Chapter 6 Review: History of Earth

Front

What were Earth's earliest multicellular organisms?

Back

Invertebrates.

Front

What is the method used by geologists to determine the absolute age of rocks?

Back

Radioactive dating.

Front

What does the geologic time scale record?

Back

Geologic events and life forms.

Front

Why do scientists use mass extinctions to separate one era from another?

Back

Mass extinctions signify major changes in biodiversity, marking the transition between different geological eras.

Front

Will the geologic time scale change over the next 20 years? Why or why not?

Back

The geologic time scale will likely change because it is based on evidence from the rock and fossil records, and new evidence is always being discovered.

Front

What are the two main types of dating used in geology?

Back

Relative dating and absolute dating.

Front

What is relative dating?

Back

A method of determining the age of rocks by comparing them to other rocks.

Front

What is absolute dating?

Back

A method of determining the exact age of a rock or fossil using radioactive decay.

Front

What is a mass extinction?

Back

A widespread and rapid decrease in the biodiversity on Earth.

Front

Name one major mass extinction event in Earth's history.

Back

The Permian-Triassic extinction event.