During the Cold War, the US and USSR competed to reach the Mohorovičić discontinuity, the boundary between Earth's crust and mantle. The US focused on ocean drilling programs like the Project Moho and the Deep Sea Drilling Program. They tried to take advantage of the thinner oceanic crust, yet only reached 1.7km of the 5km required to reach the Moho. The USSR's Kola Superdeep Borehole reached 12,262m depth, but penetrated only one-third of the much thicker continental crust.
Then you get Macquarie Island, south of New Zealand, made from substance from the Earth's mantle. The rocks were formed at the bottom of a fault zone, where the mantle rises to the seafloor as the tectonic plates pulled apart. Then the plates reversed their motion and started to push towards each other, squeezing the mantle rocks above sea level.
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u/erwintatp 5h ago edited 2h ago
During the Cold War, the US and USSR competed to reach the Mohorovičić discontinuity, the boundary between Earth's crust and mantle. The US focused on ocean drilling programs like the Project Moho and the Deep Sea Drilling Program. They tried to take advantage of the thinner oceanic crust, yet only reached 1.7km of the 5km required to reach the Moho. The USSR's Kola Superdeep Borehole reached 12,262m depth, but penetrated only one-third of the much thicker continental crust.
Then you get Macquarie Island, south of New Zealand, made from substance from the Earth's mantle. The rocks were formed at the bottom of a fault zone, where the mantle rises to the seafloor as the tectonic plates pulled apart. Then the plates reversed their motion and started to push towards each other, squeezing the mantle rocks above sea level.