Plate TectonicsPlate TectonicsEvolution of the Earth

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How do we know anything about the EarthHow do we know anything about the Earth

Page 20,22:Pg. 203 Column Vocab1. Mid ocean Ridge2. Sea floor spreading3. Plate Tectonics4. Asthenosphere5. Lithosphere6. Convection cell7. Pangaea

Pg. 22

8. Subduction zone9. Rifting10. Divergent boundary11. Convergent boundary12. Transform boundary**Not all terms are in glossary—some are italicized within the chapter

How to do 3 column vocab.

Word Definition Picture

Page 16

How are scientists able to study the composition and size of the interior layers of the Earth?a. By direct observationb. By analyzing surface rock samplesc. By using seismic wavesd. By deep drilling into the interior layers

Page 16

• Which statement BEST describes how new scientific views become accepted?a) A group of scientists come to common agreement

over an idea at the same time.b) New ideas become a theory when hypotheses are

proven to be correct.c) When a theory gains so much support it becomes

a scientific law.d) When observations of our natural world produce

plausible explanations.

In: pg 18,19

• Watch the movie clip “ The Earth’s Interior” and write down 15 facts.

1.2.3.4.5.

Use the diagrams below to answer the question.

Page 16

• Which type of plate boundary is shown in the diagram?a. Divergentb. Transformc. Convergentd. Universal

Page 16

• Prior to Alfred Wegener’s theory of continental drift geologists thought continents were fixed in their locations. In developing his theory which of the following evidence was NOT used by Wegener?a) Fossil similarities between southern continents.b) Evidence of polarity change in found along the Mid-

Atlantic Ridge.c) Similarities in the paleoclimates of South America and

Africa.d) The apparent fact the South America and Africa seemed

to fit together.

20

Warm up

Wrap up

21,23,25

Earth’s interiorChapter 10

InteriorInterior

InteriorInterior

Thru 1: Pg 21

The Earth’s Interior Questions• Read the front and complete the questions on

the back.• Tape in as a flap

Thru 1: pg. 21Please copy this concept map and then complete it by filling in one appropriate descriptor at the end of each arrow. Use pages 239-241 in the textbook.

Theory of Continental

Drift

Scientist

What is missing? Supporting Evidence

Definition

When discovered

FossilsContinents Rock Formations

Climatic

Quiz #1 Sep. Sheet1. Pg. 25 What is the title of Ch. 10? 2. Pg. 27 What is the answer to #2?3. Pg. 27 What is the answer to #10?4. Pg. 27 How thick is the core?5. Pg. 29 What is the answer to #5?6. Pg. 29 What is the answer to #10?7. Pg. 31 What was the name of the scientist who

came up with the Theory of Continental Drift?8. Pg. 31 The Theory of Continental Drift says that

the continents are___________.

Thru 2

Pg. 23-use the supercontinent on pg. 33 and the book to answer these questions.Analysis Questions:1. What are 3 pieces of

evidence you used to fit together the continents?

2. Why is this called a supercontinent?

3. How does this model help support the Theory of Continental Drift?

4. Why aren’t the continents still in this location today?

Pg. 25

Supercontinent Cutout.Cutout the continents and fit them together to make the supercontinent that Wegener proposed. Glue them on this page.

Alfred Wegener

Theory of continental

drift

• Harry Hammond Hess Harry Hess commanding the USS Cape Johnson.• Born May 24, 1906 Died August 25, 1969

Suggested that the convection of the Earth's mantle was the driving force behind plate tectonics. .

Tectonic PlatesTectonic PlatesToday plate boundaries are determined by examining the location of volcanoes and earthquakes.

Volcanoes result from the friction (heat) of the platesmotion.

Earthquakes occur where plate rub against one another

Tectonic PlatesTectonic Plates

Tectonic PlatesTectonic Plates

Tectonic PlatesTectonic Plates

Tectonic PlatesTectonic Plates

Evidence of Continental Drift

Pangea• What is Pangaea? • Pangaea was a super continent at one time.• Scientists use the similarity of rock types and fossil types that date to the

same age to support their theory that the continents were connected to form a super continent.

• The map below give just one example of areas on different continents that show the same fossils and rock types.

