Colorado Plateau

The Colorado Plateau (CP) occurs in the northern third of the county. This region contains a series of normally faulted, stair-step plateaus that rise successively to the east. The first jump is the Shivwits Plateau along the Grand Wash Fault at the Grand Wash Cliffs. The cliffs also mark the western end of the Grand Canyon. Nearly horizontal-lying Paleozoic (544-248 million years ago) sedimentary rocks unconformably overlie Proterozoic igneous and metamorphic rocks (<1.4 billion years old) on the elevated Colorado Plateau. The Paleozoic rocks compose most of the cliffs and slopes in the Grand Canyon and consist of marine sandstones, shale, limestone and dolomite, and nonmarine sandstones and shale. The Grand Wash Cliffs expose Proterozoic and Cambrian through Mississippian units.

The unconformity between these rocks and the Proterozoic rocks represents ~1 billion years of time in which no rock record is preserved. Pennsylvanian through Permian continental and marine sedimentary rocks are well exposed along the north-south oriented Hurricane Cliffs and Toroweap Cliffs. Mesozoic rocks, primarily Triassic and Jurassic (248-120 million years old), are present on the plateau in the northeasternmost section of the county near and along the Utah border at the Vermillion Cliffs. They consist mostly of continental sandstones and shales. The plateau is cut by several major north-south oriented normal faults, including the Hurricane Fault in the Hualapai Indian Reservation south of the Grand Canyon and along the Hurrican Cliffs north of the canyon, the Toroweap Fault along the Toroweap Cliffs north of the canyon, and the Grand Wash Fault at the western edge of the plateau. The Hurricane and Toroweap faults are two of the most active faults in the state.

Stratigraphy of the Plateau Rocks in Mohave County (highlighted rocks have been collected)

• Proterozoic rocks: coarsely crystalline granitic bodies, pegmatite and diabase dikes, gneisses, and schists.
• Cambrian Period - Tapeats Sandstone, Bright Angel Shale, Muav Limestone
• Devonian Period - Temple Butte Formation
• Mississippian Period - Redwall Limestone
• Pennsylvanian Period - Calville Limestone, Esplanade Sandstone
• Permian Period - Hermit Formation, Coconino Sandstone, Toroweap Formation, Kiabab Limestone
• Triassic Period - Moenkopi Formation, Chinle Formation, Moenave Formation
• Jurassic Period - Kayenta Formation, Navajo Sandstone
• Cenozoic Era - Quaternary Basalts (Hat Knoll)

Campus Display Photos

Colorado Plateau display looking north

Colorado Plateau display looking south 1-22-04

Comments or suggestions about these Science web pages to: mrourke@mohave.edu. This web page was last updated by Tawna Evans on November 30, 2004. The following material is copyrighted (2004), but is free to use for non-commercial educational purposes. Please give credit to any used material to D. Wilson.

of Mohave County

COLORADO PLATEAU ROCKS - Each digit on picture represents a rock.

1. Proterozoic Granite
2. Tapeats Sandstone
3. Bright Angel Shale
4. Muav Limestone
5. Temple Butte Formation
6. Redwall Limestone
7. Callville Limestone
8. Esplanade Sandstone
9. Hermit Formation
10. Coconino Sandstone
11. Toroweap Formation
12. Kiabab Limestone
13. Moenkopi Formation
14. Chinle Formation
15. Moenave Formation
16. Kayenta Formation
17. Navajo Sandstone
18. Hat Knoll Basalt