Plate tectonics
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The Earth's crust is divided into tectonic plates that are in constant motion due to convection currents in the upper mantle. There are three types of plate boundaries: divergent where plates move apart and new crust is formed, convergent where plates collide and can cause mountain building, and transform where plates slide past each other. Alfred Wegener first proposed the theory of continental drift in 1912, and the modern theory of plate tectonics explains how plate motions and interactions have shaped Earth's surface over geological time through subduction, volcanism, earthquakes and mountain formation.
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This document discusses Earth's interior structure based on seismic wave evidence. It begins by introducing seismic waves like P and S waves. Observing how they travel through Earth reveals its layered structure. The crust and mantle can be detected by changes in wave speeds at boundaries like the Mohorovicic discontinuity. Liquid layers are identified by S waves stopping at the outer core. A solid inner core is known from P wave reflections. Together, precisely tracking seismic wave paths and speeds informs our understanding of Earth's composition and properties within each internal layer.
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The document discusses the structure and layers of the Earth. It is composed of four main layers from outermost to innermost:
1) The crust, which is the thin solid outer layer people live on made of rocks and minerals. It is divided into thicker continental crust and thinner oceanic crust.
2) The hot, dense mantle that behaves like a solid but can flow very slowly over geologic timescales. Its convection currents influence plate tectonics at the surface.
3) The liquid outer core that is composed of melted nickel and iron due to extreme heat and pressure.
4) The inner solid core formed from compressed metals vibrating in place like a solid.
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2) All new rock starts as igneous rock, formed from cooled lava or magma.
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Volcanoes and volcanic Activity
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- Volcanoes form when magma reaches the Earth's surface, causing eruptions of lava and ash. They occur at destructive and constructive plate boundaries.
- The Mid Atlantic Ridge under the Atlantic Ocean was formed when plates separated and lava came to the surface, cooled and hardened.
- Most earthquakes and volcanoes occur along the Pacific Ring of Fire.
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The document summarizes the internal structure of the Earth based on seismic wave studies. It describes the three main layers as the crust, mantle, and core. The crust is the outermost solid rocky layer, varying in thickness between continents and oceans. Below is the mantle, making up most of the Earth's volume, with the upper asthenosphere partially molten. The innermost layer is the core, divided into a solid inner core and liquid outer core composed primarily of iron and nickel. Seismic waves have revealed details of each layer and helped determine the Earth has a liquid outer core, differing from the Moon's internal structure.
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1) The crust, which is the thin solid outer layer people live on made of rocks and minerals. It is divided into thicker continental crust and thinner oceanic crust.
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1) There are three major types of rock: igneous, sedimentary, and metamorphic.
2) All new rock starts as igneous rock, formed from cooled lava or magma.
3) Igneous rock can be intrusive or extrusive depending on whether the magma cools below or above the surface.
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Distribution of Volcanoes
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A volcano is generally a conical shaped hill or mountain built by accumulations of lava flows, tephra, and volcanic ash. About 95% of active volcanoes occur at the plate subduction zones and at the mid-oceanic ridges. The other 5% occur in areas associated with lithospheric hot spots. These hot spots have no direct relationships with areas of crustal creation or subduction zones. It is believed that hot spots are caused by plumes of rising magma that have their origin within the asthenosphere.
Over the last 2 million years, volcanoes have been depositing lava, tephra, and ash in particular areas of the globe. These areas occur at hot spots, rift zones, and along plate boundaries where tectonic subduction is taking place within the asthenosphere.
The most prevalent kinds of volcanoes on the Earth's surface are the kind which form the "Pacific Rim of Fire". Those are volcanoes which form as a result of subduction of the nearby lithosphere.
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- Volcanoes form when magma reaches the Earth's surface, causing eruptions of lava and ash. They occur at destructive and constructive plate boundaries.
- The Mid Atlantic Ridge under the Atlantic Ocean was formed when plates separated and lava came to the surface, cooled and hardened.
- Most earthquakes and volcanoes occur along the Pacific Ring of Fire.
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The document summarizes the internal structure of the Earth based on seismic wave studies. It describes the three main layers as the crust, mantle, and core. The crust is the outermost solid rocky layer, varying in thickness between continents and oceans. Below is the mantle, making up most of the Earth's volume, with the upper asthenosphere partially molten. The innermost layer is the core, divided into a solid inner core and liquid outer core composed primarily of iron and nickel. Seismic waves have revealed details of each layer and helped determine the Earth has a liquid outer core, differing from the Moon's internal structure.
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- Magma evolves as it differentiates through fractional crystallization, assimilation, and mixing. Early crystallizing minerals remove elements from the magma, changing its composition over time according to Bowen's reaction series.
- Magma rises towards the Earth's surface where it cools and crystallizes to form either plutonic or volcanic rocks, depending on the cooling rate. Slow cooling results in large mineral crystals in plutonic rocks, while rapid cooling of lava forms volcanic rocks like obsidian with little
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The document discusses the structure of the Earth by comparing it to an apple. It explains that both have a thin outer crust/skin, a thick inner core, and layers in between. The Earth has an inner solid core and outer liquid core of iron and nickel. Between the core and crust is the mantle, made of solid but hot rock. The crust floats on the mantle and is divided into thinner oceanic crust and thicker continental crust made of different materials.
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Plate tectonics
1. Plate tectonics refers to the theory that the Earth's crust is divided into tectonic plates that slowly move and interact with one another.
2. The main types of plate boundaries are divergent boundaries where plates move apart, convergent boundaries where plates collide, and transform boundaries where plates slide past one another.
