Patterns in rocks resulting from sand dunes that were blown into patterns by the wind

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

A subdivision of a geological period

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

Rock layers with distinguishable characteristics and sequences of sediments

Any remains, trace, or imprint of animal or plant life presented in Earth's crust

All the fossils on Earth

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

A fossil that characterizes a particular period of time

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 time

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

The study of fossils

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

A span of time within an era

A geological era; all of Earth's history that occurred before the paleozoic era

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

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

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