Tag Archives: crust

Scientists begin another attempt to drill through the Earth’s crust

An expedition to the Indian Ocean is about to begin an effort to drill a core down through the Earth’s crust and into its mantle.

Geologists have been trying to drill through the contact between the crust and the mantle, called the Moho, since the 1960s, with no success. Either the projects have gone way over budget and been shut down, have failed due to engineering problems, or were stopped by the geology itself. This last issue is maybe the most interesting.

Expeditions have come close before. Between 2002 and 2011, four holes at a site in the eastern Pacific managed to reach fine-grained, brittle rock that geologists believe to be cooled magma sitting just above the Moho. But the drill could not punch through those tenacious layers. And in 2013, drillers at the nearby Hess Deep found themselves similarly limited by tough deep-crustal rocks

This new project hopes to learn from these past problems to obtain the first rock samples from below the Earth’s crust.

The first results from the two GRAIL space probes have revealed the Moon has a much thinner crust than previously believed.

The uncertainty of science: The first results from the two GRAIL space probes have revealed that the Moon has a much thinner crust than previously believed.

These preliminary results have also found that the Moon’s surface topography closely matched the variations in the gravitational field, and that there appears no evidence in the gravitational field of the giant ancient impact basins that scientists have for decades assumed were there, based on surface evidence. This last result is especially surprising, and will force an almost complete rewrite of the Moon’s geological history.

Interestingly, these results are only peripherally related to GRAIL’s main research goal, which was to map the Moon’s deep structure and core. I suspect there are even more surprises coming when this data gets released.