3. Key features associated with these boundaries include mountain building at convergent zones, volcanism and rifting at divergent zones, and strike-slip faulting along transform boundaries.
Formation of igneous rocks
The document discusses different methods of classifying igneous rocks, including based on their chemical composition (e.g. silica content into acid/felsic, intermediate, basic/mafic, and ultramafic types), mineralogy (presence of saturated vs. unsaturated minerals), texture (phaneritic or aphanitic), and mode of occurrence (intrusive vs. extrusive). It also describes classification based on the proportions of light-colored minerals like quartz and feldspar versus dark-colored minerals like pyroxene and olivine.
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1. The Earth is composed of layers including a solid crust, mantle of hot rock, and an inner and outer core made of iron and nickel.
2. Earthquakes send seismic waves that are detected by seismometers around the world, allowing scientists to learn about the Earth's internal structure.
3. There are two types of seismic waves - P waves and S waves. S waves cannot pass through liquids, which provides evidence that the outer core is liquid based on waves not being detected on the opposite side of the Earth from some earthquakes.
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This document provides tips for getting more engagement from content published on SlideShare. It recommends beginning with a clear content marketing strategy that identifies target audiences. Content should be optimized for SlideShare by using compelling visuals, headlines, and calls to action. Analytics and search engine optimization techniques can help increase views and shares. SlideShare features like lead generation and access settings help maximize results.2015 Upload Campaigns Calendar - SlideShare
Each month, join us as we highlight and discuss hot topics ranging from the future of higher education to wearable technology, best productivity hacks and secrets to hiring top talent. Upload your SlideShares, and share your expertise with the world!
What to Upload to SlideShare
Not sure what to share on SlideShare?
SlideShares that inform, inspire and educate attract the most views. Beyond that, ideas for what you can upload are limitless. We’ve selected a few popular examples to get your creative juices flowing.
How to Make Awesome SlideShares: Tips & Tricks
Turbocharge your online presence with SlideShare. We provide the best tips and tricks for succeeding on SlideShare. Get ideas for what to upload, tips for designing your deck and more.
Getting Started With SlideShare
SlideShare is a global platform for sharing presentations, infographics, videos and documents. It has over 18 million pieces of professional content uploaded by experts like Eric Schmidt and Guy Kawasaki. The document provides tips for setting up an account on SlideShare, uploading content, optimizing it for searchability, and sharing it on social media to build an audience and reputation as a subject matter expert.
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How To Get More From SlideShare - Super-Simple Tips For Content Marketing
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Plate tectonics
- 1. Chapter 6Chapter 6 Earth’s Crust &Earth’s Crust & Plate TectonicsPlate Tectonics
- 2. The Earth’s Crust and Plate Tectonics The Earth’s Crust This is where we live! The Earth’s crust is made of: Continental Crust - thick (10-70km) - buoyant (less dense than oceanic crust) - mostly old Oceanic Crust - thin (~7 km) - dense (sinks under continental crust) - young
- 3. If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle…
- 4. World Plates
- 5. Plate Tectonics • The Earth’s crust is divided into many major plates which are moved in various directions. • This plate motion causes them to collide, pull apart, or scrape against each other. • Each type of interaction causes a characteristic set of Earth structures or “tectonic” features. • The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction.
- 6. What are tectonic plates made of? Plates are made of rigid lithosphere. The lithosphere is made up of the crust and the upper part of the mantle.
- 7. Pangaea Alfred Wegener proposed the Continental Drift Hypothesis in 1912, that stated Earth’s continents were once joined in a single landmass and gradually moved or drifted apart.
- 8. Theory of Plate Tectonics Fossils, Climate, & Geology • http://library.thinkquest.org/17701/high/pangaea/ • http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.plateintro/plate-tectonic
- 9. Evidence from the Sea Floor http://library.thinkquest.org/17457/platetectonics/4.php
- 10. Three types of plate boundary Divergent Convergent Transform
- 11. Divergent Boundaries Also called spreading ridges As plates move apart new material is erupted to fill the gap
- 12. Iceland has a divergent plate boundary running through its middle Divergent Boundaries
- 13. Where plates slide past each other Transform Boundaries
- 14. Convergent Boundaries • 2 plates that are pushing together • There are three types of convergent plate boundaries – Continent-continent collision – Continent-oceanic crust collision – Ocean-ocean collision
- 15. Continent-Continent Collision Forms mountains, e.g. European Alps, Himalayas
- 16. Himalayas
- 17. Oceanic-Continental Subduction • Oceanic lithosphere subducts underneath the continental lithosphere • Oceanic lithosphere heats and dehydrates as it subsides • The melt rises forming volcanism • Deep ocean trenches & Coastal mountains
- 18. Oceanic-Oceanic Plate Subduction • When two oceanic plates collide, one runs over the other which causes it to sink into the mantle forming a subduction zone. • Island arcs form • The subducting plate is bent downward to form a very deep depression in the ocean floor called a deep ocean trench. • The worlds deepest parts of the ocean are found along trenches. – E.g. The Mariana Trench is 11 km deep!
- 19. Convection Currents “Plates” of lithosphere are moved around by the underlying hot mantle convection cells
- 20. Magnetic Reversal• After molten lava emerges from a volcano, it solidifies to a rock. In most cases it is a black rock known as basalt, which is faintly magnetic (iron) • Its magnetization is permanently fixed like tiny compass needles pointing north & south. • Instruments can measure the magnetization of basalt. • Surprisingly, this procedure suggested that times existed when the magnetization had the opposite direction from today's. All sorts of explanation were proposed, but in the end the only one which passed all tests was that in the distant past, indeed, the magnetic polarity of the Earth was sometimes reversed.