Clues to Earth's Past

What type of event usually marks the end of an Era

• A Mass Extinction

• A Quinceanera

• An earthquake

• Evolution of a species

The age of a rock compared to the ages of other rocks.

• relative age
• half-life
• absolute age
• radioactive decay

The age of a rock given as the number of years since the rock formed.

• relative age
• half-life
• absolute age
• radioactive decay

A type of fossil that provides evidence of the activities of ancient organisms.

• trace fossil
• mold fossil
• petrified fossil
• cast fossil

A type of fossil that is a hollow area in sediment in the shape of an organism or part of an organism.

• trace fossil
• mold fossil
• petrified fossil
• cast fossil

A fossil that is a solid copy of an organism's shape, formed when minerals seep into a mold.

• trace fossil
• mold fossil
• petrified fossil
• cast fossil

An animal with a backbone.

• vertebrate
• carbon film
• invertebrate
• fossil

Change over time for organisms.

• geologic time scale
• evolution
• era
• period

A record of the geologic events and life forms in Earth's history.

• index fossil
• half-life
• radioactive dating
• geologic time scale

Fossils of abundant, widely distributed organisms that lived during a geologically short period.

• index fossil

• half-life

• radioactive dating

• geologic time scale