DOCSLIB.ORG

Grade 6 – Grade 12

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Grade 6 – Grade 12 Educator Guide Grade 6 – Grade 12 What’s Inside: A. Exhibit Overview B. Exhibit Map c. Key Concepts d. Vocabulary E. museum connections f. Resources A. exhibit overview Earthquakes provide dramatic evidence that we live on a dynamic planet. Welcome to Earthquake, where the focus is on how earth processes, including earthquakes, shape Earth’s surface, affect the evolution and distribution of life on our planet, and directly impact people’s lives. Use this guide to: The exhibit areas interpret how seismic activity has driven » Plan your field trip to evolutionary change and biodiversity and shaped human culture, the California Academy acting on timescales from seconds to billions of years. of Sciences’ Earthquake exhibit. At Earthquake, students can discover what earthquakes are, what » Learn about exhibit causes earthquakes, and how earthquakes fit into the larger story themes, key concepts and behind–the–scenes of plate tectonics—a constant process that builds mountains, information to enhance moves continents and creates the landscape in which life evolves and guide your students’ or goes extinct. After exploring the science behind earthquakes, experience. students can learn how to prepare for and respond to them. The » Link to exhibit–related activities you can earthquake simulator provides students with the opportunity to download. experience a high–magnitude jolt. The exhibit concludes with a » Connect your field trip review of the impacts of the 1906 earthquake and fire—the largest to the classroom. disaster in San Francisco’s history. The following main themes are woven throughout Earthquake: » The earth is a dynamic planet that is always changing. » The richness and diversity of life on Earth is affected by the movement of Earth’s crust. » Studying the movement of Earth’s crust tells us where most earthquakes will occur, but cannot tell us when they will happen. » Earthquakes affect people and we can prepare to survive the next major one. 02 Earthquake Educator Guide California Academy of Sciences a Observation Living Roof deck Planetarium exit b Upper Gallery Classroom c Naturalist B.Level exhibit 3 map Center California Academy of Sciences Map d Forum Level 2 Sta Entrance g j Swamp Earthquake Early Explorers Cove Aquarium Project View into Store stairs Lab Collections h Planetarium East pass pick-up l Earthquake Garden e Islands of Evolution k Rainforests Piazza of the World West f Science (Exits in Garden in Action Aquarium) Reef Lagoon m Garden n Moss Room Cafe Restaurant Penguins i African Hall Information m Academy Cafe Store Entrance Level 1 Level 1 Swamp N Store Level 1 stairs o Philippine Coral Reef p Water r Northern t Amazon Planet California Flooded Lower Level Coast Forest (Aquarium) s Discovery q Animal Tidepool Lower Level Attraction (Aquarium) California Academy of Sciences Earthquake Educator Guide 03 B. exhibit map Earthquake Map SHAKE EXPERIENCE DOME THEATER RATITES SAN FRANCISCO SHAKES PLATE TECTONICS FOSSIL EVIDENCE LIFE DRIFTS PLANTS PEOPLE PREPARE MARSUPIALS METEORITE EARTH QUAKES PLATES SHIFT N Rainforest The Earthquake exhibit consists of five areas: Earth Quakes, Life Drifts, San Francisco Shakes, People Prepare, and Plates Shift. You will encounter an abundance of specimens, as well as numerous interactive stations, video presentations, ratites and an earthquake simulator. Before you visit the exhibition spend some time viewing the information on the Academy’s website at www.calacademy.org to begin planning your visit. 04 Earthquake Educator Guide California Academy of Sciences SHAKE EXPERIENCE DOME THEATER c. key concepts: EarTH QUAKES RATITES Heat andSAN Gravity FRANCISCO SHAKES PLATE TECTONICS A constant heating and cooling cycle FOSSIL EVIDENCE LIFE DRIFTS in the mantle drives plate movement PLANTS PEOPLE PREPAREon the Earth’s surface. Heat combined MARSUPIALS with the effects of gravity causes METEORITE irregular pieces of Earth’s crust, called tectonic plates, to move. Main ideas: EARTH QUAKES » Heat rising from Earth’s core puts pressure on PLATES SHIFT the bottom of the rigid outer mantle and crust (lithosphere) causing it to fracture and move. » The earth continues to produce its own internal heat by a process known as radioactive decay. Take a closer look! Plate movement Moving mantle creates Mantle motion currents that cause Rising mantle loses plates to shift. heat, becomes heavier, sinks back down and is reheated. Inner core Outer core Lithosphere A rigid shell of tectonic Mantle plates made of crust and uppermost mantle. Crust