Plate Boundaries | Earth Science

<!DOCTYPE html> <html lang="en" dir="ltr"> <head>  <meta http-equiv="X-UA-Compatible" content="ie=edge"> <meta charset="utf-8"> <base href="https://www.visionlearning.com"> <title>Plate Boundaries | Earth Science | Visionlearning</title> <link rel="canonical" href="https://www.visionlearning.com/en/library/earth-science/6/plate-boundaries/66"> <meta name="description" content="Learn about the three different types of plate boundaries and the events that occur at each. Includes an explanation of plate composition, types of volcanoes, and earthquakes."> <meta name="keywords" content="what are plate boundaries, types of plate boundaries, what are earth's plates made of, types of volcanoes, how do earthquakes happen"> <meta name="viewport" content="width=device-width, initial-scale=1.0, shrink-to-fit=no"> <meta name="msvalidate.01" content="D8E20F39AD48052260032E56DE409970"> <script type="application/ld+json"> { "@context": "http://schema.org/", "@type": "Article", "mainEntityOfPage": { "@type": "WebPage", "@id": "https://visionlearning.com/en/library/earth-science/6/plate-boundaries/66" }, "name": "Plate Boundaries", "headline": "Plate Boundaries: Tectonic activity where plates interact", "author": { "@type": "Person", "name": "Anne E. Egger, Ph.D." }, "datePublished": "2003-03-18 14:47:36", "dateModified": "2017-02-12T08:30:00+05:00", "image": { "@type": "ImageObject", "url": "/img/library/moduleImages/featured_image_66-23061209065501.jpg", "width": 696, "height": 464 }, "publisher": { "@type": "Organization", "name": "Visionlearning, Inc.", "logo": { "@type": "ImageObject", "url": "http://visionlearning.com/images/logo.png", "width": 278, "height": 60 } }, "description": "Earthquakes and volcanoes can reveal a lot about plate boundaries. This module looks at the nature of tectonic plates and discusses the different boundary types that exist between them – convergent, divergent, and transform. Forces that drive the push and pull of these landmasses are explored.", "keywords": "what are plate boundaries, types of plate boundaries, what are earth's plates made of, types of volcanoes, how do earthquakes happen", "inLanguage": { "@type": "Language", "name": "English", "alternateName": "en" }, "copyrightHolder": { "@type": "Organization", "name": "Visionlearning, Inc." }, "copyrightYear": "2003"} </script> <meta property="og:url" content="https://visionlearning.com/en/library/earth-science/6/plate-boundaries/66"> <meta property="og:title" content="Plate Boundaries | Earth Science | Visionlearning" /> <meta property="og:type" content="website"> <meta property="og:site_name" content="Visionlearning"> <meta property="og:description" content="Learn about the three different types of plate boundaries and the events that occur at each. 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aria-controls="acc-panel-hazards" aria-expanded="false"> <span class="accordion__button__label"> Hazards </span> </button> <div class="accordion__panel" id="acc-panel-hazards" data-accordion="panel" aria-labelledby="acc-button-hazards" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/natural-hazards-and-risk/288">Natural Hazards and Risk</a></li> </ul> </div> <button class="accordion__button" id="acc-button-earth-history" data-accordion="button" aria-controls="acc-panel-earth-history" aria-expanded="false"> <span class="accordion__button__label"> Earth History </span> </button> <div class="accordion__panel" id="acc-panel-earth-history" data-accordion="panel" aria-labelledby="acc-button-earth-history" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/extinction/295">Extinction</a></li> <li><a href="/en/library/earth-science/6/mass-extinctions/294">Mass Extinctions</a></li> </ul> </div> </div> </div> <button 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<li><a href="/en/library/environmental-science/61/ecosystem-services/279">Ecosystem Services</a></li> <li><a href="/en/library/environmental-science/61/population-biology/287">Population Biology</a></li> </ul> </div> <button class="accordion__button" id="acc-button-earth-cycles" data-accordion="button" aria-controls="acc-panel-earth-cycles" aria-expanded="false"> <span class="accordion__button__label"> Earth Cycles </span> </button> <div class="accordion__panel" id="acc-panel-earth-cycles" data-accordion="panel" aria-labelledby="acc-button-earth-cycles" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/the-nitrogen-cycle/98">The Nitrogen Cycle</a></li> <li><a href="/en/library/environmental-science/61/the-carbon-cycle/95">The Carbon Cycle</a></li> <li><a href="/en/library/environmental-science/61/the-phosphorus-cycle/197">The Phosphorus Cycle</a></li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-research" 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</button> <div class="accordion__panel" id="acc-panel-general-science" data-accordion="panel" aria-labelledby="acc-button-general-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-methods" data-accordion="button" aria-controls="acc-panel-methods" aria-expanded="false"> <span class="accordion__button__label"> Methods </span> </button> <div class="accordion__panel" id="acc-panel-methods" data-accordion="panel" aria-labelledby="acc-button-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-scientific-method/45">The Scientific Method</a></li> </ul> </div> <button class="accordion__button" id="acc-button-measurement" data-accordion="button" aria-controls="acc-panel-measurement" aria-expanded="false"> <span class="accordion__button__label"> Measurement </span> </button> <div class="accordion__panel" id="acc-panel-measurement" data-accordion="panel" aria-labelledby="acc-button-measurement" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-metric-system/47">The Metric System</a></li> </ul> </div> <button class="accordion__button" id="acc-button-physical-properties" data-accordion="button" aria-controls="acc-panel-physical-properties" aria-expanded="false"> <span class="accordion__button__label"> Physical Properties </span> </button> <div class="accordion__panel" id="acc-panel-physical-properties" data-accordion="panel" aria-labelledby="acc-button-physical-properties" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/temperature/48">Temperature</a></li> <li><a href="/en/library/general-science/3/density-and-buoyancy/37">Density and Buoyancy</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-math-in-science" data-accordion="button" aria-controls="acc-panel-math-in-science" aria-expanded="false"> <span class="accordion__button__label"> Math in Science </span> </button> <div class="accordion__panel" id="acc-panel-math-in-science" data-accordion="panel" aria-labelledby="acc-button-math-in-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-equations" data-accordion="button" aria-controls="acc-panel-equations" aria-expanded="false"> <span class="accordion__button__label"> Equations </span> </button> <div class="accordion__panel" id="acc-panel-equations" data-accordion="panel" aria-labelledby="acc-button-equations" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/unit-conversion/144">Unit Conversion</a></li> <li><a href="/en/library/math-in-science/62/linear-equations/194">Linear Equations</a></li> <li><a href="/en/library/math-in-science/62/exponential-equations-i/206">Exponential Equations I</a></li> <li><a href="/en/library/math-in-science/62/exponential-equations-ii/210">Exponential Equations II</a></li> <li><a href="/en/library/math-in-science/62/scientific-notation/250">Scientific Notation</a></li> <li><a href="/en/library/math-in-science/62/measurement/257">Measurement</a></li> </ul> </div> <button class="accordion__button" id="acc-button-statistics" data-accordion="button" aria-controls="acc-panel-statistics" aria-expanded="false"> <span class="accordion__button__label"> Statistics </span> </button> <div class="accordion__panel" id="acc-panel-statistics" data-accordion="panel" aria-labelledby="acc-button-statistics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/introduction-to-descriptive-statistics/218">Introduction to Descriptive Statistics</a></li> <li><a href="/en/library/math-in-science/62/introduction-to-inferential-statistics/224">Introduction to Inferential Statistics</a></li> <li><a href="/en/library/math-in-science/62/statistical-techniques/239">Statistical Techniques</a></li> </ul> </div> <button class="accordion__button" id="acc-button-trigonometric-functions" data-accordion="button" aria-controls="acc-panel-trigonometric-functions" aria-expanded="false"> <span class="accordion__button__label"> Trigonometric Functions </span> </button> <div class="accordion__panel" id="acc-panel-trigonometric-functions" data-accordion="panel" aria-labelledby="acc-button-trigonometric-functions" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/wave-mathematics/131">Wave