The Grand Canyon is one of the most important, interesting, and awe-inspiring examples of the Southwest’s unique geology. For over a hundred years, it has captivated tourists, prospectors, and geologists alike. In the 1850s, Dr. John Strong Newberry started studying the geology of the Grand Canyon and the investigation has continued ever since, continually providing us with new information and insights about the Earth’s past.
Ready to build a solid foundation of geological knowledge ahead of your visit to the Grand Canyon? Let’s dig in.
The Colorado Plateaus Province
The Colorado Plateaus Province covers the region known as the “Four Corners”, where Arizona, Utah, Colorado, and New Mexico meet. The Plateau occupies 240,000 square miles of land, and is home to a number of America’s incredible National Parks and Monuments:
ArizonaCanyon de Chelly National MonumentGlen Canyon National Recreation Area Arizona & Utah) Grand Canyon National Park Hubbell Trading Post National Historic Site Lake Mead National Recreation Area (Arizona & Nevada) Navajo National Monument Petrified Forest National Park Pipe Springs National Monument Sunset Crater National Monument Walnut Canyon National Monument Wupatki National Monument | UtahArches National ParkBryce Canyon National Park Canyonlands National Park Capitol Reef National Park Cedar Breaks National Monument Dinosaur National Monument (Colorado & Utah) Glen Canyon National Recreation Area (Arizona & Utah) Hovenweep National Monument (Colorado & Utah Natural Bridges National Monument Rainbow Bridge National Monument Zion National Park |
ColoradoBlack Canyon of the Gunnison National ParkColorado National Monument Curecanti National Recreation Area Dinosaur National Monument (Colorado & Utah) Hovenweep National Monument (Colorado & Utah) Mesa Verde National Park Yucca House National Monument | New MexicoAztec Ruins National MonumentChaco Culture National Historical Park El Malpais National Monument El Morro National Monument |
In addition to these locations, the Plateau houses a variety of geological formations ranging from deep canyons to ancient volcanic mountains reaching over 13,000 feet in elevation.
Formed by sediments and lava over millions of years, the most iconic part of this area (in our unbiased opinion) was gradually carved out by the Colorado River to produce one of the Plateau’s crown jewels: the Grand Canyon.
Geology of the Grand Canyon
The Canyon itself is made up of several types of rock, including:
Sedimentary | Igneous | Metamorphic |
|---|---|---|
| Shale Sandstone Liestone | Granite | Schist |
Approximately 5-6 million years ago, rain, snow melt, and the Colorado River began eroding these rocks and shaping them into the Grand Canyon. The various rocks’ different physical properties are what contribute to the Canyon’s spectacular appearance because different types of rock erode faster or in a different fashion than others:
- Sedimentary rock is more susceptible to erosion, lending a more rounded and soft looking appearance in some areas, such as the upper canyon.
- Igneous or metamorphic rock, like you’ll find in the lower or “inner” Canyon, is more resistant to erosion, so it appears sharp and defined.
FOSSIL FACT: You won’t find dinosaur fossils at the Grand Canyon because the rock layers from the Mesozoic Era—the “Age of Dinosaurs”—have mostly eroded away.
Erosion has done more than simply provide us with an awe-inspiring visual wonder. It’s also given us the incredible opportunity to view a cross section of billions of years of history—a timeline shown in layers of rock, giving us insight into the evolution, geological changes, and environmental conditions occurring during these time periods.
There are almost 40 layers that have been identified in the Canyon, one as recently as the 1970s!
PRO TIP: At the South Rim, you can explore the Canyon’s geological history at the Trail of Time exhibit.
When you walk around the rim of the Canyon during your tour, you are walking on rocks that have been here for millions of years—approximately 270 million, to be exact. Not only does seeing the Grand Canyon visually awe you, it is a place where you can step back in time and physically feel and see Earth’s history.
Grand Canyon Rocks
For additional information on the geology of the Grand Canyon, check out these reliable sources:
GrandCanyon.com
NPS: Grand Canyon – Geological Formations
NPS: Colorado Plateaus Province
Grand Canyon Geology Training Manual by Stacy S. Timmons
