Earth Science Chapter 5 Plate Tectonics

Convection and the Mantle Drifting continents Sea-floor Spreading Big Ideas Earth’s Interior Convection and the Mantle Drifting continents Sea-floor Spreading Plate Tectonics

How far do you think it is to the center of the Earth? Earth’s Interior How far do you think it is to the center of the Earth?

Almost 4,000 miles! The deepest mine in the world is only 2 miles

How do you think scientists know about the center of the Earth?

Geologists use 2 main types of evidence to learn about Earth’s interior: Direct Evidence from rock samples Indirect evidence from seismic waves

Humans have drilled holes and extracted rock from depths of 12 miles Evidence from Rocks Humans have drilled holes and extracted rock from depths of 12 miles Blasts from the Earth have brought rocks from 100 ft to the surface

Evidence from Seismic Waves Earthquakes produce seismic waves The speed of seismic waves and the path they take show the structure of the planet

The three main layers of Earth are the crust, mantle, and the core These layers differ in size, composition, temperature, and pressure

Temperature The first 20 meters beneath Earth’s crust is cool After this depth, temperature rises 1 degree Celsius per 40 meters Heat comes from the molten layer and radioactive substances

The deeper you go, the higher the pressure This pressure is equal to that of a swimming pool

Pressure

Lab Skills Activity Work with a partner, Read the directions to the Lab Zone Skills Activity Create the Data Table on page 129

Crust is a layer of rock that forms Earth’s outer skin Crust includes both dry land and ocean floor Crust is very thin compared to the other layers of Earth, only 5-70 km thick

Crust

Crust The crust beneath the ocean is oceanic crust and usually made of basalt Continental crust consists of rocks such as granite

Mantle The mantle is about 40 km below the surface It consists of a hot, solid rock It can be divided into layers The mantle is about 3000 km thick

Mantle

Lithosphere The crust and the uppermost part of the mantle form the lithosphere It is about 100 km thick Lithos means “stone” in Greek

Lithosphere

Asthenosphere Under increase heat and pressure Less rigid-soft like tar, but still solid Asthenes means “weak” in Greek

Beneath the asthenosphere the mantle is solid The Lower Mantle Beneath the asthenosphere the mantle is solid This material extends to the Earth’s core

Lower Mantle

The Core Consists of mostly nickel and iron Made of two parts, a liquid outer core and solid inner core Together it is about 3486 km thick

Despite extreme pressure, the outer core is molten surrounding a dense, solid inner core Evidence suggests that the extreme pressure in the inner core will not allow the solid metal to spread and become liquid

Core

Core and Magnetic field Scientists think that movements in Earth’s liquid outer core create Earth’s magnetic field. This magnetism is what attracts a compass’ needle towards north (it aligns with Earth’s magnetic field)

Individually Complete the section 1 assessment on page 131, including the “writing in science” assignment. If you do not complete these in class, they will become your homework and will be due tomorrow.

OPEN NOTE POP QUIZ QUIETLY TAKE OUT A PIECE OF PAPER AND ANSWER THE GFOLLOWING QUESTIONS: 1. WHAT TYPE OF EVIDENCE DO SCIENTISTS USE TO LEARN ABOUT EARTH’S INTERIOR? 2. WHAT HAPPENS TO TEMPERATURE AS YOU TRAVEL INTO EARTH’S INTERIOR? 3. GIVE A BRIEF DESCRIPTION OF THE THREE MAIN LAYERS OF EARTH’S INTERIOR.

Make a Chart Types of Heat Transfer Radiation Explanation/definition Conduction Explanation/Definition Convection

When you complete the chart Read the sections “Convection Currents”, and “Convection Currents in Earth.” 1. Define Convection Currents 2. Explain how convection currents work, using a real example 3. Create an illustration of a convection current

Bellwork What are the three types of heat transfer and give an example of one that is not in your book!

What are some of your theories as to what made scientists wonder about drifting continents in the first place?

