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Welcome to the Plate Tectonics Basics Tutorial<\/strong>. This resource is designed to be used in full-screen mode with the table of contents always displayed. To set this mode, click the Expand button in the top right of the header AND click the Navigation Menu button in the top left of the header. Then begin making your way through the tutorial by watching the video below.<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"d81742fe-db3d-41d7-b734-0b54721a1f2c"},"useSeparator":"auto"},{"content":{"params":{"visuals":{"fit":true,"controls":true},"playback":{"autoplay":false,"loop":false},"l10n":{"name":"Video","loading":"Video player loading...","noPlayers":"Found no video players that supports the given video format.","noSources":"Video is missing sources.","aborted":"Media playback has been aborted.","networkFailure":"Network failure.","cannotDecode":"Unable to decode media.","formatNotSupported":"Video format not supported.","mediaEncrypted":"Media encrypted.","unknownError":"Unknown error.","invalidYtId":"Invalid YouTube ID.","unknownYtId":"Unable to find video with the given YouTube ID.","restrictedYt":"The owner of this video does not allow it to be embedded."},"sources":[{"path":"https:\/\/www.youtube.com\/watch?v=2uh8W4vGLQ0&t=2s","mime":"video\/YouTube","copyright":{"license":"U"}}]},"library":"H5P.Video 1.6","metadata":{"contentType":"Video","license":"U","title":"Plate Tectonics Basics"},"subContentId":"4d246739-7909-4647-9323-ee2790c63b60"},"useSeparator":"auto"},{"content":{"params":{"panels":[{"content":{"params":{"text":"

[music]
\nTo understand plate tectonics, we need to look closely at the convecting asthenosphere. The convecting asthenosphere will cause heat to pile up under certain portions of the lithosphere and cold material to sink under other parts. What does that do to the lithosphere? It causes it to break into pieces we call plates. Where heat rises, material must be pushed away in opposite directions to make room for the continual rising of new hot material (much like boiling water). That drags on the lithosphere above and causes it to stretch and thin and break apart. On the surface we call the zone where two plates are moving apart a divergent plate boundary<\/strong>. The build-up of heat and material below pushes the plate upward at this point and creates a linear mountain ridge (when these form along the ocean floor, we call them ocean ridges and rises). As the plates separate, a rift valley forms atop the ridge. The drop in pressure on the underlying mantle rock causes it to melt, and now that it\u2019s lower density, the melted rock, or magma, rises to the surface and erupts along the center of the rift valley. When new convection cells form under a continent, divergence tears the continent apart. The most recent supercontinent that tore apart to create the current geometry of Earth\u2019s plates was called Pangaea, and based on fossil evidence, it existed 250 million years ago when all the continents we know today were fused together \u2013 one continent and one surrounding ocean. After this supercontinent began to break apart, and the plates thinned enough, dense basaltic magmas erupted, and the new plate that formed was oceanic, producing oceanic plate, fused to broken halves of continental plate now moving away from each other. Through this process, new oceans form and spread. We call this seafloor spreading<\/strong>. The new ocean crust that forms at these ocean ridges consists of four main layers \u2013 the magma that erupts on the seafloor cools quickly under high-pressure, cold water, and forms structures that look similar to hardened toothpaste squirted out of a tube. They are called pillow basalts<\/strong>. The cracks in the crust that fed the magmas to the surface cool to form vertical walls of basalt called sheeted basalt dikes<\/strong>. The chambers that hold the magmas under these ridges will also spread; as their outer edges cool, they crystallize slowly to form a larger-crystal rock with the same composition as basalt, but now called gabbro<\/strong>. As this crust spreads apart to allow new crust to form between it, the ocean will deposit fine grains of dust, ash, shells, and other debris \u2013 otherwise known as sediment<\/strong>. These are the four layers of ocean crust. Under the ocean crust is the mantle rock that melted to produce the magmas in the first place. It is sometimes referred to as depleted mantle, because it has had magmas produced from it. And it is attached to and underplates the crust above it, making up the base of the ocean lithosphere. So ocean lithosphere, everywhere in the world, is basically made of this same sequence of rock \u2013 sediment of varying thicknesses above pillow basalt above basalt dikes above gabbro above mantle rock. And what happens to this ocean lithosphere as it spreads? Not much. It grows gradually colder and older and denser and collects a thicker sequence of sediment atop and a thicker section of mantle plating underneath it (thus thicker lithosphere), until eventually it\u2019s so dense that it becomes denser than the rock underneath it. It detaches and sinks back into the mantle, possibly sinking or subducting <\/strong>as deep as the core-mantle boundary before finally melting and becoming reabsorbed back into the mantle. Dense, cold lithosphere sinks down, pulling the distant seafloor spreading center further apart, driving, together, a recycling engine for mantle material.
\n
\nPause now. [music]
\n
\nWhere the old ocean lithosphere sinks, we get a deep trench on the seafloor above. When next to a continent, this trench can fill with lots of sediment. When next to ocean islands, it tends to be deeper, like the Marianas Trench.
\n
\nLet\u2019s look more closely at these subduction zones<\/strong>. Remember that at divergent plate boundaries, the plates move apart. The old continental portions of these plates that were torn apart are also now spreading further and further apart. What happens at the outside of this spreading where continents are shoved towards other plates? They will collide at boundaries referred to as convergent plate boundaries<\/strong>. If continents collide with ocean plates, the ocean plate, being denser, will be forced under the continents. If the ocean crust is cold and dense, it will sink to the core mantle boundary to be recycled as already discussed. If the ocean crust is young and it not yet dense enough to sink, it will push under the continental plate and cause the continental crust above to be deformed. Convergent plate boundaries can also exist between two ocean plates, if one plate is much older than the other and convergence brings the two together. The older one subducts under the younger one. Convergent plate boundaries can also exist between two continents, when the ocean that existed between them entirely subducts, and the two collide and accrete together to form a larger continent. Just as divergence is the method for breaking up continents, convergence is the method for conjoining them. In fact, even as ocean floor still exists and subducts alongside a continent, accretion and continental growth is happening. Islands, continental fragments, sediment, and the crust that carries them can get scraped off and accreted to the edge of the continent. We call these accreted fragments terranes<\/strong>, and they are the basic building blocks of all continents. The other source of new continental material are the volcanic eruptions that happen alongside the subduction. Why? When ocean crust subducts, it carries with it a large amount of water that had soaked into the sediment over millions of years. That water is squeezed out by the high pressures at depth in a subduction zone. Because water is less dense than anything else, it rises upwards into the overlying asthenosphere. Water reduces the melting point of the asthenosphere causing it to melt. That molten magma is now less dense and so it, too rises, with the water, to the surface, where it erupts in a chain of active volcanoes known as a volcanic arc or island arc. Subduction zone volcanoes always happen above the subduction zone on the plate that does NOT subduct and produces some of the most hazardous volcanoes in the world. Why? Among other things, all that water can produce high amounts of pressure underground.
