History of Arizona’s Colorado Plateau and Related Landforms GCU 221

Game Plan:  Cenozoic history of the Colorado Plateau - Time step 1 – Compression (Kaibab Plateau) - Time step 2 – Extensive Ponding and Deposition - Time step 3 – Local Ponding / Deposition (Bidahochi) (Bidahochi) - Time step 4 – Erosion (Grand Canyon) - Time step 5 – Extension (Hurricane Cliffs)

Cenozoic History of the Colorado Plateau

 Time Step to 40 million years ago Compression formed a bunch of broad domal uplifts, sags, and laccoliths across the Colorado Plateau

Cenozoic History of the Colorado Plateau  Time Step to 40 million years ago Kaibab Plateau (Domal Uplift)

Cenozoic History of the Colorado Plateau  Time Step to 40 million years ago St. John’s Sag (Synclinal downwarp)

Cenozoic History of the Colorado Plateau  Time Step to 40 million years ago Navajo Mountain (laccolith) Igneous Intrusion – Kind of similar to a Metamorphic Core Complex, but more related to compression instead of extension

 Time Step to 20 million years ago Drainage northeasterly onto the Colorado Plateau from the Mogollon Highlands, leads to wide spread lake and river deposition. Cenozoic History of the Colorado Plateau Bryce Canyon and the Claron Formation

 Time Step to 20 million years ago Cenozoic History of the Colorado Plateau Bryce Canyon and the Claron Formation

 Time Step to 20 million years ago Cenozoic History of the Colorado Plateau Green River Formation and the Flagstaff Limestone

 Time Step 3 – 20 to ~5 million years ago Extension breaks apart the Mogollon Highlands and disrupts drainage leading to deposition on the southern edge of the Colorado Plateau. Cenozoic History of the Colorado Plateau

 Time Step 3 – 20 to ~5 million years ago Cenozoic History of the Colorado Plateau Bidahochi Formation – Where was the Colorado River at this time?

 Time Step 4 – ~5 to ~1 Grand Canyon incision leads to dramatic drop in base level. Cenozoic History of the Colorado Plateau

 Time Step 4 – ~5 to ~1 Cenozoic History of the Colorado Plateau How did the Colorado River cross the Kaibab Upwarp?

 Time Step 4 – ~5 to ~1 Cenozoic History of the Colorado Plateau Can you say KNICKPOINTS!?!

 Time Step 5 – ~1 to the present Extension is moving onto the Colorado Plateau Cenozoic History of the Colorado Plateau Hurricane Fault

Cenozoic History of the Colorado Plateau  Time Step 5 – ~1 to the present Extension is moving onto the Colorado Plateau Hurricane Fault

Things to know:  Colorado Plateau History - Time step 1 – Compression (Kaibab Plateau) - Time step 2 – Extensive Ponding and Deposition northwest drainage (Rim Gravels) - Time step 3 – Local Ponding / Deposition (Bidahochi) - Time step 4 – Erosion (Grand Canyon) southwest drainage (Colorado River) southwest drainage (Colorado River) - Time step 5 – Extension (Hurricane Cliffs) Questions: Ask Dr. Douglass