California Academy of Sciences Earthquake Educator Guide 05 SHAKE EXPERIENCE DOME THEATER c. key concepts: EarTH QUAKES RATITES Earth’s MantleSAN FRANCISCO Materials SHAKES PLATE TECTONICS Mineral specimens are evidence FOSSIL EVIDENCE LIFE DRIFTS of what the Earth’s mantle is made PLANTS PEOPLE PREPAREof. Here are some examples of the MARSUPIALS compounds that make up the mantle METEORITE of our planet. Main ideas: » Earth’s mantle is the layer above the core and EARTH QUAKES beneath the crust and is divided into two parts. PLATES SHIFT » The lower mantle is solid rock. » The upper mantle has a partially molten layer (asthenosphere) underlying a thin solid layer that is fused to the crust (lithosphere). » The asthenosphere is the molten layer on which the tectonic plates ride. Take a closer look! Foresterite Magnesiohornblende (magnesium-rich olivine) (an amphibole) Mg₂ SiO₄ Ca₂Mg₄Al(AlSi₂Si₇O₂₂)(OH)₂ Olivine—the mantle’s most This mineral forms under common mineral—flows under pressure when magma cools. pressure, greasing the slow slide It can appear as small, dark of Earth’s tectonic plates. crystals in igneous rocks. Augite Bytownite (a pyroxene) Calcium feldspar (Ca,Na)(Mg,Fe₂+,Al,Fe₃,Ti) (Ca,Na)(Si,Al)₄O₈ (Si,Al)₂O₆ This type of feldspar is Augite crystals form in magma especially rich in calcium. as it cools and hardens. 06 Earthquake Educator Guide California Academy of Sciences SHAKE EXPERIENCE DOME THEATER c. key concepts: EarTH QUAKES RATITES Earth’s CrustSAN FRANCISCO Materials SHAKES PLATE TECTONICS Mineral specimens provide evidenceFOSSIL EVIDENCE LIFE DRIFTS as to how Earth’s crust is formed. PLANTS PEOPLE PREPARE Minerals and rocks in the crust are MARSUPIALS more diverse than those in the inner METEORITE layers of the earth. Main ideas: » Earth has two types of crust: oceanic and continental. EARTH QUAKES » Continental crust is 22 to 44 miles thick and is PLATES SHIFT less dense and more rigid than oceanic crust, so continents ride higher on the mantle and shed water lower and underlies most of the surface covered by into the ocean basins. oceans. » Oceanic crust is four to six miles thick and is more » The crust and uppermost part of the mantle together dense and flexible than continental crust. It sits make up a rigid layer known as the lithosphere. Take a closer look! Oceanic crust Continental crust Basalt pillow Granodiorite Oceanic crust is mostly Continental crust is made dark, fine–grained basalt of silica–rich rocks that formed by volcanic contain common minerals eruptions. Pillows form like quartz and feldspar. on the seafloor where water quickly cools molten lava. Continental crust Granodiorite Oceanic crust Basalt pillow California Academy of Sciences Earthquake Educator Guide 07 SHAKE EXPERIENCE DOME THEATER c. key concepts: EarTH QUAKES RATITES Earth’s InnerSAN FRANCISCO Core SHAKES PLATE TECTONICS Earth’s inner core is similar to a very FOSSIL EVIDENCE LIFE DRIFTS hot iron meteorite. Scientific data PLANTS PEOPLE PREPAREindicate that Earth’s core is mostly MARSUPIALS iron, with about 4% nickel plus METEORITE small parts of lighter elements. Iron meteorites are remnants of our solar system’s formation. EARTH QUAKES Main ideas: PLATES SHIFT » The iron in the Earth’s inner core is derived from a previous generation of stars. » The composition of iron meteorites closely » Iron meteorites are remnants of previous stars, matches scientific predictions about the chemical or iron that was subsequently incorporated into composition of Earth’s core. asteroids or planets. » Earth’s core is almost as hot as the Sun. Take a closer look! Iron Meteorite This iron meteorite is made of the same material that makes up Earth’s inner core. The only difference is that the iron in the inner core is nearly as hot as the surface of the Sun. Canyon Diablo meteorite, Barriner Meteor Crater, Arizona, 221 lbs. 08 Earthquake Educator Guide California Academy of Sciences SHAKE EXPERIENCE DOME THEATER c. key concepts: EarTH QUAKES RATITES Reading SANEarthquakes FRANCISCO SHAKES PLATE TECTONICS Earthquakes provide evidence of FOSSIL EVIDENCE LIFE DRIFTS Earth’s structure, which includes the PLANTS PEOPLE PREPAREcore, mantle and crust. Much of what MARSUPIALS we know about the Earth’s interior METEORITE comes from waves generated by earthquakes. Main ideas: EARTH QUAKES » The energy earthquakes release travels in the form PLATES SHIFT of waves called seismic waves. Each earthquake produces three basic types of seismic waves. detected before slower secondary S wave. The » Each seismic wave has a different type of motion and farther away from the epicenter, the greater the time travels