4 th Grade PSI The History of Planet Earth 2015-11-10 - - PDF document

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4th Grade PSI

The History of Planet Earth

2015-11-10 www.njctl.org

Slide 3 / 107 The History of Planet Earth

· The Structure of Earth

Click on the topic to go to that section

· Rock Layers · Fossils and Relative Time · Rock Formations and Earth Forces · Earth's Visible Features · Patterns of Earth's Features · Tectonic Plates

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The Structure of Earth

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Slide 5 / 107 The Structure of Earth

When you look at the world around you, have you ever asked How did the Earth get to be the way it is today?

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The things that we see today on the surface of the Earth exist 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.

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Working with your table, come up with a list of structures on Earth that you think might tell some of the story of Earth's past.

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The things we see on the surface of Earth today have gotten to be that way over many, many years. The surface of Earth - what we see with our eyes - is the

• utermost layer of Earth and is called the crust.

Even though the crust is the outer layer, there are still parts of the crust that are too deep for us to see.

crust

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Earth has other layers underneath the crust. These are called the mantle and the core.

mantle core

But when we talk about the history of Earth, it is the crust - 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?

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Most of the crust is made up of rock. 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.

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1 Can the things we see on Earth's surface can tell us about Earth's history? Yes No

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2 Is it possible Earth's surface has gotten to be the way it is within the past 50 years? Yes No

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3 The outer layer of Earth is called the: A skin B mantle C crust D core

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4 We can see all of Earth's crust with our eyes. Yes No

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5 Which layer of Earth tells us the most about Earth's history? A the core B the mantle C the outside D the crust

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Rock Layers

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Slide 17 / 107 Rock Layers

Sedimentary rock, which makes up much of Earth's crust, is made from sediment. Sediment is broken down pieces of rock and other solid material that settles to the bottom of a liquid. sediment Sediment is often dirt and rock particles that settle at the bottom

• f bodies of water, but it also

refers to any solid material that settles at the bottom of a liquid, such as these particles in this glass of water.

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Sedimentary rock is formed over many years. Where on Earth might we see evidence of layering? How could that have happened? Can you brainstorm any ways sedimentary rock could come to be? Remember our definition of sediment.

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So here's how it happens: Sediments are deposited (usually by water). Sediments 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.

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deposition sedimentation compaction cementation deposition sedimentation compaction cementation

txstate.edu

Rock Layers Slide 21 / 107 Rock Layers

Sedimentary rocks provide a history of the evolution of Earth, especially within the past billion years. When sediments are deposited and compacted to form sedimentary rock, sediments are accumulated in beds one on top of another - in layers. 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 formed over a long period of time.

Slide 22 / 107 Rock Layers

Which layer of rock in this diagram do you think is the youngest? Which is the oldest? Label the top and bottom layers and then move the boxes to reveal the answers.

move for answer move for answer

This is called the Law of Superposition .

Slide 23 / 107 Rock Layers

Geologists study ancient sedimentary rocks to determine what environment they formed in. Determining ancient environments is very important to understand the history of Earth. 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.

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6 The most important characteristic of a sediment is: A that it settles to the bottom of a liquid B that it floats in liquid C its color D that it is small

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7 Order the following steps from first to last in the process

• f sedimentary rock formation (enter all 4 letters on your

responder in the correct order): A compaction B deposition C cementation D sedimentation

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8 Sedimentary rocks form in layers. Yes No

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9 The Law of Superposition says: A rock layers that are closer to the surface are old B old and new rocks are found in the same place C rock layers get older as you go further down D rock layers that are deep down are the most recent

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10 Geologists study ancient rocks to learn about: A people B environments C sediments D cementation

Slide 29 / 107 LAB: Rock Layers

In this lab, we will look more at how sedimentary rocks form, focusing on the questions: How are different sediments deposited differently? How do sedimentary rocks form?

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Fossils and Relative Time

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Slide 31 / 107 Fossils and Relative Time

Sedimentary rocks not only contain sediments such as dirt, sand, and pebbles, but also fossils - preserved remains of plants or animals. Fossils come in many forms. They can be bones, tracks, plants, or bodies of animals, among other things.

Slide 32 / 107 Fossils and Relative Time

Rocks of the same age contain the same, or very similar, fossils. So, for example, very recently formed rocks may have a lot 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 the more recent rock. while in rocks from an older time period there may be none of those fossils, but many of these fossils,

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So if fossils of this organism are found in these three places, then the rocks they were found in are all the same age.

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 exists - we know that the rocks are the same age. How?