\n
\nDoes continental crust ever subduct? No. Why not? It\u2019s the least dense material on the planet.
\n
\nHow old does ocean lithosphere need to be before it detaches and subducts all on its own? All we can find to answer that question is the age of the oldest ocean rock currently residing in the oceans, and that\u2019s 200-million-year-old rock subducting under the Marianas Trench in the Pacific. Why is the Marianas Trench the deepest part of the planet? Because it\u2019s a convergent plate boundary where two ocean plates are colliding. That means that both plates are already riding low isostatically. Now combine that with one subducting under the other, and no nearby continents to fill the trench with sediment, and there you have an answer!
\n
\nDo ocean-ocean subduction zones produce the same types of features as continental-ocean subduction zones? Trenches? Volcanoes? Accreted terrane material that forms coastal mountain ranges? Yes. The only difference is that the volcanoes erupt through thinner oceanic lithosphere, and that makes them slightly less dangerous than the magmas that rise through thicker continental lithosphere. Why? The thicker the lithosphere, them more likely the gas content will increase in the magmas, and this gas leads to higher pressures and more explosive volcanoes.
\n
\nLet\u2019s look again at what happens when two continental plates collide. Subduction brings the two together, but then after they collide, the subducting plate completely detaches and sinks into the mantle. Volcanism stops. The trench disappears. And the largest mountains found on the planet form as terrane accretion mashes the two continents up into a folded faulted mountain system that rises high above the surface and has a deep isostatic root beneath.
\n
\nPause now. [music]
\n
\nThat leaves one remaining plate boundary to discuss \u2013 transform \u2013 where plates slide past each other. There\u2019s no way to have plate motion moving apart and together without having some edges slide past each other. It\u2019s really easy to see how transform plates form when we look again at divergent plate boundaries and remember that the tearing apart of the lithosphere has to accommodate a spherical surface. Like seams on a baseball, it\u2019s hard to sew together or pull apart two pieces of fabric on a spherical surface without buckling or tearing. To accommodate divergent motion along ridges that run along a spherical surface, the ridges break into sections, and each section is offset from the next one by a transform boundary<\/strong>. As this image shows, there are two plates, but in these zones the boundaries are divergent. In these zones the boundaries are transform. Let\u2019s test our understanding with a few questions. Where is the youngest rock in this image? Let\u2019s put a Y there. Where is the oldest rock? Let\u2019s put an O there. How do points A and B compare?
\n
\nPause now. [music]
\n
\nRocks at points A and B formed at different locations but are now found alongside each other, so they will look very different. They will have different thicknesses of sediment. The younger one will be higher in elevation. There will be a cliff between them. And that cliff marks a line that runs outward from the active transform faults and creates a spectacular scar. We call this old scar a fracture zone<\/strong>. Occasionally there are small amounts of residual transform motion along these zones, but mostly they are now part of the ragged edges of a single plate.
\n
\nPause now. [music]
\n
\nFor more information and more detail, continue on to the next video in this series. [music]
\n
\n[end credits]
\n
\nPlate Tectonics Video Series:
\nPart I: Earth's Layers and Isostasy
\nPart II: Plate Tectonics Basics
\nPart III: Plate Tectonics Global Impacts
\nPart IV: Plate Tectonics and Calif. Geology
\nPart V: Hotspots
\nPart VI: Paleomagnetism
\nPart VII: Hydrothermal Vents
\n
\nPlate Tectonics Basics Produced by Katryn Wiese
\n
\nCopyright: Creative Commons: Attribution \u2013 Noncommercial \u2013 Share Alike 3.0
\n
\nAll media produced by Katryn Wiese unless indicated below:
\n*Intro and exit music: used with permission \u00a9 Alexis Harte
\n*Review music: used with permission \u00a9 Proceed With Caution
\n*Pangaea \u2013 GNU Free license
\n*Pangaea Fossil Evidence -- USGS
\n*Pillow Basalt photo \u2013 USGS*Line drawings of Accreting Terranes and Earth's Convection: used with permission \u00a9 The Cambridge Guide to the Solar System, 2nd Edition 2011, Kenneth R. Lang
\n*Subduction Zone 3D cross section drawing: USGS
\n*Bobbing Cork \u2013 source unknown.
\n*Age isochrons \u2013 world\u2019s oceans \u2013 NOAA
\n*Animated squares puzzle \u2013 source unknown
\n*Sphere with spreading and transforms \u2013 source unknown<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"27a45d78-dbdf-4cf4-9b76-b6e2f90c182f"},"title":"Plate Tectonics Basics Video Script (for review as needed)"}],"hTag":"h2"},"library":"H5P.Accordion 1.0","metadata":{"contentType":"Accordion","license":"U","title":"Plate Tectonics Basics Video Script (for review as needed)"},"subContentId":"8952e932-68cb-4dd3-aab2-feef250ffcb1"},"useSeparator":"enabled"},{"content":{"params":{"text":"

When done with the video above, continue through the remaining pages of this book to review content and images from the video, explore some content more deeply, and test your understanding through interactive ungraded quiz questions. The final page of the tutorial is a list of Additional Resources for students who want to dig even deeper into some of the video contents. When you've reached that page, you're done.<\/p>\n\n

To navigate to the remaining pages of this tutorial, use the arrow keys that appear in the header and footer. Or use the table of contents navigation menu, which you can toggle open or closed by using the button on the top left of the screen. <\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"cc02119a-7061-40fc-82e6-7544ab133bca"},"useSeparator":"enabled"}]},"library":"H5P.Column 1.18","subContentId":"d7bf0253-f2f2-423c-a80e-6146a7588f15","metadata":{"contentType":"Column","license":"U","title":"Video: Plate Tectonics Basics"}},{"params":{"content":[{"content":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-62b758ab3ca75.png","mime":"image\/png","copyright":{"license":"U"},"width":913,"height":624},"alt":"Plate Boundaries","expandImage":"Expand Image","minimizeImage":"Minimize Image"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"85bc2e51-c9a1-4210-a22b-72b7134bdbe6"},"useSeparator":"auto"},{"content":{"params":{"text":"

Above image: Global Plate Boundaries, USGS<\/span><\/span><\/em><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"c7f0e848-ad53-4f63-9b3f-02417807111b"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"7247f798-f552-4ea2-a059-e2999ae0b253","metadata":{"contentType":"Column","license":"U","title":"Plate Boundaries"}},{"params":{"content":[{"content":{"params":{"decorative":false,"contentName":"Image","alt":"Convection inside the mantle","file":{"path":"images\/file-63790af96eebe.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":500,"height":381},"expandImage":"Expand Image","minimizeImage":"Minimize Image"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"5204b4d9-557a-4e2a-8c7e-5ffeeb137c8b"},"useSeparator":"auto"},{"content":{"params":{"text":"

