During Lesley Urasky’s expedition, “Glacial History in Antarctica”, the team collected rock samples which were taken back to the University of Washington to be dated using cosmogenic (exposure) dating. This method of radiometric dating measures the ratio of isotopes of Beryllium (9Be:10Be) produced by the interaction of cosmic rays with minerals in rocks. This lesson will introduce the student to cosmic rays.


Resource Details

Author(s): Lesley Urasky


  • Transparent plastic box (must have flat sides and an open top). Acrylic boxes about 6" x 12" x 6" high work well
  • Aluminum plate, about 5 mm thick, slightly larger than the opening of the box
  • Black felt (large enough to cover the bottom of the container) or black blotter paper
  • Gorilla glue (or other adhexive that is solvent resistant)
  • Black electrical tape
  • Small Styrofoam cooler lid or shallow insulated box
  • Dry ice (approximately 1 lb.), crushed
  • Very intense, concentrated light source (strong flashlight, projector, etc.)
  • 91% Isopropyl alcohol (NOT the 70% commonly found in stores)
  • Insulated gloves (for handling dry ice)
  • Gloves (for handling alcohol)
  • Safety goggles



Completion time

About 1 period

Grade Level

High school and Up


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Physical Science