Ocean current hemisphere due to imposed wind stresses. In these wind-driven currents, the Ekman spiral effect results in the currents flowing at an angle to the driving winds. In addition, the areas of surface ocean currents move somewhat with the seasons; this is most notable in equatorial currents. Deep ocean basins generally have a non-symmetric surface current, in that the eastern equatorward-flowing branch is broad and diffuse whereas the western poleward flowing branch is very narrow. These western boundary currents (of which the Gulf Stream is an example) are a consequence of the rotation of the Earth. Deep ocean currents are driven
Geography of Europe the Caucasus), and on to the Black Sea. The Bosporus, the Sea of Marmara, and the Dardanelles conclude the Asian boundary. The Mediterranean Sea to the south separates Europe from Africa. The western boundary is the Atlantic Ocean. Iceland, though on the Mid-Atlantic Ridge and nearer to Greenland (North America) than mainland Europe, is generally included in Europe for cultural reasons and because it is over twice as close to mainland Europe than to mainland North America. There is ongoing debate on where the geographical centre of Europe falls. Some geographical texts refer to a Eurasian continent given that Europe