An explorer’s intuition has been spectacularly vindicated almost a century later by a team of scientists determined to discover the truth in the wild and inhospitable mountains of Alaska.
Ruth Glacier descends from the highest mountain in North America carrying megatons of compacted ice between the vast granite ridges of Denali National Park.
Explorer Bradford Washburn and pilot Don Sheldon were among the first to see it when they flew over the area in 1937.
The couple was amazed to realize that at one point the glacier forces its thousands of years of accumulated snowfall across a pass just a mile wide.
Ninety-seven years later, Sheldon’s son Robert and a team of scientists discovered that the gorge under the ice is deeper than the Grand Canyon and, in fact, the deepest in North America.
“Not only do you have this incredible landscape above you, but you also have an equally incredible landscape buried in ice below you,” scientist Martin Truffer told the New York Times. “That’s something I’ll never quite get over.”
The mystery of Denali National Park’s Great Gorge has finally been solved
Scientists Jack Holt of the University of Arizona (left) and Martin Truffer of the University of Fairbanks were among those who established that it is the deepest in North America.
It was in 1991 when scientists made their first attempt to understand what was beneath their feet beneath the summit of Mount Denali.
Around them stood the jagged granite ridges of Moose’s Tooth, Bear’s Tooth, and Eye Tooth standing guard over the ice field below.
The group, including Fairbanks geophysicist Chris Larsen, got to work with ground-penetrating radar, but found that the gorge was simply too deep to measure.
And the data that emerged was hopelessly compromised by echoes bouncing off the sides of the steep ridge.
The following summer they returned, this time armed with explosives that they hoped would send vibrations strong enough to reach the bottom and return to the top.
They reported their findings after tentatively estimating that they were on about 4,000 feet of ice and that nearly 9,000 feet separated the summit from the ground.
But the scientific community was not convinced, and 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 mount an expedition that would finally solve the mystery that had intrigued his father.
“Let’s do this once and for all,” Robert told the New York Times, to honor “the legacy that both my father and Brad left behind.”
Don Sheldon, pictured with his wife, Tilly Reeve, left the mystery for his son Robert to solve.
Ruth Glacier descends from Mount Denali, the highest mountain in North America.
It took three years to assemble the team and they settled at Sheldon House, a cabin built on a rocky nunatak in the middle of the glacier by the famous pilot in 1966.
Holt, Truffer and researchers Brandon Tober and Michael Christoffersen brought state-of-the-art radar equipment that sent 1,000 radio waves per second to the glacier while towing it behind a snowmobile.
“Just looking at the data as we acquired it, I thought this was working really well,” Dr. Truffer recalled.
Explorer Bradford Washburn sensed that a nearby gorge might be even deeper
But as more data came in, they realized that not even 30 years of technological progress had been enough to solve the problems that confounded the 1991 expedition.
The radio waves were simply bouncing off the walls and not 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 entered the gorge and how fast it flowed.
Then they discovered that NASA had calculated how much it cost.
Putting the numbers together allowed them to conclude that the gorge plunges 8,085 feet from the top of Moose’s Tooth to the valley floor, more than a mile and a half.
That makes it deeper than the deepest river gorge in North America, Hells Canyon, on the Idaho-Oregon border.
The solution to the mystery was published in the Journal of Glaciology last week, but it has only whetted the team’s appetite to discover what other secrets the Alaskan mountains are willing to reveal.
Climate change is thinning the glacier by about a meter a year, but it is so deep that, at the current rate, it would take more than a millennium for anyone to see what is at the bottom of the abyss.
Don Sheldon built the shelter on the glacier that served as the base for his son’s team.
Currently, the glacier is melting at a rate of about one meter per year.
The techniques used for its discovery could represent a great advance in the study of other glaciers in the depopulated mountain region.
But many other Alaska glaciers are changing at such a rate 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 represent a great advance in the study of other glaciers in the depopulated mountainous region.
“Across Alaska, there are many places where we are still missing those measurements,” Dr. Tober said.
Sheldon, whose family helped map the mountain range, said his father’s friend had another bothersome thought about the western fork of the glacier he shared before his death in 2007.
“Brad told me this mysteriously, as he was getting a lot older,” Sheldon told the NYT.
“I have a feeling it could be deeper.”