Above image: Convection of Earth\u2019s mantle, in asthenosphere and lower mantle. Also note the convection of the outer iron core. Note: the convection shown in the lower mantle is different from the rest because the material there is considered solid. The arrows represent the fact that lithospheric plates in subduction zones can descend all the way to the core-mantle boundary and that hotspot plumes can rise up from the core to the crust.<\/em><\/p>\n\n

Image from Kenneth R. Lang's book The Cambridge Guide to the Solar System, Second Edition 2011.<\/span><\/span><\/em><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"f2ab70f5-fbc6-4e82-a982-d6266f637f85"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"fa3d8596-dcd1-4c4b-bb78-5e595f372d77","metadata":{"contentType":"Column","license":"U","title":"Convection Inside Earth's Layers"}},{"params":{"content":[{"content":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-62b7af2ace24e.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":1821,"height":833},"alt":"Cross section through a Divergent Plate Boundary","expandImage":"Expand Image","minimizeImage":"Minimize Image"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"31b11505-ad4f-4bd1-8c05-11dccb4f99a3"},"useSeparator":"auto"},{"content":{"params":{"text":"

DIVERGENT <\/span><\/span><\/span><\/strong>MOTION: <\/span><\/strong>Apart<\/span><\/span><\/span><\/p>\n\n

FEATURES: <\/span><\/span><\/span><\/strong>Oceanic ridges. Seafloor spreading. Melted mantle rock due to reduced overlying pressure. Rift valleys with volcanism, pillow basalts, hydrothermal vents, and hydrothermal circulation. Serpentinites form at depth in mantle rocks that are undergoing hydrothermal alteration. Transform faults (associated with transform plate boundaries) break up divergent boundaries into small sections offset from one another.<\/span><\/span><\/span><\/p>\n\n

WORLD EXAMPLES: <\/span><\/span><\/span><\/strong>Mid-Atlantic Ridge (and all ridges worldwide), Iceland.<\/span><\/span><\/span><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"b10d8ca5-3978-4fd6-9652-3c47572feba9"},"useSeparator":"auto"},{"content":{"params":{"decorative":false,"contentName":"Image","alt":"Cross-section through a seafloor spreading center showing details (close up)","expandImage":"Expand Image","minimizeImage":"Minimize Image","file":{"path":"images\/file-65da3fb22af30.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":2595,"height":1400}},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"87e220f5-33bb-491b-86b3-76f36b45e10f"},"useSeparator":"auto"},{"content":{"params":{"text":"

Explanation of above figure: <\/strong><\/p>

At seafloor spreading centers<\/strong> (divergent plate boundaries in the oceans),<\/p>

Magmas <\/strong>form as mantle melts under the thinned crust (a drop in pressure causes melting).<\/li>
As magmas are produced and rise, they collect in the crust in a magma chamber.<\/li>
The rising magmas and thin crust make this area of the ocean shallower than the surrounding areas, thus producing an ocean ridge<\/strong>.<\/li>
Atop the ocean ridge, as the crust spreads, a rift valley<\/strong> depression forms along the center. <\/li>
When new magmas rise into a magma chamber, they push some of the existing magma out. These magmas rise to the surface and erupt in the rift valley under water as pillow basalts<\/strong>.<\/li>
The vertical cracks that formed between the top of the magma chamber and the bottom of the seafloor to allow the basalt through will then solidify under the pillows and form basalt dikes<\/strong>.<\/li>
As the new crust spreads aside to make room for the next series of pillow basalts and dikes, the seafloor collects sediment <\/strong>(debris such as shells of plankton and airborne dust raining down from the surface of the oceans)<\/em>.<\/li>
Meanwhile, the spreading edges of the magma chamber cool to form gabbro<\/strong> (a rock that is the same in composition as basalt, but physically made of much larger crystals because it had time to cool slowly underground).<\/em><\/li>
As the crust spreads, seawater descends through cracks formed from spreading, leaving salt minerals in the cracks, and leaching metals from the ocean crust. Eventually this water gets heated by the magma chamber and rises back up in the center of the rift valleys producing hydrothermal vents<\/strong>. The circulation of the hot water is called hydrothermal circulation<\/strong>. Where it exits the crust, metal sulfides will precipitate around the vents, making chimneys<\/strong> (much like mineral deposits that form on the inside of plumbing pipes).<\/li>
In places where the hot water reaches mantle rock, the olivine mineral in the mantle metamorphoses into the mineral serpentine (a rock made entirely of this mineral is called serpentinite<\/strong>) <\/strong>thus creating a serpentinized top to the mantle. Serpentinite is less dense than ocean crust (because of all the water in it), and over time, as the crust spreads, it will migrate up cracks and form serpentinite ridges on the seafloor.<\/li>
As the ocean crust spreads and cools, the top portion of the mantle attaches to it, turning the ocean crust into ocean lithosphere<\/strong>. The colder and older the crust becomes, the more mantle has attached itself. The increasing amount of attached mantle increases the density of the plate and causes it to sink lower into the asthenosphere (like a dense piece of wood floating in the water). Eventually the ocean crust picks up so much attached mantle that the plate will detach from its fused continental edges and subduct. <\/li><\/ul>
Note: While sediment and attached mantle get thicker with time as ocean lithosphere spreads away from the divergent plate boundary, the basalts and gabbro that sit between them will undergo no more changes. They cannot be added to because that's happening only at the seafloor spreading center. They cannot be eroded because sediment is collecting atop them and creating a nicely protected and preserved \"cage\" for them. To erode, they'd have to be in contact with rivers, waves, glaciers, wind, or gravity collapse (landslides). But on the bottom of the seafloor, none of these are present. It's a quiet life for them!<\/em><\/p>"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"dee17987-024f-4ecc-a606-86c63f38dd45"},"useSeparator":"auto"},{"content":{"params":{"introPage":{"showIntroPage":false,"startButtonText":"Start Quiz","introduction":""},"progressType":"dots","passPercentage":100,"questions":[{"params":{"media":{"disableImageZooming":false},"taskDescription":"
