A NEW PERSPECTIVE ON THE WORLD MAP


The Ocean Floor is Anything but Flat!
Usually, when you look at a world map, the continents are shown with mountains, valleys and plains, and the oceans are shown as flat blue surfaces.  But that doesn't really give a true picture of the ocean. When you take a closer look past the surface of the water and down to the sea floor, ocean basins are anything but flat. Ocean floors have just as many mountains, valleys and plains as the continents do. 

To focus on the ocean floor, we've blacked out the continents on this map. This map is an ocean basin bathymetry  map.  It shows the depth from sea surface to sea floor. It's a different way of looking at the earth's surface.  The key for reading the map is:

Light Blue	 	1,000-2,000 meters	       continental shelves
		                           															 oceanic plateaus

Blue	     				2,000-3,300 meters 	      ocean-floor mountains 

Purple	     		3,400 - 5,000 meters	      valleys
		                           																deep plains

Yellow	     		line drawn on map	   				Mid-Ocean Ridge System
	         					(no depth indication)


The Longest Chain of Volcanoes on the Planet

You're probably wondering about the features highlighted by the yellow lines in the middle of the ocean basins. Those lines indicate a chain of volcanoes called the midocean ridge system. At a total length of 50,000 kilometers, the midocean ridge system is the longest continuous chain of volcanoes on the planet. This chain of volcanoes forms as the result of plate spreading.  As the oceanic plates spread apart from each other, cracks are created that are immediately filled in with magma (molten rock) from the mantle below.  Twenty cubic kilometers of new oceanic crust are created along this interconnected network of volcanoes every year.  If all this new rock were poured into the Grand Canyon, the Grand Canyon would be filled in every eight to ten years.