Front

The Earth is thought to be this old.

Back

4.6 billion years old.

Front

The vast amount of time is called ________________time.

Back

geological

Front

Rocks hold the key to much of what we know today about the Earth.

Back

True

Front

Evidence of ancient life is present in these.

Back

fossils

Front

The type of fossil that tells about a species' activities like tracks and impressions.

Back

Trace

Front

Most fossils are found in _____________________rocks.

Back

sedimentary

Front

What happens to the soft part of organisms that do not fossilize?

Back

decay.

Front

The name of a person that studies fossil ages.

Back

Paleontologist

Front

Half life is the amount of ____________ it takes for a radioactive element to decay.

Back

time

Front

The current "era" of geological time.

Back

Cenozoic