This is a good time to provide an update on the status of Dr. Marchant’s field work for this field season. In addition to the team’s ongoing research on late Cenozoic climate change, Dr Marchant wanted to reach two specific drilling goals this drilling season: (1) drill to 20 m in 3 locations; and (2) test the new ICDS (Ice CoreA cylindrical section of ice removed from a glacier or an ice sheet using a specialized type of hollow drill. Enter the definition here. Drilling Services) drill.
The drilling began at Site 1 in Mullins Valley where the team surpassed the goal depth of 20 m and drilled to 23 m.
The drilling was relatively easy because at this site the ice is clean. Dave explained that the glacier contains scattered debris further down glacier (sites 2 and 3). The debris is a mixture of rockfall and sand veins, the latter being the vertical extension of sand filled cracks associated with polygons on the ground surface.
I joined the team at Site 2 in Beacon Valley. The team reached a depth of 4 m and hit ice cement - the drilling name for ice-cemented sand veins. After several unsuccessful attempts to penetrate through the ice cement, the decision was made to abandon the hole and move to Site 3 located approximately 30 m south of Site 2.
The team had reached a depth of 8 m on Monday, November 24, 2008 at which time drilling stopped due to equipment failure. This required Tanner Kuhl, the driller, to go to McMurdo to have the equipment repaired. The weather took a turn for the worst in McMurdo, and Tanner did not return to Beacon Valley Camp until Monday December 1, 2008.
Dr. Marchant also excavated numerous soil pits down to the ice in preparation for additional drilling. In one pit he uncovered a volcanic ash layer directly on top of cobble-rich ice (the cobbles represent an ancient rock fall onto the glacier accumulation zone). Based on Dave's past research, the gray volcanic ash at the site is probably around 4 million years old, providing a minimum age for underlying ice. Dave and the team need to drill down though this rocky ice layer to get to pristine glacier ice. This will be the hardest test of the season.
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