Half-lives are given in each box

Carbon dating glaciers

Uranium-series uses the decay of uranium and thorium isotopes U, U and Th in calcites in particular, such as stalactites and stalagmites in caves. In addition to yearly layering, individual strong events such as large-scale volcanic eruptions can be observed and correlated between ice cores.

Several hundred thousand measurements are

Scientists have extended this calibration even further. If the samples are beyond the range of radiocarbon e. This allows the dating of these materials by their lack of thorium. So for ages to appear longer than actual, all the half-lives would have to be changing in sync with each other.

Optically Stimulated Luminescence dates the radiation

This starts the dating clock. During the ice age, long-lived trees grew in different areas than they do now.

Optically Stimulated Luminescence dates the radiation accumulated in quartz or feldspar grains within sand. Several hundred thousand measurements are sometimes made for a single technique on a single ice core. From then on, the ratio of radiocarbon to stable carbon will decrease, because the unstable radiocarbon atoms will slowly decay. Essentially all of these strongly favor an old Earth.