Front

What is an index fossil?

Back

An index fossil is a fossil that is used to define and identify a particular time period in the geological time scale. It is typically widespread, abundant, and existed for a relatively short period.

Front

Which fossil is considered the best index fossil?

Back

Trilobite is considered the best index fossil due to its wide distribution and the short time span of its existence.

Front

What does it mean if an element is radioactive?

Back

An element is radioactive if it has unstable nuclei that break down and release particles and energy.

Front

What is half-life in terms of radioactive decay?

Back

Half-life is the time required for half of the radioactive atoms in a sample to decay into a different element or isotope.

Front

If the half-life of a radioactive substance is 100 years, how old is a rock after two half-lives?

Back

200 years.

Front

What percentage of the parent isotope remains after two half-lives?

Back

25%.

Front

How does absolute age differ from relative age?

Back

Absolute age provides a specific age in years, while relative age determines the order of events without providing exact dates.

Front

What is the significance of using index fossils in geology?

Back

Index fossils help geologists correlate the age of rock layers and understand the history of life on Earth.

Front

Can a fossil be an index fossil if it existed for a long time?

Back

No, an index fossil must have existed for a relatively short time to be useful in dating rock layers.

Front

What characteristics make a good index fossil?

Back

A good index fossil is widespread, abundant, easily recognizable, and existed for a short geological time.