Geologic Time Test Review

Front

What is the law of superposition?

Back

The law 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

Which layer is the youngest according to the law of superposition?

Back

The youngest layer is the one at the top of the sequence.

Front

What is a half-life?

Back

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

Front

If a radioactive isotope has a half-life of 20 years, how much of a 100g sample remains after 40 years?

Back

25 grams remain after 40 years.

Front

What percent of carbon-14 remains after 11,460 years?

Back

25% of carbon-14 remains after 11,460 years, which is two half-lives.

Front

True or False: The geologic record can help scientists determine past environmental and climate conditions.

Back

True.

Front

What is relative dating in geology?

Back

Relative dating is the method of determining the age of a rock or fossil in relation to other rocks or fossils.

Front

What is absolute dating?

Back

Absolute dating is the process of determining the exact age of a rock or fossil, often using radiometric techniques.

Front

What is the significance of fossils in the geologic time scale?

Back

Fossils provide evidence of past life and help to establish the relative ages of rock layers.

Front

What is the geologic time scale?

Back

The geologic time scale is a system of chronological dating that relates geological strata to time.