PangeaPangea• Pangea

Tectonic PlatesEvidence

Tectonic PlatesEvidence

Our first evidence of tectonic motion is based on similar fossils and rock types on opposing sides of the ocean

Tectonic PlatesTectonic Plates

Tectonic PlatesTectonic Plates

Radioactive Dating

Another source of evidence is based on seafloor ages which get younger as we approach sea floor ridges

Tectonic PlatesTectonic Plates

Our final piece of evidence is the magnetic record of the ocean floor.

This shows the pattern of reversal and we find a near perfect mirror image on opposing sides of the ridge

Where are we going?Where are we going?

We appear to be headed for another super continent as North America,

South America, Asia and Australia converge in the ever shrinking Pacific Ocean

Composition vs. MotionComposition vs. Motion

We can look at the interior of the Earth based on the composition of the rocks or based on the movement

Based on CompositionBased on Composition

• Crust – solid, relatively low density silicate rock• Mantle – Semi fluid, denser, mafic (iron and magnesium

bearing) rocks• Core – Liquid then solid iron and nickel with traces of

heavier elements

Based on MotionBased on Motion

• It turns out that the upper section of the mantle is adhered (stuck to the underside side of the crust to form what we call tectonic plates

Plate TypesPlate Types• Oceanic plates: basalt

– Dark (black) and dense rock type composed of silicates, iron and magnesium

• Continental plates – granite and andesite– Light colored (pink, white and

gray) and low density rock type composed almost entirely of silicates.

Plate BoundariesPlate Boundaries• Convergent – plates move toward one

another

• Divergent – plates move away from each other

• Transform – plate moves sideways from each other

Plate BoundariesPlate Boundaries

Convergent PlatesConvergent Plates

Convergent PlatesConvergent Plates

Convergent PlatesConvergent PlatesThe only subduction zone in the AtlanticThe only subduction zone in the Atlantic

Convergent PlatesConvergent Plates

Black arrows show subduction zones and the direction of plate movement

• Subduction.swf

ocean-con

ocean-ocean

con-con

Divergent PlatesDivergent Plates

• Divergent• sfloorspreading.swf

Divergent PlatesDivergent Plates

Divergent PlatesDivergent Plates

Divergent PlatesDivergent Plates

Transform PlatesTransform Plates

• Trboundary.swf

Transform PlatesTransform Plates

San Andreas Fault

Mid-Plate HotspotsMid-Plate Hotspots

Mid-Plate HotspotsMid-Plate Hotspots

Mid-Plate HotspotsMid-Plate Hotspots

Mid-Plate HotspotsMid-Plate Hotspots

Hotspotvol.swf

Why do the Plates Move?Why do the Plates Move?

Why do the Plates Move?Why do the Plates Move?• No single idea explains everything but we can

identify several forces that contribute to the movement of the plates.– Slab pull

• The sinking of the cooled dense oceanic plates pulls on the rest of the plate

– Ridge rises• The material deposited on the top of the ridge slides downs from

the rise pushing on the plate– Convection

• Movement within the mantle could be part of the driving force behind the motion of the plates.

The Big PictureThe Big Picture

VolcanoesVolcanoes• Volcanoes are the result of hot spots within the crust

or mantle of the earth.• The hot, liquid rock will break through weak spots in

the surface and form volcanoes or flood basalts.• Many volcanoes do not release lava, instead they spit

ash and small bits of lava called lapilli.• Some eruptions are quiet with very fluid (low

viscosity) lava flows while others are explosive

VolcanoesVolcanoes

Quiet lava flows

VolcanoesVolcanoes

Mt. St. Helen before the explosive eruption

VolcanoesVolcanoes

VolcanoesVolcanoesTime lapse of the eruption

VolcanoesVolcanoes

Mt. St. Helen after the eruption

VolcanoesVolcanoes

EarthquakesEarthquakes

Tidal waves or Tsunamis result when the low amplitude long wavelength wavesreach the shallow shoreline and begin to feel the bottom of the sea floor. This Shortens the wavelength and increase the amplitude (height).

EarthquakesEarthquakes

Location of worldwide earthquakes

Tsunami

Ch. 10 Plate Tectonics

Thru 1: pg 35Cornell Notes

The Theory of Continental Drift

• Continents were once in a single landmass or supercontinent that drifted apart into the continents we see today.– Supercontinent was called Pangaea

• Alfred Wegener came up with the Theory of Continental Drift in 1911.

• Used the shape of continents, distribution of fossils and rock formations to hypothesize that the continents were at one time all together.

• No mechanism until 30 years later.

