Fcat Study Guide Plate Tec Earth Sci '10

The crust is solid, while the mantle is plastic. Because the mantle is plastic and very hot, it can bend, flow, and move.

The Earth is composed of five layers.

The Earth’s crust is solid but is broken into a number of large tectonic plates plus a number of smaller ones. The tectonic plates are located right on top of the mantle. Because the mantle can bend, flow, and move, the tectonic plates can also bend and move.

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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.

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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 aligned and locked into North/South orientation. 3

Plates can move: 1.

TOWARDS each other. This is a CONVERGENT BOUNDARY.

2.

AWAY from each other. This is a DIVERGENT BOUNDARY.

3.

ACROSS or AGAINST each other. This is a TRANSFORM-FAULT BOUNDARY.

Click here to see an animation of the three types of plate boundaries 650 million years of Earth’s plate movement

or Pangaea to present

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The Mid-Atlantic Ridge is a divergent boundary (two plates moving apart from each other) running in north-south orientation for almost the entire length of the Atlantic Ocean. 5

Use what you know about divergent plate boundaries to interpret the image below of the Great Rift Valley which runs through the Middle East, the Red Sea and East Africa.

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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 – continental-continental

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.

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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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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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Subduction Zones surround most of the Pacific Ocean and form an almost continuous line of volcanic activity.

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 10 Australian Plate.

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

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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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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. As the oceanic plate moves over a “hot spot”, magma pushes through the lithosphere forming volcanic mountains.

Click on the link below to view a QuickTime Video on Plate Tectonics: The Hawaiian Archipelago

The graphic above shows the formation of new islands as the plates continue to move over the “hot spot”. 13

List the major plate boundaries and describe the direction in which they are moving in relationship to each other.

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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. hot spot B. abyssal plain C. mid-ocean ridge D. composite volcano

FCAT Science Sample Test Book 2007

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The correct answer is D (composite volcano). 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. 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 Ridges are formed at divergent boundaries rather than convergent 16

2.

Uplift mountain building would most likely occur:

A. B. C. D.

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

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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. Mountains 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 crustal plate. They are not associated with any particular plate boundary, and may form anywhere, including the interior of plates.

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1.

The Aleutian Island archipelago is formed just north of a long subduction zone of 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.

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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.

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1. As a result of the drifting continents, what landforms were created? The drifting continents create many landforms including mountain ranges, rift valleys, undersea mountains, volcanoes, and the MidAtlantic Ridge.

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2. What causes earthquakes and volcanic activity? 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.

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3. Describe the movement of divergent, convergent, and transform boundaries. At divergent boundaries, plates move apart, and new oceanic crust forms. At convergent boundaries, plates move toward each other, and oceanic crust is consumed (subducted). At transform boundaries, plates slide past each other, and the crust is neither formed nor consumed.

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