Imagine a world-shaking event that not only created a famous crater but also triggered a series of events leading to a hidden lake deep within the Grand Canyon. This intriguing story begins with two iconic landmarks in northern Arizona: the Grand Canyon and the Barringer Meteorite Crater.
Recent research suggests these two natural wonders might be more connected than we ever imagined. The impact that formed the Barringer Crater around 56,000 years ago could have also caused landslides in the Grand Canyon, temporarily damming the Colorado River and creating an 80-kilometer-long lake. This groundbreaking discovery was published in Geology, shedding light on a hidden chapter in the region's history.
Dr. Karl Karlstrom, a retired geologist from the University of New Mexico, grew up in Flagstaff, Arizona, with these iconic features as his backyard. His father, also a geologist, explored the caves of the Grand Canyon, leading to a fascinating discovery in 1970.
In Stanton's Cave, a cavern located more than 40 meters above the Colorado River, Dr. Karlstrom's father found driftwood. This was unexpected, as routine flooding couldn't have carried woody debris to such a height. "It would have required a flood ten times bigger than any known flood over the last 2,000 years," Karlstrom explained.
The driftwood's age, estimated at around 35,000 years old using the best radiocarbon dating available at the time, led to a theory that an ancient landslide had temporarily dammed the Colorado River, raising water levels. The researchers even identified the potential landslide site - a wall of limestone in Nankoweap Canyon.
But what caused this landslide in the first place? This was the question Karl Karlstrom and his team set out to answer. In 2023, they collected additional driftwood samples from a cave 5 kilometers downriver from Stanton's Cave, and the results were astonishing.
Modern radiocarbon dating revealed that both the archival and newly collected driftwood samples were approximately 56,000 years old, with a few thousand years of uncertainty. This timing coincided strikingly with the estimated age of the Barringer Meteorite Crater's formation.
"That coincidence was striking," said Karlstrom. Could these two famous landmarks be linked? The impact that created the Meteor Crater is believed to have produced ground shaking equivalent to an M5.2-5.4 earthquake. At the distance of Nankoweap Canyon, this shaking would have been attenuated to around M3.3-3.5, which could have dislodged the limestone boulders.
While it's impossible to know for sure, future modeling work will help clarify this. "Fault slip earthquakes release energy from several kilometers depth, whereas impacts may produce larger surface waves," Karlstrom explained.
Chris Baisan, a dendrochronologist at the University of Arizona, added, "There was an area where it looked like the canyon wall had collapsed across the river." Using the heights above the Colorado where the driftwood and sand samples were collected, the team estimated the ancient lake's extent, which would have measured roughly 90 meters at its deepest point.
John Spray, a planetary scientist at the University of New Brunswick, not involved in the research, commented, "They're certainly close, if not contemporaneous." While causation is difficult to prove, the team's assertion that the impact set off landslides in the Grand Canyon area is convincing.
Karlstrom and his collaborators continue to collect samples from caves in Grand Canyon National Park, uncovering more evidence of material dating back to around 56,000 years ago and even older samples. "The story is getting more complicated," Karlstrom said, suggesting multiple generations of lakes in the Grand Canyon area.
This research not only deepens our understanding of the Grand Canyon's history but also highlights the interconnectedness of natural phenomena. It invites us to consider the far-reaching consequences of events like asteroid impacts and the hidden stories they might reveal.