The Supercontinent

Mid-ocean Ridges

• Undersea chains of volcanic mountains that run along the ocean floor.

• Have deep valleys in the center where magma comes up.

Sea Floor Spreading

• The ocean floor is moving outward from the mid-ocean ridges.– The rock closer to the ridges is younger than the

rock far from the ridges– Oceanic rock is much younger than continental

rock.– Explains how the continents move.

• Magma rises to the surface and solidifies and new crust forms

• Older Crust is pushed farther away from the ridge

Sea Floor Spreading Animation

Lithosphere and Asthenosphere

• Lithosphere is the rigid outer layer of the Earth.• Made of the crust and

the solid outer layer of mantle.

• Asthenosphere is the layer of “plastic” rock in the lower mantle.• Flows like a very thick

liquid.

Lithospheric Plates

• Lithospheric Plates-The rigid lithosphere is broken into blocks or plates– Also called Tectonic Plates.– Float on the semi rigid,

moving asthenosphere.

Tectonic Plates

Theory of Plate Tectonics

• Theory of Plate Tectonics explains how the lithospheric plates move.

Convection Currents

Convection currents -caused by the very hot material at the deepest part of the mantle rising, then cooling and sinking again --repeating this cycle over and over.

***Remember…this heat is generated by the core!!

HOT!!!!

How Plates Tectonic Works

As magma heats up and rises, it exits through the rift in the middle of the mid-ocean ridge. It cools and pushes the plates apart. The Asthenosphere is also moving in convection currents(created by unequal heating), carrying the plates outward.

Now!

• Write 3 questions in the left hand column and a 3 sentence summary at the bottom.

Out

Tent Paragraph-use the following words correctly in a paragraph. Highlight the words within the paragraph.• Lithosphere• Asthenosphere• Tectonic plate• Convection cell

• The movement of tectonic plates is inferred by many scientists to be driven by a. tidal motions in the hydrosphere.b. density differences in the troposphere.c. convection currents in the asthenosphere.d. solidification in the lithosphere.

In: pg. 38• Use your notes on pg. 35 to answer these questions:1. Who came up with the Theory of Continental Drift?2. _______ are undersea chains of volcanic mountains that run

along the ocean floor.3. ________ spreading explains that the ocean floor is moving

outward from the mid-ocean ridges.4. The ______is the rigid outer layer of the Earth.5. The ______ is the layer of the lower mantle that flows like a

thick liquid.6. The lithosphere is broken into _____ plates.7. The Theory of ______ ______ explains how the plates move.8. The mantle moves in _________ currents created by the

unequal heating of mantle material.

Thru 1: Pg. 39

Plate Boundaries Diagramshttp://geology.com/nsta/

Plate boundaries

Different Types of Boundaries

http://pubs.usgs.gov/gip/dynamic/understanding.html

Divergent Boundary – Arabian and African Plates

Arabian Plate

African Plate

Red Sea

Convergent Boundary – Indian and Eurasian Plates

Indian Plate

Eurasian Plate

Convergent Boundary – Oceanic & Continental

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Convergent Boundary – Oceanic & Oceanic

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

NOTE – PLATES ARE REVERSED

Convergent Boundaries - Continental

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Transform Boundary – San Andreas Fault

www.geology.com

Out

When 2 plates converge, one plate will normally subduct.• What does the word “subduct” mean?• What is a subduction zone?• What determines which plate will subduct?

Wed. 2/27 and Thurs. 2/28

In: pg. 40

• Match the type of boundary with the structure that will form.

1. Oceanic/oceanic2. Oceanic/continental3. Continental/continental

A. Mountain ranges. B. Trenches and island arcsC. Trenches and volcanic arcs

Thru 1: pg. 41

• Tectonic Plates Map Worksheet.– Complete the questions and tape in the

worksheet.

Out

• A friend tells you that California is going to fall off and Nevada will one day be waterfront property. Please explain what is wrong about this statement.

In: pg. 34• Take the cup at your table to the sink and fill it about ½ full of

water. Return to your table and drop the colored ice cube in the cup. Watch the water that melts off of the ice cube and draw what you see. Use arrows to represent the movement of the red water.

1. Did the cold water coming off of the ice cube sink or float?

2. Which is more dense-cold or warm water?

Convection

• When a substance is heated it becomes less dense and rises.

• When a substance cools, it becomes more dense and sinks.

• This creates a circular movement in the material called a convection cell or current.