Unit Test #7: Earth’s Place in the Universe

Certain fossils (called index fossils) help scientists estimate the age of a rock because these fossil species only existed for a relatively short time. What happened to the species that are now used as index fossils?

• They became extinct
• They changed their diets
• They hid in marine sediments.
• They migrated to new environment

One of the methods of relative dating that scientists use to determine the relative age of rocks is the cross-cutting relationship. The cross-cutting relationship states that an intrusion or fault is younger than the rocks it cuts across. Which of the following features is an example of a cross-cutting relationship? (Select all that apply)

• A
• B
• C
• D
• E

Observe layers 6, 8 & 10. Select the best inference as to why there are no fossils present in the selected rock strata.

• There was water flowing between the layers.
• There was magma flowing through the layers and the remains of living things were destroyed due to the extremely high temperatures.
• There was a mass extinction.
• This was the point one era transitioned into another era.

According to the Geologic Time Scale, at which point did life first appear on Earth?

• Cenozoic Era
• Mesozoic Era
• Paleozoic Era
• Precambrian

Study the model below. Answer the question below the model. Which feature shown in the figure is the oldest?

• Q
• P
• H
• L

The Law of Uniformitarianism states that the geological processes we observe today have occurred in the past in similar ways. Which of the following is the best example of this principle?

• A volcano erupting and forming new land
• A fossil being discovered in a rock layer
• The erosion of a river cutting through rock over time
• A sudden earthquake shifting the Earth's crust

Lifeforms have changed throughout Earth's geologic history. Scientists learn about these changes by studying the fossil record. For example, scientists have learned when different groups of organisms first appeared. These events can be placed within specific periods on the geologic time scale, which is shown below. Dinosaurs first appeared during the Triassic period, and large mammals first appeared during the Tertiary period. Fish with jaws first appeared before both dinosaurs and large mammals. Using this information and the geologic time scale above, choose the period in which fish with jaws first appeared.

• Quaternary
• Silurian
• Jurassic
• Cretaceous

The diagram below represents a series of rock layers from a single location. Each different type of shape shown in the layers represents a fossil of a different species. Suppose the blue star represents a certain fish species. When did this species go extinct at this location?

• at the end of the Triassic
• during the Permian
• at the end of the Jurassic
• at the end of the Cretaceous

The image below shows tilted rock layers. According to the Law of Original Horizontality, what is the most likely explanation for their current position?

• The rock layers were deposited in a tilted position.
• The rock layers were originally horizontal but were later tilted by geological forces such as tectonic activity.
• The rock layers were tilted by the flow of water when they were being deposited.
• The rock layers were formed by volcanic activity, which caused them to tilt naturally.

In sedimentary rock, the ________________ fossils are usually found in the deepest layers.

• youngest
• oldest
• softest
• mammal