Earth History Unit 2 Geology

How old something is compared to something else

• relative age

• relative dating

• absolute age

• absolute dating

Which best describes a fossil that helps determine the relative age of a rock layer?

• trace fossil
• index fossil
• radioactive fossil
• unconformity fossil

The absolute age of an igneous rock can best be determined by ...

• comparing radioactive isotopes
• comparing crystal sizes

The bottom layer of rock is

• the oldest
• has fossils

Which is a process that allows scientists to compare different rock layers in a sequence to determine their age?

• radiometric dating

• absolute dating

• relative dating

• speed dating

Scientists found two ammonite fossils in rock layers far across the ocean floor from each other. Ammonite fossils are a type of index fossil. Knowing this, which of the following could scientists infer about the rock layers containing the fossils?

• The rock layers are about the same relative age.

• Both rock layers formed because of volcanic activity.

• The rock layers experienced the same kinds of erosion.

• The same climate existed where both rock layers formed.

Why are index fossils used as guides to determine the age of rocks?

• Each index fossil lived during a specific geologic time period.

• Index fossils are found in igneous rocks.

• Index fossils are very rare and are not commonly found in rocks.

• All index fossils lived during all the periods of geologic time.

The absolute age of an igneous rock can best be determined by ...

• comparing radioactive isotopes
• comparing crystal sizes

Which time period on the chart was the longest?

• Permian
• Cambrian

How old something is compared to something else

• relative age

• relative dating

• absolute age

• absolute dating