Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Development of Atmosphere and Oceans Earth’s atmosphere developed in stages: Hot gases- volcanoes and fissures. Free oxygen- photosynthesis by cyanobacteria. Ozone formation- upper atmosphere. Water vapor condensed- oceans.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Continental margin: Continental shelf—shallow, underwater extension of the continent. Continental slope—boundary between continental and oceanic crust. Continental rise—wedge of accumulated sediment at base of continental slope.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The Ocean Floor: Abyssal Plain Mid-ocean Ridge

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Depth of seafloor The deepest parts - the ocean trenches in the Pacific. The shallowest waters- mid-ocean ridge system.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Salinity in Steady State Equilibrium Even though salts are continually washed into the sea, the average salinity has remained the same for the last billion yrs. Several mechanisms exist to remove salt: –Salt spray on land and into air –Salts precipitating along coastlines and marginal ocean basins –Marine organisms use salt ions to build shells, then die and are incorporated into sediments

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Ocean Waves Crest Trough Wave height Wavelength Wave period-time interval between the passage of two successive crests.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Water particles move in a circular orbit as wave passes through. The orbits get smaller with depth. The point where there is no water movement is called wave base. Wave base = ½ of wavelength

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Ocean Waves Waves on the ocean surface are orbital waves. Wave energy moves forward: the disturbance moves, not the water. Occurs in the open sea in deep water.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Waves at the shoreline: Shallow water; wave base intersects bottom - “feel bottom” Wave grows higher as it slows and wavelength shortens Steep wave front collapses, wave breaks Turbulent water goes up the shore and forms surf

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Ocean waves get their energy from the wind. Size of waves depend on: Wind speed Length of time wind has blown Fetch—the distance that the wind has traveled across open water

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Ocean Shorelines Surf forms erosional features: Beach Spit Barrier islands Lagoons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Wave are refracted as they hit the headlands, and concentrate their energy there. Eventually, this causes the coastline to straighten out.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Ocean Tides Tides occur because of the gravitational pull exerted on Earth by the moon. A bulge of water forms on the side closest to the moon.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Centrifugal force causes a bulge on the opposite side. The result is two bulges of water. The Earth spins underneath these bulges.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Ocean Waves, Tides, and Shorelines Because Earth spins on its axis once a day, it should have two distinct tides 12 hours apart. But because the Moon moves around Earth, the times of the tides vary each day.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Ocean Waves, Tides, and Shorelines Alignment of the Sun, Earth, and Moon causes spring tides—more dramatic highs and lows.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Ocean Waves, Tides, and Shorelines When the pull of the Sun and Moon are perpendicular to each other, we get neap tides—lower highs and higher lows.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Layered Ocean Several vertical layers: surface zone, transition zone, and deep zone.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley How are water masses separated? Density differences In the ocean, dense water sinks and less dense water rises. Density differences cause the ocean water to circulate.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oceanic Circulation Ocean currents are streams of water that move within the ocean. Surface currents are created by wind. Deep ocean currents move by density differences. Ekman transport: A way to bring deep water to the surface: UPWELLING

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley A global view of ocean circulation Shallow currents move towards the poles and cool off. Cold water sinks and moves along the bottom until it warms up in the Indian and mid-Pacific. Water takes 1000 yrs to complete the circuit. Heat transported by circulation.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oceanic Surface Circulation: Factors that influence ocean currents: For short distances, wind is strongest factor For longer distances, Coriolis effect comes into play: —Coriolis causes surface currents to turn and twist into semicircular whirls called gyres. —Northern Hemisphere gyres rotate clockwise. —Southern Hemisphere gyres rotate counterclockwise.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The importance of ocean circulation Distribute heat – regulates climate Distributes nutrients – basis for food chain in ocean