Lesson 2: Geologic Time Scale

An 'Era' in the context of geology is:

• a period of time lasting millions of years, marked by significant geological events.

• a type of rock formation found in the Earth's crust.

• a specific location where fossils are found.

• a tool used by geologists to measure time.

Answer explanation

An 'Era' in geology refers to a significant period lasting millions of years, characterized by major geological events, making the first choice the correct answer.

Match the following descriptions with their corresponding terms.

• History Timeline

• A calendar of ancient civilizations.

• Geologic Time Scale

• A chart of the solar system's planets.

• Planetary Chart

• A timeline of human history.

• Ancient Civilization Calendar

• A record of the geologic events and the evolution of life forms as shown in the rock and fossil records.

(a)   of Earth's history is covered by the Precambrian Time.

• 50%

• 88%

• 75%

• 95%

Answer explanation

The Precambrian Time covers about 88% of Earth's history, making it the longest geological time period. This includes the formation of the Earth and the development of early life forms.

The Precambrian Time covers from 4.6 billion years ago to _______ million years ago.

• 541

• 600

• 700

• 800

Answer explanation

The Precambrian Time spans from 4.6 billion years ago to 541 million years ago, marking the end of this era and the beginning of the Cambrian period, which is significant for the development of complex life.

Match the following geological time units with their descriptions.

• Subdivisions of periods, characterized by significant events in Earth's history.

• Eons

• Divisions of geologic time that last tens of millions of years.

• Ages

• The largest divisions of geologic time, lasting hundreds of millions of years.

• Epochs

• Shorter spans of time marked by notable events or changes in Earth's history.

• Periods

Which era is characterized by increased complexity of life forms, including the earliest fish, amphibians, and arachnids?

Answer explanation

The era characterized by increased complexity of life forms, including the earliest fish, amphibians, and arachnids, is the Paleozoic Era. This period saw significant evolutionary advancements in marine and terrestrial life.

Pangea formed during the (a)   era.

• Pangea formed during the late Paleo

• Pangea formed during the Mesozoic e

• Pangea formed during the Cenozoic e

• Pangea formed during the Precambria

Answer explanation

Pangea formed during the late Paleozoic era, specifically in the Carboniferous period, when the continents began to merge. The other options refer to eras after Pangea's formation.

During which era did dinosaurs dominate the land?

Answer explanation

Dinosaurs dominated the land during the Mesozoic Era, which is divided into three periods: Triassic, Jurassic, and Cretaceous. This era is known for the rise and fall of dinosaurs as the dominant terrestrial vertebrates.

The Mesozoic era lasted from approximately ___ to 66 million years ago.

• 252 million years ago

• 200 million years ago

• 150 million years ago

• 100 million years ago

Answer explanation

The Mesozoic era began approximately 252 million years ago and lasted until 66 million years ago. Therefore, the correct answer is 252 million years ago.

What significant geological event began during the Mesozoic era?

Answer explanation

The significant geological event that began during the Mesozoic era is the breakup of the supercontinent Pangaea, leading to the formation of the Atlantic Ocean and the rearrangement of continents.