It was discovered about a decade ago that cosmic ray interaction with silica and oxygen in quartz produced measurable amounts of the isotopes Beryllium-10 and Aluminium-26.Researchers suggested that the accumulation of these isotopes within a rock surface could be used to establish how long that surface was exposed to the atmosphere.
These samples most likely represent the true age of the moraine.
The implication is that climate during the Last Glacial Maximum was generally synchronous at the global scale.
However, the late-glacial readvance to 95% of the extent of the largest advance during the Last Glacial Maximum at 14.4±0.9 ka is distinctively “Antarctic” in nature.
Spallation reactions occur in minerals in the rocks upon bombardment by cosmic rays.
By sampling the rocks and separating certain minerals (such as quartz or pyroxene) and calculating the amount of these minerals (as a ratio to other, stable, minerals), we can work out how long the rock has been exposed on the earth’s surface.