EAR 110 1st Edition Lecture 5 Outline of Previous Lecture:I. Ways to Depict Features in the subsurfaceII. Why are Cross Sections so important?III. Qualitative vs Quantitative DataIV. Geologic Time ScaleV. Data versus interpretations at YellowstoneVI. Using Qualitative vs Quantitative Data to determine leakage from tanks (example)Outline of Current Lecture:I. Review of previous conceptsII. Plate tectonicsIII. Three types of relative plate motionsLecture 5: Ch 3: Plate TectonicsI. Review of previous conceptsa. Earth has both continental and oceanic crustb. The thickest layer of earth is the mantlec. The deepest layer of earth is the core (made of iron-nickel)d. Some layers of earth are stronger than othersi. Lithosphere is stronger than the asthenosphere (behaves plastically)e. The rock cycle explains the different paths/processes that can happen to a rocki. Big picture: The rock cycle is tied to the unifying theory of plate tectonics to form the features of earth and geology we know todayII. Plate tectonicsa. World map – areas of interest and observationsi. Pacific northwest/South America – high standing mountains on coast with oceanic trenches off of the coastii. South Atlantic - mid ocean ridge pushing continent apartiii. Arabian Peninsula – rifting, divergent boundaryiv. Japan – is an island arc, lots of earthquakes, indicates tectonic activityv. Tibet – Indian colliding with Asia creates a high plateau b. Intro to plate tectonicsi. To accommodate the curvature of the earth, the cold rocks at the bottom of the ocean floor (rigid), break and crack because they can’t bend well. This creates large fracture systems. ii. Passive margins – not active boundaries, big shelves, no trenchesiii. Triple junctions – where three or more plate meet; often where new plates formc. Proposal of continental drifti. Observation: corner of Brazil in South America matches indentation of Africaii. Wegener proposed the continental drift hypothesisThese 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.1. Supported by the shapes of the continents (Pangea = map showing a supercontinent with all of the continents fitting together like puzzle pieces)2. Supported by similar fossils found on continents now separated by oceans3. Tropical fossils found in Alaska indicate it was once nearer to the equatoriii. Problems with continental drift1. Can’t move continents across the ocean floor due to the strength of the rock 2. The outline of the continents isn’t a perfect fitd. World War II and the proposal of plate tectonicsi. In WWII, ships mapped the ocean floor in a search for enemy submarines. In the process, they made some interesting discoveries about the topography of the sea floor, magnetized stripes on the sea floor, and earthquakes in the oceanii. Evidence for plate tectonics1. Pattern of earthquakes: activity occurs in distinct belts a. Mid ocean ridges, rifts, and plate boundaries2. Pattern of volcanoes: activity occurs in distinct belts3. Pattern of elevation: large mountain belts along belts of earthquakes and volcanoesIII. Three Types of Relative Plate Motionsa. Divergent – plate move apart from one another in opposite directionsi. Oceanic divergent boundary1. Where new ocean crust is made2. Oceanic plates move apart at mid ocean ridges (seafloor spreading)ii. Ridge axis – is a long, narrow trough or rift1. The mantle is heated from radioactive decay in the earth’s core. This causes convection currents as warmer mantle material rises. This upwelling (rising) of material toward the surface means there is also lessmaterial above, so less pressure. When pressure is reduced, the mantle spontaneously melts and rises through fractures. Magma then erupts orsolidifies at great depths in the ocean. iii. Triassic basins1. Early attempts to split Africa from North America and create an ocean2. The Hudson River valley could have been an ocean!b. Convergent – plates move towards each otheri. Creates subduction zonesc. Transform – plates move horizontally past one another i. Example – San Andreas fault (strike