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Transcript
2nd Semester Earth Science Ch 21- Planet Earth & Ch 22 Climate Chapter 21- Section 1: all; Section 2: p 709-710, 714 middle; 716-717; Section 3: all Chapter 22- Section 3 Climate 760-762 Section 1: Earth’s Interior and Plate Tectonics What is Earth’s Interior Like? • The Earth is made up of three layers: the crust, the mantle and the core. • _________ the thin and solid outermost layer of Earth above the mantle • _________ the layer of rock between Earth’s crust and core • _________ the center part of the Earth below the mantle Structure of the Earth DRAW AND LABEL your own diagram • • Earth’s interior gets ____________________________________. • Geologists believe that the mantle is much hotter than the crust, reaching temperatures higher than 1250° C (2280° F). • The core is hotter than the mantle, reaching temperatures higher than 6000° C (10,800° F). Radioactive elements contribute to Earth’s high internal temperature. • The breakdown of ______________________________ uranium, thorium and potassium ________________________ that contributes to Earth’s _____________________________________________________________. Plate Tectonics • Around 1915, German scientist Alfred Wegener proposed the idea that the continents were once united as a _____________________________________________________. • He pieced the continents together like a ________________ and called the supercontinent they formed _____________________________. 1 • • • • Evidence for Wegener’s ideas came later. • Wegener’s theory of continental drift was ignored until structures discovered on the ocean floor provided evidence for a mechanism for the movement of continents. • Symmetrical bands on either side of a mid-ocean ridge indicate that the two sides of the ridge were moving away from each other and new ocean floor was rising up between them. _________________________________________ supports the theory of moving plates. • Iron in molten rock aligns itself with Earth’s magnetic field as it cools. • The Earth’s magnetic field reverses polarity about every 200,000 years • The process is recorded as magnetic bands in rock, based on the age of the rock. • Symmetrical bands on either side of the Mid Atlantic Ridge suggest that the crust was moving away from the ridge. Earth has _____________ that ______________________________________________. • • Wegener found ___________________________ on widely separate continents, which supported his idea. The crust and upper portion of the mantle are divided into about seven large pieces called ___________________________. ____________________________ the solid, outer layer of Earth, that consists of the __________ and the rigid ___________________ Plate tectonics the theory that explains how the outer parts of Earth ______________________________, and that explains the relationships between _______________________________, sea-floor spreading, ____________________________, and volcanic activity • It is unknown exactly why tectonic plates move. • One hypothesis suggests that plate movement results from __________________ in the asthenosphere, the hot, fluid portion of the mantle. • Another hypothesis suggests that plate movement results from the ___________ ________________ acting on the plates. Plate Boundaries • Mid-ocean ridges result from ____________________________________________. • The border between two plates is called a boundary. 2 • Divergent boundary a place where two plates are ______________________________ • _____________________ forms between divergent boundaries. • Magma __________________ produced under Earth’s surface • Oceanic plates ______________________continental plates at convergent boundaries. • • Plates ______________________________________ at a convergent boundary. _______________________the process by which one lithospheric plate moves ______________________________ as a result of tectonic forces • The area where one plate slides over another is called a subduction zone. Subduction zones produce ________________________, ____________________, and ___________________. • • • Subduction of ocean crust generates __________________________. • Chains of volcanoes form on the upper plate in a subduction zone. • These volcanoes can form far inland from their associated oceanic trench. Colliding tectonic plates create __________________________. • When two _________________________, mountains are formed at the boundary of the collision. • The ____________________ formed during the collision between the continental tectonic plate containing India and the Eurasian continental plate. Transform fault boundaries can ___________________________. 3 • • Plate movement can cause ___________________________________________. _________ a crack in Earth created when rocks on either side of a break move • Plate movement at transform fault boundaries is __________________________ ______________________________. Section 2 Earthquakes and Volcanoes What are Earthquakes? • Earthquakes _____________________________________________________. • Earthquakes are ___________________ resulting from rocks ______________________ each other at __________________ • Seismic waves are _______________________________________during an earthquake • Focus= the area along a fault at which the _________________of an earthquake occurs • ___________________= the point on Earth’s surface directly above an earthquake’s focus • Energy from earthquakes is ________________________________________. • Earthquakes generate three types of waves: • ________________________________________ • ________________________________________ • ________________________________________ • Longitudinal waves travel by _____________________ and _________________ crust, also called primary waves (P waves) (SLINKY!) • Transverse waves travel in an ________________________________movement, also called secondary waves (S waves) • Surface waves seismic waves that can _____________________________________, move in a ___________________________ motion DRAW! Longitudinal Wave Transverse Wave 4 Volcanoes • • _______= an opening at the surface of Earth through which volcanic material passes • • • • A volcano is ___________________ in Earth’s _____________through which magma has reached Earth’s surface. Volcanoes generally have one central vent, but they can also have several smaller vents. Magma that reaches Earth’s surface is called ____________. Shield volcanoes have ________________________________. • Lava from shield volcanoes is _________________________and forms a gently sloping mountain. • Shield volcanoes are some of the _________________________ volcanoes. Composite volcanoes have ___________________________. • Composite volcanoes are made up of alternating layers of ash, cinders, and lava. • The lava is thicker than that of shield volcanoes. • Gases are trapped in the magma, causing eruptions that alternate between ______ and _____________________________ that produces cinders and ash. • • Composite volcanoes are typically _____________________________________. Most volcanoes occur at ________________________________________ boundaries. 