The Grand Canyon, one of America’s most famous landmarks, may have been created when an ancient supercontinent cracked apart, according to new research.
Roughly 800 million years ago, the supercontinent Rodinia broke apart in a gradual process, taking close to 300 million years. Now, an international team of researchers says that an analysis of the Grand Canyon’s interior rock reveals it may have been exposed long before geologists previously suspected.
The geologists investigated an ancient cliff face that extends for thousands of kilometers and marks a boundary of the Grand Canyon, detailing their findings in a recent paper published in the journal Geology.
Forming the Grand Canyon
Geologists believe the Colorado River slowly carved out the Grand Canyon over five to six million years. A team of international scientists led by the UK’s University of Southampton turned back the clock to study how the environment changed in much more remote periods.
Simulations and computer models were essential to the researchers’ work. They utilized landscape evolution data and reconstructed plate tectonics over massive time scales to better understand how North America fared in the destruction of Rodinia.
Before there was a “Grand Canyon,” the team claims that their work reveals there was likely a “great escarpment,” an earlier landform of rocky cliffs produced in Rodinia’s demise. These cliffs would have been a kilometer high, with a crystalline floor at their base resembling the one now at the bottom of the Grand Canyon. They say this great escarpment would have encompassed much of the western United States, covering parts of Arizona, Utah, Idaho, Wyoming, Colorado, Texas, Oklahoma, Arkansas, Missouri, and Illinois.
Rocks of the Grand Canyon
Erosion along this great escarpment eventually produced the Grand Canyon and exposed some of America’s most ancient rocks.
“Our paper suggests the Canyon’s basement rocks were progressively brought to the surface as part of an immense escarpment that developed during the breakup of an ancient supercontinent,” said lead author Thomas Gernon, Professor of Earth Science at the University of Southampton. “The findings also shed light on the formation of the Great Unconformity, a mysterious gap in the rock record that spans over a billion years.”
One of the biggest surprises is that what is now the Grand Canyon and some of South America and Brazil’s major escarpments once occupied the same positions relative to the continent’s perimeter. They believe that about eight kilometers of rock were ripped away as the escarpment moved inland from the continental margin. Known physical evidence of extreme erosion before the formation of the Grand Canyon corroborates this finding.
“This long-lived tectonic landscape provides a missing piece in understanding why erosion associated with the Great Unconformity varies so dramatically across the southwestern US,” Gernon explained. “Our work suggests that tectonic uplift related to continental rifting and breakup created both steep slopes and high ground, providing the mountainous terrain that rivers and glaciers could readily erode.”
Forming North America
The team’s findings don’t stop at the Grand Canyon, though. They suspect that the mountainous rim exerted a massive influence on North America’s development, including the flow of rivers, locations of sediment buildup, and when flooding occurred; all of which could have been driven by the great escarpment.
“By comparing Grand Canyon’s ancient history with active landscapes like the Great Escarpment of South Africa, we’re able to see North America’s most iconic geologic landmark in an entirely new light,” Professor Gernon concluded.
“Our findings could help geologists reinterpret other ancient continental interiors where similarly large gaps occur in records, offering a better understanding of how Earth’s continents have changed over hundreds of millions of years.”
The paper, “Exhumation of Grand Canyon’s Basement Along the Great Escarpment of Laurentia,” appeared in Geology on August 17, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org.