A few days ago we reached our main study area in the eastern Amundsen Sea. Here we are using sonar to map the contours of the seafloor in great detail. During the last glaciation the Antarctic ice sheet was much larger and covered most of the continental shelf, an underwater extension of the continent that can stretch for miles. The moving ice gouged marks into the seafloor, and those marks now tell us which way the ice was flowing. By analyzing them, we can reconstruct past ice flow. Our ultimate goal is to understand how the ice was flowing, and how fast it retreated as the earth came out of its last glaciation about 18,000 years ago.