5 • 75% of the active volcanoes on Earth are located in an area known as the ______________________________. • The Ring of Fire is located along the edges of the ______________________, where __________________ tectonic plates are ______________________ with ____________________plates. • Underwater volcanoes occur at ____________________ plate boundaries. • As plates move apart at divergent boundaries, magma rises to fill the gap. • This magma creates the volcanic mountains that form ocean ridges. • ________________ is a volcanic island on the Mid-Atlantic ridge that is growing outward in opposite directions. • Volcanoes occur at __________________________. • Some volcanoes occur in the middle of plates. • ___________________________ are mushroom shaped trails of hot rock that rise from deep inside the mantle, melt as they rise, and erupt from volcanoes at hot spots at the surface. • The plumes remain in the same place as the tectonic plate moves, creating a trail of volcanoes. • The _____________________________ are an example of this type of volcanic activity. Section 3 Minerals and Rocks Structure and Origin of Rocks • All rocks are composed of ____________________________. • • There are about 3500 known minerals in Earth’s crust. Each combination of rock-forming minerals results in a rock with a unique set of properties. • ___________________ a natural, usually inorganic solid that has a characteristic chemical composition, an orderly internal structure, and a characteristic set of physical properties • Molten rock cools to form igneous rock. • • Nearly all igneous rocks are made of crystals of various minerals. ________________________________ rock that forms with magma cools and solidifies 6 • Extrusive igneous rock cools _____ Earths surface • Intrusive igneous rock cools while ___________________________ Earth’s surface • Remains of older rocks and organisms form _________________________________. • • All rock breaks down over thousands of years. ______________________ the natural process by which atmospheric and environmental agents, such as _________, ____________, and ___________________________, disintegrate and ________________________ rocks • As pieces of rock accumulate, they can form another type of rock. • ______________________________ a rock formed from compressed or cemented layers of sediment • Sediment= accumulated pieces of rock and other particles • Loose sediment forms rock in two ways. 1. Layers of sediment ________________________________ from weight above, forming rock. 2. ____________________________________ seep between bits of sediment and “________” them together. • Sedimentary rocks are named according to the size of the fragments they contain. • Rocks that undergo pressure and heating without melting form ________________ rock. • • Heat and pressure within Earth cause changes in the texture and mineral content of rocks. Metamorphic rock= a rock that forms from other rocks as a result of intense __________, ______________________, or _________________________________ • __________rocks in the rock cycle form _________ rocks. • The sequence of events in which rocks can be weathered, melted, altered, and formed is described by the ___________________________. • Rock formation occurs _________________________, often over tens of thousands to millions of years. 7 How Old Are Rocks? • The relative age of rocks can be determined using the _________________________________________________. • The principle of superposition states the following: • Assuming no disturbance in the position of the rock layers, the ________________will be on the ____________________, and the ________________ will be on ___________. Law of Superposition • ____________________________ can determine a more exact, or _____________, age of rocks. • The radioactive elements that make up minerals in rocks _____________ over billions of years. • Physicists have determined the ______________ at which these elements decay. • Geologists can use this data to determine the ___________________________. 8 CHAPTER 22 Section 3: Pages 760(climate) – 762 Climate • Climate the _______________________________________________ in an area over a _________________________ of time. • • Temperatures tend to be higher close to the _________________________. • Sunlight strikes the earth ___________________________ close to the equator. • The suns rays are less concentrated at __________________________, and do not warm the atmosphere as much. Earth’s ____________________________________ account for our ________________. • When the North Pole is tilted toward the sun, the ________________________ Hemisphere experiences ________________. • When the South Pole is tilted toward the sun, the _________________________________________ experience summer. • Summer solstice the ______________________________of the year • Winter solstice the _______________________________ of the year • Vernal equinox the point in the __________ when the ___________________________ are ________________________________ • Autumnal equinox the point in the _______ when the _____________________are _____________________________ • • Global climate changes over time. • Many factors produce changes in Earth’s climate, such as: • _______________________________________ • slight changes in Earth’s ________________ • _______________________________________ • changes in the _______________________________________ Earth’s climate is likely to continue changing over the millennia to come. 9