Drifting Continents http://www.youtube.com/watch?v=WaUk94AdXPA

Prior to Columbus, mapmakers did not know about the new worlds Continental Drift Prior to Columbus, mapmakers did not know about the new worlds Shortly after they began to notice how the coastlines of several countries seemed to fit together like a puzzle

Early 1900s German Scientist Alfred Wegener made a hypothesis: Continental drift Early 1900s German Scientist Alfred Wegener made a hypothesis: All of the continents were once joined together in a single land mass and have since drifted apart.

The Origin of Continents and Oceans Wegener gathered evidence from different scientific fields to support his ideas about continental drift. He studied land features, fossils, and evidence of climate change

Write a Book! Make your own version of Wegner’s book Use the same title as he did Read pages 138-138 about the evidence he found Create a page for each type of evidence Explain how the evidence supports his hypothesis and include illustrations if appropriate.

The Origin of Continents and Oceans Page 1: Title Page 2: Evidence from land features Page 3: Evidence from fossils Page 4: Evidence from climate Page 5: Conclusion

WHAT DID YOU FIND? In your notebook, write what you found from Wegner’s evidence.

Review Game Each group take out a piece of paper With your desk partner, you will quietly discuss and write your answer to the following questions The group with the most points at the end of the game will get to choose a homemade treat from me;-)

How far is it to the center of the Earth? 2 pts How far is it to the center of the Earth? 4000 miles

2 pts Geologists use 2 main types of evidence to learn about Earth’s interior, what are they? Seismic waves and rock samples

2 pts What are the three main layers of the Earth? Core, Mantle, Crust

2 pts Describe Earth’s outer most layer Made of Rocks, includes Earth’s Land, Mountains, and water, only 5-70 km thick, thinnest layer

2 pts Describe Earth’s middle layer Mantle, several different layers, made of different materials and containing different textures.

2 pts Describe Earth’s inner most layer (include both sub layers) Inner and outer core, both are made of nickle and iron, outer is liquid, inner is solid, outer core determines Earth’s magnetic poles

2 pts What happens to the temperature are you travel into Earth’s interior? Cooler for the first 20 meters, then it begins to become hotter at a constant rate of increase

3 pts What are the three types of heat transfer? Radiation, conduction, convection

2 pts Explain radiation and give an example Transfer of heat energy through space, sun’s radiating heat

2 pts Explain conduction and give an example Transfer of heat energy directly from the heat source…by touch, touching something hot

2 pts Explain conduction and give an example Movement of heated material from heat source to cooler space, creates a cycle the circulates heated and cooled material. Mocement of hotter and cooler water in a heated pot

3 pts What was Alfred Wegner’s hypothesis? The continents were once joined together in one super continent

3 pts What were the three main sources of evidence Alfred used to support his thesis? Fossils, land features, climate change evidence

2 pts Explain and give an example of Wegner’s evidence from land features.

2 pts Explain and give an example of Wegner’s evidence from fossils

2 pts Explain and give an example of Wegner’s evidence from climate.

Why was Wegner’s hypothesis not accepted by the scientific community?

Who was Harry Hess and how was he connected to Alfred Wegner?

Explain the theory of sea-floor spreading

What were all of the pieces of evidence Hess used to support his thesis?

How does the existence of lava pillows at deep ocean trenches help support Hess’ theory?

How does magnetic stripes help support Hess’ theory?

How do core samples from the ocean floor help support Hess’ theory?

What tends to occur at deep ocean trenches and why?

Explain how the atlantic ocean is getting bigger and the Pacific is getting smaller.

Sea-Floor Spreading http://www.youtube.com/watch?v=p0dWF_3PYh4

Mid Ocean Ridges

Mid Ocean Ridge Curve like seams through Earth’s oceans Most mountains are under water, except Iceland!

Iceland

Hess and Sea-floor spreading Harry Hess in 1960 realized that Wegener was right and the continents were being moved by sea-floor spreading: The sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added The ocean floors act like conveyor belts carrying the continents along with them

Read pages 144-145

Editorial You are Harry Hess! (or Harriet Hess) You have just concluded your research about sea-floor spreading Prepare a speech for your science conference in which you will share your findings Include your theory, the evidence that supports if from molten material, magnetic stripes, and drilling samples, and end with a conclusive argument!

