Unit 4 The Restless EarthPart I Lessons 1, 2, & 3 The Big Idea: The movement of tectonic plates accounts for important features of Earth’s surface and for major geologic events.
Unit 4 Lesson 1 Earth’s Layers Peeling the layers • Crust-outermost solid layer of Earth. (composed of O, Si & Al) • Continental • Oceanic-denser; contains 2x Fe, Ca & Mg • Mantle-region of hot, slowing flowing solid rock (composed of more Mg & less Al & Si) • Core- densest layer, mostly Fe & some Ni. Makes up about 1/3 of Earth’s mass.
Unit 4 Lesson 1 Earth’s Layers Heat it up! • Convection-movement of matter that results from differences in density caused by variations in temperature. • Convection in the mantle causes cooler rock to sink and warmer rock to rise.
Unit 4 Lesson 1 Earth’s Layers Earth’s 5 physical layers • Lithosphere—outermost layer, made of crust & the rigid part of the mantle divided into pieces called tectonic plates • Asthenosphere-layer of weak/soft mantle made of rock that moves very slowly. • Mesosphere-strong, lower part of mantle, rock flows more slowly than the rocks above. http://www.spring.net/geo/JohnVolos/Public/Portal/EARTH_MECHAN/structure_all.htm
Unit 4 Lesson 1 Earth’s Layers Physical layers continued • Outer core-liquid layer of Earth’s core • Inner core-the solid, dense center of our planet • Open to • pg. 198 • cut out Earth’s • layers & • glue into notes http://www.spring.net/geo/JohnVolos/Public/Portal/EARTH_MECHAN/structure_all.htm
Unit 4 Lesson 2 Plate Tectonics Puzzling Evidence • Alfred Wegener- proposed continental drift; the continents once formed a single landmass, broke up, & drifted. • Pangaea-single landmass formed about 245 mya • Evidence • Fossils • Locations of Mtn ranges • Rock types • Ancient climatic conditions
Unit 4 Lesson 2 Plate Tectonics Modern day proof • Mid-ocean ridges-underwater mtn ranges • Youngest rock closest to ridge • Oldest rock further away • Sea-floor spreading-molten rock from inside Earth rises at the ridges & forms new oceanic crust. Older crust is pushed away from the ridge, & the sea floor slowly spreads apart. • Ocean trench-oceanic crust sinks into asthenosphere.
Unit 4 Lesson 2 Plate Tectonics A giant jigsaw • Plate tectonics- theory that describes large-scale movements of Earth’s lithosphere • Tectonic plates- lithosphere is divided into pieces which move around on TOP of the asthenosphere
Unit 4 Lesson 2 Plate Tectonics Plate boundaries • Convergent boundaries -form where two plates collide. This can happen in three ways, depending on the types of crust involved. • Divergent boundary -two plates move away from each other, and magma rises to form new lithosphere at mid-ocean ridges. • Transform boundary-two plates move past each other horizontally. The motion of the two plates often produces earthquakes. http://www.scec.org/education/k12/learn/plate4.htm http://geology.com/teacher/plate-tectonics.shtml
Unit 4 Lesson 3 Mountain Building Stressed out • Stress- amount of force per unit area that is placed on an object • Deformation- process by which rocks change shape when under stress. • Folding- when rock layers bend under stress • Syncline-youngest rock layers are at the core of the fold. Usually arched upward, like a bowl. • Anticline-oldest rock layers are at the core of the fold. Usually arched downward. http://geology1a-1.wikispaces.com/Folds+and+Faults+with+captions
Unit 4 Lesson 3 Mountain Building faulted • Fault- a crack formed when large blocks of rock break & move past each other. • 3 Main Kinds of Faults • strike-slip fault-fault blocks move past each other horizontally (common along transform boundaries) http://geomaps.wr.usgs.gov/parks/deform/
Unit 4 Lesson 3 Mountain Building • Normal Fault- the hanging wall moves down relative to the footwall (Common along divergent boundaries) • Reverse Fault- then hanging wall moves up relative to the footwall. (Common along convergent boundaries) http://geology1a-1.wikispaces.com/Folds+and+Faults+with+captions
Unit 4 Lesson 3 Mountain Building Moving on up • Uplift-process that can cause land to rise, can also contribute to mountain building. • Formation of Mountains • Folding-rock layers are squeezed together & pushed upward (convergent boundaries) • Volcanism-melted rock erupts onto Earth’s surface • Faulting –tension makes • the lithosphere break into • many normal faults. http://freeroamingphoto.photoshelter.com/image/I000010wCG15TEDo