Plate Tectonics PDF

Science 10 Lesson 1 PLATE TECTONICS Do you know why? Have you ever noticed how well continents seem to fit together like puzzle pieces? It might seem like a coincidence, but there's actually a scientific explanation! PLATE TECTONICS Let's work together in small groups. Your m...

Science 10 Lesson 1 PLATE TECTONICS Do you know why? Have you ever noticed how well continents seem to fit together like puzzle pieces? It might seem like a coincidence, but there's actually a scientific explanation! PLATE TECTONICS Let's work together in small groups. Your mission is to put the continents back together as accurately as possible. Once everyone is finished, we'll discuss if you noticed any interesting patterns!  Introduction At the start of the 20th century, the Raisin Theory likened Earth to a grape shrinking into a raisin as it cooled after the Big Bang about 13.77 billion years ago. Scientists thought this cooling caused the crust to contract, resulting in mountain formation from upward movement and ocean basins from downward buckling. Note: Based on Scientific theory: Earth began as a hot, molten mass.  Isostacy Proposed by: American Seismologist and Geologist CLARENCE EDWARD DUTTON in 1889 Isostasy is the idea that the Earth's surface is balanced (Earth's crust in a state of equilibrium).  Isostacy For this balance: Equal Mass Under Equal Area: Areas of the Earth's surface with the same size must have the same mass underneath them. Continental vs. Oceanic Crust: Continents are lighter and float higher on the Earth's mantle, while the denser ocean floor sinks lower. ALFRED WEGENER He proposed the Continental Drift Theory in his book ‘’The Origins of Continents and Oceans in 1915’’. Continental Drift Theory suggest that the continents had once been joined, and over the time had drifted apart. Basis of the Modern day Plate Tectonics theory. SUMMARY OF THE BREAK OF PANGAEA PERMIAN: 250 million years ago (permian period) Earth continents were joined together in a supercontinent called PANGAEA (this landmass began to break apart later). TRIASSIC: 250-200 million years ago, PANGAEA started to split into two smaller continents: LAURASIA (north) and GONDWANA (south). JURASSIC: from 200-145 million years ago, these two supercontinents continue to break apart. SUMMARY OF THE BREAK OF PANGAEA CRETACEOUS: ABOUT 145-66 million years ago, the continents moved closer to their current positions. PRESENT DAY: The continents are in the positions we recognize REMEMBER: They are not static but continue to move due to PLATE TECTONICS Supercontinent Timeline Supercontinent Timeline  Please Take Note! Rodinia It is the supercontinent that existed around 1,100 million years ago, before Pangaea.  TYPES OF LITHOSPHERIC PLATES OCEANIC LITHOSPHERE CONTINENTAL LITHOSPHERE Continental Plates VS Oceanic Plates Continental plates are thick, rigid slabs of rock that make up Earth's continents. They are less dense (lighter) than oceanic plates due to their composition of lower-density materials, such as granitic rocks. Continental Plates VS Oceanic Plates Oceanic crust are thin, dense slabs of rock that form the ocean floor. They are composed of heavier basalt and gabbro rocks, making them denser than continental crust, and are generally younger than continental crust. PLATE TECTONICS THOERY States that surface of the Earth is composed of large and small segments called plates, which have moved throughout Earth's history.  PLATE TECTONICS THEORY EARTH’S outer shell, known as LITHOSPHERE, fragmented into large and small plates. It floats on a semi-fluid layer called ASTHENOSPHERE PLATES fit together like a JIGSAW PUZZLE Movement ranges from 1 to more than 15cm per year. Earth’s Mechanism of Plate Tectonics Plate tectonics is considered the most important theory in geology. It explains Earth's environment and subsurface activities using geologic and geophysical data. The theory links earthquakes, volcanoes, and mountain formation to the movement of lithospheric plates. Lithospheric plates move due to mantle movements. The Mantle Convection Theory and Slab Pull Theory explain plate movement mechanisms.  