- 71% of the Earth's surface is covered in ocean
- global ocean= divided by the continents into four main oceans
- Largest ocean is the Pacific ocean (Asia - the Americas)
- Second largest ocean is the Atlantic ocean (half the volume of the Pacific)
- Third largest ocean is the Indian Ocean
- Smallest ocean is the Arctic Ocean (much of its surface is covered with ice so it is not fully explored)
- About 245 million years ago the continents were connected as one and was called "Pangaea" and the oceans were one giant body of water called Panthalassa
- About 180 million years ago Pangaea slowly started breaking apart and the North Atlantic Ocean and the Indian Ocean began to form
- About 65 million years ago the South Atlantic Ocean was much smaller than it is today
- Today, 2013, the continents continue to move at a rate of 1 to 10 cm per year and the Pacific Ocean is getting smaller and smaller. On the other hand, the other oceans are taking its place and growing.
- The volcanic explosions 4.5 billion years ago created volcanic gases which formed Earth's atmosphere. Earth started cooling and 4 billion years ago water started to condense. This condensation created rain and the rain filled the deeper levels of Earth's surface and oceans began to form
- Ocean water is not safe to drink
- Ocean water is salty because of sodium chloride that dissolved when rivers and streams flowed to the ocean and carried small minerals.
- Salinity= A measure of the amount of dissolved salts in a given amount of liquid
- Salinity is usually measured as grams of dissolved solids per kilogram of water.
- Climate affects salinity
- hotter drier climates typically has a lower salinity
- heat increases the evaporation rate and evaporation removes water but leaves salts and other dissolved solids behind.
- Water movement affects salinity
- open ocean and slower-moving areas of water develop higher salinity
- temperature of ocean water decreases as depth increases slowly
- water cycle= continuous movement of water from the ocean to the atmosphere to the land and back to the ocean
- Condensation= gas to liquid
- Evaporation= liquid to gas
- Precipitation= falling back to Earth's surface
Section 2: The Ocean Floor
- Sonar: SOund Navigation And Ranging
- based on echo-ranging behavior of bats
- send sound pulses from a ship down into the ocean
- sound moves through the water, bounces off the ocean floor, and returns to the ship
- longer time for the sound to return if the ocean is deeper
- about 1,500 m/s
- Oceanography via Satellite
- 1978 scientists launched the satellite "Seasat" which is focused on the ocean sending images back to Earth that allowed scientists to measure the direction and speed of ocean current
- Studying the Ocean with "Geosat"
- top-military satellite
- measure slight changes in the height of the ocean's surface
- maps are made
- world's largest mountain chain (64,000 km 40,000 mi and canyons deeper than the Great Canyon) is underwater
- continental shelf= the gently sloping section of the continental margin located between the shoreline and the continental slope
- continental slope= the steeply inclined section of the continental margin located between the continental slope and the abyssal plain
- continental rise= the gently sloping section of the continental margin located between the continental slope and the abyssal plain
- abyssal plain= a large, flat, almost level area of the deep-ocean basin
- mid-ocean ridge= a long, undersea mountain chain that forms along the floor of the major oceans
- rift valley= a long, narrow valley that forms as tectonic plates separate
- seamount= a submerged mountain on the ocean floor that is at least 1,000 m high and that has a volcanic origin
- ocean trench= a steep, long depression in the deep-sea floor that runs parallel to a chain of volcanic islands or a continental margin
- Piloted Vessels: Alvin and Deep Flight
- Alvin is 7 m long and can reach some of the deepest parts of the ocean
- Deep Flight is another modern vessel that scientists use to explore the deep ocean
- Transports pilots to the deepest parts of the ocean, which are more than 11,000 m deep
- Robotic Vessels: JASON II and Medea
- these robots are designed to withstand pressures much greater than those found in the surface and is used to explore above sea floor
- Jason II is "flown" by a pilot at the surface and is used to explore the ocean floor
- Medea is attached to Jason II with a tether and explores above the sea floor.
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