Drag the words into the correct boxes<\/p>\n","overallFeedback":[{"from":0,"to":100}],"checkAnswer":"Check","submitAnswer":"Submit","tryAgain":"Retry","showSolution":"Show solution","dropZoneIndex":"Drop Zone @index.","empty":"Drop Zone @index is empty.","contains":"Drop Zone @index contains draggable @draggable.","ariaDraggableIndex":"@index of @count draggables.","tipLabel":"Show tip","correctText":"Correct!","incorrectText":"Incorrect!","resetDropTitle":"Reset drop","resetDropDescription":"Are you sure you want to reset this drop zone?","grabbed":"Draggable is grabbed.","cancelledDragging":"Cancelled dragging.","correctAnswer":"Correct answer:","feedbackHeader":"Feedback","behaviour":{"enableRetry":true,"enableSolutionsButton":true,"enableCheckButton":true,"instantFeedback":false},"scoreBarLabel":"You got :num out of :total points","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again.","textField":"All ocean crust in the world is created at a divergent plate boundary through the same volcanic and sedimentary processes and therefore has the same order:\n\nTop layer of all ocean crust (forms as shells and debris rain down atop new seafloor -- and thus gets thicker as the crust ages): *sediment*\n\nSecond layer of all ocean crust (forms as lavas erupt on the seafloor at a mid-ocean ridge): *pillow basalt*\n\nThird layer of all ocean crust (forms as the conduits that the magma used to rise upward to erupt are themselves cooled and solidified): *basalt dikes*\n\nFourth layer of all ocean crust (forms as the magma chamber under the surface spreads and its edges cool and solidify): *gabbro*\n\nUnder the ocean crust is the: *depleted mantle* (which forms as a result of continual melting of rock here to produce the magmas that rise upwards)"},"library":"H5P.DragText 1.10","metadata":{"contentType":"Drag the Words","license":"U","title":"Test Your Understanding"},"subContentId":"797cac1d-7652-42ba-ae04-6de4ece50112"},{"params":{"media":{"disableImageZooming":false},"answers":[{"correct":true,"tipsAndFeedback":{"tip":"","chosenFeedback":"
Yes, this layer grows thicker over time as more and more mantle attaches itself to the underside of the ocean crust, eventually becoming so thick it increases the overall plate density so it sinks.<\/div>\n","notChosenFeedback":""},"text":"
Attached depleted mantle (making up the lower lithosphere)<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Basalt Dikes<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Gabbro<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Pillow Basalt<\/div>\n"},{"correct":true,"tipsAndFeedback":{"tip":"","chosenFeedback":"
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Sediment<\/div>\n"}],"overallFeedback":[{"from":0,"to":100}],"behaviour":{"enableRetry":true,"enableSolutionsButton":false,"enableCheckButton":true,"type":"auto","singlePoint":false,"randomAnswers":false,"showSolutionsRequiresInput":true,"confirmCheckDialog":false,"confirmRetryDialog":false,"autoCheck":false,"passPercentage":100,"showScorePoints":true},"UI":{"checkAnswerButton":"Check","submitAnswerButton":"Submit","showSolutionButton":"Show solution","tryAgainButton":"Retry","tipsLabel":"Show tip","scoreBarLabel":"You got :num out of :total points","tipAvailable":"Tip available","feedbackAvailable":"Feedback available","readFeedback":"Read feedback","wrongAnswer":"Wrong answer","correctAnswer":"Correct answer","shouldCheck":"Should have been checked","shouldNotCheck":"Should not have been checked","noInput":"Please answer before viewing the solution","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again."},"confirmCheck":{"header":"Finish ?","body":"Are you sure you wish to finish ?","cancelLabel":"Cancel","confirmLabel":"Finish"},"confirmRetry":{"header":"Retry ?","body":"Are you sure you wish to retry ?","cancelLabel":"Cancel","confirmLabel":"Confirm"},"question":"
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TRANSFORM <\/span><\/span><\/span><\/strong>MOTION:<\/span><\/strong> <\/strong>side by side<\/span><\/span><\/span><\/p>\n\n
FEATURES: <\/strong>Fracture zones (old transform faults, no longer active, because lithosphere on both sides are part of the same plate). Rough topography (cliffs where ridges offset. Oceanic ridges and spreading centers on both sides.<\/span><\/span><\/span><\/p>\n\n
WORLD EXAMPLES: <\/strong>Central and Southern <\/span><\/span><\/span>California,all mid-ocean ridges (where they are offset)<\/span><\/span><\/span><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"273b86f1-0c0a-417a-9969-d21373481ee2"},"useSeparator":"auto"},{"content":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-62b7afcbdf2bb.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":569,"height":271},"alt":"Oblique view through offset divergent plate boundaries","expandImage":"Expand Image","minimizeImage":"Minimize Image"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"4af69c62-460d-4af6-a65c-99ceef42057e"},"useSeparator":"auto"},{"content":{"params":{"text":"
Above figure: Oblique view through a divergent plate boundary offset by a transform plate boundary.<\/em><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"f302e872-64f2-44a4-b5ac-a90d9c1195d1"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","metadata":{"contentType":"Column","license":"U","title":"Transform Plate Boundaries"},"subContentId":"63041c89-415f-4099-bee8-95222d34652d"},{"params":{"content":[{"content":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-62b87b3d83be3.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":2001,"height":1277},"alt":"Global seafloor age data","expandImage":"Expand Image","minimizeImage":"Minimize Image"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"693816d7-56a2-4929-8a79-bb92b6857120"},"useSeparator":"auto"},{"content":{"params":{"text":"
Above figure: ISOCHRON Map (lines of a particular color represent equal lithosphere age ranges) For example. All areas in yellow are lithosphere from 40 to 50 million years old. NOAA<\/span><\/span><\/em><\/p>\n\n
\n
<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"b2a31e48-f047-46cc-b987-1395815d5d7e"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","metadata":{"contentType":"Column","license":"U","title":"Map: Global seafloor isochrons (ages)"},"subContentId":"5ad48f7a-8c5c-4038-b47c-1cfdb807bc8b"},{"params":{"content":[{"content":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-62b7ada9a60cc.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":1855,"height":2819},"alt":"Cross-sections through the three kinds of convergent plate boundaries","expandImage":"Expand Image","minimizeImage":"Minimize Image"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"c38e885b-17a6-4f10-bdb0-a2ff779c0f36"},"useSeparator":"auto"},{"content":{"params":{"text":"
\n
<\/span>CONVERGENT MOTION: <\/span><\/span><\/span><\/strong>Towards each other<\/span><\/span><\/span><\/p>\n\n
\n
Continent-Ocean<\/span><\/span><\/span><\/strong><\/p>\n\n
FEATURES: <\/strong>Subduction zones (ocean crust sinks back into mantle). Melted mantle rock due to addition of water, which drops the melting point of the underlying mantle. Volcanoes above subduction zone where magmas move upward. Trenches on ocean floor where ocean crust begins subducting. Volcanism is granitic mostly, because it moves through thicker continental crust.<\/span><\/span><\/span><\/p>\n\n
WORLD EXAMPLES:<\/strong> W. coast S. America, Pacific Northwest<\/span><\/span><\/span><\/p>\n\n
\n
Ocean-Ocean<\/span><\/span><\/span><\/strong><\/p>\n\n
FEATURES: <\/strong>Subduction zones (ocean crust sinks back into mantle). Melted mantle rock due to addition of water, which drops the melting point of the underlying mantle. Volcanoes above subduction zone where magmas move upward. Trenches on ocean floor where ocean crust begins subducting. Volcanism is basaltic mostly, because it moves through thinner oceanic crust. <\/span><\/span><\/span><\/p>\n\n
