© 2014 Pearson Education, Inc. Marine Provinces Chapter 1 Clickers Essentials of Oceanography Eleventh Edition Alan P. Trujillo Harold V. Thurman © 2014 Pearson Education, Inc. Chapter 3 Lecture

© 2014 Pearson Education, Inc. Topography the detailed mapping of the land forms or surface configuration of a region

© 2014 Pearson Education, Inc. Bathymetry Determines ocean depths and ocean floor topography Measures the vertical distance from the ocean surface to mountains, valleys, plains, and other sea floor features

© 2014 Pearson Education, Inc. Bathymetry Methods 1.Sounding (old fashioned) 2.Echo Sounding 3.Precision Depth Recorder 4.Multibeam Echo Sounders 5.Sonar 6.Satellites 7.Seismic Reflection

© 2014 Pearson Education, Inc. Sounding (old fashioned) How? –Line with heavy weight and knots in it every 6 feet dropped in the water until it hit bottom! –Measured in Fathoms (=1.8 meters or 6 feet) Who? –Poseidonus made first sounding in 85 B.C. When? –85 B.C. …. Used for 2000 years! Problems? –Not (knot) very accurate! Get it?

© 2014 Pearson Education, Inc. Echo Sounding How? –Echo sounder or fathometer –Reflection of sound signals Who? –HMS Challenger When? –1872 Problems? –Lacks detail –May provide inaccurate view of sea floor

© 2014 Pearson Education, Inc. Echo Sounding Record

© 2014 Pearson Education, Inc. Precision Depth Recorder (PDR) How? –Focused high-frequency sound beam When? –1950s Positives? –First reliable sea floor maps produced –Helped confirm sea floor spreading

© 2014 Pearson Education, Inc. Multibeam Echo Sounders How? –Multiple simultaneous sound frequencies Who? –Seabeam = First multibeam echo sounder Positives? –Map sea floor strips up to 60 km (37 mi) wide

© 2014 Pearson Education, Inc. Sonar = Sound Navigation and Ranging How? –Again uses sound waves Types? –GLORIA (Geological Long-range Inclined Acoustical instrument) –Sea MARC (Sea Mapping and Remote Characterization) When? –Considered “modern” Positives? –Can be towed behind ship to provide very detailed bathymetric strip map

© 2014 Pearson Education, Inc. Satellites = Sea Floor Mapping from Space How? –Uses satellite measurements What? –Measures sea floor features based on gravitational bulges in sea surface –Indirectly reveals bathymetry

© 2014 Pearson Education, Inc. Comparing Bathymetric Maps

© 2014 Pearson Education, Inc. Seismic Reflection Profiles How? –Air guns –Strong, low-frequency sounds What? –Details ocean structure beneath sea floor

© 2014 Pearson Education, Inc. Seismic Reflection Profile

© 2014 Pearson Education, Inc. Ocean Floor Features Most generated by plate tectonics Different sea floor features exist in different oceanographic locations

© 2014 Pearson Education, Inc. Ocean Provinces Three Major Provinces Continental margins –Shallow-water areas close to shore Deep-ocean basins –Deep-water areas farther from land Mid-ocean ridge –Submarine mountain range

© 2014 Pearson Education, Inc. Ocean Provinces

© 2014 Pearson Education, Inc. Continental Margins Passive –Not close to any plate boundary –No major tectonic activity –East coast of United States Active –Associated with convergent or transform plate boundaries –Much tectonic activity

© 2014 Pearson Education, Inc. Passive and Active Continental Margins

© 2014 Pearson Education, Inc. Label - Use the Word Bank & Textbook pp81-92

© 2014 Pearson Education, Inc. Laboratory Objective Students will be creating a bathymetric map of a model seafloor.  I can sculpt a model of a passive continental margin with the following features: Mid-Ocean Ridge Abyssal Plain Continental Rise Continental Slope Continental Shelf Seamounts Guyots  I can simulate “soundings” using a bamboo skewer and butcher paper with a 5 cm grid pattern drawn on it.