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Oceanography 1 The Sea Floor. the sea floor. image source: http://www.npaci.edu/online/v6.12/hellyslides.html. The Sea Floor. Continental Margin Continental shelf Continental shelf break Continental slope Continental rise. Passive and Active Continental Margins.
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the sea floor image source: http://www.npaci.edu/online/v6.12/hellyslides.html
The Sea Floor • Continental Margin • Continental shelf • Continental shelf break • Continental slope • Continental rise
passive margin--no plate boundary exists at edge of continent
active continental margin: plate boundary exists at edge of continent
How old is the Monterey Submarine Canyon? Maybe 5 million years old
The Sea Floor • Ocean Basin Floor • Abyssal plain • Abyssal hills • Seamounts • Guyots • Fringing reefs • Barrier reefs
The Sea Floor • Ridges, Rises, and Trenches • Plate Tectonics
Mid-Atlantic Ridge: sea floor spreading (divergent boundary) …basaltic volcanism and normal faults…(tensional stress) axial valley NORTH AMERICA AFRICA spreading from: http://www.geo.duke.edu/geo41/sfs.htm
Mid-Atlantic ridge is exposed in Iceland…. fracture zone both from: http://pubs.usgs.gov/publications/text
The Sea Floor • Sediments • Particle size • Classification • Horizontal transport and sorting • Location • Classification: neritic or pelagic • Rates of deposit • Processes and variability
The Sea Floor • Sediments • Source and chemistry • Lithogenous sediments • Biogenous sediments • Hydrogenous sediments • Cosmogenous sediments Coastline near Mavericks
The Sea Floor • Sediments • Patterns of deposit on the sea floor • Processes and patterns • Climatic variations are recorded in layered sediments • Formation of rock • Sedimentary rock • Metamorphic rock
The Sea Floor • Methods for measuring depths: • Hand line and wire marked with fathoms, with a lead weight on the end • Echo sounder, or depth recorder • Laser airborne depth sounder (LADS) • Satellites
Fig. 4.21a Diatoms and coccolithophores: Siliceous Microplankton
Radiolarians: silica tests Radiolarians: Siliceous Microplankton
Sampling Methods Sampling Methods
The Sea Floor • Sediments • Sampling methods • Dredges, grab samplers, a corer, and acoustic profiling • Sediments as historical records • Distribution and isotopic composition of skeletal remains