through the earth at different speeds. interval between the arrival of P and S waves. » Surface waves ripple across the crust, while body » Scientists know about the structure and composition waves travel through the Earth’s interior in all of the Earth’s interior by studying how seismic waves directions. The faster primary P waves are always move through the Earth. Seismic Waves P-waves S-waves Travel up to Move at about 46,800 km/h half the speed (29,000 mph). of P-waves. Move with a Move with an Solid core back and forth side-to-side motion. motion. Travel through Liquid outer core Travel through both solids and solids but liquids. not through Solid mantle liquids. California Academy of Sciences Earthquake Educator Guide 09 SHAKE EXPERIENCE DOME THEATER c. key concepts: EarTH QUAKES RATITES Earthquakes: Earth Shakes Where PlatesSAN FRANCISCO Meet SHAKES PLATE TECTONICS Movement in narrow zones alongFOSSIL EVIDENCE LIFE DRIFTS plate boundaries is the causePLANTS of most PEOPLE PREPARE earthquakes.
Load more

Recommended publications
  • INTERIOR of the EARTH / an El/EMEI^TARY Xdescrrpntion
    N \ N I 1i/ / ' /' \ \ 1/ / / s v N N I ' / ' f , / X GEOLOGICAL SURVEY CIRCULAR 532 / N X \ i INTERIOR OF THE EARTH / AN El/EMEI^TARY xDESCRrPNTION The Interior of the Earth An Elementary Description By Eugene C. Robertson GEOLOGICAL SURVEY CIRCULAR 532 Washington 1966 United States Department of the Interior CECIL D. ANDRUS, Secretary Geological Survey H. William Menard, Director First printing 1966 Second printing 1967 Third printing 1969 Fourth printing 1970 Fifth printing 1972 Sixth printing 1976 Seventh printing 1980 Free on application to Branch of Distribution, U.S. Geological Survey 1200 South Eads Street, Arlington, VA 22202 CONTENTS Page Abstract ......................................................... 1 Introduction ..................................................... 1 Surface observations .............................................. 1 Openings underground in various rocks .......................... 2 Diamond pipes and salt domes .................................. 3 The crust ............................................... f ........ 4 Earthquakes and the earth's crust ............................... 4 Oceanic and continental crust .................................. 5 The mantle ...................................................... 7 The core ......................................................... 8 Earth and moon .................................................. 9 Questions and answers ............................................. 9 Suggested reading ................................................ 10 ILLUSTRATIONS
    [Show full text]
  • Tectonics and Crustal Evolution
    Tectonics and crustal evolution Chris J. Hawkesworth, Department of Earth Sciences, University peaks and troughs of ages. Much of it has focused discussion on of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, the extent to which the generation and evolution of Earth’s crust is UK; and Department of Earth Sciences, University of St. Andrews, driven by deep-seated processes, such as mantle plumes, or is North Street, St. Andrews KY16 9AL, UK, c.j.hawkesworth@bristol primarily in response to plate tectonic processes that dominate at .ac.uk; Peter A. Cawood, Department of Earth Sciences, University relatively shallow levels. of St. Andrews, North Street, St. Andrews KY16 9AL, UK; and Bruno The cyclical nature of the geological record has been recog- Dhuime, Department of Earth Sciences, University of Bristol, Wills nized since James Hutton noted in the eighteenth century that Memorial Building, Queens Road, Bristol BS8 1RJ, UK even the oldest rocks are made up of “materials furnished from the ruins of former continents” (Hutton, 1785). The history of ABSTRACT the continental crust, at least since the end of the Archean, is marked by geological cycles that on different scales include those The continental crust is the archive of Earth’s history. Its rock shaped by individual mountain building events, and by the units record events that are heterogeneous in time with distinctive cyclic development and dispersal of supercontinents in response peaks and troughs of ages for igneous crystallization, metamor- to plate tectonics (Nance et al., 2014, and references therein). phism, continental margins, and mineralization. This temporal Successive cycles may have different features, reflecting in part distribution is argued largely to reflect the different preservation the cooling of the earth and the changing nature of the litho- potential of rocks generated in different tectonic settings, rather sphere.
