Explorers have discovered more than a mile of caves underneath a glacier on Oregon’s Mt Hood. They’re the largest known glacier caves in the U.S., outside Alaska.
A survey team is using the caves to measure how much the inside of the glacier is melting each year. It’s a dangerous work, but it could reveal that some alpine glaciers are shrinking faster than anyone realized.
Visit the full digital story: Thin Ice: Exploring Mount Hood’s Glacier Caves
This story of exploration has a modern beginning. Two years ago, Eddy Cartaya got a call from his friend Brent Mcgregor, who told him to watch a video on YouTube. “We were both crazy about caving. We were both mountaineers, we both liked ice climbing and snow climbing,” Cartaya said.
The video showed a hiking group standing inside a cavern of ice. It appeared to be a newly discovered cave on Mount Hood. Brent McGregor says he knew his friend Cartaya wouldn’t be able to resist going to look for it.
“Anything I basically dare him to do, he’ll do. If he knows he isn’t going to die doing it …” McGregor recorded their search for the cave on his camera. On the Sandy glacier, he spotted something that looked like a crevasse, and wiggled into it.
The crevasse opened into a cave inside the glacier 80 feet wide. And that cave was just the beginning. McGregor and Cartaya returned to the glacier with wetsuits, ropes, and ice screws, and found more than a mile of passages.
This next part might sound strange, if caving isn’t your hobby, As they explored, they measured the height and width of all the caves they found.
Surveying and making maps is part of caving culture, Cartaya says. “It’s that sense of discovery. Documenting something that’s never been documented, it probably is the driving force of cavers.”
This summer, the cavers returned to the glacier to make a new edition of their maps, and to measure how much the caves have grown. They invited me along.
The Sandy glacier flows down a steep canyon on the north side of Mt. Hood. Cartaya and McGregor set up a base camp of colorful tents and for the volunteers from Portland Mountain Rescue who are helping them with their survey work.
Cartaya led us to a cave named Pure Imagination just a short walk from camp. “You probably want to stow your sunglasses about now. Helmets on, lights on,” he said.
We wore helmets to protect us from falling rock and ice. Cartaya told us to follow closely behind him.
“In some of these caves a broken ankle is a fatal injury. Because of hypothermia, if you can’t crawl out, you’re dead from exposure,” he explained.
The entrance to Pure Imagination is a hole in the snow just large enough to duck into. A strange, cold wind starts blowing as soon as we step inside. A stream rushes by with a deafening roar. For a while, we walk through a white tunnel. The stuff above our heads is called firn. Its snow that’s being compressed into ice over time. The natural light fades and we travel by the breams of our headlamps. Cartaya points at the wall with his ice ax.
“This is glacial ice here. It’s dark, it’s dirty. Very compact ice there.”
I asked, “So this is really, right where the glacier starts?”
Cartaya said, “Yes, this is literally the toe of the glacier. You’ll see firn and glacier mixing up together for the next hundred feet, and then it will become all glacial ice.”
Cartaya leads the group deeper into the glacier. The cave seems endless, large enough to drive a train into.
The walls are milky white, broken by ribbons of bright blue ice. Those are places where rain fell on the glacier years ago and then froze.
We rope up to climb past a steep waterfall. At this point, we’re under ice ten stories thick. And I’m pretty sure Indiana Jones never got to do anything this much fun.
“We just descended a waterfall in a glacier cave. Whooooo,” I said.
But while I’m feeling euphoric, Cartaya is thinking about all the survey work he has to do.
“We’ve got two new shafts, we’ve got to take width and height measurements all through the cave. It’s grown way more than we expected,” Cartaya said.
Most glacier caves are seasonal. They form during the melting season. And disappear in the winter, crushed underneath the weight of the ice.
But the caves in the Sandy Glacier appear to be growing larger every year. And as they grow, the glacier shrinks.
Cartaya wants to measure exactly how much the caves have grown.
“With more warm air getting in, the speed of the melting is definitely increasing. This could be an important insight into how these glaciers are decaying,” explained Andrew Fountain. Fountain is a Glaciologist with Portland State University.
Scientists like Fountain study how much ice glaciers gain or lose every year. One common approach is to set up stakes on the surface of a glacier to measure how much it melts. But Fountain says what scientists don’t know is how much the inside of a glacier is melting. They’ve never really had a way to look.
”What we don’t know is what’s happening underneath the glacier. Because we have no really easy or direct way of doing that, other than the studies Brent and Eddy are doing, looking at the enlarging size of the caverns,” he said.
Fountain says glacier mass balance is a very good indicator of long term climate change. In the Northwest, nearly every glacier is loosing ice. The sandy glacier has shrunk by about 50 percent in the last 100 years.
He predicts that little of the Sandy Glacier-or beautiful caves under it —will survive.
“As air temperatures continue to warm, we expect these glaciers to continue to retreat. What is now a small glacier just might be a very tiny remnant, high up on the mountain.”
Eddy Cartaya knows the glacier caves will disappear someday, maybe soon. And that’s part of what motivated him to try to keep track of how fast the inside of the Sandy glacier is melting.
“These are short lived treasures, and once their gone they’re gone forever, they’ll never be back.”
Cartaya says on the one hand, it’s exciting someday his maps could be part of scientific record. On the other hand, watching the caves melt is kind of like losing a friend.