Geologic Time Scale Review

What is the law of superposition?

• The oldest layer is on the bottom, and the layers get progressively younger toward the top.

• The youngest layer is on the bottom, and the layers get progressively older toward the top.

• Layers are arranged in random order.

• All layers are the same age.

What is the law of crosscutting?

• A fault or intrusion is younger than the rocks it cuts through.

• A fault or intrusion is older than the rocks it cuts through.

• A fault or intrusion is the same age as the rocks it cuts through.

• A fault or intrusion does not affect the age of the rocks.

What is the law of inclusions?

• Inclusions are older than the rock layer they are found in.

• Inclusions are younger than the rock layer they are found in.

• Inclusions are the same age as the rock layer they are found in.

• Inclusions do not affect the age of the rock layer.

What are the two basic approaches to discovering the age of rocks?

• Relative age dating and absolute age dating

• Fossil dating and mineral dating

• Carbon dating and uranium dating

• Superposition dating and isotope dating

What does the Rule of Superposition state about rock layers?

• Older rock layers are on top of newer ones

• Newer rock layers are on top of older ones

• Rock layers are randomly arranged

• All rock layers are the same age

What is absolute age dating based on?

• The color of the rock

• The size of the rock

• Fossils and radioactive decay

• The location of the rock

Why are fossils important in age dating?

• They are colorful

• They are easy to find

• They represent a period of time

• They are made of minerals

What is the definition of a half-life in the context of radioactive decay?

• The time it takes for all of a radioactive isotope to decay

• The time it takes for half of a remaining isotope to decay to a daughter product

• The time it takes for a daughter product to become stable

• The time it takes for a rock to become radioactive

Why are sedimentary rocks generally not used for radioactive dating?

• They are too old

• They are too young

• They are notoriously radioactive-free

• They contain too many fossils

What is the half-life of carbon-14?

• 1,000 years

• 5,730 years

• 10,000 years

• 1.26 billion years