Slide 1 / 107 Slide 2 / 107 4 th Grade PSI The History of Planet Earth 2015-11-10 www.njctl.org Slide 3 / 107 Slide 4 / 107 The History of Planet Earth Click on the topic to go to that section The Structure of Earth The Structure of Earth · Rock Layers · Fossils and Relative Time · Rock Formations and Earth Forces · Tectonic Plates · Earth's Visible Features · Return to Table of Contents Patterns of Earth's Features · Slide 5 / 107 Slide 6 / 107 The Structure of Earth The Structure of Earth When you look at the world around you, have you ever asked The things that we see today on the surface of the Earth exist How did the Earth get to be the way it is today? for many reasons, and they can teach us many things. The structures we can see on the surface and things underneath the surface tell us about the Earth's history.
Slide 7 / 107 Slide 8 / 107 The Structure of Earth The Structure of Earth The things we see on the surface of Earth today have gotten Working with your table, come up with a list of structures on to be that way over many, many years. Earth that you think might tell some of the story of Earth's past. The surface of Earth - what we see with our eyes - is the outermost layer of Earth and is called the crust. crust Even though the crust is the outer layer, there are still parts of the crust that are too deep for us to see. Slide 9 / 107 Slide 10 / 107 The Structure of Earth The Structure of Earth Earth has other layers underneath the crust. Most of the crust is made up of rock. These are called the mantle and the core. Much of this rock is sedimentary rock . Sedimentary rocks are one of the main reasons why the crust tells us so much about Earth's history. But when we talk mantle about the history of Earth, it is the crust - core the outer layer - that can tell us the most. Why do we rely on the crust to tell us the story and not the mantle or the core? Slide 11 / 107 Slide 12 / 107 1 Can the things we see on Earth's surface can tell us 2 Is it possible Earth's surface has gotten to be the way it is about Earth's history? within the past 50 years? Yes Yes No No
Slide 13 / 107 Slide 14 / 107 3 The outer layer of Earth is called the: 4 We can see all of Earth's crust with our eyes. Yes A skin No B mantle C crust D core Slide 15 / 107 Slide 16 / 107 5 Which layer of Earth tells us the most about Earth's history? Rock Layers A the core B the mantle C the outside D the crust Return to Table of Contents Slide 17 / 107 Slide 18 / 107 Rock Layers Rock Layers Sedimentary rock, which makes up much of Earth's crust, Sedimentary rock is formed over many years. is made from sediment. Sediment is broken down pieces of rock and other solid material Can you brainstorm any ways that settles to the bottom of a liquid . sedimentary rock could come to be? Sediment is often dirt and rock particles that settle at the bottom of bodies of water, but it also Remember our definition of sediment. refers to any solid material that settles at the bottom of a liquid, such as these particles in this glass of water. sediment Where on Earth might we see evidence of layering? How could that have happened?
Slide 19 / 107 Slide 20 / 107 Rock Layers Rock Layers So here's how it happens: deposition sedimentation compaction cementation Sediments are deposited (usually by water). S ediments build up in layers - a process called sedimentation . Sediments are compacted as the weight of the sediments on top squash the sediments at the bottom. Sediments are cemented by crystals of salt that are left after the water has been squeezed out of the rocks. txstate.edu deposition sedimentation compaction cementation Slide 21 / 107 Slide 22 / 107 Rock Layers Rock Layers Sedimentary rocks provide a history of the evolution of Earth, Which layer of rock in this diagram do you think is the youngest? especially within the past billion years. Which is the oldest? Label the top and bottom layers and then move the boxes to reveal the answers. When sediments are deposited and compacted to form sedimentary rock, sediments are accumulated in beds one on This is called the Law of top of another - in layers . Superposition . This means that when cut deep into the crust, below the surface we can see with our eyes, we find layers of different rocks that have move for formed over a long period of time. answer move for answer Slide 23 / 107 Slide 24 / 107 Rock Layers 6 The most important characteristic of a sediment is: Geologists study ancient sedimentary rocks to determine what environment A that it settles to the bottom of a liquid they formed in. B that it floats in liquid Determining ancient environments is very important to understand the C its color history of Earth. D that it is small It helps geologists understand how Earth's surface has changed over time. One way to study this is to compare the sedimentary structures in ancient rocks with sedimentary structures in modern environments.
Slide 25 / 107 Slide 26 / 107 7 Order the following steps from first to last in the process 8 Sedimentary rocks form in layers. of sedimentary rock formation (enter all 4 letters on your responder in the correct order): Yes A compaction No B deposition C cementation D sedimentation Slide 27 / 107 Slide 28 / 107 9 The Law of Superposition says: 10 Geologists study ancient rocks to learn about: A people A rock layers that are closer to the surface are old B environments B old and new rocks are found in the same place C sediments C rock layers get older as you go further down D cementation D rock layers that are deep down are the most recent Slide 29 / 107 Slide 30 / 107 LAB: Rock Layers In this lab, we will look more at how sedimentary rocks form, focusing on the questions: Fossils and Relative How are different sediments deposited differently? Time How do sedimentary rocks form? Return to Table of Contents
Slide 31 / 107 Slide 32 / 107 Fossils and Relative Time Fossils and Relative Time Sedimentary rocks not only contain sediments such as dirt, Rocks of the same age contain the same, or very similar, fossils. sand, and pebbles, but also fossils - preserved remains of plants or animals . So, for example, very recently formed rocks may have a lot of these fossils, while in rocks from an older time period there may be none of those fossils, but many of these fossils, and in rocks from an even older time period, there may be lots of these fossils, but none of the types found in Fossils come in many forms. They can be bones, tracks, the more recent rock. plants, or bodies of animals, among other things. Slide 33 / 107 Slide 34 / 107 Fossils and Relative Time Fossils and Relative Time When the same kind of fossils are found in rocks in different places - for example, fossils of an organism that no longer This means that the age of a rock can be determined by exists - we know that the rocks are the same age. How? the fossils that are found in it. A rock can also be compared to other rocks by the fossils the rocks contain. The types of fossils in the rocks being compared will show which rock is older than the other. So if fossils of this organism are found in these three places, then the rocks they were found in are all the same age. Slide 35 / 107 Slide 36 / 107 Fossils and Relative Time Fossils and Relative Time The kinds of fossils found in rocks from different time periods change because animals and plants change through time. When we compare fossils, we can form a general timeline of These patterns of fossils exist globally. organisms that existed throughout history! But in certain places, fossils are also found in different rock layers because the environment of that particular place changed throughout history. very long time ago long time ago recent
Slide 37 / 107 Slide 38 / 107 Fossils and Relative Time Fossils and Relative Time Fossils can tell us many things about the the history of: For example, imagine that a long time ago there was a lake, and many fish and shell fossils were left in that rock. Many years later, something happened in that area and the rocks from that later time one place, had many plant fossils, but no one region, fish or shell fossils. What do you think scientists would be able to tell happened in that place or the entire planet. based on what they learned from the fossils? Come up with an idea in your group you can share with the rest of the class. Slide 39 / 107 Slide 40 / 107 11 Fossils are: (choose all that apply) 12 Is it possible to tell if one rock is older or younger than another rock by looking at their fossils? A found in sedimemtary rocks Yes B living organisms No C able to help determine how old rocks are D preserved remains of plants and animals Slide 41 / 107 Slide 42 / 107 13 Rocks of the same age contain very different fossils. 14 Why do rocks from different time periods have different kinds of fossils? Students type their answers here (discuss as a class, do not answer with responders) Yes No
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