Glacier Country

Sue and I had both agreed that we wanted to hike on one of the glaciers which is only permissible if you sign up with one of the companies which provide guided tours. Independent hiking on the glaciers is forbidden unless you are experienced due to the dangers involved. After a little research, we decided to hike on the Fox glacier and to walk around the Franz Josef glacier the following day. Due to the very high chances of rain (it is the West Coast, after all and every day has a high chance of rain), we made our bookings from Christchurch, but planned to allow two extra days in the area just in case we were rained out the first day. Luckily, it turned out that we chose a very nice day to climb and we were rewarded with only clouds in the afternoon.

The Maori name for Franz Joseph glacier is Ka Roimata o Hinehukatere (the tears of Hinehukatere) which comes from the Ngai Tahu legend that Hinehukatere loved climbing in the mountains and persuaded her lover, Tawe to climb with her. He fell to his death while climbing with Hinekukatere, and broken hearted, she cried tears that formed the glacier.

The Fox and the Franz Josef glaciers both have their start in the peaks of the Alps and are only about 25km from each other. The clouds that pass over the Tasman sea, accumulating water along the way are forced to rise over the Southern Alps, thereby cooling and dropping most of their moisture as rain and snow. This process causes approximately 9 metres of snow to fall on catchment area of the glacier every year. Although some of the snow is evaporated, a lot of it remains from year to year. Each year, new layers of snow bury and compress the older layers. Over time, the layers of snow are subject to repeated freezing and thawing, which changes it into a form of granular ice called névé. Gradually the grains grow larger and the air pockets between the grains get smaller, causing the snow to increase in density and to fuse into denser firn. Over a period of years, layers of firn undergo further compaction and become glacial ice. Over time, larger ice crystals become so compressed that any air pockets between them are very tiny. In very old glacier ice, crystals can reach several inches in length. For most glaciers, this process takes over a hundred years.

The lower layers of glacial ice flow and deform plastically under the pressure, allowing the glacier as a whole to move slowly like a viscous fluid. Glaciers usually flow downslope though they do not need a slope to flow because they can be driven by the continuing accumulation of new snow at their source. The upper layers of glaciers are more brittle, and often form deep cracks known as crevasses or Bergshrunds as they move. Although much melt occurs from the surface of the glaciers at lower elevations (the ablation zone), this high snowfall continues to push ice down the valleys at very high rates. This is aided by basal sliding, caused by a layer of water beneath the glaciers, formed by the weight of the ice pushing against the valley floor. Both of these factors cause the Franz Josef and Fox Glaciers to have flow rates that are up to 10 times faster than most valley glaciers.

As the glacier moves down the valley, it expands or contracts in width to match the shape of the section of the valley through which it is passing. When the valley is wide, the ice expands to fill the gap. When the valley is narrow, the glacier is squeezed together. As the parts of the glacier move at different speeds and directions, shear forces cause the parts to break apart opening crevasses to form all along the disconnecting faces.

At the end of the glacier, called the foot or the terminal, is the deposition or ablation zone, where more ice is lost through melting than is gained from snowfall. Glaciers which are retreating have a very shallow terminal face. The Fox and the Franz Josef glaciers are advancing and so have a very steep terminal faces which are high cliffs of ice. The terminal face of the Fox and the Franz Josef glaciers are located at a height of 200m above sea level and are only a few kilometers from the ocean. There is only one other glacier that is so low in all of the world and that one is located in South America. What makes the Fox and Franz Josef glaciers even more amazing is that the surrounding valley is covered with vegetation that grows in a warm, wet climate. We had to hike through the woods to get to where we would ascend onto the glacier and it was hot! We were wearing shorts and t-shirts, walking through rainforest and just a few meters away was a massive chunk of ice.

The sides of the surrounding valley were covered with low bush from the height of the glacier up to a noticeable point on the valley wall. Above this point, the low bush gave way to taller trees. This dividing line between the low bush and tall trees marks the height where the glacier had been at one time. It can take hundreds of years for trees to grow back from the soil after a glacier retreats which is why no trees yet grew where the glacier had been.

The Fox and Franz Josef glaciers are advancing so quickly that rock and debris from the valley walls don’t have time to accumulate, leaving the glaciers white and blue in color. When light strikes the surface of the snow, it is reflected back without any preference for a particular color which is why white can be seen, but what about the blue color? When light is not reflected, but penetrates the ice, more red light is absorbed than blue light. Not much more, but enough that when light passes through a meter or more of ice, light which reemerges from the snow layer tend to be made up of more blue light than red light.

Glaciers are constantly advancing and retreating, held in delicate balance by the accumulation of snow gained in the upper glacier and ice melting in the lower part. An increase in snowfall at the nevé will result in the glacier advancing. Correspondingly, a faster melt will result in the glacier retreating. Overall the Franz Josef and Fox glaciers have been advancing since 1985, (sorry Al Gore). Our guide told us that the Fox glacier is advancing at a rate of meters a day which means that if you sit and wait long enough, you will see ice fall off of the terminal face.

