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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.
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.
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
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.