An
ice core is a
core sample that is typically removed from an
ice sheet, most commonly from the polar ice caps of
Antarctica,
Greenland or from high mountain
glaciers elsewhere. As the
ice forms from the incremental buildup of annual layers of
snow, lower layers are older than upper, and an ice core contains ice formed over a range of years. The properties of the ice and the
recrystallized inclusions within the ice can then be used to reconstruct a climatic record over the age range of the core, normally through
isotopic analysis. This enables the reconstruction of local temperature records and the history of atmospheric composition.