Features of the Ocean Floor Continental Margins

¶ … Features of the Ocean Floor Continental Margins As one travels away from the continents, water depths increase in a systematic manner. Closest to the continents are continental shelves with water depth typically less than 1000 m. Continental shelves were formed as rivers carried tons of particles of sand and soil from the land out to sea. This sand and soil then settled as layers of sediments, or layers of particles of rock and animal remains.

Commonly at the distal edge of the continental shelves, there is a marked continental slope where water depths increase quickly. The continental slope separates the continental shelf from the ocean floor. The continental rises, located at the base of the continental slopes, mark the beginning of the deep ocean basins. Submarine canyons commonly occur along continental margins and transport sediment from the margins down into the deep ocean basins. B. Mid Ocean Ridges Long mountain chains found in the deep ocean basins of all major oceans.

1) The mid ocean ridges commonly occur far from continental margins and on the edges of deep-sea basins. 2) The ridges commonly have long fracture zones associated with them; the fracture zones occur on both sides of the ridges and run perpendicular to them. C. Deep Ocean Basins Topographic basins bounded by Mid Ocean Ridges and Continental Slopes. 1) Many plains on the ocean basin are larger and flatter than any found on the Earth's surface. They are called abyssal plains. Abyssal plains are form by sediments deposited by turbidity currents.

It sediments continually falling from the seawater above. D. Deep Sea Trenches The deepest parts of the ocean are long linear trenches, which commonly occur adjacent to continental margins. E. Oceanic Rises Throughout the oceans are located isolated topographic highs of different kinds. 1) Seamounts Individual submarine mountains occur commonly in the oceans. When these reach the ocean surface they may contain reefs. Other terms that are associated with seamounts are guyots, and atolls. 2) Oceanic Plateaus There are several regions of the oceans, which are really drowned continents.

Ocean Floor Sediments A. Biogenous Sediments Biogenous sediments are particles that are produced directly by marine organism. Example: Calcareous, siliceous oozes B. Hydrogenous Sediments Hydrogenous sediments are form either by direct precipitation from seawater or as a new mineral from chemical reactions between seawater and sediments on the sea floor. Example: Manganese nodules, phosphorus deposits, salt and gypsum C. Terrigenous Sediments Terrigenous sediments are produced by the physical and chemical "weathering" of rocks exposed on continents.

Example: Quartz sand, clays, mud, glacial Oceanic current systems Large oceanic current systems have names and description based on their average locations. The water transport and speed of a current is affected by the current's cross-sectional area, by the other currents, by westward intensification and by wind speed. A. The Pacific Ocean Currents In the North Pacific Ocean, the northeast trade winds push the water toward the west and northwest; this is the North Equatorial Current.

The Westernizes create the North Pacific Current, or North Pacific Drift, moving from west to east. In the South Pacific Ocean, the southeast trade winds move the water to the left of the wind and westward, forming the South Equatorial Current. The westerly winds push the water to the east; at these southern latitudes the surface current so formed can move almost continuously around the earth. This current is the West Wind Drift. B.

The Atlantic Ocean Currents The North Atlantic westerly winds move the water eastward as the North Atlantic Current, or North Atlantic Drift. The northeast trade winds push the water to the west, forming the North Equatorial Current. The north-south continuity currents are the Gulf Stream, flowing northward along the coast of North America, and the Canary Current, moving to the south on the eastern side of the North Atlantic. C. The Indian Ocean Currents The Indian Ocean is mainly a Southern Hemisphere ocean.

The southeast trade winds push the water to the west, creating the South Equatorial Current. The Southern Hemisphere westernizes still move the water eastward in the West Wind Drift. The West Australia Current moving northward completes the gyre and the Agulhas Current moving southward along the coast of Africa. D.

The Arctic Ocean Currents The Norwegian Current supplies the Arctic Ocean from the North Atlantic; some of this flow enters west of Spits Bergen, but most flows over the top of Norway and Finland and moves eastward along the Siberian coast into the Chukchi Sea. Outflow from Siberian Rivers is caught in the eastward flow of water and ice along Siberia. Eventually this discharge joins the gyre distributing sediments and pollutants throughout the Arctic.

El Nino syndrome The world continues to be pounded by abnormal weather, due to man's indifference towards lesser mortals. The warnings of the atmosphere that is normally referred to as the "Green House Effect," is caused by the steady build up of six green house gases, emitted by the burning of petroleum by motor vehicles and coal in power plants.

It is estimated that about 20 to 30 billion tons of carbon dioxide are discharged to the air each year, and that there is 30% more carbon dioxide in the air today than in 1860. Under these.