An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ice formed over a range of years. Cores are drilled with hand augers or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old.
Ice core sample taken from drill
Mechanical drill head, showing cutting teeth
Sawing the GRIP core
Bubbles in an Antarctic ice sample. Illuminated with polarised light
A core sample is a cylindrical section of (usually) a naturally-occurring substance. Most core samples are obtained by drilling with special drills into the substance, such as sediment or rock, with a hollow steel tube, called a core drill. The hole made for the core sample is called the "core hole". A variety of core samplers exist to sample different media under different conditions; there is continuing development in the technology. In the coring process, the sample is pushed more or less intact into the tube. Removed from the tube in the laboratory, it is inspected and analyzed by different techniques and equipment depending on the type of data desired.
Rock core samples, the product of a diamond rig. A pied butcherbird perches nearby.
Core sampling by hand in a bog in Estonia (2023)
Cut Bakken Core samples
Goniometers are used to measure angles of fractures and other features in a core sample relative to its standard orientation.