    [Show full text]
  • Seismic Velocity Structure of the Continental Lithosphere from Controlled Source Data
    Seismic Velocity Structure of the Continental Lithosphere from Controlled Source Data Walter D. Mooney US Geological Survey, Menlo Park, CA, USA Claus Prodehl University of Karlsruhe, Karlsruhe, Germany Nina I. Pavlenkova RAS Institute of the Physics of the Earth, Moscow, Russia 1. Introduction Year Authors Areas covered J/A/B a The purpose of this chapter is to provide a summary of the seismic velocity structure of the continental lithosphere, 1971 Heacock N-America B 1973 Meissner World J i.e., the crust and uppermost mantle. We define the crust as 1973 Mueller World B the outer layer of the Earth that is separated from the under- 1975 Makris E-Africa, Iceland A lying mantle by the Mohorovi6i6 discontinuity (Moho). We 1977 Bamford and Prodehl Europe, N-America J adopted the usual convention of defining the seismic Moho 1977 Heacock Europe, N-America B as the level in the Earth where the seismic compressional- 1977 Mueller Europe, N-America A 1977 Prodehl Europe, N-America A wave (P-wave) velocity increases rapidly or gradually to 1978 Mueller World A a value greater than or equal to 7.6 km sec -1 (Steinhart, 1967), 1980 Zverev and Kosminskaya Europe, Asia B defined in the data by the so-called "Pn" phase (P-normal). 1982 Soller et al. World J Here we use the term uppermost mantle to refer to the 50- 1984 Prodehl World A 200+ km thick lithospheric mantle that forms the root of the 1986 Meissner Continents B 1987 Orcutt Oceans J continents and that is attached to the crust (i.e., moves with the 1989 Mooney and Braile N-America A continental plates).
    [Show full text]
  • Physiography of the Seafloor Hypsometric Curve for Earth’S Solid Surface
    OCN 201 Physiography of the Seafloor Hypsometric Curve for Earth’s solid surface Note histogram Hypsometric curve of Earth shows two modes. Hypsometric curve of Venus shows only one! Why? Ocean Depth vs. Height of the Land Why do we have dry land? • Solid surface of Earth is Hypsometric curve dominated by two levels: – Land with a mean elevation of +840 m = 0.5 mi. (29% of Earth surface area). – Ocean floor with mean depth of -3800 m = 2.4 mi. (71% of Earth surface area). If Earth were smooth, depth of oceans would be 2450 m = 1.5 mi. over the entire globe! Origin of Continents and Oceans • Crust is formed by differentiation from mantle. • A small fraction of mantle melts. • Melt has a different composition from mantle. • Melt rises to form crust, of two types: 1) Oceanic 2) Continental Two Types of Crust on Earth • Oceanic Crust – About 6 km thick – Density is 2.9 g/cm3 – Bulk composition: basalt (Hawaiian islands are made of basalt.) • Continental Crust – About 35 km thick – Density is 2.7 g/cm3 – Bulk composition: andesite Concept of Isostasy: I If I drop a several blocks of wood into a bucket of water, which block will float higher? A. A thick block made of dense wood (koa or oak) B. A thin block made of light wood (balsa or pine) C. A thick block made of light wood (balsa or pine) D. A thin block made of dense wood (koa or oak) Concept of Isostasy: II • Derived from Greek: – Iso equal – Stasia standing • Density and thickness of a body determine how high it will float (and how deep it will sink).
