Geologic History Review

Front

What is relative dating in geology?

Back

Relative dating is the method used by geologists to place rocks in order from youngest to oldest without determining their exact age.

Front

What does relative dating determine?

Back

Relative dating determines the age of fossils compared to others.

Front

What is an unconformity in geology?

Back

An unconformity is a break in the geologic record that occurs when rock layers are eroded or when sediment is not deposited for a long period of time.

Front

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

Back

The rock is 200 years old.

Front

What do scientists use radioactive decay to measure?

Back

Scientists use radioactive decay to measure absolute time.

Front

Define half-life in the context of radioactive decay.

Back

Half-life is the time required for half of the radioactive atoms in a sample to decay.

Front

What is the principle of superposition?

Back

The principle of superposition states that in undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest layers are at the top.

Front

What is the difference between relative dating and absolute dating?

Back

Relative dating places events in order without exact dates, while absolute dating provides a specific age or date for an event.

Front

What is a fossil?

Back

A fossil is the preserved remains or traces of ancient organisms, often found in sedimentary rock.

Front

What role do index fossils play in geology?

Back

Index fossils are used to define and identify specific time periods in the geologic time scale.