1 ES 104 Laboratory # 4INTRODUCTION TO PLATE TECTONICSIntroductionGoals and ObjectivesCross Section of Earth.pdfCross Section of EarthES 104 Laboratory # 4 INTRODUCTION TO PLATE TECTONICS Introduction The Theory of Plate Tectonics has revolutionized the science of Geology in the last 30 years. The theory states that the outer surface of the earth consists of 7 major lithospheric plates and numerous smaller ones, and these plates move around on a ductile layer referred to as the asthenosphere. The boundaries between the lithospheric plates, which are where they interact with one another, are characterized by distinctive topographic features and catastrophic geologic processes such as earthquakes and volcanism. Goals and Objectives • Introduce some of the basic ideas of Plate Tectonics • Study the Plate Tectonic setting of the western United States and parts of the adjacent Pacific Ocean basin • Describe the relation between earthquakes, volcanoes, and plate boundaries • Learn to use map scales to convert map measurements to real-world distancesName__________KEY______________________ Lab day ______Lab Time_____________________ Pre-lab Questions – Complete these questions before coming to lab. Briefly define the following key words, drawing diagrams where necessary, and answer the questions. 1. Lithosphere RIGID OUTER PORTION OF EARTH THAT INCLUDES THE CRUST AND THE UPPERMOST UPPER MANTLE 2. Asthenosphere PORTION OF THE UPPER MANTLE BELOW THE LITHOSPHERE THAT IS WEAK (SLUSHY, GOOEY, ETC.) 3. Divergent Plate Boundary AREA WHERE LITHOSPHERE PLATES ARE MOVING APART. CHARACTERIZED BY RIDGE AND CONSTRUCTION OF LITHOSPHERE BY UPWELLING OF HOT MANTLE MATERIAL TO FILL THE VOID LEFT BY THE DIVERGENCE OF PLATES. 4. Convergent Plate Boundary AREA WHERE LITHOSPHERIC PLATES ARE MOVING TOWARD ONE ANOTHER. IF AN OCEANIC PLATE IS INVOLVED, THEY ARE CHARACTERIZED BY SUBDUCTION OF AN OCEANIC PLATE, DESTRUCTION OF LITHOSPHERE, AND A DEEP OCEAN TRENCH. 5. Transform Plate Boundary AREA WHERE LITHOSPHERIC PLATES ARE MOVING PAST ONE ANOTHER. TRANSFORM BOUNDARIES DO NOT HAVE DESTRUCTION OR CONSTRUCTION OF LITHOSPHERE. 6. At what type of plate boundary is Oregon located? OREGON IS LOCATED AT A CONVERGENT PLATE BOUNDARY. 7. What type of plate boundary is found in southern California? THE SAN ANDREAS FAULT IS A TRANSFORM PLATE BOUNDARY. 8. Sketch a cross-section of the Earth, showing the internal structure. Include inner core, outer core, lower mantle, upper mantle, asthenosphere, lithosphere, moho, oceanic crust, continental crust (you may need an inset for the relationship of the last few items). (on next page)Cross Section of Earth Oceanic crust continental crust• Moho: boundary of crust and mantle• upper mantle• lower mantleDrawing from http://pubs.usgs.gov/gip/dynamic/inside.htmlPart A—“The Earth’s Fractured Surface” Map Examine the National Geographic map “The Earth’s Fractured Surface”, and answer the following questions: 1. What type of crust is present where most divergent plate margins occur? OCEANIC 2. What areas have groups of active volcanoes? WEST COAST OF SOUTH AMERICA, INDONESIA, JAPAN, WEST COAST OF NORTH AMERICA, ALEUTIAN ISLAND CHAIN, PHILIPPINES, ICELAND, EAST AFRICAN RIFT 3. If these are associated with plate boundaries, use the term that describes the type of plate boundary. MOST ARE AT CONVERGENT BOUNDARIES, SOME ARE AT DIVERGENT BOUNDARIES 4. Look at the Pacific Northwest area. What tectonic plates are there or nearby which may affect that area. (There are three.) Describe the type of boundaries that exist between these plates. (One type for each pair of plates.) NORTH AMERICAN—JUAN DE FUCA IS CONVERGENT JUAN DE FUCA –PACIFIC IS DIVERGENT JUAN DE FUCA—GORDA IS TRANSFORM 5. The margin of the Pacific Ocean basin is often referred to as the “Ring of Fire”. What evidence is shown on the map to justify this name? IT IS A ZONE OF ACTIVE VOLCANOES 6. List some areas that have isolated volcanoes. EAST AUSTRALIA, AUSTRAL-COOK ISLANDS, EASTER ISLAND, JUAN FERNANDEZ ISLAND, KERGUENLEN ISLAND, TIBESTI UPLIFT. ETC.7. Examine the Hawaiian Islands and surrounding area. Notice the alignment of the Hawaiian Islands and submerged seamounts of the Hawaiian Ridge extending to Midway Island and beyond. This linear string has an abrupt bend, and continues as the Emperor Seamounts to the Aleutian Trench. a. What does the yellow circle with the arrow pointing to the northwest represent? (The red triangle in the center is the symbol for an active volcano.) Also record the information this symbol gives about Hawaii. HOT SPOT, WITH MOTION OF OVERLYING PLATE SHOWN IN IN./YR PACIFIC PLATE IS MOVING NORTHWEST AT 4.0 IN./YR b. How can this information help you understand the formation of the Hawaiian Ridge? RIDGE WAS CREATED BY VOLCANOES FROM MAGMA AT HOTSPOT. AS PACIFIC PLATE MOVED NORTHWEST, DRAGGED VOLCANO OFF OF HOTSPOT AND ANOTHER FORMED IN NEW AREA OF PLATE. c. Midway Island is the small island just north and slightly east of the ‘s’ of ‘Midway Is.’ on the map. The volcanic rocks on Midway Island are 27 million years old. Determine the rate in inches/year (rate = distance/time) and direction of plate motion of the Pacific Plate over the last 27 million years. (NOTE: Scale of map: 1 inch = 758 miles. Do not forget to convert miles to inches, and use all the zeroes instead of ‘million’ years.) Show your calculations with units. .1895.1.758.5.2 miinmiin =× .000,000,120.1.12.1.5280.1895 inftinmiftmi =×× yrinyrin/4.4000,000,27.000,000,120= d. Compare your calculated value to the map data about plate movement at the Hawaiian hotspot. VERY SIMILAR 4.0 vs. 4.4 IN/YR e. If your toenails grow about 1 mm a month, is the rate of motion of the Pacific Plate comparable to this? (Like compared to how fast you can drive, or walk…) TOENAILS yrinyearmonthsmminmonthmm/47.01124.25.111=×× WALKING yrinyeardaysdayhrftinmifthrmi/1067.1125.3651241.12.15280.39×=×××× (I COULD WALK A TRILLION INCHES IN A YEAR!! 26,300 MILES!)f. Suiko Seamount (which is not labeled on the map) is located approximately beneath the second "R" in the word "EMPEROR", has yielded an age date of 65 million years. Based on the available age data and the distribution of the Hawaiian Islands chain and the Emperor Seamount chain, discuss how the movement of the Pacific Plate has changed direction through time. Is this
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