CEE 1030 1nd Edition Lecture 12: Plate TectonicsOutline of Last Lecture I. What is an earthquake?II. SeismologyIII. Distribution of earthquakesIV. Measuring the size of earthquakesV. Earthquake damageVI. Can earthquakes be predicted?VII. ReviewOutline of Current Lecture I. ReviewII. Plate tectonicsIII. Geomagnetic reversalsIV. Magnetism of seafloor rocksV. Workings of plate tectonicsa. Three types of plate boundariesVI. Plate tectonics: predictionsVII. What drives plate motions?VIII. Review, continuedIX. Measuring plate motionCurrent LectureI. Reviewa. In a basin, the youngest rocks are in the center of a syclical structureII. Plate tectonicsa. Scientific Revolution in the late 1960s was the unifying concept of Earth Sciencesb. Continental drift hypothesis: movement of continents across surfacei. Geometric evidence: computer best-fit model using continental slope rather than coastii. Fossil evidence: land-dwelling creatures are found across continentsiii. Paleoclimate evidence: evidence for ice sheets on continentsiv. Geological evidence: close match of rock types between continentsc. Supercontinent Pangaead. Objections to continental drift hypothesisIII. Geomagnetic reversalsa. Earth’s magnetic field periodically changes polarityThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.IV. Magnetism of seafloor rocksa. Symmetrical linear anomalies across ridgesb. Plates move apart, new oceanic crust is formedV. Workings of plate tectonicsa. Lithosphere: outer rigid shell of Earthi. Consists of uppermost mantle and overlying crustii. Divided into platesiii. Plates in motion relative to each otheriv. Astenosphere: weak, ductile mantle below the lithosphereb. Seven major plates and several smaller onesc. Three types of plate boundariesi. Interactions among individual plates occur along boundaries:1. Transform: slide past each othera. Most join two segments of mid-ocean ridge along breaks inoceanic crust known as fracture zones2. Divergent: seafloor spreading at ocean ridges, creation of new oceanic crusta. Continental rifting: continental crust splits at rift, can lead to creation of new ocean3. Convergent: continuous creation of ocean lithosphereVI. Plate tectonics: predictionsa. Explains global distribution of earthquakesVII. What drives plate motions?a. Plate tectonics are a response to the cooling of the Earthb. Thermal convective flow in the solid mantlec. Heat makes mantle more buoyant, rises and falls as it coolsd. Slab pull: sinking of dense oceanic lithospheric slabe. Hot spots and mantle plumesi. Rising plumes of hotter mantle material that is stationaryii. Plate moves across hot spots to create volcano chains (Hawaii)VIII. Review, continueda. Tectonic plates move about 10 cm/yearIX. Measuring plate motiona. Oceanic floor magnetic anomalies and magnetic time scale: age of oceanic crust and spreading
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