History of the Earth Review

Which method is most likely used to identify what happened before the start of the Paleozoic era?

• Scientists study fossils from the Jurassic period.

• Scientists observe index fossil records of the Mesozoic era.

• Scientists examine fossil evidence during the Precambrian time.

• Scientists explore the emergence of mammals and humans in the Cenozoic era.

Which best describes eras and periods?

• Eras have a smaller time span than periods.

• Eras and periods are independent of each other.

• Eras and periods both appear at the start of the Cambrian period.

• Eras were more recently established on the time scale than periods.

Which best explains a primary reason for the inability of life to exist in Earth’s early atmosphere?

• There was insufficient energy from material collisions to change their density.

• High temperatures during Precambrian time caused surface water evaporation.

• Volcanic eruptions and comet collisions added different gases to the atmosphere.

• Available oxygen was used to help create an ozone layer within Earth’s atmosphere.

Which information can be determined using half-life?

• age of material

• type of particle released

• percentage of rock that has aged

• number of radioactive particles left

After two half-lives, how much of the original material has decayed?

• 25 percent

• 50 percent

• 75 percent

• 100 percent

Which correctly lists the three elements that geologists measure to determine the age of an organism’s remains?

• argon, nitrogen, and carbon-12

• carbon-14, nitrogen, and carbon-12

• nitrogen, potassium, and carbon-14

• carbon-12, potassium, and argon

For which object would a geologist use carbon-14 dating to determine age?

• 
• 
• 
• 

Which phrase describes the relative age of a rock?

• uses the law of superposition to determine which rock is older or younger

• can determine the age based on location of a rock within the same layer

• requires only one rock to determine the age

• can provide the exact age of a rock

The image shows flat sedimentary rock layers in the foreground and angled sedimentary rock layers in the background.

According to the principle of original horizontality, what most likely happened to the rock layers in the background?

• They cracked at an angle.

• They were deposited at an angle.

• They were deposited vertically and then shifted by a geologic event.

• They were deposited horizontally and then shifted by a geologic event.

Which feature causes a gap in the geologic record?

• extrusion

• fault

• intrusion

• unconformity