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Earth’s Interior. Lithosphere Solid topmost part of Earth Broken up into large sections called plate. Asthenosphere Upper edge of Mantle plasticity. Crust . Igneous, Sedimentary & Metamorphic rock Silicon, Iron, Magnesium, oxygen, aluminum, calcium, sodium, potassium Solid
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Lithosphere Solid topmost part of Earth Broken up into large sections called plate Asthenosphere Upper edge of Mantle plasticity
Crust • Igneous, Sedimentary & Metamorphic rock • Silicon, Iron, Magnesium, oxygen, aluminum, calcium, sodium, potassium • Solid • Ocean crust less than 10 km thick • Continental crust 32 to 70 Km thick
Mantle • Silicon, oxygen, iron, & magnesium • Liquid that shows plasticity • 870 to 2200 degrees Celsius • Radius = 2900 Km • About 70 Km below surface • 80% of Earth’s Volume & 68% of Earth’s Mass • Moho – 1909 Abdrija Mohorovicic • Above Mantle about 32 to 64 Km below surface of Earth
Inner Core Iron & nickel Solid 5000 degrees Celsius Radius = 1300 Km 5150 Km below surface Outer Core Around inner core Iron & nickel liquid 2200 to 5000 degrees Celsius Radius = 2250 Km 2900 Km below surface Earth’s Core
Plate Tectonics Pangaea Continental Drift – Alfred Wegener Evidence Fossils Continent shapes Rock formation on different continents Mineral and rock deposits (salt, limestone, glacial deposits) Coral reefs Swamps, oil deposits
Ocean-Floor Spreading Ocean crust younger than continent crust…? Ocean floor being subducted under continents Midocean ridges Rocks younger at center/ridges
Magnetic Stripes in Ocean-Floor • In molten rock magnetic minerals line up w/ the poles • Molten rock hardens leaving solid magnetic evidence • Scientists have discovered that the pole have switched over the past 3.5 million years because the magnetic stripes switch over
Magnetic stripes match on opposite sides of the mid-ocean ridge showing that both sides have changed at the same rate…giving more proof of sea floor spreading.
Convection Currents Movement of material due to a difference in temperature Lab & overhead…
Earth’s Moving Plates Theory of Plate tectonics links continental drift and ocean-floor spreading 7 major lithosphere plates and many smaller ones (pg 65 & overhead) Plates all move in different directions and at different speeds
Plate Boundaries • Divergent – constructive • Convergent – destructive • 2 ocean plates – older subducted • Ocean plate – continent – ocean plate is subducted and continental plate folds some • 2 continental plates – continents fold up into mts (appalachian, himalayan…) • Strike-slip – conservative
Divergent Boundaries Iceland
Plate Changes Plates fuse together Plates change direction New divergent boundaries form Plates can completely be subducted and disappear
New Ocean in Africa http://www.cbsnews.com/stories/2005/12/10/tech/main1115779.shtml
Volcanoes Formed when molten rock (magma) emerges through an opening, or vent, from Earth’s interior (above or below water) Lava = magma forced out of Earth’s interior Accumulation of volcanic lava and rock debris = a cone, dome shaped structure
Volcano Terms Crater = steep, funnel shaped depression at top of volcano Caldera = larger depression formed when crater collapses Cinder cone = tall, steep, explosive eruptions Shield volcano = large, gentle slope, quiet lava flows Composite volcano = alternate explosive eruptions & gentle lava flows
Volcanic Eruptions‘ • Gases – water vapor, carbon dioxide, hydrogen sulfide, chlorine, fluorine, boron • Liquids – lava • Solids – (pyroclastics – solid magma) ash bombs
Volcanic Activity • Active volcano – erupts continually or periodically • Dormant – currently not active, but known to have erupted in modern history • Extinct – not known to have erupted in modern history • Most activity occurs at plates boundaries • Ring of fire = circle around Pacific Ocean • Middle of Atlantic Ocean, and near Mediterranean Sea
Volcanic Geological Situations Two plates converge beneath an ocean, one plate goes beneath and melts = Aleutian Islands Mid-ocean ridge – two plates separate as molten material pushes up between Ocean plate moves beneath continent plate and melts = Cascade mts in Pacific NW
Hot spots Hawaiian Islands “hot spot” beneath crust push magma up creating volcanoes islands
Volcanic Impact Most people die from burns and/or suffocating Habitat destruction (human and wildlife) Natural resourse destruction Agricultural destruction Cleanup… Thermal energy, nitrogen….
On November 14, 1963, an Icelandic fisherman noticed a plume of smoke rising from the open water. Within a day, Surtsey, a new volcanic island, had formed off the southern coast of Iceland from an undersea eruption that originated at a 130 meter depth. An island eventually rose to a height of 169 metres above sea level that had an area of 2,5km². This island was named Surtsey for Surtur, the fire possessing giant of Norse mythology who would set fire to the earth at the Last Judgment.For three and a half years Surtsey rumbled and lava flowed. Long before the eruption stopped the island was proclaimed a nature preserve and all travel there was restricted to scientist that used this unique opportunity to study the gradual development of life on a sterile landmass.