WORLD EXAMPLES:<\/strong> Japan, Philippines, Aleutian Islands<\/span><\/span><\/span><\/p>\n\n
\n
Continent-Continent<\/span><\/span><\/span><\/strong><\/p>\n\n
\u200b\u200b\u200b\u200b\u200b\u200b\u200bFEATURES: <\/strong>Fold and thrust mountains, thickened lithosphere.<\/span><\/span><\/span><\/p>\n\n
WORLD EXAMPLES: <\/strong>Himalayas (India), <\/span><\/span><\/span>Alps (Europe)<\/span><\/span> <\/span><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"89b3472f-5d1b-42cf-9aeb-8512ce1861ba"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","metadata":{"contentType":"Column","license":"U","title":"Convergent Plate Boundaries"},"subContentId":"feb1d25a-5272-4d64-86a3-c40c110a9f15"},{"params":{"content":[{"content":{"params":{"text":"
\n
An accretionary wedge <\/strong>is a mass of sediment that derives from two sources: 1) sediment that is scraped off a subducting oceanic plate (might include pieces of ocean lithosphere as well), and 2) sediment that erodes off the volcanic arc behind the subduction zone (land). This thick sequence of sediment is folded and compressed between the trench and the volcanic arc, often creating compressional mountain ranges. <\/span><\/span><\/p>\n\n
A terrane<\/strong> is anything that has been accreted to the continent and is now a hardened attachment. Terranes include ophiolites (sections of complete ocean lithosphere), accretionary wedges, continental fragments.<\/span><\/span><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"c6d4e733-2063-4f71-815e-90f00066571b"},"useSeparator":"auto"},{"content":{"params":{"decorative":false,"contentName":"Image","alt":"Cross section through subduction zone during subduction and accretion","file":{"path":"images\/file-63476f4570306.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":720,"height":720},"expandImage":"Expand Image","minimizeImage":"Minimize Image"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"bc2997a3-ef00-4a30-8c95-bd8a5f35ac77"},"useSeparator":"auto"},{"content":{"params":{"text":"
Above figure: Terrane accretion. Image: source unknown<\/span><\/span><\/em><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"7ff9cd9a-8712-400b-bc19-ea9d2b3d26ff"},"useSeparator":"auto"},{"content":{"params":{"imageSlides":[{"params":{"image":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-62b7b13de251c.gif","mime":"image\/gif","copyright":{"license":"U"},"width":358,"height":566},"alt":"Map view of the western margin of North America showing accreted terranes","expandImage":"Expand Image","minimizeImage":"Minimize Image"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"0a2884d9-5f95-4b1f-811e-030dab13bd87"}},"library":"H5P.ImageSlide 1.1","subContentId":"5612d8b4-c931-4b53-ba3a-6d4b99814475","metadata":{"contentType":"Image Slide","license":"U","title":"Untitled Image Slide"}},{"params":{"image":{"params":{"decorative":false,"contentName":"Image","expandImage":"Expand Image","minimizeImage":"Minimize Image","file":{"path":"images\/file-65c58144443b5.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":720,"height":540},"alt":"Terranes of North America"},"library":"H5P.Image 1.1","subContentId":"493cce4f-5e6b-471a-a603-c06f616628af","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"}}},"library":"H5P.ImageSlide 1.1","subContentId":"c61be623-9d58-4de6-aaf9-b8954fcf8478","metadata":{"contentType":"Image Slide","license":"U","title":"Untitled Image Slide"}}],"aspectRatioMode":"auto","aspectRatio":{"aspectWidth":4,"aspectHeight":3},"a11y":{"nextSlide":"Next Image","prevSlide":"Previous Image","gotoSlide":"Go to image %slide"}},"library":"H5P.ImageSlider 1.1","metadata":{"contentType":"Image Slider","license":"U","title":"Untitled Image Slider"},"subContentId":"7db4ce3a-7f49-43d2-93e2-f4902f67f071"},"useSeparator":"auto"},{"content":{"params":{"text":"
Above figures in slider: <\/span><\/span><\/em><\/p>\n\n
\n\t
Terrane accretion along the western margin of North America. USGS.<\/span><\/span><\/em><\/li>\n\t
Terrane accretion across North America (Pearson Publishing)<\/span><\/span><\/em><\/li>\n<\/ol>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"accdb535-9134-4c95-a2c4-857987c6d5cb"},"useSeparator":"auto"},{"content":{"params":{"media":{"disableImageZooming":false},"taskDescription":"Drag the words into the correct boxes","overallFeedback":[{"from":0,"to":100}],"checkAnswer":"Check","submitAnswer":"Submit","tryAgain":"Retry","showSolution":"Show solution","dropZoneIndex":"Drop Zone @index.","empty":"Drop Zone @index is empty.","contains":"Drop Zone @index contains draggable @draggable.","ariaDraggableIndex":"@index of @count draggables.","tipLabel":"Show tip","correctText":"Correct!","incorrectText":"Incorrect!","resetDropTitle":"Reset drop","resetDropDescription":"Are you sure you want to reset this drop zone?","grabbed":"Draggable is grabbed.","cancelledDragging":"Cancelled dragging.","correctAnswer":"Correct answer:","feedbackHeader":"Feedback","behaviour":{"enableRetry":true,"enableSolutionsButton":true,"enableCheckButton":true,"instantFeedback":false},"scoreBarLabel":"You got :num out of :total points","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again.","textField":"At an active subduction zone, ocean crust subducts and anything atop it (sediment or islands or continental fragments) can be scraped off and attached to the edge of the nonsubducting plate. We call that processes *accretion*. \n\nAt any moment in time there will be some sediment collecting between the trench and the nonsubducting plate -- sediment that comes from the continent and the ocean. That is called the *accretionary wedge*.\n\nLater, when enough time has passed and the accreted material has become a permanent part of the continent (extending the continent outward), we call the accreted material a *terrane*."},"library":"H5P.DragText 1.10","metadata":{"contentType":"Drag the Words","license":"U","title":"Test Your Understanding"},"subContentId":"e8bac953-ed83-4bc8-9ad8-12e8fd01ef7e"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"1af6b7f0-2d48-448e-a0a9-391cad13e7d3","metadata":{"contentType":"Column","license":"U","title":"Terrane Accretion"}},{"params":{"content":[{"content":{"params":{"text":"
\n
Why are there earthquakes at divergent plate boundaries, and what else happens there?<\/strong> <\/p>\n\n
As plates spread apart, they thin; there's less pressure over the underlying mantle, and that mantle melts. Molten rock rises to the surface and erupts as lavas on the surface.
\n
\nEarthquakes happen whenever you have a plate boundary of any kind, because along that boundary, you have plates wanting to move but stuck due to friction or inertia. The stress\/pressure has to build higher and higher until it builds beyond the stickiness or friction and then causes a large move all at once. That's an earthquake! If the plates just always moved very slowly, there would be no earthquakes. Where is the pressure coming from? Pulling toward subduction zones, rising heat of convection cells pushing up and outward from the mantle...
