The molten core of our planet is entirely engulfed in the mantle, the second, thickest layer of magma that supports the crust. The latter is simply the skin of our planet, a layer just a few kilometers thick at its largest point, on which everything we know, continents and oceans included, lie. But there are also significant differences between how new crust is formed beneath oceans and on solid ground. Scientists from the Brown University recently decided to investigate the formation processes closer than ever.

It is widely known in the geological community that new crust forming under continents can endure for up to billions of years, before complex processes push it out of the way, and replace it. Things are a bit different when it comes to it oceanic counterpart. The later endures for a maximum period of 200 million years, which is the age estimates put on the oldest crust discovered thus far underwater. Mostly responsible for these differences are mid-oceanic ridges, highly-active structures that exist for example in the middle of the Atlantic Ocean. They constantly release magma, forming new crust, while also pushing Africa and Europe away from the two Americas.

But investigators have until now been in the dark about what happens below the ground when these new oceanic crusts form. The BU experts have for the first time been able to observe a dramatic geological process, known as dynamic upwelling, which appears to be largely responsible for the large levels of activity. Details of the research, funded by the US National Science Foundation (NSF), appear in the latest issue of the respected scientific journal Nature. The investigation may finally help clarify the relative importance of passive and dynamic upwelling just below the Earth's crust, BU experts say.

“We know the crust of the ocean is produced by upwelling beneath separating plates. We just didn't know the upwelling pattern that took place, that there are concentrated upwelling centers rather than uniform upwelling. We found a pattern that was predicted by some of the theoretical models of upwelling in mid-oceanic ridges,” says BU professor of geological sciences Don Forsyth, who was also a part of the study. The paper provides “a basic understanding of how a majority of the Eearth's crust is formed, how it emerges from the mantle below to create the oceanic crust. It's a basic science question that helps understand how crust is created,” concludes University of Rhode Island assistant professor of geophysics Brian Savage.