For Pace http://www.youtube.com/watch?v=hSdlQ8x7cuk Future of continental drift

Sea floor spreading

Sea floor spreading http://www.youtube.com/watch?v=BCzCmldiaWQ Magnetic Stripes

http://earthguide. ucsd http://earthguide.ucsd.edu/eoc/teachers/t_tectonics/p_seafloorspreading.html http://serc.carleton.edu/files/introgeo/models/mathematical/examples/SeaFlrSpreadIpdf.pdf http://www.montereyinstitute.org/noaa/lesson02/l2la1.htm

Bellwork What were the hypotheses of both Alfred Wegner and Harry Hess and how were they connected?

http://www.youtube.com/watch?v=q_IYQdKkWsU Ice Age http://www.youtube.com/watch?v=6CsTTmvX6mc Bill Nye

http://maccallum. wikispaces http://maccallum.wikispaces.com/Lesson+15+AND+16+Continenetal+Drift+and+Sea+floor+spreading http://www.westerville.k12.oh.us/userfiles/4161/Classes/9094/Sea%20floor%20spreading%20worksheet.pdf http://science.berlinwall.org/files/bhs_science/Continental%20Drift,%20sea%20floor%20spreading%20and%20plate%20tectonics%20PDF.pdf

Subduction at Trenches Deep-ocean trenches: deep underwater canyons. At deep-ocean trenches the oceanic crust bends down and sinks beneath the continental crust.

Subduction Subduction: the process by which ocean floor sinks beneath the deep ocean trench and back into the mantle

Short Subduction Video http://www.youtube.com/watch?v=wkc4lbhhSRs

Process of Subduction As the older rock is subducted, younger rock moves away from the mid-ocean ridge New rock is hot, but it cools and becomes more dense as it ages

Old rock, Green Rock, New Rock, Red Rock

Bellwork Describe the difference between what occurs at the mid ocean ridge and deep ocean trenches.

Subduction http://www.youtube.com/watch?v=ryrXAGY1dmE

Eventually gravity pulls the older, denser rock down at the trenches Process Continued Eventually gravity pulls the older, denser rock down at the trenches

Subduction and Earth’s Oceans Subduction and seafloor spreading can change the size and shape of the oceans Ocean floor is renewed about every 200 million years The Pacific’s trenches are eating more crust than the ridges can make In the Atlantic the opposite is the case

Future Pangea http://www.youtube.com/watch?v=hSdlQ8x7cuk

http://www.youtube.com/watch?v=xsJn8izcKtg Lava Pillows http://www.youtube.com/watch?v=hmMlspNoZMs Ridge Volcano

Review http://www.youtube.com/watch?v=_5q8hzF9VVE Continental Drift Review

Bellwork Briefly discuss the progression of ideas and discoveries beginning with Alfred Wegener and ending with Plate Tectonics. Don’t ask questions, just write….remember you cannot get bellwork wrong!

Flip Book Title The Theory of Plate Tectonics Make a flip book describing the 3 types of plate boundaries Your book will need a Title The Theory of Plate Tectonics Page on each:divergent, convergent, and transform boundaries Each page should define the type of boundary, explain what types of landforms that occur at these boundaries, and have an illustration

BELLWORK What are the three types of boundaries and which one is most likely to produce earthquakes?

The Theory of Plate Tectonics

Boundaires Divergent Convergent Transform

Divergent are where plates are moving away from each other. This movement is found along the mid-ocean ridges where new crust material is being created.

Mid-Ocean Ridge, Rift Valleys African Rift Valley

Continent-Continent

Ocean-Ocean

Continent-Continent

Transform

Complete your book for homework Quiz tomorrow Complete your book for homework Bring it with you tomorrow and you may use it for our quiz over boundaries