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6th Grade Earth's Materials and Systems Part 1: The History of Planet Earth 20150827 www.njctl.org 2
Table of Contents: The History of Planet Earth Click on the topic to go to that section • Earth's Layers • Three Types of Rocks • Early Life on Earth / Fossils • Rock Strata 3
Earth's Layers Return to Table of Contents 4
Review Earth is a "terrestrial" or rocky planet. This means that it is made up of rocks and minerals. The rocks and minerals that now make up our Earth were once just small chunks revolving around our sun. Over billions of years, they combined to form the planet we live on today. What are the other rocky planets in our solar system? 5
The Makeup of Earth As Earth grew larger, its gravity increased. Pressure beneath Earth's surface caused changes to the Earth's makeup. Distinct layers began to form. Do you remember any of the names of the layers? Brainstorm with your table. 6
The Layers of Earth Our Earth is divided into four major layers: Crust Mantle Inner Outer Core Core 7
Earth's Crust Think of the crust of Earth as the crust of a pizza pie. The crust is the outermost layer of Earth, just like the crust above is the outermost layer of the pizza! 8
Earth's Crust There are 2 parts to the crust. One is the land. What is the other part? This section is very thin compared to other layers of Earth (between 5 and 25 miles thick) and it is very hard and rigid. The crust is composed of plates that slide around on top of the section below it. This portion is called the lithosphere . 9
Earth's Mantle The next layer down is the mantle. This is the largest layer about 1,800 miles thick! The mantle is made up of incredibly hot, semisolid rock (basically think of rock in a form sort of like pudding). This layer makes up about 2/3 of Earth's mass. 10
1 Which best describes the lithosphere? A The part of the atmosphere which we breathe. B The layer of Earth that makes up the greatest mass. Answer C A layer of Earth that is made of a jellolike substance. D The plates of Earth that slide around the surface. 11
2 What is true of the mantle? A It is the thickest layer of Earth. B It is the top layer of Earth. Answer C It is entirely made of liquid. D It is the least massive portion of Earth. 12
3 The mantle is composed of Earth's land and oceans. True False Answer 13
4 Choose the correct order of Earth's layers from outermost to most inner. A mantle, crust, inner core, outer core B inner core, outer core, crust, mantle Answer C inner core, outer core, mantle, crust D crust, mantle, outer core, inner core 14
Earth's Outer Core The Outer Core is so hot that it is entirely liquid. It is the only liquid layer of Earth. It is made up of mainly nickel and iron. To give you an idea of how hot it is, nickel becomes a liquid at 2,650 degrees F and iron melts at 2,800 degrees F! What temperature does ice melt at? 15
Earth's Inner Core At the very center of Earth, you will find the Inner Core. Like the Outer Core, this layer is also extremely hot and is made of nickel and iron. Although the temperature is higher, the nickel and iron here are in solid form because of the intense pressure that this layer experiences. 16
5 What separates the Inner and Outer Core? The Inner Core is made of liquid; the Outer Core is A solid. The Outer Core is hotter than the Inner Core. B The Inner Core is solid; the Outer Core is Answer C liquid. The Outer Core is under more pressure than D the Inner Core. 17
6 Which is the oldest layer of Earth? A crust B mantle Answer C outer core D inner core 18
Size of Earth's Layers 19
Three Types of Rocks Return to Table of Contents 20
Formation of Rocks The layers of Earth are constantly moving and changing due to intense heat and pressure. The energy of this heat and pressure results in the formation of Answer Rock Relatively hard, naturally rocks. forming mineral But what exactly is a rock ? With your table, come up with some characteristics of rocks. 21
Three Types of Rocks How a rock forms depends on what type of rock it is. There are three types of rocks: Sedimentary Click on the rock type to see an example. Metamorphic Igneous 22
How Do Rocks Form? The three types of rocks on the previous page each form in different ways. The animation on the next slide will introduce you to the process behind the transformation of rocks from one type to another a process known as the rock cycle . Answer the questions on the accompanying worksheet while watching the animation. 23
