Science 10 - Plate Tectonics PDF

Science 10 – Pointers to Review 1st Quarter Unit 1- MODULE 1:...

Science 10 – Pointers to Review 1st Quarter Unit 1- MODULE 1: PLATE TECTONICS Summary/Synthesis/Feedback According to the plate tectonics model, the entire lithosphere of the Earth is broken into numerous segments called plates. Each plate is slowly but continuously moving. As a result of the motion of the plates, three types of plate boundaries were formed: Divergent, Convergent, and Transform fault boundaries. Divergent boundary is formed when plates move apart, creating a zone of tension. Convergent boundary is present when two plates collide. Transform fault is characterized by plates that are sliding past each other. Plate tectonics give rise to several geologic features and events. Glossary of Terms Continental volcanic arc mountains formed in part by igneous activity associated with subduction of oceanic lithosphere beneath a continent Convergent boundary a boundary in which two plates move toward each other, causing one of the slabs of the lithosphere to subduct beneath an overriding plate Crust the outer portion of the earth Continental Crust the thick part of the Earth’s crust, not located under the ocean Oceanic Crust the thin part of the Earth’s crust located under the oceans Divergent boundary a region where the crustal plates are moving apart Earthquake vibration of Earth due to the rapid release of energy Fault a break in a rock along which movement has occurred Fracture any break in a rock in which no significant movement has taken place Geology the science that studies Earth Hot spot a concentration of heat in the mantle capable of creating magma Magma a mass of molten rock formed at depth, including dissolved gases and crystals. Mid-ocean ridge a continuous mass of land with long width and height on the ocean floor. Plates rigid sections of the lithosphere that move as a unit Plate tectonics a theory which suggests that Earth’s crust is made up of plates that interact in various ways, thus producing earthquakes, mountains, volcanoes, and other geologic features Primary (P) wave the first type of seismic wave to be recorded in a seismic station Rocks consolidated mixture of minerals Secondary (S) wave second type of earthquake wave to be recorded in a seismic station Seismogram a record made by a seismograph Seismograph a device used to record earthquake waves Subduction an event in which a slab of rock thrusts into the mantle Transform fault boundary a boundary produced when two plates slide past each other Trench a depression in the seafloor produced by subduction process Volcanic Island arc a chain of volcanoes that develop parallel to a trench Unit 1-MODULE 2: THE EARTH’S INTERIOR Summary/Synthesis/Feedback The Earth is composed of three major layers: the crust, mantle, and core which is subdivided into outer and inner core. The crust is the outermost and thinnest layer of the Earth. The mantle is the middle layer of the Earth. It makes most of the Earth’s volume and mass. The crust and a part of the upper mantle make up the lithosphere. The lithosphere is subdivided into portions called lithospheric plates. The asthenosphere is the weak layer of the mantle on which the lithosphere floats. The outer core is made up of molten material and accounts for the Earth’s magnetic field. The inner core is the deepest layer of the Earth. It is made up of solid nickel and iron. The temperature in the inner core reaches as high as 5000oC. The speed, reflection and refraction properties of seismic waves are used by scientists to study the structure and composition of the Earth’s interior. The Continental Drift Theory of Alfred Wegener states that the continents were once part of a large landmass called Pangaea which drifted away from each other. The continents moved away from each other towards their current positions. Alfred Wegener based his theory on evidences from fossils imbedded in rocks and rock formations. Seafloor spreading is believed to occur as hot magma rises at the rift in the mid-ocean ridge. This magma cools down and becomes the new seafloor as it pushes the former. The old seafloor is destroyed at the subduction zone and melts inside the mantle. The age of rocks and the magnetic stripes in the ocean floor support the Seafloor Spreading Theory. The Theory of Plate Tectonics helps explain the formation and destruction of the Earth’s crust and its movement over time. Scientists believe that the plates’ movement is due to convection currents in the mantle. Glossary of Terms Asthenosphere soft, weak upper portion of the mantle where the lithospheric plates float and move around Continental Drift Theory states that all the continents were once one large landmass that broke apart, and where the pieces moved slowly to their current locations Convection current current in the mantle because of the heat from the inner layers of the Earth, and is the force that drives the plates to move around Lithosphere the topmost, solid part of the Earth that is composed of several plates Lithospheric Plates the moving, irregularly-shaped slabs that fit together to form the surface of the Earth Mid-ocean ridge area in the middle of the ocean where a new ocean floor is formed when lava erupts through the cracks in the Earth’s crust Mohorovičić Discontinuity (Moho) the boundary that separates the crust and the mantle Plasticity the ability of solid to flow Seafloor spreading process by which new ocean floor is formed near the mid-ocean ridge and moves outward Subduction the process in which the crust plunges back into the Earth Tectonics branch of geology that deals with the movements that shape the Earth’s crust Please remember to review the notes from our previous discussions on Module 1 and Module 2, as they are included in the scope of the first quarterly examination.