Age vs depth of glacial ice at South Pole

Knowledge of age as a function of depth in glacial ice is important for both glaciology and paleoclimatology. For sites near a ridge or dome, an ice flow model together with information on accumulation rate provides a first approximation. If the accumulation rate is high enough, annual layering of isotopes and dust measured in a solid core can provide a precise age vs depth relationship. For South Pole, the flow geometry is not simple and no deep core exists, Nevertheless, by remotely sensing peaks in scattering and absorption of light from pulsed sources buried at depths down to 2200 m, we have been able to determine age vs depth for ages up to 65,000 years. Analysis of radar isochrons by Siegert and Hodgkins provides a rough extension of the age vs depth model to similar to 165,000 years near bedrock.