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Earth and Space Science. 8 th Grade Science Content Strand 4. 4.a. Lithosphere and Asthenosphere. Lithosphere- solid, rigid, rocky; divided into plates, sits on top of asthenosphere Asthenosphere- plastic, flowing, hot; mantle, contains convection currents.
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Earth and Space Science 8th Grade Science Content Strand 4
4.a. Lithosphere and Asthenosphere • Lithosphere- solid, rigid, rocky; divided into plates, sits on top of asthenosphere • Asthenosphere- plastic, flowing, hot; mantle, contains convection currents
4.a. Oceanic and Continental Crust • Oceanic- thinner, more dense, sits lower in the mantle • Continental- thicker, less dense, sits higher in the mantle
4.a. Faulting and Folding • Faulting- tension forces, pulling apart • Folding- compression forces, squeezing together
4.b. Convection Currents • Causes plates to move • Hot rocks in the mantle begin to move
4.b. Continental Drift • Pangaea- supercontinent 200 million years ago • Evidence • Similar fossils on different continents • Fit together like a puzzle • Warm weather fossils in Antarctica
4.b. Plate Boundaries • Convergent- come together • Oceanic- continental- oceanic sinks, volcanoes • Oceanic-oceanic- trench, island arc • Continental-continental- mountains
4.b. Plate Boundaries • Divergent- move apart • Oceanic-oceanic- seafloor spreading, mid-ocean ridge • Continental-continental- rift valley, volcanoes • Transform- slide past each other • Earthquakes, San Andreas Fault
4.b. Earthquake Waves • Primary waves- faster • Secondary waves- slower • Surface waves- cause most damage • Waves move faster through solids (more dense) than liquids.
4.c. Weather Forecasting • Cold front- cooler temperatures, thunderstorms • Warm front- warmer temperatures, light rain • High pressure- clear, sunny • Low pressure- cloudy, rainy • Isobars- lines that connect areas of equal air pressure
4.c. Winds • Trade winds (easterlies)- blow from east to west near the equator • Westerlies- blow from west to east above 30° North • Can steer hurricanes toward or away from equator
4.d. Global Warming • Causes: Too much CO2 • Burning fossil fuels (coal, oil, natural gas) • Deforestation (cutting down trees) • Ways to Reduce: • Recycle • Walk or ride bicycle • Energy efficient appliances • Fluorescent bulbs • Use renewable energy
4.d. Resources • Renewable- solar, wind, hydroelectric, geothermal, biomass • Nonrenewable- fossil fuels, metals, nuclear (uranium)
4.e. Seasons • Caused by tilt of the Earth • Longer daylight hours during summer than winter. • Equal amounts of daylight during spring and fall.
4.e. Climate Zones • Tropical- near equator, warm year round, most direct sunlight • Temperate- middle latitudes, warm summers, cool winters • Polar- summer temperatures much higher than winter
4.f. Structure of Universe • Age: 13.7 billion years • Largest to smallest- universe, supercluster, cluster, galaxy, solar system, Earth • Milky Way- spiral galaxy, Sun is located in a spiral arm • Red shift (long wavelength) shows universe is expanding.
4.f. Stars • Hotter stars give off higher energy radiation. • Short wavelength=high energy • Bluish-white stars give off ultraviolet.
4.g. Natural Products • Use of plants to make medicines, improve crops • Using renewable resources instead of nonrenewable • Found in nature
4.h. Hurricanes • Lower air pressure= faster winds • Trade winds- move hurricanes to west • Westerlies- blow them back to the east • Warm water- strengthens hurricanes • Cold water- weakens