Mathematics</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-physics" data-accordion="button" aria-controls="acc-panel-physics" aria-expanded="false"> <span class="accordion__button__label"> Physics </span> </button> <div class="accordion__panel" id="acc-panel-physics" data-accordion="panel" aria-labelledby="acc-button-physics" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-light-and-optics" data-accordion="button" aria-controls="acc-panel-light-and-optics" aria-expanded="false"> <span class="accordion__button__label"> Light and Optics </span> </button> <div class="accordion__panel" id="acc-panel-light-and-optics" data-accordion="panel" aria-labelledby="acc-button-light-and-optics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/physics/24/the-nature-of-light/132">The Nature of Light</a></li> <li><a href="/en/library/physics/24/electromagnetism-and-light/138">Electromagnetism and Light</a></li> </ul> </div> <button class="accordion__button" id="acc-button-mechanics" data-accordion="button" aria-controls="acc-panel-mechanics" aria-expanded="false"> <span class="accordion__button__label"> Mechanics </span> </button> <div class="accordion__panel" id="acc-panel-mechanics" data-accordion="panel" aria-labelledby="acc-button-mechanics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/physics/24/defining-energy/199">Defining Energy</a></li> <li><a href="/en/library/physics/24/waves-and-wave-motion/102">Waves and Wave Motion</a></li> <li><a href="/en/library/physics/24/gravity/118">Gravity</a></li> <li><a href="/en/library/physics/24/thermodynamics-i/200">Thermodynamics I</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-process-of-science" data-accordion="button" aria-controls="acc-panel-process-of-science" aria-expanded="false"> <span class="accordion__button__label"> Process of Science </span> </button> <div class="accordion__panel" id="acc-panel-process-of-science" data-accordion="panel" aria-labelledby="acc-button-process-of-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-introduction" data-accordion="button" aria-controls="acc-panel-introduction" aria-expanded="false"> <span class="accordion__button__label"> Introduction </span> </button> <div class="accordion__panel" id="acc-panel-introduction" data-accordion="panel" aria-labelledby="acc-button-introduction" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-process-of-science/176">The Process of Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-the-culture-of-science" data-accordion="button" aria-controls="acc-panel-the-culture-of-science" aria-expanded="false"> <span class="accordion__button__label"> The Culture of Science </span> </button> <div class="accordion__panel" id="acc-panel-the-culture-of-science" data-accordion="panel" aria-labelledby="acc-button-the-culture-of-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-nature-of-scientific-knowledge/185">The Nature of Scientific Knowledge</a></li> <li><a href="/en/library/process-of-science/49/scientists-and-the-scientific-community/172">Scientists and the Scientific Community</a></li> <li><a href="/en/library/process-of-science/49/scientific-ethics/161">Scientific Ethics</a></li> <li><a href="/en/library/process-of-science/49/scientific-institutions-and-societies/162">Scientific Institutions and Societies</a></li> </ul> </div> <button class="accordion__button" id="acc-button-ideas-in-science" data-accordion="button" aria-controls="acc-panel-ideas-in-science" aria-expanded="false"> <span class="accordion__button__label"> Ideas in Science </span> </button> <div class="accordion__panel" id="acc-panel-ideas-in-science" data-accordion="panel" aria-labelledby="acc-button-ideas-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/theories-hypotheses-and-laws/177">Theories, Hypotheses, and Laws</a></li> <li><a href="/en/library/process-of-science/49/scientific-controversy/181">Scientific Controversy</a></li> <li><a href="/en/library/process-of-science/49/creativity-in-science/182">Creativity in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-research-methods" data-accordion="button" aria-controls="acc-panel-research-methods" aria-expanded="false"> <span class="accordion__button__label"> Research Methods </span> </button> <div class="accordion__panel" id="acc-panel-research-methods" data-accordion="panel" aria-labelledby="acc-button-research-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-practice-of-science/148">The Practice of Science</a></li> <li><a href="/en/library/process-of-science/49/experimentation-in-scientific-research/150">Experimentation in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/description-in-scientific-research/151">Description in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/comparison-in-scientific-research/152">Comparison in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/modeling-in-scientific-research/153">Modeling in Scientific Research</a></li> </ul> </div> <button class="accordion__button" id="acc-button-data" data-accordion="button" aria-controls="acc-panel-data" aria-expanded="false"> <span class="accordion__button__label"> Data </span> </button> <div class="accordion__panel" id="acc-panel-data" data-accordion="panel" aria-labelledby="acc-button-data" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/data-analysis-and-interpretation/154">Data Analysis and Interpretation</a></li> <li><a href="/en/library/process-of-science/49/uncertainty-error-and-confidence/157">Uncertainty, Error, and Confidence</a></li> <li><a href="/en/library/process-of-science/49/statistics-in-science/155">Statistics in Science</a></li> <li><a href="/en/library/process-of-science/49/using-graphs-and-visual-data-in-science/156">Using Graphs and Visual Data in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-communication" data-accordion="button" aria-controls="acc-panel-scientific-communication" aria-expanded="false"> <span class="accordion__button__label"> Scientific Communication </span> </button> <div class="accordion__panel" id="acc-panel-scientific-communication" data-accordion="panel" aria-labelledby="acc-button-scientific-communication" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/understanding-scientific-journals-and-articles/158">Understanding Scientific Journals and Articles</a></li> <li><a href="/en/library/process-of-science/49/utilizing-the-scientific-literature/173">Utilizing the Scientific Literature</a></li> <li><a href="/en/library/process-of-science/49/peer-review-in-scientific-publishing/159">Peer Review in Scientific Publishing</a></li> <li><a href="/en/library/process-of-science/49/the-how-and-why-of-scientific-meetings/186">The How and Why of Scientific Meetings</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-scientists-and-research" data-accordion="button" aria-controls="acc-panel-scientists-and-research" aria-expanded="false"> <span class="accordion__button__label"> Scientists and Research </span> </button> <div class="accordion__panel" id="acc-panel-scientists-and-research" data-accordion="panel" aria-labelledby="acc-button-scientists-and-research" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-scientific-research" data-accordion="button" aria-controls="acc-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/scientists-and-research/58/from-stable-chromosomes-to-jumping-genes/184">From Stable Chromosomes to Jumping Genes</a></li> <li><a href="/en/library/scientists-and-research/58/an-elegant-experiment-to-test-the-process-of-dna-replication/187">An Elegant Experiment to Test the Process of DNA Replication</a></li> <li><a href="/en/library/scientists-and-research/58/the-founding-of-neuroscience/233">The Founding of Neuroscience</a></li> <li><a href="/en/library/scientists-and-research/58/tracking-endangered-jaguars-across-the-border/189">Tracking Endangered Jaguars across the Border</a></li> <li><a href="/en/library/scientists-and-research/58/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> <li><a href="/en/library/scientists-and-research/58/revolutionizing-medicine-with-monoclonal-antibodies/220">Revolutionizing Medicine with Monoclonal Antibodies</a></li> <li><a href="/en/library/scientists-and-research/58/uncovering-the-mysteries-of-chronic-mountain-sickness/238">Uncovering the Mysteries of Chronic Mountain Sickness</a></li> </ul> </div> <button class="accordion__button" id="acc-button-profiles-in-science" data-accordion="button" aria-controls="acc-panel-profiles-in-science" aria-expanded="false"> <span class="accordion__button__label"> Profiles in Science </span> </button> <div class="accordion__panel" id="acc-panel-profiles-in-science" data-accordion="panel" aria-labelledby="acc-button-profiles-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/luis-e.-miramontes/232">Luis E. Miramontes</a></li> <li><a href="/en/library/scientists-and-research/58/bernardo-houssay/237">Bernardo Houssay</a></li> <li><a href="/en/library/scientists-and-research/58/craig-lee/256">Craig Lee</a></li> <li><a href="/en/library/scientists-and-research/58/david-ho/241">David Ho</a></li> <li><a href="/en/library/scientists-and-research/58/louis-tompkins-wright/244">Louis Tompkins Wright</a></li> <li><a href="/en/library/scientists-and-research/58/carlos-j.