Just above the cutting head, a drill barrel will hold the ice core. The equipment shown here is for cores 10 cm in diameter, the standard for most ice drilling. At GISP2, 13.2 cm cores were drilled. Photomicrograph in cross-polarized light of ice sample from 333 m depth in the GISP2 core. Mid-sized crystals show homogeneous ice that has not been sheared by ice flow.
Small bubbles appear as round inclusion, for example in the orange crystal near center.
Record of electrical conductivity from the GISP2 ice core, Summit, Greenland. The record shows annual variations for a portion of the mid-1600s. Electrical conductivity is especially sensitive to ice acidity. The major peaks represent volcanic eruptions known from the historical record. Since 1972, Russian scientists have been drilling into the ice sheet.