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Discover how geology impacts our everyday lives, from mining to energy production and the importance of minerals. Learn about the compositional and mechanical layers of the Earth and the theory of continental drift. Explore the evidence that supports this theory and discuss its main objections. Find out how convection and radioactive decay play a role in Earth's heat engines. Get creative with a poster of Earth's layers and engage in a pair share discussion on how continents may have moved.
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BELLWORK Q: Describe the ways that your pencil is connected to GEOLOGY. How else do you use GEOLOGY everyday?
What Else? • What about your home… • Health care …. • Economy …
Basic Earth Science Objectives • Describe the compositional properties and mechanical layers of earth • Describe tectonic plates • Examine Continental Drift Theory and its development into modern plate tectonics • Discuss mechanism for movement
RCC 1 • What does composition mean? • What does mechanical describe? • What are the COMPOSITIONAL LAYERS OF EARTH? • What are the MECHANICAL LAYERS of EARTH?
RCC 1 • What does composition mean? • What does mechanical describe? • What are the COMPOSITIONAL LAYERS OF EARTH? • What are the MECHANICAL LAYERS of EARTH?
Compositional Layers • Crust 5-70 km (3-44 miles) thick; (solid & brittle) Earth elements. • Continental crust • Oceanic crust • Mantle 2,900 km (1,800 mi) thick; dense iron rich materials. • Core 3,428 km (2,130 mi) radius; hot dense nickel and iron.
Mechanical Layers • Lithosphere 15-300 km, consists of the crust and rigid uppermost mantle; tectonic plates. • Asthenosphere 250 km, solid plastic layer, very slowly flowing rock located under the lithosphere. • Mesosphere 2,550 km, “middle sphere” lower mantle section. • Outer Core 2,200 km, outer shell of core, LIQUID nickel and iron. • Inner Core 1,228 km,SOLID nickel and iron.
BONUS • HOW do scientists know that the outer core is LIQUID and the INNER CORE is solid? Look it up- get a good website (.gov, .edu or reputable scientific publication) find answer – summarize – email me 1 short paragraph with the URL included.
POSTER • LAYERS OF THE EARTH • It’s your first grade • Must have a title and some labels/explanation of layers • Be creative!
Continental Drift • In 1912 Alfred Wegener (1880-1930) proposed that the continents were once compressed into a single protocontinent which he called Pangaea (meaning "all lands"). • He is seen as the developer of the Theory of Continental Drift, or as he called it, "continental displacement".
Continental Drift Theory • Alfred Lothar Wegener • German Meterologist • Life’s work • Labeled a quack • Froze to death in Greenland • Never got credit - in life • Let’s examine the evidence….
Continental Drift Animation • Theory that all continents were once connected as part of 1 giant single landmass National Geographic Video – stop at 17 min
Continental Drift Theory Based on evidence collected by ALW: • Geographic fit of continental coastlines • Fossils • Ancient glacial evidence • Mountains • Rock record VIDEO CDT Animation
What is a THEORY? • As used in science, a theory is an explanation or model based on observation. • Can not be recreated in a lab setting.
QUICK QUIZ QUESTION • What 5 different types of evidence did Wegener use to support Continental Drift Theory?
Problems • Main objection to Wegener's proposal was its inability to provide a mechanism for the continents to move • Wegener believed the continents pushed through the ocean crust like a ship sails through water
Objectives Met – Make sure you know these • List the 3 compositional layers of the Earth (from outside in). • List the 5 Mechanical layers. • List the 5 types of evidence that Alfred Wegener used to support CDT. • What was the main problem with his theory? • How old is Earth? -4.5 X 109
PAIR SHARE -Based on what you’ve learned so far about Continental Drift Theory – How do YOU think that the continents moved? Answer and then discuss w your partner.
Discuss Ideas for Movement • Examine the Red Hot Magma Lamp…. • Please explain as completely and scientifically possible – what is happening in the lamp and how it works. • Use a diagram to explain. • Volunteer….
Convection • Convection transfers heat from the Earth’s core to the surface. • Convection is the driving heat engine that powers the motion of the Earth’s great tectonic plates. • Plate tectonics is the Earth’s way of expelling heat to space.
Earth’s Heat EnginesInner core is the internal heat engine. • Internal (heat moving from hot interior to cooler exterior) • Primary driver of most geospheric phenomena (volcanism, magmatism, tectonism) CONVECTION
Earth’s Heat EnginesExternal Heat Engine is the SUN • External (energy from the Sun) • Primary driver of atmospheric (weather) and hydrospheric (ocean currents) circulation • Controls weathering of rocks at Earth’s surface
Mantle Convection • Movie 1 – Convection • Movie 2 – Effects on Lithosphere
RADIOACTIVE DECAY • Is the energy in the inner core that fuels CONVECTION.
Mantle Convection • Movie 1 – Convection • Movie 2 – Effects on Lithosphere
So… • Radioactive decay in the inner core • CONVECTION • Plates to move • !!!! Convection IS Wegener’s mechanism for movement!!!!!
CRUST • Oceanic Crust is BASALT • Thinner • More Dense • Less Buoyant • Continental Crust is (mostly) GRANITE • Thicker • Less Dense • More buoyant
CONVERGENT PUSHES TOGETHER • Continent to continent = Mountains • Continent to Seafloor = (sub-duction zone) Trenches and volcanoes • DESTRUCTIVE b/c Lithosphere is being DESTROYED SEE PICTURE
DIVERGENT • Any type crust (continental crust or oceanic) • Pulls apart • CONSTRUCTIVE • Rifts (land) , and ridges (in water) are formed • EX: Mid Atlantic Ridge and East African rift Valley
TRANSFORM • Plates slide past each other • MANY earthquakes
WARM UP/ DO NOW • Please explain, Using a diagram and 2 sentences - How the red hot magma lamp is related to CDT.
Objectives 4. Describe Sea Floor Spreading and explain some evidence for it.
Seafloor Spreading • In the early 1960s, Princeton geologist Harry Hess proposed the hypothesis of sea-floor spreading, in which basaltic magma from the mantle rises to create new ocean floor at mid-ocean ridges. • On each side of the ridge, sea floor moves from the ridge towards the deep-sea trenches, where it is sub-ducted (pushed under) and recycled back into the mantle.