    [Show full text]
  • Label and Describe the Earth Diagram
    Name_________________________class______ Label and Describe the Earth Diagram Read the definitions then use the information to color code, label and describe IN YOUR OWN WORDS each section of the diagram below. Definitions: crust – (green) the rigid, rocky outer surface of the Earth, composed mostly of basalt and granite. The crust is the thinnest of all layers. It is thicker on continents & thinner under the oceans. inner core – (gray) the solid iron-nickel center of the Earth that is very hot and under great pressure. mantle – (orange) a rocky layer located under the crust - it is composed of silicon, oxygen, magnesium, iron, aluminum, and calcium. Convection (heat) currents carry heat from the hot inner mantle to the cooler outer mantle. outer core – (red) the molten iron-nickel layer that surrounds the inner core. ______________________________________________ ______________________________________________ ______________________________________________ _______________________________________ _______________________________________ _______________________________________ ___________________________________ ___________________________________ ___________________________________ ___ __________________________________ __________________________________ __________________________________ __________________________ Name_________________________________cLass________ Label the OUTER LAYERS of the Earth This is a cross section of only the upper layers of the Earth’s surface. Read the definitions below and use the information to locate label and describe IN TWO WORDS the outer layers of the Earth. One has been done for you. continental crust – thick, top Continental Crust – (green) the thick parts of the Earth's crust, not located under the ocean; makes up the comtinents. Oceanic Crust – (brown) thinner more dense parts of the Earth's crust located under the oceans. Ocean – (blue) large bodies of water sitting atop oceanic crust. Lithosphere– (outline in black) made of BOTH the crust plus the rigid upper part of the upper mantle.
    [Show full text]
  • Marine Science and Oceanography
    Marine Science and Oceanography Marine geology- study of the ocean floor Physical oceanography- study of waves, currents, and tides Marine biology– study of nature and distribution of marine organisms Chemical Oceanography- study of the dissolved chemicals in seawater Marine engineering- design and construction of structures used in or on the ocean. Marine Science, or Oceanography, integrates different sciences. 1 2 1 The Sea Floor: Key Ideas * The seafloor has two distinct regions: continental margins and deep-ocean basins * The continental margin is the relatively shallow ocean floor near shore. It shares the structure and composition of the adjacent continent. * The deep-ocean floor differs from the continental margin in tectonic origin, history and composition. * New technology has allowed scientists to accurately map even the deepest ocean trenches. 3 Bathymetry: The Study of Ocean Floor Contours Satellite altimetry measures the sea surface height from orbit. Satellites can bounce 1,000 pulses of radar energy off the ocean surface every second. With the use of satellite altimetry, sea surface levels can be measured more accurately, showing sea surface distortion. 4 2 5 The Physiography of the Ocean Floor Physiography and bathymetry (submarine landscape) allow the sea floor to be subdivided into three distinct provinces: (1) continental margins, (2) deep ocean basins and (3) mid-oceanic ridges. 6 3 The Topography of Ocean Floors The classifications of ocean floor: Continental Margins – the submerged outer edge of a continent Ocean Basin – the deep seafloor beyond the continental margin Ocean Ridge System - extends throughout the ocean basins A typical cross section of the Atlantic ocean basin.
    [Show full text]
  • Plate Boundaries - Where the Action Is! Modeling Activity
    Plate Boundaries - Where the action is! Modeling Activity The Earth’s outer shell, called the lithosphere, is broken up into tectonic plates. The lithosphere is rock that is rigid and brittle - it is composed of the crust and the uppermost mantle. The rigid plates move around on top of a hotter more mobile layer of the mantle known as the asthenosphere. Where the plates meet is where most of the world’s earthquakes and volcanic activity occurs. Let’s explore what happens at different plate boundaries. What you need: • Graham crackers • Waxed paper • Peanut butter or frosting and a knife to spread • Small bowl of water PUSH Set up: • Spread peanut butter or frosting on the waxed paper. Cover an area almost twice the size of a whole graham cracker. This is the asthenosphere – soft and mobile. • Break a graham cracker in half, now you have two tectonic plates. The PULL plates are rigid and brittle. When you broke the graham cracker... you caused an earthquake! What you’ll do: Place two graham cracker halves (tectonic plates) on your asthenosphere. Using one finger on each plate, very slowly and gently move your plates around on the asthenosphere. This is how tectonic plates on the Earth’s asthe- nosphere move. Now let’s check out the different types of boundaries between plates. Divergent Plate Boundary These are boundaries where two plates move away from each other. These boundaries are often found on ocean floors. Put the two graham cracker halves (tectonic plates) touching each other in the middle of your asthenosphere.
