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EARTH SCIENCE A Quick Review Where are we? • 3rd planet from the sun • About 92 million miles – Perfect distance to balance warmth – “The Water Planet” Who are we? • • • • Geosphere Hydrosphere Atmosphere Biosphere Earth’s History • About 4.6 billion years old (according to rock record) • Geologic Time scale - broken down into eons, eras, periods and epochs. (Precambrian epoch = 87% of time scale) Earth’s History • Divisions mainly dependent on rise of certain types of organisms or major events. Earth’s Composition • 3 major concentric zones • Core: – Solid inner – due to pressure (Ni & Fe) – Molten outer - creates magnetic field (Fe & S) • Mantle: – Mostly solid – Asthenosphere = slowly flowing • Lithosphere: – Thin rigid – Contains the crust Earth’s Magnetic Field Earth’s Crust • Oceanic crust – mostly basalt (more dense, ~3.0g/cm3) • Continental crust – mostly granite (less dense, ~2.7g/cm3) Plate Tectonics • Nuclear decay in the core releases heat into the mantle and asthenosphere causing convection currents that create plate movement Plate Tectonics • Convection currents have caused the mass movement of plates over millions of years. Plate Tectonics • The movement of these plates is called “Continental Drift”. Plate Tectonics • Each individual plate (about 12) is made of lithosphere and mantle. Plate Tectonics • Today, the plates are still in motion – – PLATE TECTONICS – http://sos.noaa.gov/videos/Paleo3.mov Plate Tectonics • The plates today: Plate tectonics • Plate boundaries – edges of the plates – Three types: convergent, divergent and transform Earth’s Crust • Convergence (subduction) • Creates mountains and volcanoes Earth’s Crust • Divergence (ridge formation) – Creates volcanoes and new crust Earth’s Crust • Transform – plates sliding past one another. – Creates earthquakes Volcanoes • Active • Dormant • Extinct • Subduction volcanoes – At plate boundaries • Hot spot volcanoes – In the middle of plates Volcanoes • Rift Volcanoes – Form new oceanic crust Earthquakes • Each black dot is the location of an earthquake Earthquakes • Anatomy: – Fault – Focus – Epicenter – Waves Rock Cycle • Rocks come from rocks • Time, erosion, pressure and heat create 3 basic types – Igneous – Sedimentary – Metamorphic • Erosion Rock Cycle Soil • A crucial link between biotic (living) and abiotic (nonliving) Earth’s orbit and rotation • Revolution, rotation and tilt determine our days and seasons. Seasons • Spring in the Northern, Autumn in the Southern Seasons • Summer in the Northern, Winter in the Southern Seasons • Autumn in the Northern, Spring in the Southern Seasons • Winter in the Northern, Summer in the Southern The Atmosphere • A layer of gases held close to the Earth by gravity • With the help of the sun, it’s where our weather and climates occur Atmosphere • Troposphere – all of the weather, most of the water vapor and clouds. • Well mixed layer. • Area of the atmosphere that holds the greenhouse gases The Greenhouse Effect • Without the greenhouse gases (CO2, H2O, and CH4) in the atmosphere, we wouldn’t survive. Atmosphere • Stratosphere – not well mixed. • Contains the ozone layer (O3) Atmosphere • Mesosphere – where meteors usually burn up. Atmosphere • Thermosphere (or Ionosphere) • Thinnest gas layer – Aurora’s – Space shuttles – Ionization (absorption of solar wind) – Reflects radio waves Atmosphere • Exosphere – Satellites – Lightest gases – H2 and He Atmosphere • Magnetosphere – area where the magnetic field of the earth dominantly controls the movements of gas and charged particles. Hydrosphere & Biosphere • We’ll cover these later…..