Bathymetry

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Bathymetry

  1. 1. © 2011 Pearson Education, Inc.
  2. 2.  The study of bathymetry charts ocean depths and ocean floor topography. Echo sounding and satellites are efficient bathymetric tools. Most ocean floor features are generated by plate tectonic processes. © 2011 Pearson Education, Inc.
  3. 3.  Measures the vertical distance from the ocean surface to mountains, valleys, plains, and other sea floor features © 2011 Pearson Education, Inc.
  4. 4.  Soundings  Posidonius first sounding 85 B.C.  Line with heavy weight  Sounding lines used for 2000 years Unit of measure is a fathom  1.8 meters (6 feet) First systematic measurements – HMS Challenger 1872 © 2011 Pearson Education, Inc.
  5. 5.  Echo Soundings  Echo sounder or fathometer  Reflection of sound signals  German ship Meteor identified mid-Atlantic ridge in 1925 Lacks detail May provide inaccurate view of sea floor © 2011 Pearson Education, Inc.
  6. 6. © 2011 Pearson Education, Inc.
  7. 7.  Precision Depth Recorder (PDR)  1950s  Focused high frequency sound beam  First reliable sea floor maps produced  Helped confirm sea floor spreading © 2011 Pearson Education, Inc.
  8. 8. Modern Acoustic Instruments Side scan sonar  GLORIA (Geological Long-range Inclined Acoustical instrument)  Sea MARC (Sea Mapping and Remote Characterization) Can be towed behind ship to provide very detailed bathymetric strip map Multi-beam echo sounder  Seabeam © 2011 Pearson Education, Inc.
  9. 9. © 2011 Pearson Education, Inc.
  10. 10.  Uses satellite measurements Measures sea floor features based on gravitational bulges in sea surface Indirectly reveals bathymetry © 2011 Pearson Education, Inc.
  11. 11.  Seismic Reflection Profiles  Air guns  Strong, low- frequency sounds  Details ocean structure beneath sea floor © 2011 Pearson Education, Inc.
  12. 12. © 2011 Pearson Education, Inc.
  13. 13.  Shows relationship between height of land and depth of ocean © 2011 Pearson Education, Inc.
  14. 14.  70.8% of Earth covered by oceans Average ocean depth is 3729 meters Average land elevation is 840 meters Uneven distribution of areas of different depths/elevations Variations suggest plate tectonics at work © 2011 Pearson Education, Inc.

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