-finlay/217">Carlos J. Finlay</a></li> <li><a href="/en/library/scientists-and-research/58/cecilia-payne/290">Cecilia Payne</a></li> <li><a href="/en/library/scientists-and-research/58/jazmin-scarlett/291">Jazmin Scarlett</a></li> <li><a href="/en/library/scientists-and-research/58/ramari-stewart/292">Ramari Stewart</a></li> <li><a href="/en/library/scientists-and-research/58/johnson-cerda/300">Johnson Cerda</a></li> <li><a href="/en/library/scientists-and-research/58/ellen-ochoa/201">Ellen Ochoa</a></li> <li><a href="/en/library/scientists-and-research/58/ruth-benerito/205">Ruth Benerito</a></li> <li><a href="/en/library/scientists-and-research/58/franklin-chang-díaz/219">Franklin Chang Díaz</a></li> <li><a href="/en/library/scientists-and-research/58/percy-lavon-julian/221">Percy Lavon Julian</a></li> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229">Luis Walter Alvarez</a></li> <li><a href="/en/library/scientists-and-research/58/france-anne-dominic-córdova/230">France Anne-Dominic Córdova</a></li> </ul> </div> </div> </div> </div> </div> </li> <li>  <button class="button" data-toggle="dropdown">Earth Science </button> <div class="nav__dropdown box-shadow-1 padding-1"> <div class="accordion accordion--secondary font-size-sm"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-sub-button-plate-tectonics" data-accordion="button" aria-controls="acc-sub-panel-plate-tectonics" aria-expanded="false"> <span class="accordion__button__label"> Plate Tectonics </span> </button> <div class="accordion__panel" id="acc-sub-panel-plate-tectonics" data-accordion="panel" aria-labelledby="acc-sub-button-plate-tectonics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/origins-of-plate-tectonic-theory/65">Origins of Plate Tectonic Theory</a></li> <li class="current">Plate Boundaries</li> <li><a href="/en/library/earth-science/6/earth-structure/69">Earth Structure</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-earth-cycles" data-accordion="button" aria-controls="acc-sub-panel-earth-cycles" aria-expanded="false"> <span class="accordion__button__label"> Earth Cycles </span> </button> <div class="accordion__panel" id="acc-sub-panel-earth-cycles" data-accordion="panel" aria-labelledby="acc-sub-button-earth-cycles" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/the-rock-cycle/128">The Rock Cycle</a></li> <li><a href="/en/library/earth-science/6/the-hydrologic-cycle/99">The Hydrologic Cycle</a></li> <li><a href="/en/library/earth-science/6/the-carbon-cycle/95">The Carbon Cycle</a></li> <li><a href="/en/library/earth-science/6/the-nitrogen-cycle/98">The Nitrogen Cycle</a></li> <li><a href="/en/library/earth-science/6/the-phosphorus-cycle/197">The Phosphorus Cycle</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-rocks-and-minerals" data-accordion="button" aria-controls="acc-sub-panel-rocks-and-minerals" aria-expanded="false"> <span class="accordion__button__label"> Rocks and Minerals </span> </button> <div class="accordion__panel" id="acc-sub-panel-rocks-and-minerals" data-accordion="panel" aria-labelledby="acc-sub-button-rocks-and-minerals" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/defining-minerals/119">Defining Minerals</a></li> <li><a href="/en/library/earth-science/6/identifying-minerals/130">Identifying Minerals</a></li> <li><a href="/en/library/earth-science/6/the-silicate-minerals/140">The Silicate Minerals</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-atmosphere-and-oceans" data-accordion="button" aria-controls="acc-sub-panel-atmosphere-and-oceans" aria-expanded="false"> <span class="accordion__button__label"> Atmosphere and Oceans </span> </button> <div class="accordion__panel" id="acc-sub-panel-atmosphere-and-oceans" data-accordion="panel" aria-labelledby="acc-sub-button-atmosphere-and-oceans" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/ocean-currents/282">Ocean Currents</a></li> <li><a href="/en/library/earth-science/6/water-in-the-atmosphere/289">Water in the Atmosphere</a></li> <li><a href="/en/library/earth-science/6/weather-fronts-and-forecasts/303">Weather, Fronts, and Forecasts</a></li> <li><a href="/en/library/earth-science/6/history-of-earths-atmosphere-i/202">History of Earth's Atmosphere I</a></li> <li><a href="/en/library/earth-science/6/history-of-earths-atmosphere-ii/203">History of Earth's Atmosphere II</a></li> <li><a href="/en/library/earth-science/6/earths-atmosphere/107">Earth's Atmosphere</a></li> <li><a href="/en/library/earth-science/6/factors-that-control-earths-temperature/234">Factors that Control Earth's Temperature</a></li> <li><a href="/en/library/earth-science/6/circulation-in-the-atmosphere/255">Circulation in the Atmosphere</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-hazards" data-accordion="button" aria-controls="acc-sub-panel-hazards" aria-expanded="false"> <span class="accordion__button__label"> Hazards </span> </button> <div class="accordion__panel" id="acc-sub-panel-hazards" data-accordion="panel" aria-labelledby="acc-sub-button-hazards" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/natural-hazards-and-risk/288">Natural Hazards and Risk</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-earth-history" data-accordion="button" aria-controls="acc-sub-panel-earth-history" aria-expanded="false"> <span class="accordion__button__label"> Earth History </span> </button> <div class="accordion__panel" id="acc-sub-panel-earth-history" data-accordion="panel" aria-labelledby="acc-sub-button-earth-history" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/extinction/295">Extinction</a></li> <li><a href="/en/library/earth-science/6/mass-extinctions/294">Mass Extinctions</a></li> </ul> </div> </div> </div> </div> </li> </ul> </nav>  <div id="theTop"></div> <main id="skip-header-content"> <div class="margin-bottom-5"> <article class="container wide module"> <header class="grid grid--sidebar-right module__header"> <div class="module__header__title"> <span class="subcategory"> <strong><em>Plate Tectonics</em></strong> </span> <h1>Plate Boundaries: <sub><em>Tectonic activity where plates interact</em></sub></h1> <p class="byline">by Anne E. Egger, Ph.D.</p> <nav class="module__header__tabs"> <ul class="tabs-nav tabs-nav--horizontal library"> <li> <a href="/en/library/earth-science/6/plate-boundaries/66/reading" aria-current="page" >Reading</a> </li> <li> <a href="/en/library/earth-science/6/plate-boundaries/66/quiz">Quiz</a> </li> <li> <a href="/en/library/earth-science/6/plate-boundaries/66/resources">Teach with this</a> </li> </ul> </nav> </div> <script type="application/ld+json"> { "@context": "http://schema.org", "@type": "AudioObject", "contentUrl": "https://www.visionlearning.com/img/library/moduleAudio/module_66.mp3", "description": "Recording of Plate Boundaries : Earthquakes and volcanoes can reveal a lot about plate boundaries. This module looks at the nature of tectonic plates and discusses the different boundary types that exist between them – convergent, divergent, and transform. Forces that drive the push and pull of these landmasses are explored.", "encodingFormat": "mp3", "name": "module_66.mp3" } </script> <div class="module_header_audio"> <div class="audio-player border border-radius"> <audio id="audio"> <source src="https://www.visionlearning.com/img/library/moduleAudio/module_66.mp3" type="audio/mpeg"> Your browser does not support the audio element. </audio> <div class="audio-player__title"> <p>Listen to this reading</p> <span class="audio-player__timestamp" id="timestamp"> 00:00 </span> </div> <div class="audio-player__controls" id="controls"> <button class="button button--icon-only" id="play-pause-button"> <span class="icon icon-play" aria-hidden="true"></span> </button> <div class="audio-player__progress" id="progress-bar" tabindex="0" aria-valuemin="0" aria-valuemax="100" aria-valuenow="0" aria-label="Use arrow keys to forward or rewind the audio" role="slider"> <div class="audio-player__progress__fill"> <span class="audio-player__thumb"></span> </div> </div> <div class="audio-player__volume-container"> <button id="mute-button"> <span class="icon icon-volume"></span> </button> <div class="audio-player__volume" tabindex="0" aria-valuemin="0" aria-valuemax="100" aria-valuenow="100" aria-label="Use arrow keys to adjust volume" role="slider"> <div class="audio-player__volume__fill"> <span class="audio-player__thumb"></span> </div> </div> </div> </div> </div> </div> </header> <hr class="divider"/>   <div class="grid grid--sidebar-right grid--divider"> <div class="order-2 order-1--lg module__main"> <div class="narrow margin-x-auto margin-y-5"> <div class="accordion margin-bottom-5">  <button class="accordion__button" id="acc-button-key-concepts" data-accordion="button" aria-controls="acc-panel-key-concepts" aria-expanded="true" tabindex="0"> Did you know? </button> <div class="accordion__panel shown show" id="acc-panel-key-concepts" data-accordion="panel" aria-labelledby="acc-button-key-concepts" role="region"> <div class="accordion__panel__content"> <p>Did you know that earthquakes and volcanic eruptions do not happen in random places? Both are concentrated along the boundaries of tectonic plates and provide evidence for the theory of plate tectonics. Earth is a dynamic planet, and nowhere is this more evident than along the plate boundaries.