Geological Timescale

Topic 8: History of Earth

Lesson 2: Geologic Time Scale

Describing Geologic Change

You have likely changed a lot since you were born. Just imagine all of the changes the Earth has been through since it formed 4.6 bya!

Rocks Give Clues About Earth's Past

Major geologic events - such as a super-volcanic eruption, an asteroid impact, or tectonic plate movement - are recorded in the Rock Record.

Fossils Give Clue About Earth's Past

The fossil record is a compilation of all of Earth's known fossils and the information they provide about Earth's history.

Organizing Earth's History

Scientists have constructed a timeline called the geologic time scale. The GTS is used to organize Earth's long history into manageable parts. The GTS is continually updated as new rock and fossil evidence is discovered.

Multiple Choice

The Geologic Time Scale is a record of what?

• old geologists
• sweet geology music
• the known history of rocks and fossils
• a list of every living thing ever

Multiple Choice

As we go further back in the GTS, the less rock and fossil information we have.

• true

• false

Multiple Choice

Which is the longest division of time on the GTS?

• eons

• eras

• periods

• epochs

The Geologic Time Scale

Earth's history is divided into four major eons which are the longest division of time. Then there are the Eras, periods and epochs.

Multiple Choice

What are the divisions of time in order from largest to smallest?

• eons, eras, periods, epochs

• eons, eras, trilobites

• eons, eras, epochs and periods

Multiple Choice

About how long ago did the Jurassic Period end?

• 4.6 bya

• 58 mya

• 138 mya

• 267 mya

Multiple Choice

Which event marks the end of the Permian Period?

• extinction of the dinosaurs

• earliest humans appear

• formation of the Earth

• a mass extinction happned

Multiple Choice

About how long ago did the Cambrian Period end?

• 20 mya

• 250 mya

• 500 mya

• last week

Multiple Choice

When classifying time using the Geologic Time Scale which unit is the largest unit of time?

• Period

• Eon

• Epoch

• Era

What Eon, Era, Period and Epoch are we living in today?

Eon - Phanerozoic

Era- Cenozoic

Period - Quaternary

Epoch - Holocene

Multiple Choice

During this period Earth was flowing with lava, the core was unstable, and was the first Era of the Precambrian Eon.

• Paleozoic

• Hadean

• Archean

• Cenozoic

Multiple Choice

What Epoch of the Geological Time scale are we currently in?

• Holocene

• Paleocene

• Hadean

• Jurassic

Multiple Choice

During the Precambrian Eon all of the events happened except.

• Fish began to evolve

• Single cell organism like bacteria developed

• Earth was flowing with lava and their was not oxygen in the atmosphere.

• The Proterozoic Era was at the end of Precambrian Eon

Multiple Choice

During this Era Pangaea was being formed?

• Paleozoic

• Mesozoic

• Cenozoic

• Phanerozoic

Multiple Choice

Put the following units of geological time in order from largest unit of time to smallest unit of time.

• Epoch, Eon, Era, Period

• Epoch, Period, Era, Eon

• Eon, Era, Period, Epoch

• Period, Eon, Period, Era

Multiple Choice

When did the Precambrian time end?

• 540 million years ago

• 65 million years ago

• 4.6 billion years ago

• 250 million years ago

Multiple Choice

What Eon, Era, Period and Epoch are you living in today?

• Phanerozoic, Cenozoic, Quaternary, Holocene

• Triassic, Jurassic, and Cretaceous

• The Cambrian period

Multiple Choice

Which portion of the timeline is known as the "Age of Mammals"?

• Precambrian Time
• Paleozoic Era
• Mesozoic Era
• Cenozoic Era

Multiple Choice

Place the following in order starting with the OLDEST
1  Paleozoic
2  Cenozoic
3  Precambrian
4  Mesozoic

• 1 3 2 4 
• 3 1 4 2
• 4 3 2 1 
• 2 3 1 4

Divisions of Geologic Time

The GTS is broken up into eons, eras, periods and epochs. Divisions in the GTS are not equal. This is because the divisions are based on major events and changes in Earth's history, such as an extinction.

Multiple Choice

In what way are eras different from periods?

• Eras are longer spans of time

• They are subdivided into epochs

• They have a longer duration than eons

• They have boundaries marked by mass extinctions

Multiple Choice

Earth is approximately 4.6 billion year old. How did scientists determine this?

• measuring the age of the oldest fossils

• measuring the age of the oldest glaciers

• using absolute dating techniques on meteorites

• determining the chemical composition of seafloor sediments

Multiple Choice

What type of organism will we most likely see if we were to visit the Precambrian?

• dinosaur

• humans

• single celled organism

• trilobites