Two of Arizona’s most iconic landmarks, the Grand Canyon and Meteor Crater, might be secretly connected by a prehistoric twist of fate.
New research reveals that a meteorite strike near Winslow, Arizona, approximately 56,000 years ago, may have triggered a massive landslide that blocked the Colorado River, creating an ancient lake spanning 50 miles and plunging 300 feet deep into the Grand Canyon’s past.
It’s like nature’s version of a crime scene, slowly pieced together by scientists from the University of Arizona and the University of New Mexico over the course of decades. And this cosmic clue could help us better understand how meteor impacts, like the one that wiped out the dinosaurs, can reshape entire landscapes.
High above the Colorado River, Stanton’s Cave has long puzzled scientists. How did driftwood and lake sediments end up 150 feet above the river’s flow? No known flood in thousands of years could have reached that height, unless something extraordinary had happened.
Turns out, it might have. In the 1980s, geologist Richard Hereford uncovered evidence of a massive rockslide near Nankoweap Canyon, 22 miles downstream. That event could have dammed the river, forming a paleolake so deep and powerful that it floated driftwood right into the cave’s mouth.
It’s a geological detective story: clues buried in sediment, rocks that hint at ancient floods far larger than anything modern records have seen. And now, piece by piece, the mystery is coming into focus.
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Back in 1970, pieces of ancient driftwood found in Stanton’s Cave, high above the Colorado River, were dated to be over 35,000 years old; however, new technology had other ideas. Fast forward to 2019, and Jonathan Palmer, a dating specialist from the University of New South Wales, revealed the wood is even older, about 55,000 years old.
Then came a twist fit for a detective novel. Palmer happened to visit the University of Arizona’s Tree-Ring Lab, where researcher Baisan was already knee-deep in samples from Stanton Cave. On a casual road trip, Palmer stopped at Meteor Crater and noticed that its impact occurred around 50,000 years ago. The coincidence sparked a question: could the meteor strike and the flood that swept driftwood into the cave be connected?
An unexpected question popped up, one no one had ever thought to ask. As Baisan put it, it happened simply because researchers from across the globe crossed paths at the right time.
Their conversation led to a draft paper suggesting a connection between Meteor Crater and a massive ancient flood in the Grand Canyon. However, the case wasn’t airtight, the evidence was primarily circumstantial, and not everyone agreed on the existence of a rockfall dam and paleolake.
To dig deeper, they shared the draft with Karl Karlstrom, a Grand Canyon geomorphology expert, hoping his insights might help confirm or challenge the theory.
To dig deeper into the mystery, geomorphologist Karl Karlstrom teamed up with senior author Laura Crossey from UNM. Together, they uncovered wood and sediment samples from a new site downstream, at the same dizzying height as Stanton’s Cave. When dated, both samples yielded ages of 55,600 years, cementing a critical piece of the puzzle.
Meanwhile, in Nankoweap Canyon, more clues surfaced. Scientists spotted chaotic dam debris layered beneath smooth river cobbles, evidence that the Colorado River had once surged over the rockfall dam and slowly worn it down. Based on comparisons with today’s concrete dams, researchers estimate that this erosion occurred over less than 1,000 years.
Like any good mystery, this one circles back to the big question: Whodunnit? Could a space rock have shaken the ground enough to trigger a canyon-sized landslide?
Meteor Crater Science Coordinator David Kring crunched the numbers. When the 300,000-ton nickel-iron meteorite slammed into what is now northern Arizona, the impact unleashed a quake estimated to be between magnitude 5.4 and 6. That shockwave would’ve raced the 100 miles to the Grand Canyon in seconds, still holding a powerful jolt of magnitude 3.5–4.1 by the time it arrived.
“We don’t know exactly what the ground shaking intensity was,” Baisan said, adding that he believes the effect was more than just a gentle shaking of the ground. “There would have been the shock wave as the object passes through the air, then the blast wave, and finally the impact, which might have been enough to trigger a landslide in the canyon.”
Though no one can trace the meteor’s exact path or altitude, researchers believe its arrival may have triggered a perfect storm. The impact itself, the quake it unleashed, and the already unstable terrain might’ve been just enough to shake loose cliffs in the Grand Canyon that were, as they say, “waiting and ready to go.”
While more minor rockfalls happen regularly in the canyon, the kind that can block the mighty Colorado River and spawn a lake, like the one suspected at Nankoweap, are geological unicorns.
“We put together these arguments without claiming we have final proof,” Karlstrom said. “There are other possibilities, such as a random rockfall or local earthquake within a thousand years of the Meteor Crater impact that could have happened independently. Nevertheless, the meteorite impact, the massive landslide, the lake deposits, and the driftwood high above river level are all rare and unusual occurrences.”
Journal Reference:
- K.E. Karlstrom; C.H. Baisan; D.A. Kring; R. Hereford; C. Turney; A. Hogg; L.M. Norman; P. O’Brien; J.G. Palmer; T.M. Rittenour; J. Ballensky; L.J. Crossey. Grand Canyon landslide-dam and paleolake triggered by the Meteor Crater impact at 56 ka. Geology. DOI: 10.1130/G53571.1