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7 Which of the following is not a type of rock? Metamorphic A Glacier Answer B Igneous C Sedimentary D 25
Sedimentary Rock "Sediments" are small fragments of rock. To form Sedimentary rock, these fragments combine together. These rocks are typically multicolored with many different textures. 26
Igneous Rock "Igneous" has the same root word as "ignite." What does ignite mean? Igneous rocks form when magma, which we can think of as "liquid fire," cools down. These rocks are typically dark, very shiny, and made up of crystals. 27
Types of Igneous Rock There are two types of igneous rock. "Intrusive" igneous rock is still in side Earth. "Extrusive" igneous rock has ex ited Earth. 28
Metamorphosis A "Metamorphosis" is when something changes into something new. You have learned about a few organisms which undergo metamorphosis in your science classes over the years. At your table, talk for a few minutes about the 2 organisms below and the metamorphosis they undergo during their lives. 29
Metamorphic Rock Just like the frog, metamorphic rock is formed when another one type of rock changes into a new type of rock. Metamorphic rock forms when another type of rock changes its chemical makeup because of heat and pressure. These rocks are typically made up of layers that formed as the rock was squashed under pressure. 30
8 Which type of rock is made up of pieces of other rocks? Metamorphic A Extrusive Igneous B Answer Intrusive Igneous C Sedimentary D 31
9 Which type of rock is formed of magma below the surface of Earth? Metamorphic A Extrusive Igneous B Answer Intrusive Igneous C Sedimentary D 32
10 Which type of rock is formed when other rocks undergo a transformation due to heat or pressure? Metamorphic A Answer Extrusive Igneous B Intrusive Igneous C Sedimentary D 33
11 Which type of rock is formed from magma cooling on Earth's surface? Metamorphic A Extrusive Igneous B Answer Intrusive Igneous C Sedimentary D 34
12 This is an example of ________ rock. A Sedimentary B Igneous Answer C Metamorphic 35
13 This is an example of ________ rock. A Sedimentary B Igneous C Metamorphic Answer 36
14 This is an example of ________ rock. A Sedimentary B Igneous Answer C Metamorphic 37
15 This is an example of ________ rock. A Sedimentary B Igneous Answer C Metamorphic 38
Early Life on Earth / Fossils Return to Table of Contents 39
The Age of Earth Scientists estimate that the Earth formed around 4.6 billion years ago. We can learn about the history of Earth by studying rocks and fossils. 40
First Life on Earth There is evidence within the rocks on Earth that suggests that life first appeared on Earth about 3.6 billion years ago. The image above is of stromatolites , the oldest fossils on record. They provide us with evidence of very simple life forms like bacteria as long as 3.5 billion years ago. 41
Prokaryotes The first cells that existed on Earth were closely related to prokaryotes. These are cells that do not have a nucleus. Most prokaryotes are singlecelled organisms. bacteria Why were the first organisms on Earth very simple? What is a more common name for prokaryotes? Move the image once you come up with an idea. 42
Prokaryotes Very specific conditions were needed for these living organisms to form. Organic chemicals (chemicals that include carbon) as well as some sort of heat were needed to form these cells. 43
Photosynthetic Organisms Food was scarce on the early Earth. Why do you think this was? What do most organisms that we know of today eat? Come up with a theory at your table. 44
Photosynthetic Organisms Food was scarce on the early Earth because there were only a few organisms to begin with! Some prokaryotes developed the ability to create their own food by converting sunlight, carbon dioxide, and water into sugar and oxygen. The creation of oxygen through this process led the way for more complex organisms, like animals, to evolve. 45
How Do Scientists Reconstruct the Past? Scientists can estimate what life was like billions of years ago thanks to the discovery of fossils. What is a fossil? 46
How Do Scientists Reconstruct the Past? A fossil is the preserved remains of an organism which is found in rock formations. In what type of rock do you think fossils usually can be found ? Fossils are typically found in Think about how Sedimentary Rock rocks are formed. The answer is under the photo to the right 47
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