These layers of sedimentary rock were deposited in Cambrian time ... and sponges. Known as the Grand Canyon Supergroup, these layers of rock lie at an angle relative to the layers of rock above.

"The Tonto Group of Grand Canyon holds a treasure trove of sedimentary layers and fossils chronicling ... developed 50 years ...

In the Grand Canyon, the layers of strata are nearly ... superposition states that in an undeformed sequence of sedimentary rocks, each layer of rock is older than the one above it and younger ...

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.

Southern Utah’s Zion and Bryce Canyon National Parks are spectacular, dazzling, stunning… I quickly ran out of adjectives ...