The Grand Canyon may rewrite the textbooks on the Cambrian Explosion—a key turning point in Earth’s history when there was a sudden boom in complex life and the emergence of all the major animal groups seen alive today.
This is the conclusion of a U.S. team of researchers, led by the University of New Mexico and the Utah State University, who studied the “Tonto Group”, a 0.3-mile-thick collection of five rock formations that are exposed along the sides of the canyon.
“The Tonto Group of Grand Canyon holds a treasure trove of sedimentary layers and fossils chronicling the Cambrian Explosion some 500 million years ago,” paper author and Utah State University geology professor Carol Dehler said in a statement.
At the time the Tonto Group was being laid down, sea levels were rising, covering the submerged land with emerging marine life. However, the team has determined that the traditional model of this process—developed from a previous study of the Tonto Group in the 1940s—oversimplified this process.