(8) Geologic Time Scale

Front

What are fossils?

Back

Preserved remains or traces of organisms that lived in the past.

Front

What is the principle of Uniformitarianism?

Back

Processes that operate today also operated in the past.

Front

What does the law of superposition help geologists determine?

Back

The relative age of a rock layer.

Front

What are trace fossils?

Back

Footprints and trails left by organisms.

Front

What can cause rock layers to be overturned?

Back

Geological processes such as folding and faulting.

Front

What is the geologic time scale?

Back

A system of chronological dating that relates geological strata to time.

Front

What are the main divisions of the geologic time scale?

Back

Eons, eras, periods, and epochs.

Front

What is an era in the geologic time scale?

Back

A major division of geological time, subdivided into periods.

Front

What is the significance of the Cambrian explosion?

Back

A rapid diversification of life forms that occurred around 541 million years ago.

Front

What is a period in the geologic time scale?

Back

A subdivision of an era, characterized by specific geological and biological events.