Ocean basins

• how much of earth's surface do ocean basins cover?

  three fifths
• what are mid ocean ridges?

  areas where new oceanic crust are being created
• why is crust at the mid ocean ridges incredibly thin?

  it has not had time to cool and thicken
• why can the ocean ridge not continue on indefinitely in one straight line?

  faulting (transform faults)
• what can be found adjacent to mid ocean ridges?

  abyssal plains
• what are abyssal plains?

  very flat regions of sea floor
• what is a transform fault?

  a fracture zone between offset ridges (a plate boundary)
• how many layers are there to the oceanic crust?

  three
• what are the three main sources of sediment in layer one of the oceanic crust?

  terrigenous sediment, pelagic clays and pelagic oozes
• what is layer one of the oceanic crust?

  ocean sediments
• what is layer two of the oceanic crust?

  volcanic rock (basalt)
• name two features that can be found in layer two of the oceanic crust?

  pillow lavas and sheeted dykes
• what is layer three of the oceanic crust?

  intrusive rock (gabbro)
• what is found below layer three of the oceanic crust?

  the Moho transition to mantle peridotites
• what focal depth do earthquakes tend to be at mid ocean ridges?

  shallow
• what are earthquakes at mid ocean ridges associated with?

  extensional stresses (normal faulting)
• what focal depth do earthquakes tend to be between mid ocean ridges?

  shallow
• what are earthquakes between mid ocean ridges associated with?

  strike slip faulting
• what focal depth do earthquakes tend to be at ocean trenches?

  shallow to deep
• what type of faulting is seen at oceanic trenches?

  extensional (normal) or compressional (thrust) faulting
• what do scientists use to classify faults?

  the angle of the faults (dip) and the direction of the slip along the fault
• what are faults which move along the direction of the dip plane called?

  dip-slip faults
• what are the two types of dip-slip faults?

  normal or reverse (thrust)
• what are faults which move horizontally known as?

  strike slip faults
• what are the two types of strike-slip faults?

  right lateral and left lateral
• what are faults which show both dip-slip and strike-slip motion called?

  oblique-slip faults
• what is normal faulting a result of?

  extension
• what is reverse (thrust) faulting a result of?

  compression
• where do strike-slip faults occur?

  when two blocks slide past each other