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All sediments and soils contain trace amounts of radioactive isotopes of elements such as potassium, uranium, thorium, and rubidium.
These slowly decay over time and the ionizing radiation they produce is absorbed by mineral grains in the sediments such as quartz and potassium feldspar.
This information is vital for numerical models, and answers questions about how dynamic ice sheets are, and how responsive they are to changes in atmospheric and oceanic temperatures.
Unfortunately, glacial sediments are typically difficult to date.
The significant improvement of the OSL dating method in recent years makes it applicable to objects ranging in age from 0 to 150 000 years (in some cases to 300 000 or more) with a typical accuracy between 5 and 10%.
When compared with the radiocarbon method it makes possible dating objects containing no organic matter or originating in periods for which the radiocarbon method is less accurate due to the shape or lack of the calibration curve.
There are so many other methods of dating Quaternary sediments and organic material that it is impractical to cover them all here in detail.
The sediments can be compared to palaeo magnetostratigraphic data, and this can be used as a proxy age determination.
Luminescence dating refers to a group of methods of determining how long ago mineral grains were last exposed to sunlight or sufficient heating.
Optically Stimulated Luminescence dates the radiation accumulated in quartz or feldspar grains within sand.
The radiation emanates from radioactive grains within the sediment, such as zircons.