Cesty do hlubin zamrzlého času Journeys into the depth of frozen
time by Petr Pokorný. Cores through the polar ice sheets provide
a remarkable record of past environmental conditions. Ice coring
evolved as a specific science since 1960s through pioneering
effort of scientists from USA and other nations. Snow
accumulating on polar plateaus of Antarctic and Greenland does
this in a regularly ordered fashion that preserves a
stratigraphic sequence accessible by drilling vertical borings
into the ice. Collecting these cores is a specialized
engineering challenge. Because ice is a deformable material, and
flows, ice coring locations must be chosen carefully to extract
the most reliable information. Deep cores require large
equipment, and fluid-filled boreholes to avoid freezing and
collapse of the hole. The deepest cores are collected during
multi-year campaigns and provide views more than 700 000 years
deep into the past.