Unit 10 Lesson 2 What Was Ancient Earth Like?€¦ · Unit 10 Lesson 2 What Was Ancient Earth Like? Copyright © Houghton Mifflin Harcourt Publishing Company . Title: PowerPoint Presentation

Unit 10 Lesson 2 What Was Ancient Earth Like?

Copyright © Houghton Mifflin Harcourt Publishing Company




How Rocks and Fossils Tell a Story


• Sedimentary rock forms in layers. Many sedimentary rocks contain fossils.

• The oldest rock layers are at the bottom, and the youngest rock layers are at the top.

• The relative age of a layer of rock is the age of that layer when compared to other layers.

The Grand Canyon Evidence of Earth's Past Science Classroom Resources PBS LearningMedia.mp4




• Fossils form when sediment buries dead organisms.

• The fossil record is made up of all the fossils in Earth’s rock layers.

• The fossil record contains information about Earth’s history and the history of life on Earth.

The Fossil Record at Grand Canyon - Kids' Videos.mp4



C.W 10.2 : Q1


C.W 10.2 : Q2





• Over time, the movement of Earth’s crust can cause layers of rock to become tilted. It can also lift rocks formed in the ocean to above sea level.

• The rock layers of the Grand Canyon were tilted and lifted millions of years ago.

10.2 videos/The Fossil Record at Grand Canyon - Kids' Videos.mp4


Divisions in Time


• Scientists developed the geologic time scale to divide Earth’s history into manageable units. The fossils each unit contains define it.

10.2 videos/geologic time.wmv


Divisions in Time


• Large tree ferns were common during the late Paleozoic Era.

• The large coal deposits in the eastern United States formed from plants like these.

• Trilobites were so common that the earliest part of the Paleozoic Era is called the Age of Trilobites.


Divisions in Time


• Trees that produce seeds in cones appeared at the beginning of the Mesozoic Era.

• The middle and end of this era is known as the Age of

Dinosaurs. Large animals, such as Stegosaurus, lived during this time.


Divisions in Time


• Flowering plants, such as grasses, and saber-toothed cats existed during the Ice Age.


Divisions in Time



Divisions in Time


• Index fossils help identify a very short period of Earth’s history and must meet four requirements.

1.The organisms from which they formed lived during a short period of Earth’s history.

2.The organisms must have had large populations so that many fossils formed.

3.The fossils must be widespread 4.The fossils must be easily

recognized.

10.2 videos/index fossils.wmv

10.2 videos/index fossils 1.wmv


Big Changes on Earth


• Fossils tell how life on Earth has changed over time.

• Fossils also tell how Earth’s continents and landforms have changed.

• Scientists have found fossils of a Mesosaurus—a small, lizard-like reptile that lived in fresh water—on both sides of the Atlantic Ocean.

10.2 videos/Alfred Wegener's Theory of Continental Drift - Video Lesson Transcript Study.com.mp4




• Mesosaurus was too small to have been able to swim across the Atlantic.

• At the end of the Paleozoic Era, all of Earth’s masses were joined. These masses began to break apart during the Mesozoic Era.

• The single landmass

(Pangea) explains how Mesosaurus could move across land.




• The landmasses breaking apart supports the idea of continental drift, and helps scientists understand the movement of Earth’s plates.





Changing Environments


• Fossils provide clues about changing environments.

• Finding a fossil sea snail at the top of a mountain would lead to the conclusion that the environment has changed.

10.2 videos/ancient environment.wmv







• Fossils of plants and animals at La Brea Tar Pits, in Los Angeles, California, show that the climate has not changed much in the last 40,000 years.




• Falls of the Ohio is a state park in Indiana where summers are hot and winters are cold and snowy.

• Fossils of coral, clams, and other organisms that lived in shallow, warm, tropical seas show how the climate has changed in the last 380 million years.


The Great Die Offs


• Several times in history, many species became extinct at once. These large events, caused by climate change, are called mass extinctions.

• Worldwide volcanic eruptions blow large amounts of ash and dust into the air, blocking sunlight so plants can’t grow.

• Other plants die as ash settles on them and smothers them.

10.2 images/mass extinction.PNG

10.2 videos/mass extinction.wmv


The Great Die Offs


• At the end of the Mesozoic Era, an asteroid sent huge amounts of dust into the air, blocking sunlight and changing the climate.

• These changes may have led to the extinction of many organisms, including dinosaurs.


The Great Die Offs



The Great Die Offs



The Great Die Offs


Effects: Drought _ Dust and ash in air _

•Results: - Lack of sunlight causes plant to die and

animals too.(2)

-Plants and animals die

-Habitats are destroyed and organisms too.

Cause: - Meteor impact

-Too much rain





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Unit 10 Lesson 2 What Was Ancient Earth Like?€¦ · Unit 10 Lesson 2 What Was Ancient Earth Like? Copyright © Houghton Mifflin Harcourt Publishing Company . Title: PowerPoint Presentation