mid-ocean+ridges

 __Isostasy of the Mid-Atlantic Ridge__

Isostasy is the reason we have mountain ranges under the ocean like the Mid-Atlantic Ridge. These ridges are formed by two crustal plates moving apart while molten magma arises from the mantle to fill the void between the two plates. The Mid-Atlantic Ridge is higher than the surrounding ocean floor because it is made up of less dense material [//Malory//, 2012]. The gravitational attraction varies very little across the ocean despite the depth of the water at certain points in the ocean [//Malory//, 2012]. This anomaly demonstrates nearly perfect isostatic compensation [//Malory//, 2012]. This shows that the Mid-Atlantic Ridge must therefore be supported by a less dense rock then the surrounding sea floor although the chemical compositions of both rocks are nearly identical. There is also speculation that the uprising ridges are less dense due to the hotter upwelling activity that is taking place at these ridges [//Malory,// 2012]. Once the plates are expanded beyond the upwelling zone, the crust begins to cool and slowly sinks back to its original denser form as it ages. There are theories that if we were to heat up the older ocean floor that the plates would begin to upwell back to their previous height at the divergent zone.