Fluent Essays

According to plate tectonic theory, Earth’s surface is divided into moving plates. A plate is a large, mobile slab of rock that is part of Earth’s rigid out shell known as the lithosphere. This includes rocks of the crust and upper mantle.The boundaries between plates are of three general types. The boundary between plates that are moving apart is termed diverging while a boundary between plates that are moving toward each other is called converging. A transform boundary is found where two plates are moving horizontally past each other. inferred_properties_of_earth_chart.pdf tectonic_plate_map_of_earth.pdf topic_2_tectonics_lab_1_.doc topic_2_tectonics_powerpoint_1__1_.ppt Unformatted Attachment Preview Name: Date: LAB # : Crustal Boundaries Introduction: According to plate tectonic theory, Earth’s surface is divided into moving plates. A plate is a large, mobile slab of rock that is part of Earth’s rigid out shell known as the lithosphere. This includes rocks of the crust and upper mantle. The boundaries between plates are of three general types. The boundary between plates that are moving apart is termed diverging while a boundary between plates that are moving toward each other is called converging. A transform boundary is found where two plates are moving horizontally past each other. Objective: You will distinguish between diverging, converging and transform tectonic plate boundaries. Vocabulary lithosphere: divergent plate boundary: convergent plate boundary: transform plate boundary: subduction: Andes Mountains: Procedure: A. Fill in the data chart below using the Tectonic Plates map provided. Place a check in the appropriate box identifying the type of plate boundary. Procedure B: 1. On the graph provided, construct a cross-section along line AB on your map of South America to show the depth of earthquake foci. 2. After plotting the depth of earthquake foci, connect the points with a smooth line. 3. On your cross-section, copy the arrows that show the direction the crustal plates are moving. 4. Determine which side of the cross-section represents continental crust. Print the word “continental” in this location. 5. Determine which side of the cross-section represents oceanic crust. Print the word “oceanic” in this location. 6. Write in the average density of the continental crust and the oceanic crust on the crosssection. Refer to the “Inferred Properties of Earth’s Interior” diagram. 7. On the cross-section, predict the direction of any movement where these two crustal plates meet. Draw arrows on the cross-section showing the direction of plate movements. Procedure C: 1. Note that on the “United States Pacific Coastline” map, thick arrows show the directions of plate movement but no arrow for the North American Plate is shown. Referring to the attached Tectonic Plate map, draw a thick arrow on the North American Plate indicating its direction of movement. 2. What is the relative movement of rocks on the west side of the San Andreas fault compared to the direction the North American Plate is moving? 3. Using separate paper, cut out two pieces of paper that are rectangles 3 cm x 6 cm. 4. The dashed lines in the diagram below represent the rectangles that you cut out. 5. Placing the two cutouts side by side, label each one as shown in the diagram. 6. Place the labeled cutouts side by side on the diagram with the fault at the boundary between them. The cutout below represents the Pacific Plate and the one on the right represents the North American Plate. Both are moving in the direction of the arrows. 7. By moving the cutout “plates” in the direction of the arrows, determine how their differing rates of movement are producing the displacement of rocks on either side of the San Andreas Fault. Write your conclusions below. Discussion Questions: (Answer in complete sentences). 1. Using the cross-section of South America, describe the pattern of earthquake depth from west to east along line AB. 2. Based on your answer to question 1, what appears to happen as the ocean plate to the west collides with the continental plate to the east? 3. Referring to a world map, what surface feature on the west coast of South America has apparently formed as a result of collision of two crustal plates? 4. According to your data chart and the Tectonic Plates map, where are most divergent plate boundaries found? 5. Referring to Procedure C, what type of plate boundary is the San Andreas fault? 