\n
\nHigh amounts of lava and heat rising under a divergent plate boundary means the crust is pushed up and creates uplifted crust (mountain system).
\n
\nBecause molten rock is close to the surface, waters from the surface can sink down and get heated up and then rise again bringing with them leached metals and gases. On land, that would look like a geyser or hot spring. Underwater, those create hydrothermal vents.<\/p>\n\n
\n
Will the Atlantic Ocean ever stop spreading?<\/strong><\/p>\n\n
Look at the edges of the Atlantic Ocean. Though no subduction zones today, and still growing larger, the oldest rocks are already some of the oldest in the world's oceans. Eventually the ocean lithosphere will be so dense it will separate from the continent and begin subduction, and when it does, it will bring both sides of the Atlantic Ocean back together, <\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"83bad3ad-a2be-4f29-a508-5970a6d3685e"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"8fc2af25-e4c0-4161-ac5b-4716112e2862","metadata":{"contentType":"Column","license":"U","title":"FAQs (Frequently Asked Questions):"}},{"params":{"content":[{"content":{"params":{"introPage":{"showIntroPage":false,"startButtonText":"Start Quiz","introduction":""},"progressType":"dots","passPercentage":100,"questions":[{"params":{"scoreShow":"Check","submit":"Submit","tryAgain":"Retry","scoreExplanation":"Correct answers give +1 point. Incorrect answers give -1 point. The lowest possible score is 0.","question":{"settings":{"size":{"width":620,"height":400}},"task":{"elements":[{"x":79.06468504886806,"y":73.21771428750993,"width":7.3209078745104215,"height":2.666958183231329,"dropZones":["0","1","2"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Plate moving apart <--><\/p>\n"},"subContentId":"c775fffb-a56e-45dd-9582-5c7126674737","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":79.06468504886806,"y":58.762714900276215,"width":7.338020484548047,"height":2.7287042623784368,"dropZones":["0","1","2"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Plate moving together --><--<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"11004a33-a874-4798-a2d2-fa9868a79846"},"backgroundOpacity":100,"multiple":false},{"x":68.92818696567984,"y":87.35611726343294,"width":11.261422022846366,"height":2.35227371788504,"dropZones":["0","1","2"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Plate moving sideways past each other<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"43fa5343-53b2-4d03-9a04-d8a87328e56f"},"backgroundOpacity":100,"multiple":false},{"x":83.11928428214334,"y":25.139129369102125,"width":5.709580628803246,"height":1.5590563387423935,"dropZones":["0","1","2"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
earthquakes<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"f60f6c2b-788c-4c3b-bc2b-3384a909a705"},"backgroundOpacity":100,"multiple":true},{"x":81.700174550497,"y":0,"width":6.311409186100024,"height":3.128522787861341,"dropZones":["0","1","2"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
New seafloor forming<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"ee916a44-6559-48db-b52c-90daaf2aed22"},"backgroundOpacity":100,"multiple":false},{"x":79.06468504886806,"y":35.19478111674297,"width":7.310490480850285,"height":1.5667003614025834,"dropZones":["0","1","2"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Fracture zones<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"5e24a6b2-8473-4424-b398-3f249565853b"},"backgroundOpacity":100,"multiple":false},{"x":71.36094650564502,"y":15.711955855688828,"width":4.959198275862068,"height":1.5590563387423935,"dropZones":["0","1","2"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Rift valley<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"6455611b-4764-4b18-b28f-58ca3dc4c77d"},"backgroundOpacity":100,"multiple":false},{"x":77.64557531722171,"y":45.5646719814976,"width":7.87300631160016,"height":2.3539168748830055,"dropZones":["0","1","2"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
mid-ocean ridge (mountain)<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"75c2a935-ee2d-4347-a8e4-2ccf42c11a64"},"backgroundOpacity":100,"multiple":false},{"x":86.7684235920911,"y":16.026194972802603,"width":4.326708671399595,"height":1.5584967038539552,"dropZones":["0","1","2"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Accretion<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"7f9ebc49-9961-4062-9d53-f5bad52fae63"},"backgroundOpacity":100,"multiple":false}],"dropZones":[{"x":1.1617377057193405e-6,"y":5.653946813851025,"width":28.28082965209511,"height":7.070207413023778,"correctElements":["4","3","0","7","6"],"showLabel":true,"backgroundOpacity":100,"tipsAndFeedback":{"tip":""},"single":false,"autoAlign":true,"label":"
Divergent plate boundary<\/strong><\/div>\n"},{"x":1.1617377057193405e-6,"y":38.649054110797564,"width":28.28082965209511,"height":7.070207413023778,"correctElements":["3","2","5"],"showLabel":true,"backgroundOpacity":100,"tipsAndFeedback":{"tip":""},"single":false,"autoAlign":true,"label":"
Transform plate boundary<\/strong><\/div>\n"},{"x":1.1617377057193405e-6,"y":72.27501791653965,"width":28.28082965209511,"height":6.933328197507637,"correctElements":["1","3","8"],"showLabel":true,"backgroundOpacity":100,"tipsAndFeedback":{"tip":""},"single":false,"autoAlign":true,"label":"
Convergent plate boundary<\/strong><\/div>\n"}]}},"overallFeedback":[{"from":0,"to":100}],"behaviour":{"enableRetry":true,"enableCheckButton":true,"singlePoint":false,"applyPenalties":true,"enableScoreExplanation":true,"dropZoneHighlighting":"dragging","autoAlignSpacing":2,"enableFullScreen":false,"showScorePoints":true,"showTitle":true},"grabbablePrefix":"Grabbable {num} of {total}.","grabbableSuffix":"Placed in dropzone {num}.","dropzonePrefix":"Dropzone {num} of {total}.","noDropzone":"No dropzone.","tipLabel":"Show tip.","tipAvailable":"Tip available","correctAnswer":"Correct answer","wrongAnswer":"Wrong answer","feedbackHeader":"Feedback","scoreBarLabel":"You got :num out of :total points","scoreExplanationButtonLabel":"Show score explanation","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yRetry":"Retry the task. Reset all responses and start the task over again.","localize":{"fullscreen":"Fullscreen","exitFullscreen":"Exit fullscreen"}},"library":"H5P.DragQuestion 1.14","metadata":{"contentType":"Drag and Drop","license":"U","title":"Plate Boundary Drag and Drop"},"subContentId":"830cec6e-3aad-4632-8c5b-19c6525c2a09"},{"params":{"media":{"disableImageZooming":false},"correct":"false","behaviour":{"enableRetry":true,"enableSolutionsButton":false,"enableCheckButton":true,"confirmCheckDialog":false,"confirmRetryDialog":false,"autoCheck":false,"feedbackOnCorrect":"Correct. Plates vary in size from about 100 km wide to thousands of km wide."},"l10n":{"trueText":"True","falseText":"False","score":"You got @score of @total points","checkAnswer":"Check","submitAnswer":"Submit","showSolutionButton":"Show solution","tryAgain":"Retry","wrongAnswerMessage":"Wrong answer","correctAnswerMessage":"Correct answer","scoreBarLabel":"You got :num out of :total points","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again."},"confirmCheck":{"header":"Finish ?","body":"Are you sure you wish to finish ?","cancelLabel":"Cancel","confirmLabel":"Finish"},"confirmRetry":{"header":"Retry ?","body":"Are you sure you wish to retry ?","cancelLabel":"Cancel","confirmLabel":"Confirm"},"question":"
