A subdivision of a geological period

Strata with distinguishable characteristics and sequences of sediments

The period of time ranging from the formation of Earth about 4.6 billion years ago

A fossil that characterizes a particular period of time

an era when dinosaurs existed; means "middle animal life"

an era when trilobites, corals, brachiopods, early fish, and early amphibians existed; means "ancient animal life"

a geologic era; all of Earth's history that occurred before the Paleozoic era

an era when mammals exist; means "recent life"

a broad span of geologic time based on the general type of life existing during that time

a gap in the geologic record during which either no rocks were deposited or existing rocks eroded

the surface that is revealed when something is cut through, typically at a right angle to its axis

all the fossils on Earth

the study of the order and correlation of Earth's rocks

a principle that says the same kinds of fossils found in rocks from different places are the same age and that the kinds of plants and animals found as fossils change over geologic time

the study of fossils

sequence of events based on data that shows the order in which they occur

an remains, trace or imprint of an animal or plant life preserved in Earth's crust

a snap of time within an era