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Edible Tectonics. Agenda: None Turn in your Model of Earth Assignments to your number. Clear off desk except for journal.
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Edible Tectonics Agenda: None Turn in your Model of Earth Assignments to your number. Clear off desk except for journal. Bellwork: With your team, sort the cards about the plate boundaries. Try to put the correct plate boundary image with the correct label and definition of that plate boundary.
Today’s Journey • 0507.7.1 Create a model to illustrate geologic events responsible for changes in the earth’s crust. State Performance Indicators • SPI 0507.7.1 Describe internal forces such as volcanoes, earthquakes, faulting, and plate movements that are responsible for the earth’s major geological features such as mountains, valleys, etc.
Edible Tectonics • As you know the Earth’s crust and upper mantle combine to make the lithosphere. These plates “float” on the asthenosphere or lower mantle. As the convection currents rise and fall, the plates move in a variety of ways. These ways are known as boundaries.
There are 4 main types of boundaries. • Divergent • Convergent • Subduction(a type of convergent boundary) • Transform
Edible Milky Way Tectonics • Each of you have 2 fun size milky ways. We are going to use these to demonstrate the types of boundaries present that cause geologic features such as volcanoes, earthquakes, mountains. trenches, etc. • 1-Take a moment with your team and come up with an operational definition for plate tectonics
Look at one of the fun size candy bars. • Observe the cross-section of the candy bar. • Illustrate this and label it candy-bar cross-section in your journal. • Carefully pull the candy-bar apart in half. • Illustrate your observations. Label it “pulled apart.”Talk with your partners; what do you notice? • The candy-bar will be used as a model of Earth. Identify Characteristics of the candy-bar which make it suitable to model the layers of the Earth. • Draw the inside cross-section of the candy-bar and label what each part could represent.
Divergent Boundaries • An area where two plates move apart • Creating new crust(land) • Also called Sea Floor Spreading or spreading centers because they are fractures in the lithosphere where the plates are moving apart, as in the Mid-Ocean Ridge system or rift valleys like the one running through eastern Africa. • As the plates separate, pressure on the mantle directly below decreases. The decrease in pressure causes the temperature in that portion of the mantle to rise above its melting point. The small amount of melting mantle produced rises to the surface. • What types of geologic features could be created by this?
Diverging Boundaries New Crust/Islands (where two oceanic plates diverge) The small part of the mantle that rises to the surface hardens and cools adding new land to existing land or sometimes creating new islands altogether! Mid-ocean Ridges Rift-valleys Some Volcanoes
Now take the candy-bar and gently push it back together. What happens to the chocolate? • Illustrate what the candy-bar looks like now. Label it “pushed together.” • What type of geologic features could this make?
Convergent Boundaries- Mountains and Mountain Ranges • An area where two plates collide together • This movement of plates causes mountains and mountain ranges • They buckle and are pushed upward, creating towering mountain ranges like the Himalayas, the Alps and the Appalachians. (The Rockies were not created by convergent plates. They were formed by glaciers.)
Another type • Now take the candy bar and force it even harder together. • What happens? Illustrate this cross-section now. You should notice that the parts pushed hard together are forced so tightly that one half goes below the other. What types of features do you think this makes?
Subduction Boundaries-Volcanoes & Volcanic Islands • Occur at some convergent boundaries • When a plate carrying continental crust collides with a plate carrying oceanic crust, subduction occurs. • Ocean crust, which is more dense than continental crust, slides beneath the continental crust. • The continental crust is forced into the mantle. • As the rock material in the ocean crust begins to melt in the mantle, some of the melted rock is forced upwards producing volcanoes and trenches. • Volcanic Islands occur the same way but between two ocean crusts.
How are subduction boundaries similar to converging boundaries? • These are similar because they are both being pushed together! • However, in subducting boundaries, the denser crust will bend and slide under the continental crust. One side goes under like a submarine!
Now open your other candy-bar. • Place both candy-bars side by side- one in each hand. • Now gently push the right hand piece of candy away from you while pulling the left hand piece toward you. The sides may stick together so you may have to increase the force of your push. What do you observe?
Transform Boundaries-Earthquakes • A point where two plates slide past each other, moving in opposite directions. • Earth’s crust is neither created nor destroyed. • These plates catch and grind causing powerful earthquakes. • The San Andreas Fault, responsible for the devastating earthquakes in San Francisco and Los Angeles, is this type of boundary between the Pacific Plate and the North American Plate.
Today’s Journey • 0507.7.1 Create a model to illustrate geologic events responsible for changes in the earth’s crust. State Performance Indicators • SPI 0507.7.1 Describe internal forces such as volcanoes, earthquakes, faulting, and plate movements that are responsible for the earth’s major geological features such as mountains, valleys, etc. Wrap-Up Name the 4 types of boundaries. Which boundary is responsible for valleys and new crust? Transform Boundaries create what? Convergent boundaries create _______ and _____ ______.
Exit Ticket: Complete the Slip, Sliding Away Sheet at your desk and place in your number as you finish.
Let’s look at a couple videos! • Basic Boundaries http://www.wwnorton.com/college/geo/animations/basic_plate_boundaries.htm • http://www.classzone.com/books/earth_science/terc/content/visualizations/es0804/es0804page01.cfm?chapter_no=visualization • Divergent http://www.wwnorton.com/college/geo/animations/the_process_of_rifting.htm • Subducting: http://www.wwnorton.com/college/geo/animations/the_process_of_subduction.htm • Let’s look at all the types. Can you identify them? http://www.wwnorton.com/college/geo/animations/earth3e/04.htm Brainpop-Plate Tectonics http://www.brainpop.com/science/earthsystem/platetectonics/