All plates are roughly the same size.<\/p>\n"},"library":"H5P.TrueFalse 1.8","metadata":{"contentType":"True\/False Question","license":"U","title":"Plate sizes True\/False Question"},"subContentId":"4b306fa0-b031-42c7-9654-79c3d8ed8967"},{"params":{"media":{"disableImageZooming":false},"correct":"true","behaviour":{"enableRetry":true,"enableSolutionsButton":true,"enableCheckButton":true,"confirmCheckDialog":false,"confirmRetryDialog":false,"autoCheck":false},"l10n":{"trueText":"True","falseText":"False","score":"You got @score of @total points","checkAnswer":"Check","submitAnswer":"Submit","showSolutionButton":"Show solution","tryAgain":"Retry","wrongAnswerMessage":"Wrong answer","correctAnswerMessage":"Correct answer","scoreBarLabel":"You got :num out of :total points","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again."},"confirmCheck":{"header":"Finish ?","body":"Are you sure you wish to finish ?","cancelLabel":"Cancel","confirmLabel":"Finish"},"confirmRetry":{"header":"Retry ?","body":"Are you sure you wish to retry ?","cancelLabel":"Cancel","confirmLabel":"Confirm"},"question":"
North America AND the western half of the Atlantic Ocean that sits next to the east coast of North America are all bound together in the same plate.<\/p>\n"},"library":"H5P.TrueFalse 1.8","metadata":{"contentType":"True\/False Question","license":"U","title":"Atlantic Ocean True\/False Question"},"subContentId":"55b36b53-da6a-41d2-9538-10c516c6ae4a"},{"params":{"scoreShow":"Check","submit":"Submit","tryAgain":"Retry","scoreExplanation":"Correct answers give +1 point. Incorrect answers give -1 point. The lowest possible score is 0.","question":{"settings":{"size":{"width":620,"height":310}},"task":{"elements":[{"x":13.177447508144677,"y":68.92944463140994,"width":3.9141013893084273,"height":1.275818927680141,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Basalt<\/p>\n"},"subContentId":"38fcb9fc-718c-4983-b3d5-5b36f0dcd31c","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":0,"y":69.33491195277117,"width":3.9141013893084273,"height":1.275818927680141,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Granite<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"33a9973b-b1b8-431f-a5e1-90af8594b4b7"},"backgroundOpacity":100,"multiple":false},{"x":42.72843434877797,"y":77.32095112908937,"width":4.998938910547006,"height":3.579466478311328,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
New rocks forming today<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"bb2b061d-c8b6-45b0-a794-7e06f40d5101"},"backgroundOpacity":100,"multiple":true},{"x":59.00593314831243,"y":77.32095112908937,"width":7.0845649634977095,"height":3.5780966415450606,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Contains the oldest rocks on the planet<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"3b363655-468a-4e93-88ab-42625ac6de84"},"backgroundOpacity":100,"multiple":false},{"x":81.38396798980583,"y":77.32095112908937,"width":6.295215330962246,"height":3.574013944411847,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
All rocks are younger than 200 Ma<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"3118739b-97e8-4a54-a012-8824060f7b25"},"backgroundOpacity":100,"multiple":false},{"x":0,"y":81.49893159360822,"width":6.296123615395259,"height":2.786919401964694,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Thinnest: 3 to 10 km<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"16ebd8b4-a14f-4841-9a62-96c500ae78a5"},"backgroundOpacity":100,"multiple":false},{"x":20.272996166376426,"y":81.09346427224698,"width":6.296123615395259,"height":2.786919401964694,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Thickest: 30 to 50 km<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"18f4ce98-6ac7-4a6b-aa26-8268e4af9322"},"backgroundOpacity":100,"multiple":false},{"x":26.556469202958915,"y":69.33266223000945,"width":4.795305331595261,"height":1.0860184240989161,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Densest<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"5fe65133-d24f-40a2-b188-deb8e4ca3516"},"backgroundOpacity":100,"multiple":false},{"x":85.1465726868638,"y":64.87477141779759,"width":4.718679994810113,"height":1.5629750310651975,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"
Subducts<\/p>\n"},"metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"0b644248-aa7d-489e-99bd-fbd686d3e32d"},"backgroundOpacity":100,"multiple":true}],"dropZones":[{"x":1.1617377057193405e-6,"y":8.105512847738904,"width":18.13154691069948,"height":11.783679021706297,"correctElements":["0","2","4","5","7","8"],"showLabel":true,"backgroundOpacity":100,"tipsAndFeedback":{"tip":""},"single":false,"autoAlign":true,"label":"
Oceanic crust<\/strong><\/div>\n"},{"x":48.85675879914554,"y":8.105512847738904,"width":19.7071819116219,"height":11.783679021706297,"correctElements":["1","2","3","6"],"showLabel":true,"backgroundOpacity":100,"tipsAndFeedback":{"tip":""},"single":false,"autoAlign":true,"label":"
Continental crust<\/strong><\/div>\n"}]}},"overallFeedback":[{"from":0,"to":100}],"behaviour":{"enableRetry":true,"enableCheckButton":true,"singlePoint":false,"applyPenalties":true,"enableScoreExplanation":true,"dropZoneHighlighting":"dragging","autoAlignSpacing":2,"enableFullScreen":false,"showScorePoints":true,"showTitle":true},"grabbablePrefix":"Grabbable {num} of {total}.","grabbableSuffix":"Placed in dropzone {num}.","dropzonePrefix":"Dropzone {num} of {total}.","noDropzone":"No dropzone.","tipLabel":"Show tip.","tipAvailable":"Tip available","correctAnswer":"Correct answer","wrongAnswer":"Wrong answer","feedbackHeader":"Feedback","scoreBarLabel":"You got :num out of :total points","scoreExplanationButtonLabel":"Show score explanation","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yRetry":"Retry the task. Reset all responses and start the task over again.","localize":{"fullscreen":"Fullscreen","exitFullscreen":"Exit fullscreen"}},"library":"H5P.DragQuestion 1.14","metadata":{"contentType":"Drag and Drop","license":"U","title":"Crust Drag and Drop"},"subContentId":"b7059de5-af4b-4dd1-b15e-604b09a77b9a"},{"params":{"media":{"disableImageZooming":false},"answers":[{"correct":true,"tipsAndFeedback":{"tip":"","chosenFeedback":"
