@fengjianchen

A beautiful map of the Atlantic Ocean floor published in 1968 based on a large amount of deep-ocean soundings compiled by Bruce Heezen and Marie Tharp, painted by Heinrich Berann for National Geographic Magazine. That segmented central structure is the Mid-Atlantic Ridge. Entirely submerged by the ocean, it is like a "wound" in what can be considered the skin of our planet: the crust. Here the crust opens and a "cut" is formed from which molten magmas flow from the mantle to form new oceanic crust of basaltic composition. This ridge, together with other mid-ocean ridges, are formed where two plates move apart. Mid-ocean ridges are not always below sea level: the highest peaks can emerge forming volcanic islands like Iceland.

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