1. The Sea Floor GLG 101 - Physical Geology Bob Leighty

2. These lecture notes are very similar to the ones I use in my traditional classes. You’ll find they are loaded with imagery and streamlined text that highlight the most essential terms and concepts. The notes provide a framework for learning and, by themselves, are not meant to be a comprehensive source of information. To take advantage of the global knowledge base known as the Internet, I have included numerous hyperlinks to external web sites (like the Wikipedia, USGS, NASA, etc.). Follow the links and scan them for relevant info. The information from linked web sites is meant to supplement and reinforce the lecture notes – you won’t be responsible for knowing everything contained in them. As a distance learning student, you need to explore and understand the content more independently than in a traditional class. As always, I will help guide you through this learning adventure. Remember, email Dr. Bob if you have any questions about today’s lecture (rleighty@mail.mc.maricopa.edu).rleighty@mail.mc.maricopa.edu Leave no questions behind! Explore and have fun! These notes and web links are your primary “lecture” content in this class. Additionally, various articles are assigned each week to supplement this “lecture” information. I believe you’ll have enough information to reference without having to purchase a costly textbook.

3. The Sea Floor  Earth's early history - volcanic “outgassing” & asteroids/comets  Oceans include >97% of all water on Earth  Much of Earth’s surface is underlain by oceanic crustoceanic crust Sea Floor

4. Mapping  Mapped mainly by sonar & satellite radar since WWII

5. Oceanic Sediment  Derived from land (terrigenous) – mud & sand  Derived from critters (biogenic) – chert & limestone Sea Floor

6. Continental Margins Passive  Example - east coast of N & S America, west coast of Africa  Minimal tectonism; no oceanic trench or volcanic arcoceanic trenchvolcanic arc Sea Floor

7. Continental Margins Passive Continental Shelf  Gently-sloping; underlain by continental crustcontinental crust  Shallow water (<135 m deep); affected by waves Sea Floor

8. Continental Margins Passive Continental Shelf Sea Floor

9. Continental Margins Passive Continental Slope  Deeper water (>135 m); not affected by waves Sea Floor  Steeper than the shelf; submarine canyonssubmarine canyons

10. Continental Margins Passive Continental Rise  Very deep water; grades into the abyssal plain of the deep oceanabyssal plain  Gently-sloping; underlain by oceanic crust Sea Floor

11. Continental Margins Active  Example - west coast of N & S America  Lots of tectonism; develop at subduction zonessubduction zones Sea Floor

12. Continental Margins  Dense, “muddy” underwater currents Turbidity Currents Sea Floor

13. Deep Ocean Basins Abyssal Plains  Flattest places on Earth (deep-sea sediment covers & subdues topography)  Deep ocean (avg ~5000 m) Sea Floor

14. Deep Ocean Basins Oceanic trenches  Deepest parts of the ocean (some >10,000 m)  Develop at subduction zones, parallel to volcanic arcs Sea Floor

15.  Volcanic mountains that form above mantle plumesmantle plumes  Example: Hawaiian Island-Emperor Seamount chainHawaiian Island-Emperor Seamount chain Deep Ocean Basins “Hot spots” Sea Floor

16.  Guyots = old, high seamounts eroded flat Guyots  Isolated volcanic peaks that may rise above sea level Deep Ocean Basins Seamounts Sea Floor

17.  Organisms typically prefer warm, clear, shallow water Deep Ocean Basins Coral Reefs & Atolls Sea Floor

18.  Divergent plate boundaries (spreading centers) Deep Ocean Basins Mid-ocean Ridges Sea Floor

19.  Total >70,000 km long! Deep Ocean Basins Mid-ocean Ridges Sea Floor

20.  Rise 2-3 km above ocean basins Deep Ocean Basins Mid-ocean Ridges Sea Floor

21.  Normal faults & transform faults Deep Ocean Basins Mid-ocean Ridges Sea Floor  Mostly mafic rocks (basalt & gabbro); pillow lavas pillow lavas

22.  Black smokers & “weird” critters Black smokers Tube worms Black smokers Deep Ocean Basins Mid-ocean Ridges Sea Floor

23. WWW Links in this Lecture > Oceanic crust - http://en.wikipedia.org/wiki/Oceanic_crusthttp://en.wikipedia.org/wiki/Oceanic_crust > Oceanic trench - http://en.wikipedia.org/wiki/Oceanic_trenchhttp://en.wikipedia.org/wiki/Oceanic_trench > Volcanic arc - http://en.wikipedia.org/wiki/Volcanic_archttp://en.wikipedia.org/wiki/Volcanic_arc > Continental crust - http://en.wikipedia.org/wiki/Continental_crusthttp://en.wikipedia.org/wiki/Continental_crust > Continental shelf - http://en.wikipedia.org/wiki/Continental_shelfhttp://en.wikipedia.org/wiki/Continental_shelf > Submarine canyon - http://en.wikipedia.org/wiki/Submarine_canyonhttp://en.wikipedia.org/wiki/Submarine_canyon > Shelf-slope break - http://en.wikipedia.org/wiki/Continental_shelf#Continental_shelf_break.2C_slope.2C_and_rise http://en.wikipedia.org/wiki/Continental_shelf#Continental_shelf_break.2C_slope.2C_and_rise > Abyssal plain - http://en.wikipedia.org/wiki/Abyssal_plainhttp://en.wikipedia.org/wiki/Abyssal_plain > Subduction zone - http://en.wikipedia.org/wiki/Subductionhttp://en.wikipedia.org/wiki/Subduction > Hot spot - http://en.wikipedia.org/wiki/Hotspot_%28geology%29http://en.wikipedia.org/wiki/Hotspot_%28geology%29 > Mantle plume - http://en.wikipedia.org/wiki/Mantle_plumehttp://en.wikipedia.org/wiki/Mantle_plume > Hawaii-Emperor seamount chain - http://en.wikipedia.org/wiki/Hawaiian-Emperor_seamount_chain http://en.wikipedia.org/wiki/Hawaiian-Emperor_seamount_chain > Seamount - http://en.wikipedia.org/wiki/Seamounthttp://en.wikipedia.org/wiki/Seamount > Guyout - http://en.wikipedia.org/wiki/Guyothttp://en.wikipedia.org/wiki/Guyot > Atoll - http://en.wikipedia.org/wiki/Atollshttp://en.wikipedia.org/wiki/Atolls > Mid-ocean ridges - http://en.wikipedia.org/wiki/Mid-ocean_ridgeshttp://en.wikipedia.org/wiki/Mid-ocean_ridges > Pillow lava - http://en.wikipedia.org/wiki/Pillow_lava#Pillow_lavahttp://en.wikipedia.org/wiki/Pillow_lava#Pillow_lava > Black smoker - http://en.wikipedia.org/wiki/Black_smokershttp://en.wikipedia.org/wiki/Black_smokers Sea Floor