1. Chapter 3C Sections 1, 2, 3 MESSANA Science 8

2. Ocean Waters Contains NaCl, dissolved solids & gases (O2, N2, CO2) Salinity = 35g salt/1000g seawater Higher salinity = higher density of water Objects are more buoyant in water that is more dense (Dead Sea – 10X saltier than ocean->more dense ->humans more buoyant)

3. Buoyant Force vs. Gravity

4. 3 Layers of Ocean 1. Surface = warm water, less dense, coldest at poles, warmest at equator, 0-300 m, 25 C 2. Thermocline = temperature drops fast as depth increases, 300 – 700 m, 25->5 C 3. Deep = cold all year, barely above freezing, 0-3 C

6. Ocean Floor Features 1. Continental Shelf = flat or gently sloping land that extends underwater from the edges of a continent to a continental slope 2. Continental Slope = land that drops down steeply at the edge of a continental shelf 3. Submarine Canyons = cut through continental shelf & slope 4. Ocean Trenches = narrow, steep-sided clefts farther out in ocean floor, convergent boundary where old rock sinks down

7. Ocean Floor Features 5. Mid-Ocean Ridge = chain of mountains that runs through an ocean basin, divergent boundary where molten rock rises out of rift valley pushing old rock aside 6. Seamounts = underwater mountains (over a hot spot) 7. Volcanic Islands = underwater volcanoes tall enough to reach above the surface (Ex:Hawaii) 8. Abyssal Plain = wide, flat area of ocean floor covered with thick sediment layer

8. Ocean Floor Topography

10. Ocean Currents Currents = mass of moving water, distributes heat & nutrients Surface Currents – caused by WINDS Top 200 meters Rotate different directions in each hemisphere Pull warm water from equator & cold water from poles Gulf Stream = surface current that moves water from the Gulf across Atlantic Ocean, northeastward toward Britain, makes climate there more mild El Nino = change in surface currents in Pacific due to winds not blowing as strongly west across the Pacific, affects weather patterns globally

11. Surface Currents surrounding US

12. Ocean Currents Deep Currents – caused by DIFFERENCES IN DENSITY (due to temperature & salinity) 1. Upwelling: movement of water up to surface, brings up nutrients, good for animal life 2. Downwelling: movement of water from surface to greater depths, carries O2 down, allows for life

13. Upwelling & Downwelling

14. Exploring the Ocean Floor How can we overcome ocean obstacles to learn more?... Pressure Darkness Lack of air Cold Wildlife

15. Exploring the Ocean Floor Technology to use: Submarines Submersibles (Alvin) Robots with cameras Sonar = using sound waves to measure distances, depths, locate objects Satellite Imagery – light waves from space

16. University of Miami Submersible

17. The Ocean Pearl

18. Sonar for measuring depth of ocean floor:

19. Satellite Image of Ocean Floor

21. http://www.nytimes.com/interactive/2011/03/13/world /asia/satellite-photos-japan-before-and-after- tsunami.html