountains, South Mountain, and the Papago Buttes. Most of the rock that forms these craggy hills is volcanic, but they were created less by geysers of lava than by the inexorable seismic shifting that tilted up huge blocks of the Earth’s crust.
To the north lies the high, flat Colorado Plateau. Sedona  sits in the southwestern part of this high-desert region, which covers the four corners area where northeastern Arizona, southeastern Utah, southwestern Colorado, and northwestern New Mexico meet. But to get there from Phoenix, you have to climb the Mogollon Rim, a long, snaking cliff that bisects the state from east to west. This dramatic drop-off separates the low desert surrounding Phoenix from the grasslands and Ponderosa pine forests of this vast plateau, and the trails along its edge offer fabulous views of the Sonoran Desert below.
The area around Sedona is known as Red Rock Country  thanks to the red-tinged sandstone cliffs towering above Oak Creek Canyon . The color comes from iron deposits that rust as the rock weathers and exposes them to air and water. But the majestic formations, called “fins,” came to be thanks to a much simpler process: the combination of weak ground and flowing water. Oak Creek tumbles down from the north through a fault line. Over the millennia, thousands of small earthquakes fractured the ground above the fault, and water seeped in and carried away layer after layer of rock to form Oak Creek Canyon. The strongest rock formations stood up to this liquid attacker and now soar far above the canyon floor.