The beginning and end of each chunk of time in the geologic time scale is determined by when some species appeared or disappeared from the fossil record. When many species went extinct around the same ...

The Geologic Time Scale-- all 4.56 billion years of it -- is the way Earth scientists converse about time. It started off based on the relative occurrence of fossils and the periods were named after ...

The geologic time scale provides the official framework for ... The Jurassic Period is named after fossil-rich rocks in France’s Jura Mountains, while the Cambrian Period got its moniker from ...

By looking at differences among the fossils over time, the researchers learned that while the fish's large-scale features, like its body shape, have stayed consistent since the Cretaceaous more ...

One of the biggest ongoing debates in science is whether or not human activity, such as burning fossil fuels and ... to be a formal unit of the Geologic Time Scale. "It is extremely disappointing ...

A Timescale is a scale used to represent periods of time ... of the Earth that is characteristic of a particular span of geologic time or environment. We will look at a few index fossils and see if we ...