Slide 34 / 107 Fossils and Relative Time

This means that the age of a rock can be determined by 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.

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very long time ago long time ago recent

When we compare fossils, we can form a general timeline of

• rganisms that existed throughout history!

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The kinds of fossils found in rocks from different time periods change because animals and plants change through time. These patterns of fossils exist globally. But in certain places, fossils are also found in different rock layers because the environment of that particular place changed throughout history.

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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 had many plant fossils, but no fish or shell fossils. What do you think scientists would be able to tell happened in that place 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.

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Fossils can tell us many things about the the history of:

• r the entire planet.
• ne place,
• ne region,

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11 Fossils are: (choose all that apply) A found in sedimemtary rocks B living organisms C able to help determine how old rocks are D preserved remains of plants and animals

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12 Is it possible to tell if one rock is older or younger than another rock by looking at their fossils? Yes No

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13 Rocks of the same age contain very different fossils. Yes No

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14 Why do rocks from different time periods have different kinds of fossils? (discuss as a class, do not answer with responders)

Students type their answers here

Slide 43 / 107 ACTIVITY: Sediment Fossil Surprise

In this activity we will explore how fossils are deposited in rock layers. We will make our own models to better understand how fossils work and what they tell us. We will focus on the question: How are fossils deposited in sediment layers?

Slide 44 / 107 ACTIVITY: Relative Age with Edible Rocks

In this activity we will closely examine the inside of edible rocks to learn about their "sediments" relative age based on patterns of their deposition. We will focus on the question: How is relative age dating used when observing rock layers?

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Rock Formations and Earth Forces

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Slide 46 / 107 Rock Formations and Earth Forces

Sometimes rock layers are disturbed by different Earth forces. This means that the pattern we typically see in rocks - of older rocks being farther underground and newer rocks being closer to the surface - can sometimes be mixed up, with rock layers existing in different

• formations. What do you think might cause this?

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Earth forces can disturb the Law of Superposition. Some Earth forces include earthquakes , rivers , and erosion.

Slide 48 / 107 Rock Formations and Earth Forces

EARTHQUAKES Patterns in rock formations can show where earthquakes - shaking caused by the movement of rock under Earth's surface - occurred and layers are no longer aligned.

fault line

Rock layers impacted by an earthquake will often show distinct change at the fault line where the earthquake occurred.

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RIVERS Rivers are strong forces that can impact rocks. Often times rivers will cut through rocks, leaving rock layers exposed. Rivers may also deposit new sediment in the middle of old rock layers.

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EROSION Different forces such as rain, wind, flowing water, and living animals can make rocks erode, or wear down. This erosion wears down rocks and creates new patterns in rock layers.

eroded rock layers

Slide 51 / 107 Rock Formations and Earth Forces

Often the cause of Earth forces that disrupt rock patterns is plate tectonics , the movement of plates that make up Earth's crust.

crust

Remember, we said the crust is not a solid layer on the outside

• f Earth.

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geology.er.usgs.gov

You can see the plates here with a map of the continents underneath. These plates move slowly and interact at their boundaries. It is broken into sections called plates .

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Tectonic plates fit closely together along their boundaries.

mantle

The plates are many miles thick. They bump and rub agains each other, while pulling apart, and pushing together. The plates float on top of Earth's mantle which is made up of liquid rock.

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So in a cross-section under Earth's surface, the layers of rock that make up the crust are floating on top of the thick mantle of liquid rock.

Earth's surface mantle crust Earth's surface mantle crust

Slide 55 / 107 Rock Formations and Earth Forces

Earthquakes are one example of Earth forces caused by tectonic plate movement. Earthquakes occur when the plates interact - typically when they are pushing together or sliding past each other - and, as we saw, they disturb rock layers. Earthquakes often leave visible marks on Earth's surface, but especially leave visible marks on rock layers.

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Tectonic plates can also cause rock layers to bend and fold.

Slide 57 / 107 Rock Formations and Earth Forces

When Earth forces disturb typical rock formations, it can be trickier to understand what has happened in Earth's history. But using fossils and other clues can help scientists understand rocks and their ages even in these cases when the layers are mixed up and not in straight lines.

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recent

• ldest

youngest very old

• ld

For instance, if these fossils were found in these layers, we could figure out which layers were oldest and youngest even though the layers are diagonal.

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15 If Earth forces have impacted rocks in an area, will younger rocks still always be located on top of

• lder ones?