    [Show full text]
  • Continental Crust - Irina M
    GEOPHYSICS AND GEOCHEMISTRY – Vol.II - Continental Crust - Irina M. Artemieva CONTINENTAL CRUST Irina M. Artemieva Uppsala University, Sweden Keywords:Anisotropy, brittle crust, composition, continental arc, continental margin, cratons, crustal thickness, crustal types, ductile crust, extended crust, juvenile crust, lower crust, Moho discontinuity, Orogens, plate tectonics, platforms, Poisson’s ratio, Rift, reflectivity, Rheology, seismic velocities, shear-wave splitting, shields, subcrustal velocity, transitional crust, upper crust, upper mantle Contents 1. Introduction 2. Methods of Continental Crust Studies 2.1 Seismic Studies 2.2 Geologic Mapping 2.3 Petrologic Studies 2.4 Heat Flow Studies 2.5 Electromagnetic Studies 2.6 Gravity Studies 2.7 Laboratory Ultrasonic Measurements 2.8 Continental Drilling 2.9 Geochronology 3. Average Seismic Structure of Continental Crust 3.1 Crustal Thickness and Seismic Velocities 3.2 Crustal Reflectivity 3.3 The Moho Discontinuity 4. Types of Continental Crust 4.1 Shields and Platforms 4.2 Collisional Orogens 4.3 Continental Rifts and Extended Crust 4.4 Continental Margins 5. Physical Properties of Continental Crust 5.1 Seismic Velocities in Typical Crustal Rocks 5.2 Seismic Anisotropy in Continental Crust 5.3 Poisson’sUNESCO Ratio – EOLSS 5.4 Crustal Density 5.5 Crustal Rheology,SAMPLE Brittle-Ductile Crust CHAPTERS 6. Composition of Continental Crust 6.1 Methods of Estimating Crustal Composition 6.2 The Upper and Middle Continental Crust 6.3 The Lower Continental Crust 7. Crustal Evolution 7.1 Hypotheses for the Continental Crust Origin 7.2 Age Distribution of Continental Crust 7.3 The Formation of Continental Crust and Mantle Dynamics Acknowledgments ©Encyclopedia of Life Support Systems (EOLSS) GEOPHYSICS AND GEOCHEMISTRY – Vol.II - Continental Crust - Irina M.
    [Show full text]
  • Lithospheric Strength Profiles
    21 LITHOSPHERIC STRENGTH PROFILES To study the mechanical response of the lithosphere to various types of forces, one has to take into account its rheology, which means knowing how it flows. As a scientific discipline, rheology describes the interactions between strain, stress and time. Strain and stress depend on the thermal structure, the fluid content, the thickness of compositional layers and various boundary conditions. The amount of time during which the load is applied is an important factor. - At the time scale of seismic waves, up to hundreds of seconds, the sub-crustal mantle behaves elastically down deep within the asthenosphere. - Over a few to thousands of years (e.g. load of ice cap), the mantle flows like a viscous fluid. - On long geological times (more than 1 million years), the upper crust and the upper mantle behave also as thin elastic and plastic plates that overlie an inviscid (i.e. with no viscosity) substratum. The dimensionless Deborah number D, summarized as natural response time/experimental observation time, is a measure of the influence of time on flow properties. Elasticity, plastic yielding, and viscous creep are therefore ingredients of the mechanical behavior of Earth materials. Each of these three modes will be considered in assessing flow processes in the lithosphere; these mechanical attributes are expressed in terms of lithospheric strength. This strength is estimated by integrating yield stress with depth. The current state of knowledge of rock rheology is sufficient to provide broad general outlines of mechanical behavior but also has important limitations. Two very thorny problems involve the scaling of rock properties with long periods and for very large length scales.