MANTLE CONVECTION Mantle convection is a key force behind plate tectonics. Arthur Holmes proposed this theory in 1929, building on Wegener's observations. As the mantle heats, its density decreases, causing it to rise. When the mantle cools, it sinks, creating a conveyor belt-like movement. Holmes theorized that this pressure breaks continents apart, causing them to drift. When the material sinks, continents may be brought back together. MANTLE CONVECTION  THE SLAB PULL THEORY The Slab Pull Theory states that gravity and plate subduction drive tectonic movements. In subduction zones, older, cooler, and denser rocks sink into the mantle, pulling the rest of the plate with them. Denser slabs exert more force and sink faster, driving plate movement. The theory argues that mantle convection results from subduction, not the other way around.  Science 10 Lesson 2 EVIDENCE OF PLATE MOVEMENT  Introduction The idea of moving lithospheric plates is now widely accepted, though some skepticism remains. Alfred Wegener's continental drift theory faced initial skepticism, with critics ignoring the plasticity of deep rocks. Wegener's theory was not appreciated during his lifetime and was considered improbable until after his death in 1930. The 1950s discovery of magnetic reversals led to the acceptance of Wegener's ideas and the development of Plate Tectonics Theory.  Evidence of Plate Movement 1. Paleontological Evidence - Similar fossils found on continents across the Atlantic suggest they were once connected. - Fossils of land-dwelling reptiles Lystrosaurus and Cynognathus from the Triassic Period are widespread. - Antonio Snider Pellegrini used identical plant fossils from Europe and the US to support the idea of a connected supercontinent during the Pennsylvanian Period. - Edward Seuss noted similarities in Late Paleozoic plant fossils across India, Australia, South Africa, and South America. - Fossil distribution of the seed fern Glossopteris supports the idea of continental drift, as it could not be dispersed by wind alone. Evidence of Plate Movement  Evidence of Plate Movement 2. Evidence From Glaciation - Glacial till deposits in the southern hemisphere suggest past glacier movement, which aligns when continents are fit together like a puzzle. - The discovery of coal deposits in Antarctica supports the idea of abundant past flora and fauna in now-icy regions. - During the late Paleozoic Era (around 300 million years ago), glaciation affected much of the southern hemisphere. - Glacial deposits show that ice moved inland from the oceans in South America, India, and Australia, implying a connected landmass where ocean basins now exist. Evidence of Plate Movement  Evidence of Plate Movement 3. Evidence From Paleoclimates - Paleoclimatology studies past climatic conditions to show how climate belts have shifted over time. - Wegener used rock types to reconstruct ancient climates, finding glacial till and striations near the poles indicating polar climates, while sand dunes and coral reefs pointed to desert and tropical climates. - Large coal deposits in Antarctica suggest that abundant flora and fauna once existed there, indicating a much warmer climate in the past.  Evidence of Plate Movement 4. Evidence From Paleomagnetism - Paleomagnetism examines ancient magnetic fields to find past magnetic pole directions and latitudes. - Wegener noted that rocks from different locations had different magnetizations, indicating pole movement. - Magnetic minerals show that Earth's poles have reversed many times over geological periods. - At mid-ocean ridges, cooling materials align with Earth's magnetic field, creating parallel strips of normal and reversed polarities. 1. What is the earth’s interior made of? 2. How will you describe its internal structure? 3. How did scientists deduce which layer of the earth is solid, liquid or semisolid?  EARTH composed of 58 crustal plates 15 Major Plates 7 or 8 Primary Plates Others are Smaller Plates PRIMARY PLATES SECONDARY PLATES 1. Africal Plate 1. Arabian Plate 2.Eurasian Plate 2.Carribean Plate 3.Indo-Australian Plate 3.Cocos Plate 4.North American Plate 4.Indian Plate 5.Pacific Plate 5.Juan de Duca Plate 6.South American Plate 6.Philippine Sea Plate 7.Nazca Plate  The boarder between two tectonic plates. The place where two plates meet or diverge. 3 types includes: Convergent, Divergent and Transform plate boundary.