Earth Science

• Plate Tectonics Theory

  • 200 million yrs. ago - pangea
  • now is called continental drift
• Plate Boundaries

  • Divergent
  • Convergent
  • Transform
• Mid-ocean ridges - underwater mountains
• Subduction zone - convergent
• Mountain ranges - collision of continental plates
• Rift Valley - crust being pulled apart
• Igneous rocks

  • solidification of molten lava
  • intrusive (below the earth) and extrusive (on the earth)
  • ex. granite and basalt
• Sedimentary Rocks

  • accumulation or sedimentation of sediments
  • Clastic- fragments from other rocks
  • Chemical-precipitation of minerals
  • Organic- remains of plants and animals
  • ex. sandstone, limestone, and coal
• Metamorphic Rocks

  • alteration of existing rocks
  • ex. marble and schist
• Strata - study of rock layers
• Law of Superposition - undisturbed rocks, top (young) and bottom (old)
• Principle of Original Horizontality - subsequent deformation or tilting
• Principle of Lateral Continuity - extend laterally until they thinned out
• P waves - fastest
• S waves - slowest
• Love waves - side to side motion
• Rayleigh waves- up and down motion
• Seismometers - detect ground motion
• Seismographs - record amplitude
• Mechanical Weathering - physical breakdown of rocks
• Frost Wedging - water seeps into the cracks of the rocks
• Exfoliation - outer peels
• Abrasion - wearing of rocks
• Chemical Weathering - chemical alteration of rocks
• Biological Weathering - influenced by living organisms
• River Deltas - form at the mouth of rivers
• Alluvial Fans - deposits of sediments
• Sand Dunes - wind of action
• Glacial Moraines - deposits of till
• Flood Plains - low lying areas adjacent to river