Top: Age of the oceanic crust. The youngest oceanic crust (red, orange) is always found along the mid-ocean-ridge systems. The age progressively increases away from the ridge and toward the continents (gray). In the central North Atlantic Ocean, the oldest oceanic crust (purple) is ~200 million years, and occurs adjacent to eastern North America and northwest Africa. Bottom: Detail of the age of oceanic crust in the Atlantic. Modified from an image produced by NOAA's National Geophysical Data Center: http://www.ngdc.noaa.gov/mgg/image/images.html#crustage