From ancient inland oceans to some of the oldest rocks on earth the Grand Canyon is a 1.2 billion year timeline of the earths history. Although the Grand Canyon itself only began forming 10 million years ago, its geologic timeline is a priceless record of the origins of our planet, and a precious gift to both scientists and humankind. Even if geology is not your cup of tea, learning even the basic on your grand canyon trip will give you a greater understanding and appreciation of this awesome National Park.
At 250 million years old the Kaibab limestone is the youngest geologic layer found in the Grand Canyon. Although it is now 7,000 feet above sea level this layer was formed due to deposition from an ocean full of fish, brachiopods, and other marine life. It was the geologic uplift of the Colorado Plateau that moved this layer to its current elevation. The oldest geologic layer in the Grand Canyon is the Vishnu Complex, comprised primarily of Vishnu Schist, ancient formations metamorphosed into the black schist we see today, which is some of the oldest exposed rocks on earth.
Except for the Vishnu complex, the Grand Canyon is made of metamorphic rock. The major layers of the Grand Canyon are the; Kaibab Limestone, Toroweap Formation, Coconino Sandstone, Hermit Shale, Supai Group, Redwall Limestone, Temple Butte Limestone, Muav Limestone, Bright Angel Shale, Tapeats Sandstone, the Super Group, and the Vishnu Complex. This is just a basic summary of Grand Canyon Geology as people can and do spend their whole life studying it.