</p> </div> </div>  <button class="accordion__button" id="acc-button-table-of-contents" data-accordion="button" aria-controls="acc-panel-table-of-contents" aria-expanded="false" tabindex="0"> Key concepts </button> <div class="accordion__panel" id="acc-panel-table-of-contents" data-accordion="panel" aria-labelledby="acc-button-table-of-contents" role="region" aria-hidden="true"> <div class="accordion__panel__content"> <ul class="bulleted"> <li><p>Earthquakes and volcanoes occur primarily along plate boundaries; the frequency and type of events vary with the type of boundary.</p></li> <li><p>Plates interact with one another at boundaries in one of three ways: they diverge, converge, or slide past one another.</p></li> <li><p>Plates are made up of two types of crust – oceanic and continental; oceanic crust is thinner and denser than continental crust. A single plate can have both continental and oceanic crust.</p></li> <li><p>Gravity and mantle convection are two driving forces for the movement of plates.</p></li> </ul> </div> </div>  <button class="accordion__button" id="acc-button-terms-you-should-know" data-accordion="button" aria-controls="acc-panel-terms-you-should-know" aria-expanded="false" tabindex="0"> Terms you should know </button> <div class="accordion__panel" id="acc-panel-terms-you-should-know" data-accordion="panel" aria-labelledby="acc-button-terms-you-should-know" role="region" aria-hidden="true"> <div class="accordion__panel__content"> <dl> <dt><a href="/en/glossary/view/boundary">boundary </a></dt> <dd> a line or limit that divides one area from another </dd> <dt><a href="/en/glossary/view/buoyant">buoyant </a></dt> <dd> able to float </dd> <dt><a href="/en/glossary/view/dense">dense </a></dt> <dd> compact, packed close together, having a high mass in relation to volume</dd> </dl> </div> </div> </div> <hr class="border-color-dark" /> <section> <div class="container narrow"> <p>By 1962, the idea that pieces of the Earth's <mark class="term" data-term="surface" data-term-def="The outside or external part; the topside face of something." data-term-url="/en/glossary/view/surface/8275">surface</mark> moved around no longer seemed radical. The concepts of <mark class="term" data-term="continental drift" data-term-def="The theory proposed in 1915 by Alfred Wegener, a German geophysicist and meteorologist. The theory stated that the continents had once&hellip;" data-term-url="/en/glossary/view/continental+drift/866">continental drift</mark> and <mark class="term" data-term="seafloor" data-term-def="The bottom surface of the ocean." data-term-url="/en/glossary/view/seafloor/8280">seafloor</mark> spreading had revolutionized geology (see our module <a href="/en/library/Earth-Science/6/The-Origins-of-Plate-Tectonic-Theory/65">The Origins of Plate Tectonic Theory</a>), and scientists excitedly began to revise their <mark class="term" data-term="interpretation" data-term-def="An explanation of patterns observed in the data." data-term-url="/en/glossary/view/interpretation/8235">interpretations</mark> of existing <mark class="term" data-term="data" data-term-def="(plural form of <b>datum</b>) A collection of pieces of information, generally taking the form of numbers, text, bits, or facts, that&hellip;" data-term-url="/en/glossary/view/data/3729">data</mark> into a comprehensive <mark class="term" data-term="theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;" data-term-url="/en/glossary/view/theory/4854">theory</mark> of <mark class="term" data-term="plate tectonics" data-term-def="The study of the processes by which the earth's crust has attained its present structure." data-term-url="/en/glossary/view/plate+tectonics/11229">plate tectonics</mark>. For example, geologists had long recognized that <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark> are not randomly distributed on the Earth (see Figure 1).</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_5576.png"> <img src="/img/library/modules/mid66/Image/VLObject-5576-110727010729.png" alt="Figure 1. Map showing earthquakes from 2003-2011 with magnitude greater than 3. Colors indicate depth of hypocenter, or origin of the earthquake: Red is 0-33 km, yellow is 33-100 km, green is 100-400 km, and blue is >400 km depth. Data are from the Advanced National Seismic System." /> </button> <figcaption> <p><b>Figure 1.</b> Map showing earthquakes from 2003-2011 with magnitude greater than 3. Colors indicate depth of hypocenter, or origin of the earthquake: Red is 0-33 km, yellow is 33-100 km, green is 100-400 km, and blue is >400 km depth. Data are from the Advanced National Seismic System.</p> <span class="credit">image ©Dr. Anne E. Egger CC BY-NC-SA 4.0</span> </figcaption> </figure> </div> <p>In fact, <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark> are concentrated along the plate boundaries drawn by <mark class="term" data-term="Harry Hess" data-term-def="American marine geologist born in New York, New York (1906-1969). Hess was key scientist in the establishment of the theory of&hellip;" data-term-url="/en/glossary/view/Hess%2C+Harry/4564">Harry Hess</mark> along <mark class="term" data-term="mid-ocean ridge" data-term-def="A linear, elevated region of the ocean floor where magma is upwelling and extruding, and new crust is forming. The ridges&hellip;" data-term-url="/en/glossary/view/mid~ocean+ridge/868">mid-ocean ridges</mark> and <mark class="term" data-term="subduction" data-term-def="The process by which one tectonic plate moves beneath another." data-term-url="/en/glossary/view/subduction/871">subduction</mark> zones. Not all earthquakes occur at the same depth, however. Where Hess had postulated that the rocks of the ocean floor were diving down into <mark class="term" data-term="subduction zones" data-term-def="A region where one plate is being subducted beneath another, manifesting in a deep, linear trench, frequent earthquakes, and a chain&hellip;" data-term-url="/en/glossary/view/subduction+zones/873">subduction zones</mark>, earthquakes occur at shallow depths of 0 to 33 km below the <mark class="term" data-term="surface" data-term-def="The outside or external part; the topside face of something." data-term-url="/en/glossary/view/surface/8275">surface</mark> near the trenches and at depths of almost 700 km below the surface further inland (illustrated in Figure 1 by different colored circles). On the other hand, only shallow earthquakes (depths of 0 to 33 km, shown in red in Figure 1) are recorded at the spreading ridges. These <mark class="term" data-term="data" data-term-def="(plural form of <b>datum</b>) A collection of pieces of information, generally taking the form of numbers, text, bits, or facts, that&hellip;" data-term-url="/en/glossary/view/data/3729">data</mark> helped geologists draw more detailed cross-sections showing that plates are thin at spreading ridges, and that subduction extends long distances, taking plates deep beneath the continents.</p> <p>Similar to <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark>, volcanoes are located preferentially on or near plate boundaries (see Figure 2).</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_5577.png"> <img src="/img/library/modules/mid66/Image/VLObject-5577-110727010733.png" alt="Figure 2. Map showing volcanoes that have been active in the last 10,000 years. Colored triangles indicate different volcano types: Red triangles are primarily calderas; green triangles are stratovolcanoes; blue triangles are shield volcanoes and fissure vents. Data are from the Smithsonian Institution, Global Volcanism Program." /> </button> <figcaption> <p><b>Figure 2.</b> Map showing volcanoes that have been active in the last 10,000 years. Colored triangles indicate different volcano types: Red triangles are primarily calderas; green triangles are stratovolcanoes; blue triangles are shield volcanoes and fissure vents. Data are from the Smithsonian Institution, Global Volcanism Program.