The modern Geologic Time Scale as shown above is a compendium of both relative and absolute age dating and represents the most up-to-date assessment of Earth's history.
century, the modern principles underlying geologic time were defined.
It follows the Cambrian period and is followed by the Silurian period.
The Modern Geologic Time Scale, as shown above, documents intervals of geologic time relative to one another, and has been continuously developed and updated over the last two centuries.
If oxygen has changed through time, when was it high and when low?
To discuss the model results for atmospheric oxygen levels over time, we thus need to refer to the geological timescale.
It received international sanction in 1906, when it was adopted as an official period of the Paleozoic era by the International Geological Congress. 2006) have suggested a ten-second gamma ray burst could have been responsible, destroying the ozone layer and exposing terrestrial and marine surface-dwelling life to radiation; most scientists continue to agree that extinction events are complex events with multiple causes.
The Ordovician period started at a minor extinction event some time about 488.3 million years ago ( mya) and lasted for about 44.6 million years. The dates given are recent radiometric dates and vary slightly from those used in other sources. Ordovician rocks contain abundant fossils and contain major petroleum and gas reservoirs in some regions.