An explorer’s suspicions are spectacularly confirmed nearly a century later by a team of scientists determined to discover the truth in the wild and inhospitable mountains of Alaska.
Ruth Glacier plunges down from North America’s tallest mountain, carrying megatons of compressed ice between the vast granite ridges of Denali National Park.
Explorer Bradford Washburn and bush pilot Don Sheldon were among the first to see it when they flew over the area in 1937.
The pair were stunned to realize that at some point the glacier forces its thousands of years of accumulated snowfall through a pass only a kilometer wide.
Ninety-seven years later, Sheldon’s son Robert and a team of scientists have discovered that the canyon beneath the ice is deeper than the Grand Canyon, and even the deepest in North America.
“Not only do you have this incredible landscape above you, but you have an equally incredible landscape buried in ice below you,” scientist Martin Truffer told the newspaper. NY times. “That’s something I’ll never completely get over.”
The mystery of the Great Rift in Denali National Park has finally been solved
Scientists Jack Holt of the University of Arizona (left) and Martin Truffer of Fairbanks University were among those who determined it to be the deepest in North America
It was 1991 before scientists made their first attempt to get to grips with what was beneath their feet beneath the summit of Mount Denali.
Around them towered the jagged granite ridges of Moose’s Tooth, Bear’s Tooth, and Eye Tooth, keeping watch over the ice field below.
The group, including Fairbanks geophysicist Chris Larsen, started working with ground-penetrating radar, but discovered that the rift was simply too deep to measure.
And the data that did emerge was hopelessly compromised by echoes bouncing off the sides of the steep ridge.
The next summer they were back, this time armed with explosives that they hoped would create tremors loud enough to reach the bottom and return to the top.
They reported their findings after tentatively calculating that they were standing on about 4,000 feet of ice and that the peak was nearly 3,000 feet away from the floor.
But the scientific community was not convinced, as improved satellite technology cast doubt on the results.
In 2019, Jack Holt, a geologist at the University of Arizona, decided that the glacier had kept its secrets long enough and contacted Sheldon’s son Robert to organize an expedition that would finally solve the mystery that had intrigued his father .
“Let’s get this done once and for all,” Robert told the New York Times, honoring “the legacy that both my father and Brad left behind.”
Don Sheldon, pictured with his wife Tilly Reeve, left the mystery to his son Robert to solve
The Ruth Glacier flows down from Mount Denali, the highest mountain in North America
It took three years to get the team together and they settled in Sheldon House, a hut the famous pilot built in 1966 on a rocky nunatak in the middle of the glacier.
Holt, Truffer and researchers Brandon Tober and Michael Christoffersen brought a state-of-the-art radar rig that sent 1,000 radio waves per second into the glacier as they towed it behind a snowmobile.
“Just looking at the data as we collected it, I thought this worked really well,” Dr. Truffer recalled.
Explorer Bradford Washburn believed that a nearby gorge could be even deeper
But as more data poured in, they realized that even thirty years of technological progress had not been enough to solve the problems that baffled the 1991 expedition.
The radio waves simply bounced off the walls and not off the floor.
In the end, it was pure mathematics, rather than radar or explosives, that got to the bottom of the mystery.
They knew how much ice flowed into the canyon and how fast it flowed.
Then they discovered that NASA had calculated how much came out.
Putting the numbers together, they were able to conclude that the gorge plunges from the top of Moose’s Tooth 8,000 feet – more than a mile.
That makes it deeper than North America’s deepest river gorge, Hells Canyon, on the Idaho-Oregon border.
The solution to the mystery was written last week in the Journal of Glaciology, but has only whetted the team’s appetite to discover what other secrets Alaska’s mountains are willing to give up.
Climate change is thinning the glacier by about a meter per year, but it is so deep that at current rates it would take more than a millennium for anyone to see what is at the bottom of the abyss.
Don Sheldon built the glacier shelter that provided the base for his son’s team
The glacier is currently melting at a rate of about one meter per year
The techniques used for their discovery could represent a breakthrough in the study of other glaciers in the unpopulated mountain region
But many other glaciers in Alaska change so quickly that they are unrecognizable from one decade to the next.
“It’s worse than watching a child grow up,” Dr. Larsen said.
The techniques they used for their discovery could provide a breakthrough in research into other glaciers in the unpopulated mountain region.
“Across Alaska, there are just a lot of places where we’re still falling short of those measurements,” Dr. Tober said.
Sheldon, whose family helped map the range, said his father’s friend had another nagging thought about the glacier’s western fork, which he shared before his death in 2007.
“Brad said this to me in a mysterious way when he got much older,” Sheldon told the NYT.
“I feel like it could be deeper.”