The Mantle
The dense shell then gives way to the mantle, an unexplained inner layer. Nearly 40% of the Earth’s mass is contained within this deeper layer. As far as scientists and researchers are concerned, this led to an interesting journey.
Project Mohole
With the launch of Project Mohole in 1958, the United States took the lead. It is close to the Mexican city of Guadalupe. A team of engineers worked on the project, which involved drilling through the Pacific Ocean bed.