Radioactive elements, either of natural origin or created by nuclear testing, can be used to date the layers of ice.
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Ice is lost at the edges of the glacier to icebergs, or to summer melting, and the overall shape of the glacier does not change much with time.
Impurities in the ice provide information on the environment from when they were deposited.
Hand augers can be rotated by a T handle or a brace handle, and some can be attached to handheld electric drills to power the rotation.
With the aid of a tripod for lowering and raising the auger, cores up to 50 m deep can be retrieved, but the practical limit is about 30 m for engine-powered augers, and less for hand augers.
The proportions of different oxygen and hydrogen isotopes provide information about ancient temperatures, and the air trapped in tiny bubbles can be analysed to determine the level of atmospheric gases such as carbon dioxide.