Start Compare and contrast radiocarbon dating and thermoluminescence

Compare and contrast radiocarbon dating and thermoluminescence

In East Asia and Siberia, the same unit is split into Alexian, Atdabanian, and Botomian stages.

For example, the boundary between the Cretaceous period and the Paleogene period is defined by the Cretaceous–Paleogene extinction event, which marked the demise of the non-avian dinosaurs and many other groups of life.

Older time spans, which predate the reliable fossil record (before the Proterozoic eon), are defined by their absolute age.

The geology or deep time of Earth's past has been organized into various units according to events which took place.

Different spans of time on the GTS are usually marked by corresponding changes in the composition of strata which indicate major geological or paleontological events, such as mass extinctions.

Other subdivisions reflect the evolution of life; the Archean and Proterozoic are both eons, the Palaeozoic, Mesozoic and Cenozoic are eras of the Phanerozoic eon.

The three million year Quaternary period, the time of recognizable humans, is too small to be visible at this scale.

The existence, timing, and terrestrial effects of the Late Heavy Bombardment is still debated.