Interim Slides Part 3

Part 3 Earth Science

Cross Section of the Earth Earth is a Spherical Planet with a Diameter of More than 12,000 Kilometers (8,000 Miles) The crust is solid, while the mantle is plastic. Because the mantleis plastic and very hot, it can bend, flow, and move. 

T h e E a rth is co m p o se d o f five la ye rs.

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The Earth’s crust is solid but is broken into a number of large tectonic plates plus a number of smaller ones. 

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The tectonic plates are located right on top of the mantle. 

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Because the mantle can bend, flow, and move, the tectonic plates can also bend and move. 

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History of Discovery The Mid-Atlantic Ridge •

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In 1947 scientists discovered the Mid-Atlantic Ridge, an underwater mountain range stretching along the Atlantic Ocean, between North and South America, Europe and Africa. Geologists discovered the ocean floor was composed of basalt, an igneous rock. Igneous Rock is produced through volcanic processes.

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Some igneous rock contains magnetite. This mineral is affected by the Earth’s magnetic field. When it cools and hardens, magnetite crystals are

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The Theory Of Plate Tectonics: Boundaries  

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Plates can move:

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1. TOWARDSeach other. This is a CONVERGENT BOUNDARY. 2. 3. AWAYfrom each other. This is a DIVERGENT BOUNDARY. 4. 5. ACROSS or AGAINSTeach other. This is a TRANSFORMFAULT BOUNDARY.

C lick h e re to se e a n a n im a tio n Click o f th thpicture re e tyabove p e s too fview p laanteanimation b o u n dofa r2 onethe 

1. 2)

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Pangaea to present day.

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Seafloor Spreading Divergent Boundary

T h e M id - A tla n tic R id g e is a d iv e rg e n t b o u n d a ry ( tw o p la te s m o v in g a p a rt fro m e a ch o th e r) running in n o rth -so u th o rie n ta tio n fo r a lm o st th e e n tire le n g th o f th e A tla n tic O ce a n . 5

Continental Divergent Plate Boundaries U se w h a t yo u kn o w a b o u t d iv e rg e n t p la te b o u n d a rie s to in te rp re t th e im a g e b e lo w o f th e G re a t R ift V a lle y which runs th ro u g h th e M id d le E a st, th e R e d S e a a n d E a st A frica .

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Convergent Plate Boundaries Subduction Zones •

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Places where two tectonic plates are moving towards each other are convergent boundaries. There are three types of convergent boundaries. – oceanic – oceanic – oceanic – continental – continentalcontinental

Above is an example of an “oceanic – continental” convergent plate boundary. The ocean floor moves underneath the continental crust. This is called a subduction zone. The ocean crust is forced down, and subjected to very high pressure and temperature, turning it back into molten rock. 7

Convergent Boundaries Subduction Zones Create Volcanoes The Cascade Mountain Range is a long chain of volcanoes produced by a subduction zone off the coast of the Pacific Northwest. Mount St. Helen is one of a long chain of volcanoes produced by a subduction zone off the coast of the Pacific Northwest.

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Question Review • Describe convergent boundaries and the features associated with it.   

Answer: There are three types of convergent boundaries: oceanic-oceanic; oceaniccontinental; and continental-continental. In oceanic-continental convergent boundaries the oceanic plate is subducted under the continental plate. Volcanic activity and mountain uplifting occurs at convergent boundaries.

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The Pacific “Ring Of Fire” Subduction Zones surround most of the Pacific Ocean and form an almost continuous line of volcanic activity. 

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The “Ring of Fire” is formed by the subduction of the Pacific plate, the Juan De Fuca plate and the Nazca underneath the continental plates of North America, South America and Filipino Plate and Australian Plate.

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Transform-Fault Boundaries Earthquakes

Transform - Fault Boundaries move laterally . When pressure builds and releases , we experience an Earthquake . One of the most active Transform - Fault boundary is the San Andreas Fault in California .

Click on link below to view a QuickTime Video on Earthquakes: Los Angeles http://www.teachersdomain.org/resources/ess05/sci/ess/Earthsys/thrustfault/index.html

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Making Connections Transform Fault Boundaries Transform fault boundaries differ from divergent and convergent boundaries because crust is only deformed or fractured. Crust is not created (divergent boundary) nor destroyed (convergent boundary).

Triple Venn Diagram

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Plate Movement and Hot Spots •

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Most volcanoes form along plate boundaries. However, some volcanoes form in the middle of a plate which is then called a “hot spot”. An example of a “hot spot” are the Hawaiian Islands.

