North Rim of Grand Canyon National Park Over 1,800 million years of geologic history stand before you at the strata of the Grand Canyon. The North Rim is less accessible than the South Rim and ...

"The Tonto Group of Grand Canyon holds a treasure trove of sedimentary ... "From the Tonto Group's 500-meter-thick strata, we ...

The Grand Canyon was carved out of rock by the Colorado River over millions of years. The strata of the canyon is discussed to explain what the layers tell us about how the canyon formed.

Located in the state of Arizona, it cuts across the Grand Canyon National Park. Its horizontal strata retrace the geological history of the past 2 billion years. There are also prehistoric traces of ...