Yes, this layer grows thicker over time as more and more mantle attaches itself to the underside of the ocean crust, eventually becoming so thick it increases the overall plate density so it sinks.<\/div>\n","notChosenFeedback":""},"text":"
Attached depleted mantle (making up the lower lithosphere)<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Basalt Dikes<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Gabbro<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Pillow Basalt<\/div>\n"},{"correct":true,"tipsAndFeedback":{"tip":"","chosenFeedback":"
Yes, this layer grows over time as more and more sediment collects on the seafloor.<\/div>\n","notChosenFeedback":""},"text":"
Sediment<\/div>\n"}],"overallFeedback":[{"from":0,"to":100}],"behaviour":{"enableRetry":true,"enableSolutionsButton":false,"enableCheckButton":true,"type":"auto","singlePoint":false,"randomAnswers":false,"showSolutionsRequiresInput":true,"confirmCheckDialog":false,"confirmRetryDialog":false,"autoCheck":false,"passPercentage":100,"showScorePoints":true},"UI":{"checkAnswerButton":"Check","submitAnswerButton":"Submit","showSolutionButton":"Show solution","tryAgainButton":"Retry","tipsLabel":"Show tip","scoreBarLabel":"You got :num out of :total points","tipAvailable":"Tip available","feedbackAvailable":"Feedback available","readFeedback":"Read feedback","wrongAnswer":"Wrong answer","correctAnswer":"Correct answer","shouldCheck":"Should have been checked","shouldNotCheck":"Should not have been checked","noInput":"Please answer before viewing the solution","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again."},"confirmCheck":{"header":"Finish ?","body":"Are you sure you wish to finish ?","cancelLabel":"Cancel","confirmLabel":"Finish"},"confirmRetry":{"header":"Retry ?","body":"Are you sure you wish to retry ?","cancelLabel":"Cancel","confirmLabel":"Confirm"},"question":"
As new seafloor forms and is pushed away at seafloor spreading centers, which layers increase in thickness as they age? (Look at cross-section images to confirm.) Choose all that apply.<\/em><\/p>\n"},"library":"H5P.MultiChoice 1.16","metadata":{"contentType":"Multiple Choice","license":"U","title":"New seafloor"},"subContentId":"e1c8a269-e87d-4d45-998c-986c81cec581"}],"disableBackwardsNavigation":false,"randomQuestions":false,"endGame":{"showResultPage":true,"showSolutionButton":false,"showRetryButton":true,"noResultMessage":"Finished","message":"Your result:","scoreBarLabel":"You got @finals out of @totals points","overallFeedback":[{"from":0,"to":100}],"solutionButtonText":"Show solution","retryButtonText":"Retry","finishButtonText":"Finish","submitButtonText":"Submit","showAnimations":false,"skippable":false,"skipButtonText":"Skip video"},"texts":{"prevButton":"Previous question","nextButton":"Next question","finishButton":"Finish","submitButton":"Submit","textualProgress":"Question: @current of @total questions","jumpToQuestion":"Question %d of %total","questionLabel":"Question","readSpeakerProgress":"Question @current of @total","unansweredText":"Unanswered","answeredText":"Answered","currentQuestionText":"Current question","navigationLabel":"Questions"},"override":{"checkButton":true,"showSolutionButton":"off","retryButton":"on"}},"library":"H5P.QuestionSet 1.20","metadata":{"contentType":"Question Set","license":"U","title":"Test Your Understanding"},"subContentId":"6540110a-a4e2-4942-843b-bb4dfb270de5"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"d853d1ee-37e5-42fc-9c22-158169f5e2e0","metadata":{"contentType":"Column","license":"U","title":"Test Your Understanding"}},{"params":{"content":[{"content":{"params":{"text":"
\n
The following resources are optional and intended for deeper exploration or clarification.<\/p>\n\n
Textbook chapters<\/strong><\/p>\n\n
\n\t
Open Textbook: Physical Geology, by Steven Earle -- Fundamentals of Plate Tectonics<\/a> and Geology of the Seafloor<\/a><\/li>\n\t
Open Textbook: Introduction to Geology, SLCC -- Plate Tectonics<\/a><\/li>\n\t
ONLINE Vision Learning Textbook: Earth Sciences: Plates, Plate Boundaries, and Driving Forces<\/a><\/li>\n\t
Open Geology--Historical Geology--Bentley, C. and others--Plate Tectonics<\/a><\/li>\n<\/ul>\n\n
\n
Plate tectonics resources<\/strong><\/p>\n\n
\n\tAmerican Museum of Natural History -- Video and website: Plates on the Move<\/a><\/li>\n\t
ANIMATIONS: Plate Tectonics and Continental Drift<\/a><\/li>\n\t
BrainPOP -- Video: Plate Tectonics<\/a><\/li>\n\t
Chris Merkert -- Video: Plate Boundaries<\/a><\/li>\n\t
National Geographic -- Video: Tectonic Plates<\/a><\/li>\n<\/ul>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"1cdd0efd-bc6a-4cab-8b6f-745edb7128ba"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"e715bdae-f5a4-4d15-8783-a9eca0bfd6f0","metadata":{"contentType":"Column","license":"U","title":"Additional Resources"}}],"behaviour":{"defaultTableOfContents":true,"progressIndicators":true,"progressAuto":true,"displaySummary":false,"baseColor":"#1768c4","enableRetry":true},"read":"Read","displayTOC":"Display 'Table of contents'","hideTOC":"Hide 'Table of contents'","nextPage":"Next page","previousPage":"Previous page","chapterCompleted":"Page completed!","partCompleted":"@pages of @total completed","incompleteChapter":"Incomplete page","navigateToTop":"Navigate to the top","markAsFinished":"I have finished this page","fullscreen":"Fullscreen","exitFullscreen":"Exit fullscreen","bookProgressSubtext":"@count of @total pages","interactionsProgressSubtext":"@count of @total interactions","submitReport":"Submit Report","restartLabel":"Restart","summaryHeader":"Summary","allInteractions":"All interactions","unansweredInteractions":"Unanswered interactions","scoreText":"@score \/ @maxscore","leftOutOfTotalCompleted":"@left of @max interactions completed","noInteractions":"No interactions","score":"Score","summaryAndSubmit":"Summary & submit","noChapterInteractionBoldText":"You have not interacted with any pages.","noChapterInteractionText":"You have to interact with at least one page before you can see the summary.","yourAnswersAreSubmittedForReview":"Your answers are submitted for review!","bookProgress":"Book progress","interactionsProgress":"Interactions progress","totalScoreLabel":"Total score","a11y":{"progress":"Page @page of @total.","menu":"Toggle navigation menu"}}

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