science

• The world’s earthquakes are not randomly distributed over the earth’s surface. They tend to be concentrated in narrow zones
• Mountain Range - made out of series of mountains where volcanoes and earthquake epicenters are located
• Convergent Boundary - two tectonic plates move towards one another
• Divergent Boundary - two tectonic plates move away from one another
• Transform Boundary - two tectonic plates slide past one another
• Tectonic Plate - large slabs of rock that make up Earth's crust, floating on top of magma.
• Continental Drift Theory - proposed by Alfred Wegener, states that continents were once joined together as a single landmass called Pangaea
• Seafloor Spreading - process by which new oceanic crust is formed at mid-ocean ridges
• Plate Tectonics - theory that explains how Earth's outer layer is divided into several large pieces (plates) that float on top of the mantle
• Continental Crust - thicker than oceanic crust; composed mostly of granite (light-colored) rocks
• Oceanic Crust - thinner than continental crust; composed mostly of basalt (dark-colored) rocks
• Mid-Ocean Ridge - long underwater mountain range running through the Atlantic Ocean
• Hotspot - area of intense heat beneath the surface of the earth
• Volcano - opening in the earth's surface through which molten rock or ash can be ejected
• Core - inner part of Earth made mostly of iron and nickel
• Crust - thin outermost layer of Earth
• Convection Currents - movement of hot material from deep within the earth to its surface
• Subduction Zone - area where two plates collide, with one being forced beneath the other
• Lithosphere – consists of the crust and the uppermost part of the mantle, divided into tectonic plates that move and      interact with each other causing geological phenomena like earthquakes

  Asthenosphere – partially molten layer of the mantle located below the lithosphere, it is hotter and more fluid, and is responsible for the movement of plates
• Seismic Waves


  Vibrations that travel through earth's interior, generated by earthquakes, volcanic eruptions, and other sources of energy release
• Types of Seismic Waves

  • Body Waves
  • Surface Waves
• Body Waves


  • Waves that travel within the body of the earth
• Primary Waves (P-waves)


  • Fastest wave and can travel to any matter
• Secondary Waves (S-waves)


  • Can travel in solid but not liquid, move as a transverse wave
• Surface Waves


  • Waves that travel only on the surface of the earth
• Rayleigh Waves


  • Has a circular wave motion
• Love Waves


  • Moves either side to side or up and down
• Modern Examples Of Divergent Plate Boundaries:

                 Baha, California

                 Iceland

                 Great African Rift

                 Mid-Atlantic Ridge

                 East African Ridge
• Trench – also called submarine valleys, it is the deepest part of the ocean. One of the deepest is the Philippine trench with a depth of 10,540m

  Continental Volcanic Arc – forms along the margin of a continent where oceanic crust subducts beneath continental crust
• SUMMARY FOR THE GEOLOGIC FEATURES THEY FORM:

  CONVERGENT

  Continental-Continental: Mountain ranges

  Oceanic-Oceanic: Trenches (submarine valleys), Volcanic Island Arc

  Continental-Oceanic: Trenches, Continental Volcanic Arc

   

  DIVERGENT

  Mid-Ocean Ridges and Rift Valleys

   

  TRANSFORM

  Narrow Valleys, Broken bed streams, Fault lines/Transform fault

   
• Geologic/Geological Stress


  A force applied to a rock that may cause deformation
• Types of Stress

  • Compression stress
  • Tension Stress
  • Shear Stress
• Compression stress


  • Causes the rocks to push or squeeze against one another
  • Vertical Compression Stress can cause the crust to thin out or break off, mountains can be a result of this stress
  • Horizontal Compression Stress can cause the crust to thicken or shorten
• Tension Stress


  • Opposite of compression, forces the rocks to pull apart
  • Can happen when two separate plates move farther away from each other
  • Can happen when the ends of one plate move in different directions
• Tension Stress


  • Some scientists think that tension stress caused the ancient, massive continent Pangaea to break off into the seven continents that we have today
• Shear Stress


  • Happens when 2 plates rub against each other
  • The friction of a shear stress at the edges of the plate can cause earthquakes