Earth Science

This is our last glacier day of the trip. We visited the terminal face of the Fox Glacier, where we again made a short GPS survey, keeping about 10 metres in front of the ice. A large part of the ice front is high and unstable, making it a very hazardous to go near. Following our brief visit we headed North and home, and that was the end of our real life geology and glaciology adventure. Here is our video of the expedition:

We packed early, walked down to the road and drove up to Franz Josef for a look at the lower part of the glacier. Brian had two 4 metre ablation stakes which needed to be redrilled and inserted deeper in the ice. We also wanted to record the position of the terminus with the GPS. The glacier is spectacular at any time. Walking towards it we had to negotiate a boulder field of flood debris. The true left of the glacier is covered with rock. This was from a time when dammed up water within the lake had burst out in a spectacular flood, spreading the debris all over the surface. Because of the debris cover, this part of the glacier has been protected from melting and has remained more or less static for a number of years whereas the true right of the glacier which has no rock cover, is retreating quite rapidly Jake is using a hand drill to make a hole for inserting an ablation stake on Franz Josef Glacier

Yesterday was a bad weather day which we spent mainly in the hut. Brian Anderson joined us in the evening. He is a glaciologist at the Antarctic Research Centre at Victoria University Wellington and has been studying the Brewster Glacier for several years. This morning we hiked across to the glacier again. While Brian went to check the stream gauge, I took the students along the front of the glacier with a GPS to mark its position. We kept a few metres of clearance from the ice as there were places where large blocks had fallen quite recently. Then we all roped up and walked the length of the glacier to look for the highest ablation stakes in the network. A couple were missing, but number 18 – right at the top, was there, melted out by 5.2 metres, a record for this altitude. On the way down we gathered as many stakes as we could. They will be redeployed again in the spring. It was fun trying to negotiate our way around the crevasses. By 6pm we were again off the ice.

Today we left the hut at 9 am and hiked 200m higher and then horizontally leftwards (North) to the glacier. The weather was fine and by midday we were roped up to step off the rock onto the ice. Initially this is a bit hazardous as the ice is undercut and could potentially break off right where you are standing. Soon however we were established on the centre of the glacier snout, a couple of hundred metres above the ice cave at the terminus.. Our job was to measure the length of a network of plastic stakes (ablation stakes) that had been inserted into the ice in November last year. This gives information on the amount of melting of the ice surface over the summer months. The data is combined with information from a weather station that is set up nearby and allows an analysis of the factors that effect the annual mass balance of the glacier over time. We found that most of the 6 metres stakes had melted out of the ice by 5 to 5.5 metres. Some of them had melted out completely and were found lying on the surface or in shallow crevasses, and some remained unfound. I was quite amazed at the condition of the ice this year. Normally the previous winter snow would cover the slopes from about one third or one half of the way up the glacier. This time there was hard ice all the way up the slopes to the peak of Mount Brewster, and instead of smooth snow the surface was broken up by numerous crevasses.By 4pm we were back off the ice. We explored the glacier margin and checked out the terminal ice cave. There are fantastic glacial landforms in front of the ice terminus. As the ice has retreated it has left behind all sorts of randomly scattered boulders, scratched rock slabs and sculpted pot holes in the bedrock. At 7pm we were back in the hut.

This morning we got up early to have a close up look at the Tasman Glacier Lake. The icebergs had moved a lot since my visit a month ago, but I could still recognise some of the bigger ones. We scrambled down the moraine below the viewpoint and walked along the edge of the lake for a while. The third photo shows a view along the Tasman Glacier terminal moraine that provides the dam that creates the lake. A collection of icebergs had gathered next to it. They will slowly shrink in size and final flow away down the river towards Lake Pukaki. The debris of a glacier, transitioning slowly from the mountains to the sea floor… After our walk we got back in the car and headed to Haast Pass and the start of the track to Brewster Hut. A steep 2 hour uphill hike with heavy packs saw us at the hut with several days of food and all the personal gear needed for a few days work on the glacier.

This trip to the glaciers involves 3 students from Raphael House Rudolf Steiner School in Lower Hutt. We are going to help with some glacier monitoring at the Brewster Glacier near Haast Pass, with a brief visit to Mount Cook village on the way, and a short stop at Fox and Franz Josef Glaciers on the way back. Left to right in the photo is Elwin, Lucianna, Jake and Eric. The students are each doing year 13 projects. Jake Smythe is focussing on climate change, Elwin Burger is interested in landscape photography and Lucianna Howell – Kress is researching bush and mountain safety and survival. Assisting us also is Elwin’s father Eric Burger.  After catching the night ferry to Picton, we arrived in Mount Cook village in time for a steep walk up the Mueller track to the ridge just below the Mueller Hut. The view is spectacular, looking straight across to the East Face of Mount Sefton, as well as up the Hooker Glacier to Mount Cook. We were able to see the whole range of glacial landforms from proglacial lakes to moraines, steep alpine faces with icefalls and crevasses. While we were watching there were several large avalanches thundering down the big rock wall on Mount Sefton.