Plate Tectonics Notes PDF

Opening Most Sacred Heart of Jesus Prayer Have Mercy on us Most Sacred Heart of Jesus We trust in you Most Sacred Heart of Jesus Make our Hearts like unto yours AMEN PREREQUISITE KNOWLEDGE  ROCK CYCLE GEOLOGIC PROCESS PLATE MOTION Plate...

Opening Most Sacred Heart of Jesus Prayer Have Mercy on us Most Sacred Heart of Jesus We trust in you Most Sacred Heart of Jesus Make our Hearts like unto yours AMEN PREREQUISITE KNOWLEDGE  ROCK CYCLE GEOLOGIC PROCESS PLATE MOTION Plate motions cause mountains to rise where plates push together, or converge, and continents to fracture and oceans to form where plates pull apart, or diverge. The continents are embedded in the plates and drift passively with them, which over millions of years results in significant changes in Earth's geography.  Continent Accretion Theory --the continents have always been stationary, with the gradual addition of new material around a central nucleus. --proposed by James Dwight Dana  Continental Assimilation Hypothesis --the ocean areas accumulated the denser elements then subsided to form basins.  Expanding Earth Hypothesis --the present continents split apart with the expansion of Earth and that the continents combined could cover half of the current Earth’s surface area Expanding Earth Hypothesis  Continental Drift Theory ALFRED WEGENER  Pangaea was covered by one big ocean called Panthalassa. A sea called Tethys divided the Pangaea into two huge landmasses: Laurentia (Laurasia) to the north and Gondwanaland to the south of Tethys. Drift started around 200mya (Mesozoic Era, Triassic Period, Late Triassic Epoch). Evidences for Continental Drift Theory The Fit of Continental Shorelines Distribution of Glacial Sediments Paleoclimate Distributions of fossils Distribution of Rocks Evidence 1 The Fit of Continental Shorelines Evidence 2 Distribution of Glacial Sediments Evidence 3 Paleoclimate  Paleoclimate One piece of evidence Wegener provided was paleoclimatic indicators that linked South America and Africa (Plate Tectonics: Continental Drift). He noted that glacial, tropical rain forests, and desert deposits were aligned when the continents were placed together (Plate Tectonics: Continental Drift). Evidence 4 Distributions of fossils Evidence 5 Distribution of Rocks Sea-Floor Spreading  Seafloor Spreading -- In 1960, Harry Hess studied Wegener’s theory -- is a geologic process in which tectonic plates split apart from each other as a result of mantle convection. -- it occurs at divergent plate boundaries --formation of mid-ocean ridges (large mountain ranges) arising from the ocean floor  Seafloor Spreading Picture of Harry Hess while explaining his theory of Seafloor Spreading Sea-Floor Spreading  Ocean floor moves like a conveyor belt carrying continents with it. New ocean floor forms along cracks in the ocean crust as molten material erupts from the mantle spreading out and pushing older rocks to the sides of the crack. New ocean floor is continually added by the process of sea-floor spreading. Sea-Floor Spreading  Sea-Floor Spreading Mid-Ocean Ridge – the longest chain of mountains in the world--- these are divergent plate boundaries. Sea-Floor Spreading  Plate Tectonics and Plate Movements SEVEN MAJOR PLATES LARGEST MINOR PLATES African Plate Arabian Plate Antarctic Plate Caribbean Plate Eurasian Plate Cocos Plate Australian Plate Juan de Fuca Plate North American Plate Nacza Plate Pacific Plate Philippine Plate South American Plate Scotia Plate Plate Tectonics and Plate Movements Plate tectonics is the theory that Earth’s outer shell is divided into several plates that glide over the mantle. The plates act like a hard and rigid shell compared to mantle. The strong outer layer is called lithosphere which is 100 km (60mi) thick The lithosphere includes crust and outer part of mantle. Below the lithosphere is the asthenosphere which is malleable allowing the lithosphere to move around.  Plate Tectonics and Plate Movements DIVERGENT BOUNDARY CONVERGENT BOUNDARY TRANSFORM BOUNDARY DIVERGENT BOUNDARY -- occurs when two tectonic plates move away from each other --frequent earthquakes strike along the rift --beneath the rift, magma rises from the mantle, it hardens into solid rock and forms new crust --oceanic crust made of basalt is created CONVERGENT BOUNDARY Continental-continental boundaries are when two continental plates converge and neither of them is subducted below the other because the continental rocks are relatively light and resist downward motion. CONVERGENT BOUNDARY Oceanic-continental boundaries are when an oceanic and a continental plate converge and the denser oceanic plate is subducted below the continental plate.  CONVERGENT BOUNDARY Oceanic-oceanic boundaries are when two oceanic plates converge. One plate is usually subducted under the other and in the process a deep oceanic trench is formed and can also result in the formation of undersea volcanoes  TRANSFORM BOUNDARY Transform boundary occurs when two plates sliding past each other. Natural or human-made structures that cross a transform boundary are offset– split into pieces and carried in opposite directions.  GROUP ACTIVITY You will be divided into 6 groups. All you have to do is choose only 1 of the evidences presented in continental drift theory and explain why. You have 10 minutes to prepare.