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Similar to Chapter 13 a ocean basins
Chapter 13 a ocean basins
- 2. Oceans - Vast bodiesof salt water that separate the continents. - They cover about 71% of the earth’s surface and hold over 97% of all the water on the planet. - Absorbs sun’s heat, making earth’s climate more uniform compared to other planets - Home to animal and plant life - -Most of the oxygen in our atmosphere comes from photosynthetic organisms living in the oceans - We need to exercise good and wise dominion of the ocean
- 4. Scientists who studythe ocean • Oceanographers • - marine scientists and engineers who work to better understand and use the ocean • Marine biologists • -investigate the plant and animal life in the ocean • Meteorologist • - study the influence of the oceans on weather and climate • Chemists • -analyze the distribution of various elements and compounds in the oceans and the ways those chemicals affect ocean processes • Physicists • -model the distribution of energy in the oceans and the motion of its great currents • Marine Engineers • -develop methods and vehicles to investigate and use oceans, design ways to produce potable water and electricity from seawater. 13.1
- 5. Ocean Basins • Oneocean • Four major basins • Arctic, Atlantic, Indian, Pacific • Sea • - large section of ocean mostly surrounded by land or islands 13.2
- 6. Ocean Basins • Originof the oceans • Old-earth view • - believe that oceans have been here from very early in Earth’s history, that the ocean basins are just the result of plate tectonics over billions of years. • -The current Atlantic, Indian & Arctic Ocean basins began forming 300 million years ago • The Pacific Ocean basin is all that remain from an earlier global sea, Panthalassa 13.3
- 7. • Young-earth view •Believe that the earth began as a water planet, with a single supercontinent created by God on Day 2. • Supercontinent wrenched apart at Flood around 5500 years ago resulting to the shapes and sizes of the present day ocean basins
- 8. • Local sealevel • Always changing height of the ocean surface at a given location • Measured by Tide gauge • Zero point for gauge positioned at imaginary surface of mathematical model of the earth called • Geoid 13.4
- 9. • Mean sealevel (MSL) • - what most people simply call “sea level” • -computed average height of high and low tides at a location • Zero height used to measure elevation • Changes over time • Risen during past 100 years 13.4
- 10. Basin Topography • Shore •-strip of land that separates the coastal regions from the ocean. 13.5
- 11. • Beaches • -ever-changingplace that extends underwater beyond the shore • Shoreline • -edge of the water at any given time. 13.5
- 12. • Berm • -area where only the highest tides or storm waves can reach, usually has soft, coarse sand or large cobbles • Beach face • - zone between the high and low tide shorelines; may have wet, compact sand or fine pebbles.
- 13. • Longshore sandbar •- shallow bottom of the beach beyond the low water shoreline • Longshore trough • - dug by the breaking action of the waves
- 14. 13.5 • Continental shelf •Submerged edges of continental plates • Varies in width • Continental slope • Steeper incline from the lip of the continental shelf into the deep ocean basins
- 15. • Submarine canyon •-complex underwater erosional feature often found in continental slope
- 16. • Continental rise •Smooth transition from continental slope to the deep, relatively flat ocean floor • Turbidity currents • Underwater landslides 13.5
- 17. • Abyssal plain •Relatively flat, deep sea floor • Sediments cover it with varying thickness 13.5
- 18. Tectonic features • Mid-oceanridges • Submerged mountain ranges at the margins of diverging tectonic plates; formed when the mantle pushed up on long faulted sections of sea floor crust. Most lie within fracture zones 13.6
- 19. • Seamounts • Submergedvolcanoes & hills • Guyots • Flat top volcanoes
- 20. • Trenches • -deepnotch in the ocean floor formed when oceanic plates slid below continental plates in convergent subduction zones • Challenger Deep –deepest point in any ocean, was found in the Mariana Trench in the western Pacific 13.6
- 22. Island arcs - long,curved strings of volcanic island Coral reefs - Accumulated skeletal material, an underwater ridge, formed from coral colonies that excrete rock –like calcium carbonate support structure or skeleton; can become islands when sea level changed. Fringing reefs - Coral reefs that grow right up to the beach along a coastline Barrier reefs -farther from the land, form a lagoon between the reef and the land Atoll -a ring of low coral islands and reefs surrounding a central lagoon.