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As the oceanic plate moves over a “hot spot”, magma pushes through the lithosphere forming k on the link below to view a QuickTime Video on mountains. e Tectonics: Thevolcanic Hawaiian Archipelago •

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The graphic above shows the formation of new islands as the plates continue to move over the “hot spot”.

http://www.teachersdomain.org/resources/ess05/sci/ess/Earthsys/hawaii/index.html

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Major Plate Boundaries and Their Movement List the major plate boundaries and describe the direction in which they are moving in relationship to each other.

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Assessment of Learning FCAT Multiple Choice Sample Questions 1.According to the Plate Tectonic Theory, when oceanic plates collide with continental plates, the denser oceanic plate is forced under the lighter continental plate. Which geologic feature is a result of this type of collision? A. B. C. D.

hot spot abyssal plain mid-ocean ridge composite volcano

FCAT Science Sample Test Book 2007 15

Assessment of Learning FCAT Answer and Distractors 

The correct answer is D (composite volcano).

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An understanding of the geologic features associated with plate tectonics is needed to answer this question. When an oceanic plate is subducted under a continental plate, composite volcanoes may form as the descending slab of ocean crust is heated and the molten rock rises to the surface as magma. 

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Distractor Rationale A. Hot spots are not the result of plate collision. Hot spots occur in areas where plumes of hot material burst through the crustal plate. They are not associated with any particular plate boundary, and may form anywhere, including the interior of plates. B. Abyssal plains are not the result of plate collision. Abyssal plains are formed in the interior of tectonic plates, occurring between continental rises and Mid-Ocean Ridge systems. C. Mid-Ocean Ridges are not the result of plate collision. Mid-Ocean 16 Ridges are formed at divergent boundaries rather than convergent 

Assessment of Learning FCAT Multiple Choice Sample Questions 

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Uplift mountain building would most likely occur:

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A .Along Convergent Plate Boundaries B .Along Divergent Plate Boundaries C .Above hot spots D .Near the center of Tectonic Plates, away from plate boundaries.

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Assessment of Learning FCAT Answer and Distractors The correct answer is A (Convergent Boundaries). An understanding of the geologic features associated with plate tectonics is needed to answer this question. When two plates move towards each other both plates may be pushed upwards in a forceful thrusting movement . Distractor Rationale B. Divergent plate boundaries occur when plates move away from each other. Mountain s that are found here will most likely be formed through volcanic processes. C.

Hot spots are not the result of plate collision. Hot spots occur in areas where plumes of hot material burst through the crust al plate. They are not associated with any particular plate boundary, and may form anywhere, including the interior of plates.

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Uplift mountain building is most likely to occur near the edge of the plate boundary, not in the central region.

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FCAT Short-Response (SR) Sample Items Read, Inquire, and Explain 1. The Aleutian Island archipelago is formed just north of a long subduction zoneof around the Pacific plate. Iceland is located on the Mid-Atlantic Ridge, a divergent boundary. The Hawaiian Islands are volcanic islands, but are located in the central region of the Pacific Plate. Use the Theory of Plate tectonics to explain how these three different archipelagos were formed. 2. 3. The Burgess Shale, located high in the Canadian Rockies, is home to one of the richest fossil beds on Earth. Although this site is situated more than 3000 feet above sea level and several hundred miles inland from the Pacific Ocean, all the fossils come from marine organisms. Dating back from some 500 million years ago, the Burgess Shale fossils give us a glimpse of ancient aquatic life. Use the Theory of Plate tectonics to explain how fossils of ocean dwelling organisms can now be found so far from the ocean. 4. 19

KEY CONCEPTS REVIEW

2. As a result of the drifting continents, what  landforms were created? 

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The drifting continents create many landforms including mountain ranges, rift valleys, undersea mountains, volcanoes, and the Mid-Atlantic Ridge. 20

KEY CONCEPTS REVIEW 3. What causes earthquakes and volcanic activity?  

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Earthquakes are caused by slow movements inside the Earth that push against the Earth's brittle, relatively thin outer layer, causing the rocks to break suddenly. This outer layer is fragmented into a number of pieces, called tectonic plates. Most Earthquakes occur at the boundaries of these plates. A volcano is a mountain topped with vents, holes, and craters. It occurs along the Earth’s tectonic plates where molten rock is forced upward from magma reservoirs deep in the Earth. 21