8 th Grade Science Content Strand 4
Lithosphere- crust + upper mantle; solid, rigid, brittle; broken into plates; sits on top of asthenosphere Asthenosphere- mantle; plastic, flowing, hot; this is where the convection currents are
Oceanic- thinner, more dense, made of basalt rock Continental- thicker, less dense, made of granite rock
Faulting- tension forces, pulling apart; normal fault Faulting- compression forces, squeezing together; reverse fault Folding - compression forces, squeezing together
Causes plates to move Hot rocks in the mantle rises and sinks
Pangaea- supercontinent 200 million years ago Evidence Similar fossils on different continents Continents fit together like a puzzle Warm weather fossils in cold places like Spitzbergen
Convergent - come together Oceanic-continental: oceanic sinks, subduction, volcanoes Oceanic-oceanic: trench, subduction, island arc Continental-continental: mountains
Divergent- move apart Oceanic-oceanic- seafloor spreading, mid- ocean ridge Continental-continental- rift valley, volcanoes Transform- slide past each other Earthquakes, San Andreas Fault
Primary (P) waves- faster Secondary (S) waves- slower Surface waves- cause most damage Waves move faster through solids (more dense) than liquids.
Cold front- thunderstorms then cool, dry air Warm front- light rain then warm, humid air High pressure- clear, sunny (happy weather) Low pressure- cloudy, rainy (lousy weather) Isobars- lines that connect areas of equal air pressure
Trade winds (easterlies)- blow from east to west near the equator; steer hurricanes when they first form Prevailing westerlies- blow from west to east across the US Jet streams - blow from west to east high across the US
Lower air pressure= faster winds Trade winds- move hurricanes to west Westerlies- blow them back to the east Warm water- strengthens hurricanes Cold water/land - weakens hurricanes CANNOT predict path of hurricane with 100% accuracy!
Causes: Too much CO 2 in atmosphere 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
Renewable- solar, wind, hydroelectric, geothermal, biomass Nonrenewable- fossil fuels (oil, coal, natural gas), metals, nuclear (uranium)
Caused by tilt of the Earth During winter, tilted AWAY from sun; shorter daylight hours Spring equinox - equal day and night hours; tilted neither toward nor away from sun During summer, tilted TOWARD sun; longer daylight hours Fall equinox - equal day and night hours; tilted neither toward nor away from sun.
Tropical- near equator, warm year round, most direct sunlight Temperate- middle latitudes, warm summers, cool winters Polar- summer temperatures much higher than winter
Age: 13.7 billion years Largest to smallest - universe, galactic cluster, galaxy, solar system, Earth Milky Way- spiral galaxy, Sun is located in a spiral arm Red shift (long wavelength) shows universe is expanding.
Hotter stars give off higher energy radiation. Short wavelength=high energy Bluish-white stars give off ultraviolet.
Use of plants to make medicines, improve crops Using renewable resources instead of nonrenewable Found in nature, so they decompose naturally