Geologic Time Review

The law of superposition tells us about the age of rock layers.

• It states that in undisturbed rock layers, the oldest layers are at the bottom and the youngest are at the top.

• It states that in undisturbed rock layers, the youngest layers are at the bottom and the oldest are at the top.

• It states that all rock layers are the same age.

• It states that the age of rock layers cannot be determined.

The relative age of a rock is different from its absolute age in that:

• relative age is determined by the order of rock layers, while absolute age is determined by radiometric dating.

• relative age is determined by radiometric dating, while absolute age is determined by the order of rock layers.

• relative age and absolute age are determined by the same methods.

• relative age is more accurate than absolute age.

Scientists use radioactive dating to determine the absolute age of a rock by:

• measuring the amount of radioactive isotopes present in the rock.

• observing the color and texture of the rock.

• analyzing the rock's position in the Earth's strata.

• comparing the rock to similar rocks of known age.

Scientists determine the order of rock layers by using clues such as _______.

• fossil content and superposition

• color and texture

• size and shape

• weight and density

When looking at rock layers, one layer might be younger or older than the others because of:

• the principle of superposition

• the color of the rock

• the size of the rock

• the type of minerals present

A fossil is a preserved remain or trace of an organism that lived in the past. What does it tell us about these organisms?

• The size and shape of the organism

• The color of the organism

• The diet of the organism

• The exact age of the organism

How does a petrified fossil form? Describe the process in simple terms.

• A petrified fossil forms when minerals replace all or part of an organism.

• A petrified fossil forms when an organism is frozen in ice.

• A petrified fossil forms when an organism is trapped in amber.

• A petrified fossil forms when an organism leaves an impression in mud.

Trace fossils provide clues about ancient organisms by:

• preserving the physical remains of organisms

• showing the behavior and activities of organisms

• indicating the age of rock layers

• providing evidence of volcanic activity

Studying fossils is important because they can teach us about Earth's history by providing insights into:

• The evolution of life and past climates

• Modern technology advancements

• Current political systems

• Future space exploration

What type of fossil forms when minerals replace all or part of an organism?

• Mold fossil

• Cast fossil

• Petrified fossil

• Trace fossil