ENVS 101 1st Edition Lecture 9Outline of Last Lecture I. EarthquakesII. Earthquake Hazards and RiskIII. Earthquakes and the Earth’s InteriorOutline of Current Lecture II. Plate TectonicsIII. Plate motion and the Driving ForceIV. Plate interactions and Earth’s LandscapesCurrent Lecture- Tectonics: Is the study of the movement of plates of the lithosphere that float on the underlying mantle.The various interactions that occur between these plates are responsible for the creation of many of Earth’s unique features, such as mountains, canyons, etc. Without these interactions, the surface of the Earth would be rather flat, and contain much less geographical diversity in terms of the formations that could be seen. - In 1914, Alfred Wegener published his Continental Drift hypothesis, which tried to explain:o Parallel shapes of Atlantic coastlineso Matching glacial landscapes, mountain ranges, plant/animal fossils on continents separated by ocean watersAlong with this theory, he suggested that these landscapes were together in a single supercontinent “Pangaea” however, he was unable to provide any sort of mechanism behind this theory in order to explain how continents moved. Overall he had very little support for hypothesis because of this.In the 1950’s, scientists began to use volcanic rock in order to measure the direction of Earth’s past magnetic field (Paleomagnetism)From apparent polar wandering, scientists concluded that continents had in fact moved, carrying magnetized rocks along with them as they did so. Another means of evidence that the These 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.continents had moved, came with the finding of seafloor spreading: In which the ocean crust moves laterally, splitting along oceanic ridges.Convection within the hot, weak, ductile upper mantle was an idea that was proposed as early as 1919, by Sir Arthur Holmes.With this new idea, plates are changing in size, new oceanic crust formed at ridges, while old, cold, dense crust is destroyed by subduction.There are several different types of plate boundaries and margins that are found within the various interactions of the plates in the Lithosphere, including: - Divergent Boundaries: Where two plates pull apart, spreading centers, and are characterized by constructive margins.- Convergent Plate Margins: Where two plates move towards each other, and are characterized by destructive margins.- Ocean-Continent Convergent Margin: In this case, the continental crust is much less dense compared to the oceanic crust.- Ocean-Ocean Convergent Margin: One plate will undergo subduction into the mantle beneath the other plate. This is known as a subduction zone.- Continent-Continent Convergence: Both plates are low density and are unable to undergo subduction, so they end up colliding and forming what is known as a continental collision zone. This process is responsible for forming mountain ranges all across the Earth
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