Ice Caves, Crevasses, and Moulins: Amazing Frozen Features of Mendenhall Glacier
By Juan Ramirez
January 2018
“The most dangerous part of the ice cave is the entrance,” said our guide as she pointed up at ice overhanging it. Chunks the size of mini-fridges littered the opening, proof that it could collapse at any moment the glacier chooses. This was how I first realized that this wasn’t going to be any old regular excursion. We were going to trek on a glacier and get to see some stuff that was breath-taking, not only because it was beautiful, but because we were going to get into some areas that made me a bit nervous!
Our guide enters the cave first, and while keeping an eye out for any falling ice, she ushers us in one at a time. The inside of the cave is amazing. Everything is colored in a deep blue, a stream flows through the center of the cave and we walk through it in waterproof boots that were given to us at the start of the tour. The ice is sculpted out as it melts into water, and we get to spend about half an hour exploring the cave and taking pictures.
Exploring the blue ice caves of Mendenhall glacier
The ice cave forms as water melting off the glacier rushes through cracks in the ice. This further melts the ice, and eventually, it gets wide enough that a person can enter and explore the cave. It goes from a crack in the ice, to gorgeous cave, to its ultimate end when it collapses as it is unable to support itself, over the course of months. It is incredibly difficult to predict when and where the next one will open up, and finding one that is easily accessible is even harder. This makes the Ice Caves an extremely rare jewel of a feature on the glacier. However, the guides will always do their best to find one that is safe to enter for their guest. While the Ice cave was definitely stunning, it wasn’t the only amazing feature we saw that day.
We exited the rear of the cave and after some snacks, our guide got us ready to walk onto the glacier itself. What they gave us included a safety harness as a precaution, a pair of micro-spikes for better traction on the ice, and a briefing on how to safely walk on the glacier. Trekking across that glacier was one of the most unique experiences of my life. It is like being on another planet. Mountains of bare rock stand straight up from the sides, while the glacier itself flows down from the Juneau Icefield for 14 miles. It stretches off into the distance, with crevasses and spires of ice covering the landscape.
The glacier is made up of two layers, a brittle top layer much like the ice you’re used to seeing, and a extremely dense bottom layer that moves more like plastic because of the thousands of tons of ice above it. As the bottom layer flows downhill, the top layer cracks open and forms deep crevasses that are sometimes hundreds of feet deep. It is awe inspiring and on cloudy days, the deep blue color really stands out. The crevasses don’t stay still. Over the course of months, they will open up and fuse shut as the glacier makes its way downhill. The glacier is incredibly dynamic, constantly changing throughout the year. You could come every day and see something new, which also means there is no best time of year to visit, because there is always something amazing happening on the ice.
Our guide leads us to what looks like a giant hole in the ice. She takes her ice axe and slams it down into the ice so that it sticks out standing straight up. “This is a moulin,” she says. “It is formed in a similar way as the ice cave earlier. As water flows off the glacier it carves out a conduit as it seeks the path of least resistance. While this is happening, the glacier continues to flow downhill, distorting and shaping the moulin. If you could take a cross section of the glacier, you would see that it is full of holes like Swiss cheese. They are also incredibly dangerous, there is no promise that if you fall into one that you will be able to come back out somewhere.” She points down to the ice axe,” Do not come past this ice axe until I tell you to. I will never ask you to do something that you are uncomfortable with, but if you want to, we are going to do something really fun.”
She proceeds to drive massive screws into the ice at the edge of the moulin, and set up a rope system attached to them. Then one at a time, she secures our harness to the ropes and we hang off of them over the moulin so we can peer into it. It’s a great blue hole getting darker and darker as it goes deeper and curves away from me. The sound of rushing water echos as it falls into the depths.
This was my introduction to ice climbing. For those who are more adventurous, ABAK offers longer, private glacier tours where guests get to use ice climbing equipment to explore accessible moulins, or to climb steep crevasses. It is well worth the price for the personal experience and the extra gear provided includes mountaineering boots, full crampons, and a guide who is experience in ice climbing.
This was my experience on Mendenhall Glacier, and for you it will be different. One of the amazing things about the glacier is that it is constantly changing and so everyone who visits will have a unique experience. It is an unfortunate fact that the glacier is currently receding at a rate of about 50 feet a year. Since the year 1500, it has retreated 2.5 miles, ¾ of that retreat (about 1.75 miles) has occurred in just the last 100 years, and the rate at which it is retreating is accelerating.
It was once possible to simply park at the visitor’s center and walk up to and touch the glacier. Now the only way to get to the glacier is by an hour long canoe ride, a 2 hour hike through dense temperate rainforest, or by helicopter. Every year the glacier becomes more difficult to get to, and scientists predict that within a decade the glacier will no longer reach Mendenhall Lake, but hang far above it.
How I wish I could have seen it 100 years ago when it had so much ice that it spread out across the valley, but, how lucky I feel to experience it now and its awe inspiring beauty. It is like a grand cathedral of ice, which offers a unique experience to every patron that passes beneath its doors. Hallowed halls built of snow and shaped by climate where we can pay our respects to the power and fragility of Mother Nature.