Yes No

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16 Earth forces can cause rock layers to: (choose all that apply) A disappear B fold up C unalign D swap

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17 What may have happened to these rocks? (discuss as a group, not a responder question)

Students type their answers here

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18 The crust is a solid layer on the outside of Earth. Yes No

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19 The crust is broken into pieces called: A continents B regions C plates D shells

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20 Tectonic plates: (choose all the apply) A never move B interact at their boundaries C can cause earthquakes D are very thin

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Tectonic Plates

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Slide 66 / 107 Tectonic Plates

The crust is divided into two types: oceanic and continental.

geology.er.usgs.gov

If you look closely at this map of tectonic plates, you can see that parts of the plates are covered with water and parts are covered with land.

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OCEANIC CRUST Where do you think oceanic crust is found? It is made of dense rocks such as basalt. This means that

• ceanic crust is heavy.

Oceanic crust is about 4 miles thick.

• cean floor

mantle

• ceanic crust

Slide 68 / 107 Tectonic Plates

CONTINENTAL CRUST Where do you think continental crust is found? It is made of less dense rocks such as granite. This means continental crust is light . Its thickness varies between 6 to 47 miles. Continental crust is almost always much older than oceanic crust.

continental crust mantle

Slide 69 / 107 Tectonic Plates

There are three types of tectonic plate boundaries: convergent , divergent , and transform .

geografas.eu

If you look closely at this map of tectonic plate movement, you can see arrows showing that different plates move in different directions relative to each

• ther.

Slide 70 / 107 Tectonic Plates

CONVERGENT BOUNDARIES At convergent boundaries, plates collide with one another . At convergent boundaries, continental crust is created and oceanic crust is destroyed as it subducts, melts, and becomes magma. The collision causes the edge of one or both plates to buckle, or causes one plate to move underneath the other, a process known as subduction .

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DIVERGENT BOUNDARIES At divergent boundaries, plates separate. At divergent boundaries, oceanic crust is created. Here, geysers spurt super-heated water, and magma, or molten rock, rises from the mantle and solidifies to form new crust.

Slide 72 / 107 Tectonic Plates

TRANSFORM BOUNDARIES At transform boundaries, plates slide past one another . Here, earthquakes tend to occur when plates move and rub against one another. New crust is neither created or destroyed at transform boundaries.

Slide 73 / 107 Tectonic Plates

USGS.gov

Here is a diagram of the three types of plate boundaries.

(The lithosphere and asthenosphere are parts of the mantle. The asthenophere is made of molten rock.)

Slide 74 / 107 Tectonic Plates

Can you find the 3 different types of plate boundaries on this diagram?

geografas.eu

Slide 75 / 107 Tectonic Plates

On this diagram each type of boundary is shown in a different color.

Did you correctly identify some of these boundaries in the last diagram?

http://johomaps.com/world/worldtecton.html

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21 The two types of crust are ______________ and ______________ . (not a responder question)

Students type their answers here

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22 Oceanic crust is heavier than continental crust. True False

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23 When tectonic pates move apart, it is called a: A divergent boundary B transform boundary C convergent boundary D subducting boundary

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24 This shows a _____________ boundary. A divergent boundary B transform boundary C convergent boundary D subducting boundary

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Earth's Visible Features

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Slide 81 / 107 Earth's Visible Features

Some rock layers indicate Earth forces that happened a long time ago, but there are also many features on Earth's surface that are visible signs of Earth forces today. This is because tectonic plates are still moving. These visible features include mountain ranges, ocean trenches, mid-ocean ridges, rift valleys, and volcanoes, all existing due to the movement of tectonic plates.

Slide 82 / 107 Earth's Visible Features

MOUNTAIN RANGES Where plates collide or push together, mountain ranges form. You can see that as the plates push together, the top layer of rock crunches up to form mountains. Sometimes one plate moves under the other plate - subducts

• and the other plate pushes upwards.

Sometimes both top layers are pushed upwards.

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quake.eas.gatech.edu

Earth's Visible Features

MOUNTAIN RANGES When a oceanic and continental plate converge, the oceanic plate subducts and the continental crust crunches up, forming a mountain range. Where two continental plates converge, they are likely to bothbuckle, or crunch up, forming a mountain range.

Slide 84 / 107 Earth's Visible Features

MOUNTAIN RANGES The Himalayas, shown here, are an example of this.

shanahan2.pbworks.com

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trench

Earth's Visible Features

OCEAN TRENCHES Where oceanic plates converge and one plate subducts underneath the other,

• cean trenches are formed.

