Sedona’s Red Rocks are comprised of sediment layers deposited over many millions of years. The shale foundation is the remainder of ancient swamp lands. Other layers are the remainder of an ancient beachfront, known as the “Schnebly Hill Formation,” that deposited iron about 275 million years ago. (This iron is what gives Sedona’s rocks their rich red color.) The Coconino sandstone layer was formed at a time when a Sahara-like dunes covered the majority of the Western US.
The Kaibab limestone layer was deposited when a warm shallow sea covered the area about 250 million years ago.
The Red Rocks we see today were formed several million years ago when the uplifting of the Colorado Plateau that created the Grand Canyon also caused water to carve out Sedona’s red rock, cake-like layers. Currently, Sedona is considered to be a part of the Colorado Plateau and is in the process of making mountains, raising an average of one inch every 60-80 years!
More information is available from the Coconino Forest Service’s Visitor Center located on the south end of the Red Rock Scenic Byway — make it your first stop!