Understanding Geological Time and Processes

What does the Law of Superposition state about sedimentary rock layers?

• Older layers are found at the top.

• Older layers are found at the bottom.

• All layers are the same age.

• Layers are deposited randomly.

The Law of Uniformitarianism suggests that:

• Geological processes are different now than in the past.

• Geological processes we see today have always been the same.

• The Earth's surface changes every day.

• All rocks are formed by volcanoes.

How can scientists determine the absolute age of a rock?

• By looking at its color.

• By using radiometric dating, radioactive decay.

• By measuring its size.

• By comparing it to other rocks.

What is the main difference between absolute age and relative age?

• Absolute age is a guess, relative age is exact.

• Absolute age is exact, relative age is a comparison.

• Both are exact numbers.

• Both are guesses.

What happens during radioactive decay?

• Atoms become larger.

• Unstable atoms release particles.

• Atoms become stable without changing.

• Atoms change color.

Why are ice cores important to scientists?

• They show the current temperature of the Earth.

• They contain air bubbles that tell us about past climates.

• They are used to find new species.

• They are used to measure the thickness of ice.

What is a geologic column?

• A list of all known rocks.

• A vertical sequence of rock layers showing Earth's history.

• A tool for measuring rock hardness.

• A type of rock found in mountains.

What does it mean if a species is extinct?

• It has moved to a new habitat.

• It no longer exists anywhere on Earth.

• It is only found in zoos.

• It is very rare.

What does an unconformity in the geologic record indicate?

• A continuous sequence of rock layers.

• A gap where rock layers are missing due to erosion.

• A new layer of rock has formed.

• A fault line is present.

What is the half-life of a radioactive substance?

• The time it takes for all of it to decay.

• The time it takes for half of it to decay.

• The time it takes for it to become stable.

• The time it takes for it to double in size.