The Commonwealth Glacier flows down into the Taylor Dry Valley. Click to enlarge .

Glaciers in the Desert

January 10, 2002

When I was a high school student, I ordered a photograph of the Commonwealth Glacier in Antarctica from the US Geological Survey. I pulled the image from the envelope and stared in awe at this strange glacier. It seemed to pour out from a narrow gap in the mountains and flow down like thick pancake batter forming a nearly perfect semicircle of white over the dark rocks of the Taylor Dry Valley. The image screamed at me "Glaciers Flow!" Then and there, I decided that I wanted to see the Commonwealth Glacier with my own eyes. This week I did.

A helicopter carried Mary Miller and me into Lake Hoare Camp in the Taylor Dry Valley. On our way to camp, we flew next to the Commonwealth Glacier. I could see the mountains that kept the dry valleys dry: They held back the ice that covered 98% of the Antarctic continent. Some ice managed to creep through the gaps in the mountains and flow into the Dry Valleys. In addition, the mountains themselves caught snow and created glaciers which flowed into the valleys. But the valleys stayed dry, beating the seemingly unstoppable flow of ice with wind; dry katabatic wind pulled down by gravity from the polar plateau, compressed and heated as it roared down toward the coast. The wind evaporated the ice just as fast as it arrived. In one of nature's greatest magic tricks, the glaciers in the Dry Valleys vanish into thin air.

	Ice falls keep the faces of the glaciers vertical. Click to enlarge .

After a welcome briefing at Lake Hoare Hut, I immediately hiked over to inspect the face of the glacier. I had never seen a glacier that ended in a cliff wall like this. The glaciers that enter the Dry Valleys are rimmed by vertical walls over 60 feet high, higher than the five-story Palace of Fine Arts that houses the Exploratorium. As the top of the glacier advances over the bottom in a motion reminiscent of the track on a caterpillar tractor, the face of the glacier gets steeper. As it starts to overhang, it suddenly fails in an avalanche of ice blocks. These blocks evaporate and melt in the sun and wind, leaving a newly steepened glacier behind. This track-like motion of the glacier is unique to polar glaciers.

My excitement grew when Thomas Nylen invited me to join his team on a data gathering expedition to the top of the Canada Glacier. Thomas knew of one place where we could climb up a ramp through the cliff wall. We had to put on crampons and use ice axes to protect ourselves from falling as we climbed to the top.

	Crampon-wearing Virginia Butler and Thomas Nylen inspect a cryoconite hole, while Sarah Tegt measures a stream. Click to enlarge .

Once on the surface of the glacier, I saw two strange things: dark circles and meandering rivulets. The circular holes ranged in size from as small as silver dollars up to the size of children's wading pools. The rivulets rushed along on the surface of the glacier. Virginia Butler, a volunteer on this expedition, told me that these were the cryoconite holes that I had heard about from Professor Andrew Fountain, the leader of this research project. Winds deposit sediments on the glacier, the sediments absorb sunlight and melt a hole in the glacier. The water-filled holes become miniature ecosystems for life. Sarah Tegt, a graduate student of glaciology, said that streams often meandered along the top of polar glaciers while they flowed inside or under temperate glaciers. Polar glaciers have few crevasses to capture the streams. Sarah was measuring the pH and also sampling the water flowing in all of the streams. So we got to explore a vast region on top of the glacier. This was an unusual year. The glaciologists reported that it was the first time in a decade of study that they had seen this much water flowing on the glacier.

At the end of the day my childhood dream had been fulfilled: I had seen the Commonwealth Glacier and climbed upon its sister, the Canada Glacier.

That night in my tent at Lake Hoare Camp, I had new dreams. I wanted to know more about these glaciers and their ecosystems, more about the mountains that created the Dry Valleys, and more about the valleys themselves. Adult dreams are seldom as easily filled as childhood ones. In the morning I woke up and started on my new adventure. I joined Andrew Fountain outside and talked about the experiments he was planning to get answers to my questions. Good science takes time. Perhaps in a few more decades my new dreams will be answered.

field notes