Darwin Rise

The Darwin Rise is broad triangular region in the south central Pacific Ocean where there is a concentration of atolls. In 1964, Henry Menard proposed that this was a superswell raised by volcanism during the Cretaceous (120-80 mya). A problem with this conjecture is that this region actually has a sea floor at a normal depth that happens to possess an abundance of sea mounts. Instead this feature may have formed from diapirs or plumes rising from the Earth's upper mantle, which results in chains of sea mounts along the direction of the plate motion. However, this idea remains in dispute and an alternate hypothesis involving multiple "plumelets" has been proposed.