Earth's History

A fossil discovered in Colorado dates from the early Mesozoic era. A year later a similar fossil is found in Wyoming that also dates from the early Mesozoic era. These two organisms most likely lived in

• the same environment at about the same time.

• the same environment at different times.

• different environments at about the same time.

• different environments at different times.

Which method would be BEST for scientists to use to determine the absolute age of a Precambrian igneous rock?

• Index fossils

• law of superosition

• radiometric dating

• law of original horizontality

A teacher gave students this diagram of rock layers. The teacher directed the students to determine the relative age of each rock layer based only on the information presented in the diagram.

Which method can BEST be used by the students to determine the relative age of these layers?

• radiometric dating

• rock type evaluation

• the law of superposition

• principle of uniformitarianism

Certain fossils can be used to help determine the age of the rock layer in which the fossils are found. Which type of fossil is BEST to use when making this determination?

• marine mammal fossil

• swamp fern fossil

• trace fossil

• index fossil

Use this geologic profile to answer the following question.

Which of the following BEST describes the fossil at Point 3 when compared with the fossils at Points 1 and 2?

• The fossil at Point 3 is less common

• The fossil at Point 3 is smaller.

• The fossil at Point 3 is older.

• The fossil at Point 3 is more complex

Trilobites are extinct animals that lived in the oceans. Fossils of these animals can be found in dry areas such as Cincinnati. What does this indicate?

• Trilobites now live underground.

• Trilobites are the ancestors of jellyfish.

• Cincinnati was once covered by the ocean where trilobites lived.

• The environment changed, creating small saltwater lakes in Cincinnati.

Which statement best describes the Law of Superposition?

• Each sedimentary layer of rock represents 1,000 years of Earth’s age, much like the rings of a tree.

• In undisturbed layers of sedimentary rock, the upper rock layers are older than the lower rock layers.

• In undisturbed layers of sedimentary rock, the lowest layers contain the older rocks.

• Rocks that form near volcanoes are older than surrounding rock.

How do scientists know that some mountains were once at the bottom of an ocean?

• Freshwater rivers flow to the ocean.

• Saltwater fish are found in some mountain streams.

• Dinosaur bones have been discovered in the mountains.

• Marine fossils have been found on the peaks of some mountains.

What is the longest unit of time?

• Eon

• Era

• Period

• Epoch

What Era are we currently in?

• Paleozoic

• Mesozoic

• Cenozoic

• Triassic