Dating fossils and rock
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.
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.
The three million year Quaternary period, the time of recognizable humans, is too small to be visible at this scale.
The geologic time scale (GTS) is a system of chronological dating that relates geological strata (stratigraphy) to time.
For example, in North America, the Lower Cambrian is called the Waucoban series that is then subdivided into zones based on succession of trilobites.
In East Asia and Siberia, the same unit is split into Alexian, Atdabanian, and Botomian stages.
The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus "early Miocene" but "Early Jurassic." Evidence from radiometric dating indicates that Earth is about 4.54 billion years old.
Corresponding to eons, eras, periods, epochs and ages, the terms "eonothem", "erathem", "system", "series", "stage" are used to refer to the layers of rock that belong to these stretches of geologic time in Earth's history.
Geologists qualify these units as "early", "mid", and "late" when referring to time, and "lower", "middle", and "upper" when referring to the corresponding rocks.
For example, the lower Jurassic Series in chronostratigraphy corresponds to the early Jurassic Epoch in geochronology.
When viewed from a biblical perspective, the evidence is consistent with what one would expect from a worldwide Flood.
This research reminds us of the caution we should accord to every fossil reconstruction.