When we arrived at the Fox glacier, we were told that huge chunks of ice had just broken off of the terminal face, resulting in a cave opening and ice being strewn about in the river flowing out from under the glacier. At the lower levels, the glacier receivers about 3m of rain annually. The remaining 80% of the water flowing out from under the glacier is due to melting ice. There was a lot of water flowing away from the glacier, yet the glacier still has enough ice to continue advancing which may give you an idea as to how massive it is. The water in the river is a dark grey color due to the high amount of glacier flour in the water (rock that has been ground by the glacier).

The ice on the terminal face and on the glacier itself is highly unstable. Crevasses open and close and the flowing water under the ice can open caves resulting in ice that looks stable, but is actually ready to collapse. There are signs around the terminal face warning people not to get too close to the ice, but the signs are routinely ignored. Our guide told us that it was just a matter of time till someone is killed by the tons of ice that fall off of the face. At the time that this email was written, the Christchurch Press is carrying a story of two Aussies who climbed into a cave on the terminal face of the Franz Josef glacier just before tons of ice collapsed onto them. The headline in the newspaper reads: “Two "bloody stupid" tourists are lucky to be alive after ignoring warnings and crossing two safety barriers designed to stop them venturing into an unstable ice cave at the face of the Franz Josef Glacier.” They had to be rescued by guides who were leading people up the glacier, but left their groups to rescue the tourists.

The valley below the glacier is mostly rock and scrub brush. Our guide told us that under the dirt below the terminal face is “dead ice”, ice that broke off of the glacier when it last retreated, but still remains intact under the ground. The sides of the valley below the terminal face are steep and littered with large boulders ready to fall. As evidence of this, there were gashes through the vegetation on the valley walls where massive boulders had come crashing down through the trees to land in the valley floor below. At one point during our walk to the glacier, we had to pass through an area prone to landslides where we had to walk in small groups, presumably so that we would have room to run if a landslide occurred. Not a very stable area!

Sue and I were in different groups because she was doing the half day walk and I was on the full day walk. Both groups were issued boots and raingear if we wished. I tried to wear my own boots, but unfortunately the special crampons that we were issued would not fit on my own boots. However, there were boots and socks to borrow.

Both hikes started with a bus ride from the town of Fox Glacier to the Fox glacier parking lot where we started our walk. The terminal face was too dangerous to ascend and so the guided groups walked through the rainforest for a mile or two to get beyond the crevasses that had formed near the terminal face. Our hike took us over streams and up the side of the valley. We had to climb up a ladder for about eight feet and there were chains to hold onto to prevent accidents. My group stared after Sue’s and we wound up passing a woman at the ladder who took one look at it and had given up. Unfortunately she and another woman who had given up at the very edge of the glacier caused huge delays for my group because we could not proceed until a guide went up to fetch them and to bring them back. So we wound up just sitting for a half an hour while all that occurred. By the time that my group finally got on the glacier, Sue’s group was already climbing down off of the ice.

At the edge of the ice, my group was issued our crampons and poles with spikes on the end to use on the ice. The crampons were not the usual kind with spikes all around the boot, but instead with spikes just extending from the middle of the boot. We were told to walk with our feet wide apart to prevent the spikes from tearing the bottom of our trousers which we had tucked into the tops of our boots. We also needed to walk with short strides to ensure that the spikes of the crampons dug into the ice. Long strides where you walk heel to toe might result in the spikes going in at an angle, resulting in a loss of grip of the ice.

The start of the full day hike was the same as the half day and we had steps cut into the ice to follow. Our guide walked ahead of us, swinging his ice axe at the steps to ensure that they were stable and to clear off melted slush so that we walked on solid ice. The guide would continue to test the ice during the entire time on the glacier because the tops or bottoms of crevasses over which we walked needed to be checked for stability. There could be hollows under the crevasses which could give way under our weight. Often, the tops of the crevasses were cut off and the debris packed into the bottom to build a more stable floor for us to walk upon. So my group of about 12 people would walk a meter or two, the guide would swing his axe a few times and then we would walk another meter.

My group continued on past where the 1/2 day group turned around and onto areas where there weren’t nice steps cut for us to walk up. There were a few places where we had to use our hands as well as our feet to climb up the ice, but overall it was easy going because we were on a tried and tested route over which other groups had passed. We stopped for lunch on the glacier around noon as clouds began to settle in over the valley. The guide explained that the huge chunk of ice in the middle of a rain forest resulted in the clouds as moisture evaporated from the forest. As we continued on, people in our group were talking and I wound up talking with a couple from Tel Aviv. It turned out that they knew an engineer at Black & Decker and after they described him, I figured out who it was.

The photos of the glacier tours often include images of people walking through caves of blue ice. I had hoped to see one of these during our hike, but the closes thing to one of these that I saw was a shallow opening in which we could stand to get our photo taken. I am really glad that I did the full day walk because I think that I would have found the half day to be too short. But at the end of the full day, I was happy to get back to take those horrible, borrowed boots off of my feet!