GEOL 1425 1nd Edition Lecture 5 Outline of Last Lecture I. Warm-up question discussionII. Start of Plate TectonicsIII. Plate tectonic theoriesIV. Concept 1V. History of Plate tectonicsVI. Concept 2VII. Convergent plate boundaryVIII. Concept 3Outline of Current Lecture I. Warm-upII. Seafloor SpreadingIII. The Wilson CycleCurrent LectureI. Warm-up Questions—a. There were no warm-up questions for today!II. Concept 1: The final confirmation of seafloor spreading from ocean floor geomagnetic plates shows that there was seafloor spreading!a. The Atlantic has opened up at some point and the continents have spread out, and they will continue to do so!b. Ophiolite= sequence of rocks created at spreading centers, but we usually don’t see them on the Earth’s surface. 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.c. Pillow Lava= it is only formed under water, but many are visible above the water after their formation. Lava cools as soon as it hits the water. d. Magnetic mapping measures the rate of the seafloor spreading from magnetic oxide frozen in time or records the movement of rocks from polarities inside various rocks. e. The direction of Earth’s field changes and is shown in 4 different chorus—Gilbert,Gauss, Matuyama, and Brunhes.III. Concept 2: The Wilson Cyclea. Width of seafloor bands isn’t always the same, showing that in some areas, seafloor spreading happens faster or slower than in other areas. This affects and changes the climates of continents around the world. b. The Supercontinent Pangaea—the first breakup of this supercontinent resulted inLaurasia and Gondwanaland. c. Supercontinent cycle: cratons break apart, move around, and then reassemble. d. Data is sketchy, but shows there have been other supercontinents before Pangaea:i. Ur (3.0 billion years ago)—smaller than Australiaii. Kenorland (2.7 billion years ago)—its breakup brought greater rainfall, increased erosion, reduced greenhouse gasses and was associated with a snowball earth episode.iii. Columbia/Nuna (1.8 billion years ago)—very large but fragmented and didn’t last long at alliv. Rodinia (1.1 billion years ago)—outline is not clear, but made from the breakup of Columbia and much bigger than anything that had gone on before. Its breakup caused a major snowball earth effect.v. Pannotia—if it did exist it was very
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