Trenches mark the position at which the flexed, subducting crust begins to descend under the crust it is colliding with. Oceanic trenches typically extend 1.9 to 2.5 miles below the level of the surrounding

• ceanic floor.

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magma

Earth's Visible Features

MID-OCEAN RIDGES Where oceanic plates diverge, mid-ocean ridges are formed. Hot magma from Earth’s mantle bubbles to the surface where plates diverge. This magma is then cooled by seawater and forms new crust. The newest oceanic crust is located near the center of the ridge. Over time, new oceanic crust pushes older crust farther away.

Slide 87 / 107 Earth's Visible Features

RIFT VALLEYS Where continental plates diverge, rift valleys are formed. Rift valleys are often narrow, with steep sides and a flat floor. Rift valleys can lead to the creation of entirely new continents, or deepen valleys in existing ones.

Slide 88 / 107 Earth's Visible Features

VOLCANOES Where tectonic plates push together, volcanoes - mountains that erupt with lava - often form. Where plates collide, pressure is built up in Earth. Magma - a mixture of gases and hot molten rock - builds up in the mantle and pushes up into rock layers. The magma opens cracks in weak spots in rocks, and eventually pushes all the way to the surface.

Slide 89 / 107 Earth's Visible Features

VOLCANOES When the magma erupts on Earth's surface, it is called lava. The place it erupts is the volcano .

lava magma volcano

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25 Mountain ranges form where tectonic plates diverge. Yes No

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26 Subduction is when: A two plates buckle up when they collide B a colliding plate goes under another C continental crust moves under oceanic crust D two plates diverge

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27 Mid-ocean ridges form where: A oceanic and continental crust converge B oceanic crust converges with oceanic crust C continental or oceanic plates diverge D oceanic crust diverges

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28 Which of the following are true of volcanoes: (choose all that apply)

A they form where plates converge B they do not need magma to form C they erupt with lava D pressure in the earth helps to cause them

Slide 94 / 107 ACTIVITY: Where Plates Meet

In this activity we will explore tectonic plate boundaries across the

• globe. We will focus on the question: What do we find on Earth’s

surface at tectonic plate boundaries?

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Patterns of Earth's Features

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Slide 96 / 107 Patterns of Earth's Features

The features we see on Earth, both visible and underground, occur in

• patterns. Think about what causes earthquakes and volcanoes.

geology.er.usgs.gov

Where do you think earthquakes and volcanoes are most likely to occur?

Slide 97 / 107 Patterns of Earth's Features

Here is a map of earthquake locations over a 15 year period.

black = earthquakes close to the surface (0 - 70km) green = earthquakes a bit farther down (70 - 300km) red = earthquakes farther down in the crust (300 - 700km)

What do you notice?

http://oceanworld.tamu.edu

Slide 98 / 107 Patterns of Earth's Features

If you place the map next to a map of the tectonic plates, you can see that earthquakes are most likely to occur along plate boundaries.

http://oceanworld.tamu.edu

geology.er.usgs.gov

This is because earthquakes are caused by plates interacting at their boundaries.

Slide 99 / 107 Patterns of Earth's Features

We know that volcanoes occur where plates are converging.

geografas.eu

From looking at this map, can you guess where volcanoes are located?

Slide 100 / 107 Patterns of Earth's Features

Here is a map of volcano locations around the world. Are any of the volcanoes where you guessed they would be?

http://www.globalchange.umich.edu

Slide 101 / 107 Patterns of Earth's Features

Similar to earthquakes, volcanoes are also found along plate boundaries. More specifically, volcanoes exist where plates converge .

http://www.globalchange.umich.edu geografas.eu

Slide 102 / 107 Patterns of Earth's Features

Many volcanoes are found around the edges of the 5 main plates in the Pacific Ocean. This area is known as The Ring of Fire. Why is it called this?

http://www.globalchange.umich.edu

Slide 103 / 107 Patterns of Earth's Features

A map of tectonic plates and their movements can help us predict and know many things about Earth's features.

geografas.eu

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29 Earthquakes occur in completely random locations that could never be predicted. True False

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30 Earthquakes are likely to occur: A anywhere B in random places C where plates diverge D around plate boundaries

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31 What is The Ring of Fire? (not a responder question)

Students type their answers here

Slide 107 / 107 ACTIVITY: Finding Plates by Mapping Quakes

In this activity we will map earthquakes across the globe and compare their locations to the location of plate boundaries. We will think more about the question: What can the location of earthquakes help us understand?

http://oceanworld.tamu.edu