</p> <span class="credit">image ©Dr. Anne E. Egger CC BY-NC-SA 4.0</span> </figcaption> </figure> </div> <p>Also similar to <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark>, different kinds of volcanoes occur along different types of plate boundaries. Most of the volcanic eruptions that make the news, such as the 1980 Mount St. Helens eruption, take place near <mark class="term" data-term="subduction" data-term-def="The process by which one tectonic plate moves beneath another." data-term-url="/en/glossary/view/subduction/871">subduction</mark> zones. This type of volcano is represented by green triangles in Figure 2. These devastating, explosive eruptions reflect the composition of the <mark class="term" data-term="magma" data-term-def="Molten rock below the surface of the Earth." data-term-url="/en/glossary/view/magma/869">magma</mark> - it is extremely <mark class="term" data-term="viscosity" data-term-url="/en/glossary/view/viscosity" data-term-def="The measurement of a fluid's resistance to shear or flow. Highly viscous fluids resist motion due to their molecular composition that&hellip;">viscous</mark>, or thick and resistant to flow, and thus results in tall, steep-sided volcanoes. In contrast, the volcanic eruptions that occur along spreading ridges are much gentler, in part because most of these eruptions occur under 2 to 3 kilometers of water, but also because the magma is far less <mark class="term" data-term="viscous" data-term-def="Used to describe substances that are gluey in character and are in between a solid and fluid." data-term-url="/en/glossary/view/viscous/7370">viscous</mark>. This type of volcano is represented by blue triangles in Figure 2. </p> <p><section id="toc_1" class=""> <h2>Plate boundaries</h2></p> <p>These <mark class="term" data-term="observation" data-term-def="1. The act of noticing something. 2. A record of that which has been noticed." data-term-url="/en/glossary/view/observation/8255">observations</mark> about the distribution of <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark> and volcanoes helped geologists define the processes that occur at spreading ridges and <mark class="term" data-term="subduction" data-term-def="The process by which one tectonic plate moves beneath another." data-term-url="/en/glossary/view/subduction/871">subduction</mark> zones. In addition, they helped scientists recognize that there are other types of plate boundaries. In general, plate boundaries are the scene of much geologic action - earthquakes, volcanoes, and dramatic topography such as mountain ranges like the Himalayas are all concentrated where two or more plates meet along a <mark class="term" data-term="boundary" data-term-def="A line or limit that divides one area from another." data-term-url="/en/glossary/view/boundary/8272">boundary</mark>. </p><p>There are three major ways that plates interact along boundaries: (1) They can move away from each other (diverge), (2) they can move toward each other (converge), or (3) they can move past each other, parallel to the <mark class="term" data-term="boundary" data-term-def="A line or limit that divides one area from another." data-term-url="/en/glossary/view/boundary/8272">boundary</mark> (transform). Each of these interactions produces a different and characteristic pattern of <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark>, volcanic activity, and topography. The results of these interactions also depend on the type of <mark class="term" data-term="crust" data-term-def="The uppermost 5-70 km of the Earth. There are two types of crust: continental and oceanic. Continental crust ranges from 10-70&hellip;" data-term-url="/en/glossary/view/crust/880">crust</mark> involved, and there are two types of crust: oceanic and continental. <mark class="term" data-term="continental crust" data-term-def="The uppermost layer of the Earth that forms the continents. Unlike oceanic crust, continental crust is created and destroyed very slowly,&hellip;" data-term-url="/en/glossary/view/continental+crust/1662">Continental crust</mark> is thick and <mark class="term" data-term="buoyant" data-term-def="The ability of an object to rise and stay afloat in a liquid or gas." data-term-url="/en/glossary/view/buoyant/8281">buoyant</mark>; <mark class="term" data-term="oceanic crust" data-term-def="The uppermost layer of the earth beneath the ocean basins. Oceanic crust is constantly forming at mid-ocean ridges and is constantly&hellip;" data-term-url="/en/glossary/view/oceanic+crust/1670">oceanic crust</mark> is thin, <mark class="term" data-term="dense" data-term-def="Compact, packed close together; having a high mass in relation to volume." data-term-url="/en/glossary/view/dense/8273">dense</mark>, and forms at <mark class="term" data-term="mid-ocean ridge" data-term-def="A linear, elevated region of the ocean floor where magma is upwelling and extruding, and new crust is forming. The ridges&hellip;" data-term-url="/en/glossary/view/mid~ocean+ridge/868">mid-ocean ridges</mark>. </p></section> <section id="toc2_1"><h3>Divergent boundaries</h3><p>The most common <mark class="term" data-term="divergent boundary" data-term-url="/en/glossary/view/divergent+boundary" data-term-def="A plate boundary where two plates are moving away from each other.">divergent boundaries</mark> are the <mark class="term" data-term="mid-ocean ridge" data-term-def="A linear, elevated region of the ocean floor where magma is upwelling and extruding, and new crust is forming. The ridges&hellip;" data-term-url="/en/glossary/view/mid~ocean+ridge/868">mid-ocean ridges</mark> that launched the <mark class="term" data-term="plate tectonics" data-term-def="The study of the processes by which the earth's crust has attained its present structure." data-term-url="/en/glossary/view/plate+tectonics/11229">plate tectonics</mark> revolution, and the Mid-Atlantic Ridge is a classic example (see Figure 3). Shallow <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark> and minor basaltic lava flows characterize divergent boundaries at mid-ocean ridges. The <mark class="term" data-term="seafloor" data-term-def="The bottom surface of the ocean." data-term-url="/en/glossary/view/seafloor/8280">seafloor</mark> at the ridges is higher than the surrounding plain because the rocks are hot and thus less <mark class="term" data-term="dense" data-term-def="Compact, packed close together; having a high mass in relation to volume." data-term-url="/en/glossary/view/dense/8273">dense</mark> and more <mark class="term" data-term="buoyant" data-term-def="The ability of an object to rise and stay afloat in a liquid or gas." data-term-url="/en/glossary/view/buoyant/8281">buoyant</mark>, riding higher in the underlying <mark class="term" data-term="mantle" data-term-def="The middle portion of the interior of the Earth, starting below the crust at 5-70 km below the Earth’s surface and&hellip;" data-term-url="/en/glossary/view/mantle/889">mantle</mark>. As the rocks move away from the spreading center, they cool and become more dense and less buoyant. Spreading has been occurring along the Mid-Atlantic Ridge for 180 million years, resulting in a large ocean basin - the Atlantic Ocean.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_5578.png"> <img src="/img/library/modules/mid66/Image/VLObject-5578-110727010734.png" alt="Figure 3. Cross-section of the Mid-Atlantic Ridge near latitude 14° S. Blue triangle represents the location of fissure volcanoes. Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key)." /> </button> <figcaption> <p><b>Figure 3.</b> Cross-section of the Mid-Atlantic Ridge near latitude 14° S. Blue triangle represents the location of fissure volcanoes. Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key).</p> <span class="credit">image ©Dr. Anne E. Egger CC BY-NC-SA 4.0</span> </figcaption> </figure> </div> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc6134"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">Divergent boundaries are most common</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6134-0-option-a" name="quiz-option-6134" type="radio" value="in the middle of oceans." > <span class="option__label"> <span class="screen-reader-only">a.</span> in the middle of oceans. </span> </label> <span class="quiz__response" id="response-6134-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6134-1-option-b" name="quiz-option-6134" type="radio" value="in the middle of continents." > <span class="option__label"> <span class="screen-reader-only">b.</span> in the middle of continents. </span> </label> <span class="quiz__response" id="response-6134-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc2_2"><h3>Convergent boundaries </h3><p>Convergent boundaries are the most geologically active, with different features depending on the type of <mark class="term" data-term="crust" data-term-def="The uppermost 5-70 km of the Earth. There are two types of crust: continental and oceanic. Continental crust ranges from 10-70&hellip;" data-term-url="/en/glossary/view/crust/880">crust</mark> involved. The activity that takes place at convergent boundaries depends on the type of crust involved, as explained next.