17 November, 1999
As I crouch inside this cavern with its beautiful, diffuse blue light and delicate ice crystals dangling from the ceiling, I can't help but think back on the course of events that brought me to this place. Two years ago making application for the TEA program; the waiting and anticipation; getting word from the head of the NSF Division of Elementary, Secondary, and Informal Science Education (ESIE) Wayne Sukow that I had been selected. The planning, the school visits, the apprehension. Meeting with John Wrenn and the training at LSU. And, then the travel. Appleton to Los Angeles, then to New Zealand; the C-141 flight to McMurdo; then an hour helo flight to Cape Roberts. Finally, a bumpy, hour-long traverse across the frozen Ross Sea in a Haggland has brought me to this place. I find myself inside an ice cave at the front of the Wilson Piedmont Glacier on the coast of the Antarctic Continent. My companion, Wojciech, and I have made our way into a small ice cave. The cave has no footprints in it. We may be the first persons to enter this parcticular cave. It is quite exhilarating.
Ice caves are formed by melt-water inside of a glacier as it runs toward the sea. The running water carves a tunnel in the ice. The tunnel may get so big that it becomes a cave. The largest of the ones we explored was about 20 feet across and 15 feet high and extending back into the glacier about 50 feet or so. We also crawled into some very small, delicate caves as well.
The light inside the cave comes from the sun passing through the blue glacial ice. In ice caves the ice is so compacted that it looks blue. The color is due to how the light interacts with the frozen water. Loose and compacted snow has a lot of air bubbles in it. As light passes through it, it appears white because of the presence of the air bubbles. (See diagram below) A blue tone indicates that the pressure from overlying ice and snow essentially has eliminated the air bubbles in the ice. The less air bubbles the bluer the light will appear as it passes through.
Inside the surfaces of the ice caves there is a coating of very delicate ice crystals. Some of the individual crystal are quite large (.5cm or larger). However, if you touch them or accidentally bump the side of the cave, the crystals disintegrate into a shower of fine snow. It is just a marvelous sight. These ice crystals forming a white deposit, called hoar, results from moisture recrystalizing from the air inside the cave.
Ice caves can be dangerous. Glaciers are dynamic places. The ice is under stress and is moving. There is often an overhang of snow at the entrance to the caves. We took precautions when entering the caves. We never went alone and there was always someone around to help in case of a problem. I am glad I had the opportunity to explore such a magical place. It was truly an awesome experience.
Here is an update on the Cape Roberts Project. The drillers have reached almost 900 meters. The scientists have been confronted with a big surprise. They have drilled into rock that they did not expect to find. This is true exploration. The geologists of the CRP hypothesized as to what they would find when they drilled into the seabed of the Ross Sea. They thought they would find rocks of the Oligocene epoch then below that rocks of the Eocene epoch. Instead, they have drilled into rock that is found in outcrop in the TransAntarctic Mountains that is much older then the rock they expected to find, perhaps Devonian in age. They are not sure why this rock is where it is. Many ideas have been discussed, but it is clear to me that in the process of unraveling this mystery, the geologists will learn a lot that they don't now know about the geologic history of the Transantarctic Mountains and the continent of Antarctica. This is science at work. I will keep you updated as the story unfolds.
Today's featured CRP Team members are a group of Italian petrologists. They are Franco Talarico and Soyna Sandroni both from the Earth Science Department at Siena University and Massimo Pompilio from the Institute of Volcanology in Catania, Italy. This group of geologists is studying the rock fragments, or clasts, that are imbedded in the sedimentary rocks in the core. By determining the age and type of clasts, they can make a determination about the nature of the area surround the place where the rocks were deposited. So far, they have examined over 20,000 clasts!
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