6. At which type of plate boundary would a subduction zone be found? 7. At which type of plate boundary is new oceanic crust created? 8. Oceanic trenches are associated with which type of plate boundary? Conclusion: Describe the three types of plate boundaries. Topic 2 The Way the Earth Works: Examining Plate Tectonics Continental drift: An idea before its time ◼ Alfred Wegener • First proposed continental drift hypothesis in 1915 • Published The Origin of Continents and Oceans ◼ Continental-drift hypothesis • Supercontinent called Pangaea began breaking apart about 200 million years ago Pangaea approximately 200 million years ago Evidence for Continental Drift Fit of Continents and Matching Mountain Ranges Evidence for Continental Drift Fossils on Different Continents Evidence for Continental Drift Paleoclimatic evidence Plate tectonics: The new paradigm ◼ Plate Tectonics ◼ Much more encompassing theory than continental drift ◼ The composite of a variety of ideas that explain the observed motion of Earth’s lithosphere (NOT just the crust). Plate tectonics: The new paradigm ◼ Earth’s major plates • Associated with Earths strong, rigid outer layer • Known as the lithosphere • Consists of uppermost mantle and overlying crust • Overlies a weaker region in the mantle called the asthenosphere Plate tectonics: The new paradigm ◼ Earth’s major plates • Asthenosphere • Exists beneath the lithosphere • Hotter and weaker than the lithosphere • Allows for motion of lithosphere Plate tectonics: The new paradigm ◼ Earth’s major plates • Seven major lithospheric plates • • • • • • • North American South American Pacific African Eurasion Australian Antarctic Plate tectonics: The new paradigm ◼ Earth’s major plates • Plates are in motion and continually changing in shape and size • Largest plate is the Pacific plate • Several plates include an entire continent plus a large area of seafloor Plate tectonics: The new paradigm ◼ Earth’s major plates • Plates move relative to each other at a very slow but continuous rate • About 5 centimeters (2 inches) per year • Cooler, denser slabs of oceanic lithosphere descend into the mantle • Grinding movement of plates generate earthquakes, volcanoes, deform large masses of rock into mountains Earth’s plates Earth’s plates Plate tectonics: The new paradigm ◼ Plate boundaries • Interactions among individual plates occur along their boundaries • Types of plate boundaries • Divergent plate boundaries (constructive margins) • Convergent plate boundaries (destructive margins) • Transform fault boundaries (conservative margins) Divergent plate boundary Divergent plate boundary Continental rifting Continental Rifting Oceanic-Continental Convergence Oceanic-Oceanic Convergence Continental-Continental Convergence Convergent plate boundaries ◼ Older parts of oceanic plates are returned to the mantle in these destructive plate margins • Surface expression of the descending plate is an ocean trench • Also called subduction zones • Average angle of subduction = 45 India-Asia Collision before Himalayas India-Asia Collision produced the Himalayas Transform fault boundaries Plates slide past one another and no new lithosphere is created or destroyed ◼ Transform faults ◼ • Most join two segments of a mid-ocean ridge along breaks in the oceanic crust known as fracture zones • A few (the San Andreas fault and the Alpine fault of New Zealand) cut through continental crust Transform faults What drives plate motions Researchers agree that convective flow in the mantle is the basic driving force of plate tectonics ◼ Forces that drive plate motion ◼ • Slab-pull: descending oceanic crust pulls the plate • Ridge-push: elevated ridge system pushes the plate • Slab suction Forces driving plate motions Importance of plate tectonics ◼ The theory provides explanations for • Earth’s major surface processes • The geologic distribution of earthquakes, volcanoes, and mountains • The distribution of ancient organisms and mineral deposits Evidence for Plate Tectonics Distribution of Volcanoes Evidence for Plate Tectonics Distribution of Earthquakes Evidence for Plate Tectonics Paleomagnetic Reversals Recorded at Mid-Ocean Ridges https://youtu. be/WhiF6IqGA Co https://youtu. be/CRx66ZpEh Og https://www.y outube.com/w atch?v=I6Ggs7 nUjxA Evidence for Plate Tectonics Hot Spots https:// youtu.be/ jHsl1lBMuwE Evidence for Plate Tectonics Age Vs. Depth of Ocean Floor Evidence for Plate Tectonics Plate motions ... Purchase answer to see full attachment