Friday, February 11, 2011

gulf stream


                        The gulf stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates at the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean.

Wednesday, February 9, 2011

oceans


        
An ocean  is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface  is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.

plate tectonics



The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, which ride on the fluid-like  asthenosphere. Plate motions range up to a typical 10–40 mm/ato about 160 mm/aThe driving mechanism behind this movement is described below in a separate section.