</p><h4>Oceanic meets continental </h4><p>These are the <mark class="term" data-term="subduction" data-term-def="The process by which one tectonic plate moves beneath another." data-term-url="/en/glossary/view/subduction/871">subduction</mark> zones first imagined by Hess, where <mark class="term" data-term="dense" data-term-def="Compact, packed close together; having a high mass in relation to volume." data-term-url="/en/glossary/view/dense/8273">dense</mark> oceanic <mark class="term" data-term="crust" data-term-def="The uppermost 5-70 km of the Earth. There are two types of crust: continental and oceanic. Continental crust ranges from 10-70&hellip;" data-term-url="/en/glossary/view/crust/880">crust</mark> is diving beneath more <mark class="term" data-term="buoyant" data-term-def="The ability of an object to rise and stay afloat in a liquid or gas." data-term-url="/en/glossary/view/buoyant/8281">buoyant</mark> <mark class="term" data-term="continental crust" data-term-def="The uppermost layer of the Earth that forms the continents. Unlike oceanic crust, continental crust is created and destroyed very slowly,&hellip;" data-term-url="/en/glossary/view/continental+crust/1662">continental crust</mark>. These boundaries are characterized by: (a) a very deep ocean <mark class="term" data-term="trench" data-term-def="In plate tectonics, trenches are tremendously deep features on the ocean floor – deep valleys that reach as far as 11&hellip;" data-term-url="/en/glossary/view/trench/896">trench</mark> next to a high continental mountain range, (b) large numbers of <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark> that progress from shallow to deep, and (c) large numbers of intermediate composition volcanoes (see Figure 4). The Andes owe their existence to a subduction zone on the western edge of the South American plate; in fact, this type of <mark class="term" data-term="boundary" data-term-def="A line or limit that divides one area from another." data-term-url="/en/glossary/view/boundary/8272">boundary</mark> is often called an Andean boundary since it is the primary example.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_5579.png"> <img src="/img/library/modules/mid66/Image/VLObject-5579-110727010736.png" alt="Figure 4. Cross-section of the South American subduction zone near latitude 22° S. Green triangles represent the locations of stratovolcanoes. Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key)." /> </button> <figcaption> <p><b>Figure 4.</b> Cross-section of the South American subduction zone near latitude 22° S. Green triangles represent the locations of stratovolcanoes. Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key).</p> <span class="credit">image ©Dr. Anne E. Egger CC BY-NC-SA 4.0</span> </figcaption> </figure> </div> <h4>Oceanic meets more oceanic </h4><p>Where two plates converge along a <mark class="term" data-term="boundary" data-term-def="A line or limit that divides one area from another." data-term-url="/en/glossary/view/boundary/8272">boundary</mark> where the <mark class="term" data-term="crust" data-term-def="The uppermost 5-70 km of the Earth. There are two types of crust: continental and oceanic. Continental crust ranges from 10-70&hellip;" data-term-url="/en/glossary/view/crust/880">crust</mark> on both sides is oceanic, a <mark class="term" data-term="subduction" data-term-def="The process by which one tectonic plate moves beneath another." data-term-url="/en/glossary/view/subduction/871">subduction</mark> zone also occurs, but the result is slightly different than an <mark class="term" data-term="Andean margin" data-term-def="A convergent plate boundary, where oceanic crust is being subducted beneath continental crust. Named after the Andes Mountains in South America,&hellip;" data-term-url="/en/glossary/view/Andean+margin/874">Andean margin</mark>. Since the densities of the two plates are similar, it is usually the plate with the older <mark class="term" data-term="oceanic crust" data-term-def="The uppermost layer of the earth beneath the ocean basins. Oceanic crust is constantly forming at mid-ocean ridges and is constantly&hellip;" data-term-url="/en/glossary/view/oceanic+crust/1670">oceanic crust</mark> that is subducted because that crust is colder and denser. <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">Earthquakes</mark> progress from shallow to deep, moving away from the <mark class="term" data-term="trench" data-term-def="In plate tectonics, trenches are tremendously deep features on the ocean floor – deep valleys that reach as far as 11&hellip;" data-term-url="/en/glossary/view/trench/896">trench</mark> like in the oceanic-continental convergence, and volcanoes form an island arc, like the mountain range along the Tonga trench in the western Pacific (see Figure 5). </p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_5580.png"> <img src="/img/library/modules/mid66/Image/VLObject-5580-110727010738.png" alt="Figure 5. Cross-section of the Tonga trench near latitude 21° S. Colored triangles represent the location of volcanoes, color-coded by type of volcano (see Figure 2 for key). Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key)." /> </button> <figcaption> <p><b>Figure 5.</b> Cross-section of the Tonga trench near latitude 21° S. Colored triangles represent the location of volcanoes, color-coded by type of volcano (see Figure 2 for key). Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key).</p> <span class="credit">image ©Dr. Anne E. Egger CC BY-NC-SA 4.0</span> </figcaption> </figure> </div> <h4>Continental meets more continental </h4><p>When two pieces of <mark class="term" data-term="continental crust" data-term-def="The uppermost layer of the Earth that forms the continents. Unlike oceanic crust, continental crust is created and destroyed very slowly,&hellip;" data-term-url="/en/glossary/view/continental+crust/1662">continental crust</mark> converge, the result is a great pileup of continental material. Both pieces of <mark class="term" data-term="crust" data-term-def="The uppermost 5-70 km of the Earth. There are two types of crust: continental and oceanic. Continental crust ranges from 10-70&hellip;" data-term-url="/en/glossary/view/crust/880">crust</mark> are <mark class="term" data-term="buoyant" data-term-def="The ability of an object to rise and stay afloat in a liquid or gas." data-term-url="/en/glossary/view/buoyant/8281">buoyant</mark> and are not easily subducted. Continental convergence is exemplified by the Himalayan mountain range, where the Indian plate runs into the Asian plate (see Figure 6). Numerous shallow <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark> occur, but there is very little volcanism.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_5581.png"> <img src="/img/library/modules/mid66/Image/VLObject-5581-110727010739.png" alt="Figure 6. Cross-section of the Himalayas along 88° E longitude. Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key)." /> </button> <figcaption> <p><b>Figure 6.</b> Cross-section of the Himalayas along 88° E longitude. Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key).</p> <span class="credit">image ©Dr. Anne E. Egger CC BY-NC-SA 4.0</span> </figcaption> </figure> </div> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc6135"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">Along convergent plate boundaries there are always big volcanoes.</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6135-0-option-a" name="quiz-option-6135" type="radio" value="true" > <span class="option__label"> <span class="screen-reader-only">a.</span> true </span> </label> <span class="quiz__response" id="response-6135-0"> <strong>Incorrect.</strong> </span> </div> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6135-1-option-b" name="quiz-option-6135" type="radio" value="false" > <span class="option__label"> <span class="screen-reader-only">b.</span> false </span> </label> <span class="quiz__response" id="response-6135-1"> <strong>Correct!</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc2_3"><h3>Transform boundaries</h3><p>Most boundaries are either convergent or divergent, but transform boundaries occur in a few places to accommodate lateral motion, where plates move horizontally past one another. This type of <mark class="term" data-term="boundary" data-term-def="A line or limit that divides one area from another." data-term-url="/en/glossary/view/boundary/8272">boundary</mark> is very rare on continents, but they are dramatic where they do occur. For example, the San Andreas Fault in California is a continental <mark class="term" data-term="transform boundary" data-term-def="A plate boundary where two plates are sliding past each other." data-term-url="/en/glossary/view/transform+boundary/895">transform boundary</mark>. Along this boundary, frequent, shallow <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark> occur (like the famous 1906 and 1989 San Francisco earthquakes), but there is little associated volcanic activity or topographic relief (see Figure 7). The Alpine Fault in New Zealand is very similar. Most transform boundaries occur not on land, however, but in short segments along <mark class="term" data-term="mid-ocean ridge" data-term-def="A linear, elevated region of the ocean floor where magma is upwelling and extruding, and new crust is forming. The ridges&hellip;" data-term-url="/en/glossary/view/mid~ocean+ridge/868">mid-ocean ridges</mark>.