DRY CALVING AT THE TERMINUS OF A POLAR GLACIER, TAYLOR GLACIER, MCMURDO DRY VALLEYS, ANTARCTICA

Rapidly retreating tidewater glaciers, which exhibit high flow velocities and calving rates, lose most of their mass through the calving of icebergs and have received significant attention in studies of climate change. Because of the difficult and dangerous nature of studying a calving tidewater margin however, the dynamics that drive calving events are poorly understood. Glaciers such as those found in the McMurdo Dry Valleys, Antarctica are accessible, have low flow velocities, and still demonstrate a calving front. Studies of the glaciers of the dry valleys will give further insight into the nature of glacier calving events.

In 2003 and 2004, five surface stake arrays and two cliff arrays were installed on the lower Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet located in the Taylor Valley, Antarctica. Stakes in these arrays were surveyed using differential GPS and a conventional total station to reveal motion data for the interior and terminus of the glacier. Preliminary results show stake velocities of approximately 2.2 myr^-1 in the down-glacier flow direction and 2.5 myr^-1 in the cliff-ward direction. Down-glacier flow velocities are shown to decrease with proximity to the cliff edge. Ablation measurements at the cliff sites show summer season ablation values from 50-100 cm compared to surface ablation values of 15 cm. Based on field observations and the surface velocities measured near the terminal cliff, these data suggest that ablation plays a large role in maintaining the morphology of the terminus.