    [Show full text]
  • Seafloor Spreading and Plate Tectonics
    OCN 201: Plate Tectonics II There are three types of plate boundaries: a) mid-ocean ridge, subduction zone, transform fault b) divergent, convergent, translational c) constructive, destructive, conservative d) All of the above: a,b, and c all describe the 3 types. Structure of Continents • Continental crust has formed throughout Earth’s history by chemical differentiation at subduction zones. – Oceanic crust: dry melting of mantle at MOR basalt – Continental crust: wet melting in subduction zones andesite of volcanic arcs Subducted H2O is from the oceans, in seafloor sediment and weathered oceanic crust. H2O comes off subducted plate as it heats, rises into mantle of plate above, and X lowers its melting temperature. Structure of Continents Continental crust exists on Earth because we have – Liquid water oceans – Subduction (Plate Tectonics) – Venus lacks liquid H2O and subduction zones no continental crust (and Venus’s mantle is too stiff and dry to convect!) Hypsometric curves: Shape of the solid surface of Earth vs. Venus Structure of Continents Oldest oceanic crust ~ 170 million years Oldest continental crust = 4.03 billion years (in Canada) What do the continents tell us about Earth history? Cratons vs. mobile belts: Terranes and Structure of Continents • Continental crust is too thick and buoyant to subduct. • When continental fragment or island arc collides with continent it “sticks”. Terranes and Structure of Continents • Fragments of cont. crust incorporated into larger cont. masses are called terranes. • Younger terranes are parts of mobile belts. • Older now stable parts (cratons) appear to have accreted as terranes in the more distant past. Terrane Structure of North America • North America age distribution illustrates terrane accretion.
    [Show full text]
  • Layers of the Earth
    Notes: Layers of the Earth Crust Outer layer; covers the whole earth; varies in thickness from 5 to 60 Km. Together with the upper mantle, is part of a zone called the lithosphere. There are 2 kinds of crust: continental crust and oceanic crust. Continental Crust Exists under continents Average thickness is 30-50 Km (thickest under mountains), although it can be as thin as 10 Km in places Chemical composition: rocks rich in calcium and aluminum silicates **Note: a silicate contains the molecule, SiO2 Common rock types: granite and rhyolite Rocks are less dense, lighter in color than oceanic crust Oceanic Crust Exists under oceans Average thickness is 7 Km Chemical composition: rocks rich in iron and magnesium silicates Common rock types: basalt, obsidian, gabbro Rocks are more dense, darker in color than continental crust Mantle (Chemical Composition: iron & magnesium silicates) Lies underneath the crust 2900 Km thick The lithosphere is a zone made of the upper mantle and entire crust. It is made of cool, hard rock. Most (but not the very upper part) of the mantle is plastic rock: is both solid and molten at the same time. This zone is called the asthenosphere. Underneath the asthenosphere is the mesosphere, which is solid. The asthenosphere has convection currents, where matter rises to the top, cools, then comes back down again, in a continuous cycle. Core Center of the Earth; ~ 3500 Km thick Outer Core Made of molten iron and nickel 2270 Km thick Inner Core Made of solid iron and nickel. Is solid because of the extreme pressures it is under.
    [Show full text]
  • Crust and Mantle Vs. Lithosphere and Asthenosphere
    Crust and Mantle vs. Lithosphere and Asthenosphere Why do we use two names to describe the same layer of the Earth? Well, this confusion results from the different ways scientists study the Earth. Lithosphere, asthenosphere, and mesosphere (we usually don't discuss this last layer) represent changes in the mechanical properties of the Earth. Crust and mantle refer to changes in the chemical composition of the Earth. Lithosphere and Asthenosphere The lithosphere (litho:rock; sphere:layer) is the strong, upper 100 km of the Earth. The lithosphere is the tectonic plate we talk about in plate tectonics. The asthenosphere (a:without; stheno:strength) is the weak and easily deformed layer of the Earth that acts as a “lubricant” for the tectonic plates to slide over. The asthenosphere extends from 100 km depth to 660 km beneath the Earth's surface. Beneath the asthenosphere is the mesosphere, another strong layer. Crust and Mantle The crust is a chemically distinct layer at the surface of the Earth. Crustal material contains lighter elements like Si, O, Al, Ca, K, Na, etc... Feldspars (Anorthite, Albite, Orthoclase) are comon minerals in the crust (CaAL2Si2O8, NaALSi3O8 , KALSi3O8). The crust may be divided into 2 types: oceanic and continental. Oceanic crust is usually 5-10 km thick and continental crust is 33 km thick on average. Beneath the crust is the mantle. The mantle is made up of Si and O, like the crust, but it contains more Fe and Mg. Thus, Olivine (Fe2SiO4-Mg2SiO4) and pyroxene (MgSiO3-FeSiO3) are abundant in the mantle. The mantle extends to the core-mantle interface at approximately 2900 km depth.
    [Show full text]