Presentation on theme: "Section 1: Earth’s Interior Who Studies Earth’s Interior?"— Presentation transcript:
1Section 1: Earth’s Interior Who Studies Earth’s Interior? GeologistsScientists who study the forces that make and shape planet Earth.They study the processes that create Earth’s features and search for clues about Earth’s history.
2What kind of evidence do scientists use to learn about the interior of the earth? Direct vs. IndirectDirect evidence: from rock samples. Scientists drill up to 12 km into the earth. Forces blast rock from as deep as 100 km.Indirect evidence: from seismic waves
3How do scientists study the Earth? To reach the Earth’s core you would have to travel over 6,000 km (3,728 miles)!Scientists record Seismic Waves – a vibration that travels through Earth carrying the energy released during an earthquakeTypes of seismic waves –P waves – travel through crust (6km/sec) and mantle (8km/sec)S waves – will not travel through liquid
4What is the Earth’s structure? The CrustThe MantleLithosphereAsthenosphereThe CoreOuter CoreInner Core
5What is the structure of the crust? A layer of rock that forms the Earth’s outer skin including the rock under the oceanTwo types of crust:Continental CrustGranite – less dense crustOceanic CrustBasalt – more dense rock
6What is the structure of the mantle? Two major parts:Lithosphere – upper part of crust and mantle together; floats on top of the asthenosphereAsthenosphere – softer than the mantle due to increasing temperature and pressureThe mantle is nearly 3,000 kilometers thick! (1,864 miles)
7What is the structure of the core? Two partsOuter Core – liquid; behaves like a thick liquid; forces the solid inner core to spin causing Earth’s magnetic fieldInner Core – solid; extreme pressure squeezes the atoms of iron and nickel so that they cannot spread out to become liquidInner core and outer core are just slightly smaller than the moon
9Section 2: Convection and the Mantle How does Heat transfer? Radiation – heat transfer through empty space; ex. sunlightConduction – heat transfer through direct contactConvection- heat transfer by movement of heated fluids
10How do convection currents affect the Earth? Heating and cooling a fluid changes its density; warmer fluids have a lower density and float; colder fluids have a higher density and sink
11Section 3: Drifting Continents Were the continents once together? Alfred Wegener hypothesized that all the continents had moved from a supercontinent known as Pangaea.
12What is the evidence for Wegener’s idea? Evidence of Continental Drift:Landforms – similar mountain rangesFossils – similar fossils of a fernlike plant existed on both continentsClimate – tropical pl ant fossils found in cold climates
13Section 4: Sea-Floor Spreading What is happening in the ocean? Using sonar scientists discovered mountains under the oceanThe longest chain of mountains in the world is under the ocean and is known as the Mid- Ocean ridge!
14Side-scan sonar locates missing plane Courtesy of NOAA. Side-scan sonar image of the remains of the submarine USS O-9 (SS-70) off the Isle of Shoals, New Hampshire in more than 400 feet of water. Courtesy of NOAA.Side-scan sonar locates missing plane Courtesy of NOAA.
15What is sea-floor spreading? Harry Hess suggested that at the mid-ocean ridge molten material rises from the mantle and erupts; pushing older rock to both sidesThis process is known as sea-floor spreading!
16What is the evidence for Sea-floor spreading? Evidence from Molten MaterialEvidence from Magnetic StripsEvidence from Drilling Samples
17How can the ocean floor keep from getting wider and wider? The older ocean floor plunges into deep-ocean trenches in a process known as subductionSea-floor spreading and subduction work together like a giant conveyer belt!
18Section 5: What is the theory of plate tectonics? The Earth’s lithosphere is cracked into separate sections known as platesGeological theory states that these plates are in constant, slow motion, driven by the convection currents in the mantle
19How is the theory of plate tectonics different from continental drift? Continental drift is based on the movement of the continents DUE to plate tectonicsContinents are NOT the same as platesTectonic plates can be made up of both oceanic crust and continental crust
20What happens where the plates meet? Plate Boundaries – where the edges of the lithosphere meet; faults form along these boundaries:TransformDivergentConvergent
21What are Transform boundaries? The place where two plates slip past each other, moving in opposite directionsEarthquakes occur frequently at these boundaries
22What are Divergent Boundaries? The place where two plates move apart, or diverge and create a rift valleyMost occur at the mid-ocean ridge although some can occur on land
23What are Convergent boundaries? The place where two plates come together, or converge creating a collisionSubduction occurs at convergent boundariesThe density of the crust determines which crust will be on top – if both plates are the same density they form a mountain range