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_5583.png"> <img src="/img/library/modules/mid66/Image/VLObject-5583-110727010741.png" alt="Figure 7. Cross-section of the San Andreas Fault in California near latitude 36° N. Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key)." /> </button> <figcaption> <p><b>Figure 7.</b> Cross-section of the San Andreas Fault in California near latitude 36° N. Colored circles represent earthquakes, color-coded by depth (see Figure 1 for key).</p> <span class="credit">image ©Dr. Anne E. Egger CC BY-NC-SA 4.0</span> </figcaption> </figure> </div> <p>A few boundaries defy simple <mark class="term" data-term="classification" data-term-def="In biology, the arranging of groups of organisms into sets or divisions on the basis of their evolutionary relationships." data-term-url="/en/glossary/view/classification/879">classification</mark> and are referred to as "plate <mark class="term" data-term="boundary" data-term-def="A line or limit that divides one area from another." data-term-url="/en/glossary/view/boundary/8272">boundary</mark> zones." For example, a complicated <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquake</mark> pattern is produced by a wide, poorly understood <mark class="term" data-term="plate boundary" data-term-def="A place where two or more tectonic plates meet and interact. Plate boundaries can be convergent, divergent, or transform boundaries, depending&hellip;" data-term-url="/en/glossary/view/plate+boundary/890">plate boundary</mark> zone between the Eurasian and African plates in the Mediterranean region.</p></section> <section id="toc_2"> <h2>Geologic activity away from plate boundaries</h2><p> The plate boundaries described above account for the vast majority of seismic and volcanic activity on Earth. The more <mark class="term" data-term="data" data-term-def="(plural form of <b>datum</b>) A collection of pieces of information, generally taking the form of numbers, text, bits, or facts, that&hellip;" data-term-url="/en/glossary/view/data/3729">data</mark> that began to fit into the <mark class="term" data-term="plate tectonics" data-term-def="The study of the processes by which the earth's crust has attained its present structure." data-term-url="/en/glossary/view/plate+tectonics/11229">plate tectonics</mark> scheme, however, the more the exceptions stood out. What could account for Hawaii, for example, a scene of long-lived volcanic activity in the middle of the Pacific plate where there is no <mark class="term" data-term="subduction" data-term-def="The process by which one tectonic plate moves beneath another." data-term-url="/en/glossary/view/subduction/871">subduction</mark> or spreading to generate magma?</p><p> There had to be something else. In 1963, <mark class="term" data-term="J. Tuzo Wilson" data-term-def="Canadian geophysicst, born in Ottawa, Ontario (1908-1993). Wilson is best known for proposing the hotspot hypothesis to explain island chains such&hellip;" data-term-url="/en/glossary/view/Wilson%2C+J.+Tuzo/4488">J. Tuzo Wilson</mark>, a Canadian geophysicist, theorized that the <mark class="term" data-term="mantle" data-term-def="The middle portion of the interior of the Earth, starting below the crust at 5-70 km below the Earth’s surface and&hellip;" data-term-url="/en/glossary/view/mantle/889">mantle</mark> contained immobile <em>hotspots</em>, thin plumes of hot <mark class="term" data-term="magma" data-term-def="Molten rock below the surface of the Earth." data-term-url="/en/glossary/view/magma/869">magma</mark> that acted like Bunsen burners as plates moved over them (Wilson, 1963). The Hawaiian Islands form a long, linear chain, with ongoing volcanic eruptions on the island of Hawaii and <mark class="term" data-term="extinction" data-term-url="/en/glossary/view/extinction" data-term-def="The complete and permanent loss of all individuals of a species of organism.">extinct</mark>, highly eroded volcanic islands to the northwest. According to Wilson's hotspot <mark class="term" data-term="theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;" data-term-url="/en/glossary/view/theory/4854">theory</mark>, the chain of islands represents the northwestward motion of the Pacific plate over a mantle plume.</p><p>One important implication of Wilson's <mark class="term" data-term="theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;" data-term-url="/en/glossary/view/theory/4854">theory</mark> was that because hotspots were stationary, hotspot tracks could be used to trace plate motion history. For example, the track of the Hawaiian chain continues to the northwest as an underwater chain of progressively older, no longer active volcanoes. Once the volcanic eruptions stop, ocean <mark class="term" data-term="waves" data-term-def="The motion of rising and falling in curves; undulation." data-term-url="/en/glossary/view/waves/8274">waves</mark> begin to take their toll, eroding the islands down to just below sea level, at which point they are called <mark class="term" data-term="seamount" data-term-def="An extinct volcano which has been eroded by ocean waves, resulting in a flat-topped feature just beneath the surface of the ocean. " data-term-url="/en/glossary/view/seamount/892">seamounts</mark>. The islands and seamounts associated with the Hawaiian hotspot provide a history of motion for the Pacific plate, which appears to have taken an eastward turn around 42 million years ago (see Figure 10). Other hotspot tracks around the world can be used in a similar manner to reconstruct a global plate tectonic history.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_9232.jpg"> <img src="/img/library/modules/mid66/Image/VLObject-9232-160118080159.jpg" alt="Figure 10: Ages of the seamounts and volcanoes in the Hawaii-Emperor chain, suggesting that the Pacific plate changed its direction of motion about 42 million years ago." /> </button> <figcaption> <p><strong>Figure 10:</strong> Ages of the seamounts and volcanoes in the Hawaii-Emperor chain, suggesting that the Pacific plate changed its direction of motion about 42 million years ago.</p> </figcaption> </figure> </div> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc6137"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">According to Wilson, hotspots can be used to track the history of plate motion because the hotspots are</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6137-0-option-a" name="quiz-option-6137" type="radio" value="relatively stationary." > <span class="option__label"> <span class="screen-reader-only">a.</span> relatively stationary. </span> </label> <span class="quiz__response" id="response-6137-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6137-1-option-b" name="quiz-option-6137" type="radio" value="constantly in motion." > <span class="option__label"> <span class="screen-reader-only">b.</span> constantly in motion. </span> </label> <span class="quiz__response" id="response-6137-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc2_4"><h3>What are the driving forces?</h3><a name="convection"></a><p>Hotspots added further proof to confirm that plates move constantly and steadily. Ironically, however, the question that incited ridicule for Wegener continues to launch heated <mark class="term" data-term="debate" data-term-def="A reasoned discussion of opposing points in an argument." data-term-url="/en/glossary/view/debate/8242">debate</mark> today: What ultimately drives plate motion? Plates are constantly shifting and rearranging themselves in response to each other. Eventually, a new <mark class="term" data-term="Pangaea" data-term-def="The supercontinent which existed from about 300-200 million years ago. During this time, all of the continents were gathered into a&hellip;" data-term-url="/en/glossary/view/Pangaea/867">Pangaea</mark> (or single supercontinent) will form, break apart, and form again on Earth. What keeps these plates moving? </p><p>Hess assumed that <mark class="term" data-term="mantle" data-term-def="The middle portion of the interior of the Earth, starting below the crust at 5-70 km below the Earth’s surface and&hellip;" data-term-url="/en/glossary/view/mantle/889">mantle</mark> <mark class="term" data-term="convection" data-term-def="The movement or circulation of a fluid due to variations in its density as a result of the transfer of heat&hellip;" data-term-url="/en/glossary/view/convection/877">convection</mark> was