3:30–4:30 pm MCP 201
Earth’s atmosphere and surface is constantly bombarded by galactic cosmic rays. The cosmic ray secondaries produce rare nuclides in the upper several meters of Earth’s crust. These radionuclides, including 10Be and 26Al, serve as tracers of exposure to cosmic rays. Their concentrations in materials can be used to gauge exposure durations, burial epochs, and erosion rates. Bedrock and sediments under the Greenland Ice Sheet archive exposure to cosmic rays, and subsequent burial. Advances in accelerator mass spectrometry have enabled high-precision measurements of 10Be, most notably 26Al, in materials collected retrieved from under the Greenland Ice Sheet. The concentration of these cosmic-ray-produced nuclides provides valuable information of the extent of the Greenland Ice Sheet over the last 1.5 Myr.