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Transcript
Chapter 3 – The Dynamic Earth Section 1: The Geosphere 1. Describe the composition & structure of the Earth 2. Describe the Earth’s tectonic plates 3. Explain the main cause of earthquakes & their effects 4. Identify the relationship between volcanic eruptions & climate change 5. Describe how wind & water alter the Earth’s surface The Earth as a System • Earth consists of ________________________, & living things AIR that interact with each other • Divided WATER into 4 parts: LIVING THINGS ROCK The Earth as a System • ___________________ – Solid portion consisting of rock – Extends from center of ____________ to surface of _____________ • Atmosphere – Mixture of _________________ – Most found in first 30 km above Earth’s surface • ________________________ – All water on or near surface – Most is _______________ • Biosphere – Where _____________ exists – Extends from 9 km above surface to bottom of ocean Discovering Earth’s Interior • _________________ used to study interior of Earth • Seismic waves Earthquake – Travel through Earth’s interior during earthquakes – Altered by type of material they move Seismic – Changes in speed & wave direction measured when passing through different layers Composition of the Earth • Divided into three layers based on ______________ – Crust – Mantle – Core • layers become progressively _____________ toward the center Crust Core Mantle Crust • Thin, _____________ layer – 5 to 8 km beneath oceans – 20 to 70 km beneath continents • Solid, ____________ • Composed of lightweight elements • Makes up less that ____ of Earth’s mass Mantle • Layer between crust & core • Composed of rock with medium density • Contains ____________ minerals • Makes up _______ of Earth’s mass • Approximately 2900 km thick Core • Innermost layer – ______________________ • Super-heated molten lava • Composed of liquid nickel & iron – ______________________ • Sphere of solid nickel & iron • Consists of densest elements • Radius approximately 3400 km Solid inner core The Structure of the Earth • Divided into 5 layers based on the ______________ properties _____________ _______________ _____________ _________ Core __________ Core Lithosphere • Composes ___________ & upper part of ____________ – 15-300 km thick (9-185 mi) • Divided into large pieces called ________________ plates – May be oceanic or continental – Slide on fluid portion of mantle – Movement can cause earthquakes Asthenosphere • Beneath lithosphere – 250 km thick (150 mi) • Solid, plastic-like material of mantle – Made of rock that ______________ – Due to temperature & pressure • Allows for movement of tectonic plates Mesophere • Lower part of mantle • More solid & rigid than asthenosphere due to increased pressure – Can’t flow Lithosphere Asthenosphere Mesosphere Outer Core Inner Core Outer Core • Super-heated molten lava – Composed of ______________ nickel & iron – 4000 to 9000 °F • Source of Earth’s magnetic field – Creates protective bubble – Deflects Sun’s solar winds Inner Core • _______________ ball • Composed of nickel & iron • 9000 °F & 45,000,000 psi • Rotates in liquid outer core Plate Tectonics • Large, irregularly shaped slabs of rock • Composed of oceanic & continental lithosphere – Continental rocks • Lightweight minerals (quartz, feldspar) • Thicker crust – Oceanic rocks • Heavier, denser basltic rocks • Thinner crust Major & Minor Tectonic Plates Plates move in different directions and speeds, thus crash together, pull apart or side swipe each other like cars in a demolition derby Plate Boundaries • Most geologic activity occurs where plates _______________or ______________ (called boundaries) • Movement of plates creates 3 types of tectonic boundaries – _______________ – plates collide, move into one another – _______________ – plates move apart – ________________ – plates move sideways in relation to one another • Movement of tectonic plates causes – Mountain formation – Earthquakes – Volcanic eruptions Plate Tectonics and Mountain Formation • Plates collide, crust thickens • Rocks break & buckle – Continental plate folds into huge mountain – Oceanic plate forms trench • Examples – Rocky mountains (N. America) – Himalaya mountains (Central Asia Earthquakes • _____________– breaks in Earth’s crust where plates slide past each other • Rocks under stress break off triggering ground vibrations - called earthquakes • Magnitude (Richter Scale) – Measure of energy released – ________ – smallest felt – _________ – largest recorded – Increase of 1 whole number = 31.7 times more energy Where Earthquakes Occur Most occur at or near plate boundaries Earthquake Hazard • Earthquake hazard level determined by past & present seismic activity • Hazards (effects) include – Ground shaking (building damage/settling of ground beneath to different level) – Ground displacement – Flooding (breakage of levies, dams, Tsunamis) – Fire (broken gas & power lines) • Human hazards due to man-made structures – Being crushed, buried or burned or drowning • National Hazards Maps used by cities, counties & local governments to update & create more stringent building codes Volcanoes • Mountains built from ______________ (molten rock) • Magma rises to surface from interior • Most common at convergent or divergent plate boundaries • Can occur on land or in oceans Block between separating faults cracks, drops into asthenosphere forming a rift. Magma seeps upward to fill in crack Volcanoes: The Ring of Fire North American Plate Eurasian Plate South American Plate • Majority of active volcanoes on land located along tectonic plate surrounding the ____________ ___________ Pacific Plate Australian Plate Antarctic Plate Local Effects of Volcanic Eruptions • Clouds of hot ash, dust, & gases flow down the slopes of volcanoes searing anything in its path – Obscures ______________, killing plants & animals • Volcanic ash mixes with water producing ________________ – Water contamination – Land contamination • _________________ of buildings, burying of crops, & damage to vehicle engines due to falling ash Global Effects of Volcanic Eruptions • Can cause changes in Earth’s ________________ • Ash & sulfur-rich gases reach upper atmosphere & ____________________reaching Earth’s surface • Reduction in sunlight reduces average global temperatures _________________ • Process resulting in materials of the Earth’s surface being loosened, dissolved or worn away & transported from one place to another by natural agents such as wind, water, ice or gravity • ______________ erosion – Rivers carve deep canyons or gorges into bedrock – Depositing of dust, pebbles, rocks forms new land areas – Oceans erode coastlines • ______________ erosion – Removal of most fertile part of soil lowering soil productivity – Creates sand dunes