the main driving force - hot, less <mark class="term" data-term="dense" data-term-def="Compact, packed close together; having a high mass in relation to volume." data-term-url="/en/glossary/view/dense/8273">dense</mark> material rises along <mark class="term" data-term="mid-ocean ridge" data-term-def="A linear, elevated region of the ocean floor where magma is upwelling and extruding, and new crust is forming. The ridges&hellip;" data-term-url="/en/glossary/view/mid~ocean+ridge/868">mid-ocean ridges</mark>, cools, and subsides at <mark class="term" data-term="subduction" data-term-def="The process by which one tectonic plate moves beneath another." data-term-url="/en/glossary/view/subduction/871">subduction</mark> zones, and the plates "ride" these convection <mark class="term" data-term="cell" data-term-def="The basic structural unit of all living things." data-term-url="/en/glossary/view/cell/8286">cells</mark> (see our <a href="/en/library/General-Science/3/Density/37">Density</a> module for more information). Though there is little doubt that convection does occur in the mantle, current modeling suggests that it is not so simple. Many geologists argue that the force of convection is not enough to push enormous lithospheric plates like the North American plate. They suggest instead that <mark class="term" data-term="gravity" data-term-def="The natural force that attracts a body toward the center of the Earth, or toward another physical body having mass." data-term-url="/en/glossary/view/gravity/11223">gravity</mark> is the main driving force: Cold, dense oceanic <mark class="term" data-term="crust" data-term-def="The uppermost 5-70 km of the Earth. There are two types of crust: continental and oceanic. Continental crust ranges from 10-70&hellip;" data-term-url="/en/glossary/view/crust/880">crust</mark> sinks at <mark class="term" data-term="subduction zones" data-term-def="A region where one plate is being subducted beneath another, manifesting in a deep, linear trench, frequent earthquakes, and a chain&hellip;" data-term-url="/en/glossary/view/subduction+zones/873">subduction zones</mark>, pulling the rest of the plate with it. According to this <mark class="term" data-term="theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;" data-term-url="/en/glossary/view/theory/4854">theory</mark>, magmatic intrusions at spreading ridges are passive - the <mark class="term" data-term="magma" data-term-def="Molten rock below the surface of the Earth." data-term-url="/en/glossary/view/magma/869">magma</mark> merely fills a hole created by pulling two plates apart.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox=""> <img src="/img/library/modules/mid66/Image/VLObject-846-021205021202.gif" alt="Figure 11. "Ridge push" and "slab pull" are both ways that gravity can act to keep a plate in motion. Note that arrows on convection cells and overlying plate are going in the same direction. Figure modified from This Dynamic Earth, a publication from the US Geological Survey." /> </button> <figcaption> <p><strong>Figure 11.</strong> "Ridge push" and "slab pull" are both ways that gravity can act to keep a plate in motion. Note that arrows on convection cells and overlying plate are going in the same direction.<br> <font size="1">Figure modified from <a href="http://pubs.usgs.gov/publications/text/dynamic.html"><i>This Dynamic Earth</i></a>, a publication from the US Geological Survey.</font></p> </figcaption> </figure> </div> <p>Undoubtedly, <mark class="term" data-term="gravity" data-term-def="The natural force that attracts a body toward the center of the Earth, or toward another physical body having mass." data-term-url="/en/glossary/view/gravity/11223">gravity</mark> and <mark class="term" data-term="convection" data-term-def="The movement or circulation of a fluid due to variations in its density as a result of the transfer of heat&hellip;" data-term-url="/en/glossary/view/convection/877">convection</mark> both supply <mark class="term" data-term="energy" data-term-def="An abstract property defined as the capacity to do work. The basic forms of energy include chemical, electrical, mechanical, nuclear, and&hellip;" data-term-url="/en/glossary/view/energy/1497">energy</mark> to keep plates moving. Their relative contributions, however, are a matter of <mark class="term" data-term="debate" data-term-def="A reasoned discussion of opposing points in an argument." data-term-url="/en/glossary/view/debate/8242">debate</mark> and ongoing <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark>. </p><p>The strength of plate tectonic <mark class="term" data-term="theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;" data-term-url="/en/glossary/view/theory/4854">theory</mark> lies in its ability to explain everything about the processes we see both in the geologic <mark class="term" data-term="record" data-term-def="A written account or description. <br> <b>[verb]</b> To write an account or description." data-term-url="/en/glossary/view/record/8239">record</mark> and in the present. Our understanding of the subtleties continues to evolve as we learn more about our planet, but <mark class="term" data-term="plate tectonics" data-term-def="The study of the processes by which the earth's crust has attained its present structure." data-term-url="/en/glossary/view/plate+tectonics/11229">plate tectonics</mark> is truly the foundation upon which the science of geology is built.</p> </div> </section> <hr class="border-color-dark" /> <footer class="module__footer"> <p class="citation"> <em> Anne E. Egger, Ph.D. “Plate Boundaries” Visionlearning Vol. EAS (2), 2003. </em> </p>  <div class="title-list" name="further"> <p class="h6 title-list__title"> Further Reading </p> <ul class="grid grid--column-2--md grid--column-3--md gap-1"> <li> <a class="no-hover-focus height-100" href="/en/library/Earth-Science/6/The-Origins-of-Plate-Tectonic-Theory/65"> <article class="flex-row align-items-center flex-column--md align-items-start--md height-100 theme-light padding-2 gap-2"> <div class="width-30 width-auto--md"> <img class="border-radius box-shadow-1" src="/img/library/moduleImages/featured_image_65-23061209065447.jpg" alt="Origins of Plate Tectonic Theory"> </div> <div class="flex-grow-shrink"> <h2 class="h6 font-weight-normal"> Origins of Plate Tectonic Theory: <em>From early ideas to mapping the ocean floor</em> </h2> </div> </article> </a> </li> </ul> </div> </footer> </div>   </div>  <div class="order-1 order-2--lg module__tools"> <div class="narrow margin-x-auto position-sticky-top font-size-md"> <div class="padding-2 border-radius box-shadow-1--lg"> <div class="tabs" role="tablist"> <nav> <button class="button button--icon-label" id="tab-button-in-this-module" aria-label="Table of Contents" aria-controls="tab-panel-module__tools" aria-selected="true" role="tab"> <span class="icon icon-list" aria-hidden="true"></span> <span class="button__text">Contents</span> </button> <button class="button button--icon-label" id="tab-button-toggle-terms" aria-controls="tab-panel-toggle-terms" aria-selected="false" role="tab"> <span class="icon icon-glossary-highlight"></span> <span class="button__text">Glossary Terms</span> </button> </nav> <hr class="divider" /> <div class="tabs__panel shown" id="tab-panel-module__tools" aria-labelledby="tab-button-module__tools" role="tabpanel"> <p class="font-weight-bold margin-bottom-1"> Table of Contents </p> <div class="table-of-contents" id="module-toc"> <ul> <li><a href="/en/library/earth-science/6/plate-boundaries/66#toc_1">Plate boundaries</a> </li> <li> <ul> <li><a href="/en/library/earth-science/6/plate-boundaries/66#toc2_1">Divergent boundaries</a> </li> </ul> </li> <li> <ul> <li><a href="/en/library/earth-science/6/plate-boundaries/66#toc2_2">Convergent boundaries </a> </li> </ul> </li> <li> <ul> <li><a href="/en/library/earth-science/6/plate-boundaries/66#toc2_3">Transform boundaries</a> </li> </ul> </li> <li><a href="/en/library/earth-science/6/plate-boundaries/66#toc_2">Geologic activity away from plate boundaries</a> </li> <li> <ul> <li><a href="/en/library/earth-science/6/plate-boundaries/66#toc2_4">What are the driving forces?</a> </li> </ul> </li> </ul> </div> </div>   <div class="tabs__panel" id="tab-panel-toggle-terms" aria-labelledby="tab-button-toggle-terms" role="tabpanel"> <div class="reading-toggle"> <div class="reading-toggle__switch"> <div class="form-entry__option__switch"> <label> <input type="checkbox" name="termsToggleSwitch" id="terms-toggle-switch" /> <span class="switch__slider"></span> <span class="option__label text-decoration-none font-size-md"> Highlight Glossary Terms </span> </label> </div> </div> <div class="reading-toggle__help"> <p> <em> Activate glossary term highlighting to easily identify key terms within the module. 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Plate Boundaries | Earth Science | Visionlearning